Signal processing apparatus, detection apparatus and terminal device

Abstract

A signal processing apparatus, a detection apparatus and a terminal device, which relate to the technical field of detection, and are used for reducing the costs and occupied spaces of optical delay lines. The signal processing apparatus comprises a first frequency modulation group (11), a second frequency modulation group (21) and an optical delay line (400); the first frequency modulation group (11) comprises a first frequency modulation photoelectric loop (110), a second frequency modulation photoelectric loop (210) and a polarization control element (300); the second frequency modulation group (21) comprises a third frequency modulation photoelectric loop (310); the polarization control element (300) is connected among the optical delay line (400), a first beam splitting element (112, 212, 312) in each frequency modulation photoelectric loop (110, 210, 310) and a frequency mixer (114, 214, 314) in each frequency modulation photoelectric loop (110, 210, 310), and is used for outputting optical signals (S11, S21, S31) in the three frequency modulation photoelectric loops (110, 210, 310) to the optical delay line (400) in orthogonal polarization directions, and outputting the delayed optical signals (S11 ', S21 ', S31 ') to the mixer (114, 214, 314) in each frequency modulation optoelectronic circuit (110, 210, 310). The signal processing apparatus can achieve the effect that the three frequency modulation photoelectric loops (110, 210, 310) share the same optical delay line (400), and reduce the number of optical delay lines (400) required to be provided in the signal processing apparatus, and the costs and occupied spaces of the optical delay lines (400).

Description

A signal processing device, a detection device, and a terminal equipment Technical Field

[0001] This application relates to the field of detection technology, and in particular to a signal processing device, a detection device, and a terminal device. Background Technology

[0002] Frequency-modulated continuous wave (FMCW) lidar (light detection and ranging) is currently a mainstream type of LiDAR. It detects distance and velocity by directly changing the frequency of the laser's emission source. As shown in Figure 1a, ideally, the frequency of the modulation signal (L1) input to the laser in an FMCW LiDAR is linearly related to time. This linear relationship is reflected linearly in the frequency of the laser's emitted beam, making the frequency change (L2) of the laser's emitted beam also linearly related to time.

[0003] However, during frequency modulation, the internal physical mechanisms of the laser (such as imperfections in manufacturing processes and thermal effects) may cause a nonlinear relationship between the modulation signal L1 input to the laser and the frequency of the laser beam emitted from the laser. This, in turn, leads to a nonlinear change in the frequency of the laser beam emitted over time, L2, resulting in a frequency modulation nonlinearity phenomenon, as shown in Figure 1b. This nonlinearity affects the measurement accuracy of the FMCW LiDAR. To address this issue, the modulation signal L1 input to the laser needs to be calibrated. However, current mainstream calibration schemes typically use an asymmetric Mach-Zehnder interferometer (AMZI) structure based on optical delay lines. This structure requires a large number of optical delay lines, especially in scenarios with a large number of lasers, where the number of optical delay lines increases exponentially. Such a large number of optical delay lines occupies a significant amount of space in the FMCW LiDAR and also results in high hardware costs.

[0004] In summary, reducing the cost and space occupied by optical delay lines is a pressing technical problem that needs to be solved in the field of FMCW LiDAR. Summary of the Invention

[0005] This application provides a signal processing device, a detection device, and a terminal device to reduce the cost and space occupied by optical delay lines.

[0006] In a first aspect, this application provides a signal processing apparatus, including a first frequency modulation group, a second frequency modulation group, and an optical delay line. The first frequency modulation group includes a first frequency modulation optoelectronic circuit, a second frequency modulation optoelectronic circuit, and a polarization control element. The second frequency modulation group includes a third frequency modulation optoelectronic circuit. Each frequency modulation optoelectronic circuit from the first to the third frequency modulation optoelectronic circuit includes a light source, a first beam splitter, and a mixer. The polarization control element is connected between the optical delay line, the first beam splitter in each frequency modulation optoelectronic circuit, and the mixer in each frequency modulation optoelectronic circuit. It is used to receive a first optical signal, a second optical signal, and a third optical signal after being split by the first beam splitter in each of the first to the third frequency modulation optoelectronic circuits, and to output the first, second, and third optical signals to the optical delay line with two orthogonal polarization directions. The first optical signal, after delay processing, is output to the mixer in the first frequency modulation optoelectronic circuit; the second optical signal, after delay processing, is output to the mixer in the second frequency modulation optoelectronic circuit; and the third optical signal, after delay processing, is output to the mixer in the third frequency modulation optoelectronic circuit.

[0007] Based on the above structure, by using a polarization control element to output the optical signals of the three frequency-modulated photoelectric circuits to the same optical delay line, it is possible to achieve the effect of the three frequency-modulated photoelectric circuits sharing the same optical delay line. This reduces the number of optical delay lines required in the signal processing device, lowers the size and space occupied by the optical delay lines, and saves hardware costs. Therefore, when this signal processing device is applied to a detection device (such as an FMCW LiDAR), the length and cost of the optical delay lines required in the FMCW LiDAR can be reduced, simplifying the FMCW LiDAR system architecture and lowering the overall system cost.

[0008] In one possible design, in the optical delay line, the first optical signal and the second optical signal have the same polarization direction, and the polarization direction of the third optical signal is orthogonal to the polarization directions of the first optical signal and the second optical signal.

[0009] Based on the above design, although the optical signals in the two frequency modulation groups will be transmitted in the same optical delay line, since the optical signals in the two frequency modulation groups are transmitted in orthogonal polarization directions in the optical delay line, they can also be separated based on the orthogonal polarization directions and return to their respective frequency modulation groups. Therefore, the optical signals in the two frequency modulation groups can be optical signals with completely identical characteristics, such as optical signals with the same frequency, wavelength, phase, and transmission time. Alternatively, they can be optical signals with at least one different characteristic, such as optical signals with different wavelengths, different phases, or different frequencies. This will not affect the functional implementation of the two frequency modulation groups.

[0010] In one possible design, the first optical signal and the second optical signal satisfy at least one of the following conditions: different wavelengths, different frequency modulation directions, and different frequency modulation slopes. For example, the first optical signal and the second optical signal have different wavelengths, or have the same wavelength but different frequency modulation directions, or have the same wavelength and the same frequency modulation direction but different frequency modulation slopes.

[0011] Based on the above design, although the optical signals of the two frequency-modulated photoelectric circuits in the first frequency-modulated group have the same polarization direction, they have different wavelengths, different polarization directions, or different polarization slopes. Therefore, the optical signals of the two frequency-modulated photoelectric circuits can be separated based on different wavelengths, different polarization directions, or different polarization slopes and returned to their respective frequency-modulated photoelectric circuits to realize the linear frequency modulation function of each frequency-modulated photoelectric circuit.

[0012] In one possible design, the specific structure of the signal processing device can be either Structure 1 or Structure 2.

[0013] In Structure 1, within the first frequency modulation (FM) group, the first beam splitting element in both the first and second FM optoelectronic circuits includes a first beam splitter and a first beam combiner / splitter. The first and second FM optoelectronic circuits share the same first beam combiner / splitter and the same mixer. The first beam combiner / splitter connects the first beam splitter in the first FM optoelectronic circuit, the first beam splitter in the second FM optoelectronic circuit, the shared mixer, and the polarization control element. The first beam splitter in the first FM optoelectronic circuit is used to split an intermediate optical signal from the optical signal output from the light source of the first FM optoelectronic circuit. The first beam splitter in the second FM optoelectronic circuit is used to split an intermediate optical signal from the optical signal output from the light source of the second FM optoelectronic circuit. The first beam combiner / splitter performs beam combining and splitting processing on the intermediate optical signals in the first and second FM optoelectronic circuits to obtain a calibration path local oscillator signal and a signal to be delayed. The calibration path local oscillator signal is output to the mixer, and the signal to be delayed is output to the polarization control element. The signal to be delayed includes the first optical signal and the second optical signal.

[0014] Based on the above structure one, the two frequency modulation optoelectronic circuits in the first frequency modulation group can share some components. In this way, the number of components in the signal processing device can be further reduced, the architecture of the signal processing device can be simplified, and the system cost can be saved.

[0015] In one possible design of structure one, the first beam splitting element in the third frequency-modulated optoelectronic circuit includes a second beam splitter and a third beam splitter. The third beam splitter is connected between the second beam splitter, the mixer in the third frequency-modulated optoelectronic circuit, and the polarization control element. The second beam splitter is used to split the intermediate optical signal from the optical signal output from the light source, and the third beam splitter is used to split the calibration path local oscillator signal and the third optical signal from the intermediate optical signal. The calibration path local oscillator signal is output to the mixer, and the third optical signal is output to the polarization control element.

[0016] Based on the above design, only one third frequency modulation optoelectronic circuit can be set in the second frequency modulation group, so that the two frequency modulation optoelectronic circuits in the first frequency modulation group and one frequency modulation optoelectronic circuit in the second frequency modulation group can share the same optical delay line.

[0017] In another possible design of Structure 1, the second frequency modulation group also includes a fourth frequency modulation optoelectronic circuit. The first beam splitting element in both the third and fourth frequency modulation optoelectronic circuits includes a second beam splitter and a second beam combiner / splitter. The third and fourth frequency modulation optoelectronic circuits share the same second beam combiner / splitter and the same mixer. The second beam combiner / splitter is connected between the second beam splitter in the third and fourth frequency modulation optoelectronic circuits, the shared mixer, and the polarization control element. The second beam splitter is used to split the intermediate optical signal from the light source output of its respective frequency modulation optoelectronic circuit. The second beam combiner / splitter is used to perform beam combining and splitting processing on the intermediate optical signals in the third and fourth frequency modulation optoelectronic circuits to obtain a calibration path local oscillator signal and a signal to be delayed. The calibration path local oscillator signal is output to the mixer, and the signal to be delayed is output to the polarization control element. The signal to be delayed includes a third optical signal and a fourth optical signal, with the fourth optical signal being the signal to be delayed in the fourth frequency modulation optoelectronic circuit.

[0018] Based on the above design, two frequency modulation photoelectric circuits can be set in the second frequency modulation group, so that the four frequency modulation photoelectric circuits, namely the two frequency modulation photoelectric circuits in the first frequency modulation group and the two frequency modulation photoelectric circuits in the second frequency modulation group, can share the same optical delay line.

[0019] Understandably, more than two frequency-modulated optoelectronic circuits can be set in the first frequency-modulated group, such as two or more first frequency-modulated optoelectronic circuits, or two or more second frequency-modulated optoelectronic circuits. All optical signals from these frequency-modulated optoelectronic circuits are mixed by the first beam combiner and split into a calibration path local oscillator signal and a signal to be delayed. Alternatively, other beam combining, splitting, or beam combining / splitting methods can be used, without limitation. Similarly, more than two frequency-modulated optoelectronic circuits can be set in the second frequency-modulated group, such as two or more third frequency-modulated optoelectronic circuits, or two or more fourth frequency-modulated optoelectronic circuits. All optical signals from these frequency-modulated optoelectronic circuits are mixed by the second beam combiner and split into a calibration path local oscillator signal and a signal to be delayed. Alternatively, other beam combining, splitting, or beam combining / splitting methods can be used, without limitation.

[0020] In one possible design of structure one, the polarization control element includes a first polarization element and a second polarization element. The first polarization element is connected between the first end of the optical delay line and the first beam combiner / splitter in the first frequency modulation group and the second beam combiner / splitter in the second frequency modulation group. The second polarization element is connected between the second end of the optical delay line and the mixer in the first frequency modulation group and the mixer in the second frequency modulation group. Alternatively, the first polarization element is connected between the first end of the optical delay line, the first beam combiner / splitter in the first frequency modulation group and the third beam splitter in the third frequency modulation optoelectronic circuit. The second polarization element is connected between the second end of the optical delay line, the mixer in the first frequency modulation group and the mixer in the third frequency modulation optoelectronic circuit. The first polarization element is used to keep the polarization direction of the optical signal output by the first beam combiner / splitter unchanged, and to make the polarization direction of the optical signal output by the second beam combiner / splitter or the third beam splitter orthogonal to the polarization direction of the optical signal output by the first beam combiner / splitter, so as to output the two sets of optical signals to the first end of the optical delay line; the second polarization element is used to keep the polarization direction of the delayed optical signal corresponding to the first beam combiner / splitter unchanged, and to output it to the mixer in the first frequency modulation group, and to make the delayed optical signal corresponding to the second beam combiner / splitter or the third beam splitter output to the mixer in the second frequency modulation group with the original polarization direction in the second frequency modulation group.

[0021] Based on the above design, at least three optical signals from two frequency modulation groups can be transmitted in the same direction on the same optical delay line using two polarization elements. Under the same delay duration, the number of optical delay lines in the signal processing device can be reduced by at least two, which can greatly simplify the architecture of the signal processing device and reduce the hardware cost of the signal processing device.

[0022] In one example of the above design, the optical signal output by the first beam combiner / splitter has an orthogonal polarization direction to the optical signal output by the second or third beam combiner / splitter. The first polarization element is a first polarization beam splitter (PBS), and the second polarization element is a second PBS. The first PBS is used to keep the polarization direction of the optical signal output by the first beam combiner / splitter unchanged, and to keep the polarization direction of the optical signal output by the second or third beam combiner / splitter unchanged, and outputs it to the first end of the optical delay line. The second PBS is used to keep the polarization direction of the delayed optical signal corresponding to the first beam combiner / splitter unchanged, and outputs it to the mixer in the first frequency modulation group, and to keep the polarization direction of the delayed optical signal corresponding to the second or third beam combiner / splitter unchanged, and outputs it to the mixer in the second frequency modulation group.

[0023] Based on the above example, the optical signal in the first frequency modulation group can be transmitted in the PBS and the optical signal in the second frequency modulation group can be reflected in the PBS. By using two PBSs, at least three frequency modulation optoelectronic circuits in the two frequency modulation groups can reuse the same optical delay line to transmit the delayed signals in at least three frequency modulation optoelectronic circuits in the same direction.

[0024] In another example of the above design, the optical signal output by the first beam combiner / splitter has the same polarization direction as the optical signal output by the second or third beam combiner / splitter. The first polarization element is a first polarization splitter rotator (PSR), and the second polarization element is a second PSR. The first PSR is used to keep the polarization direction of the optical signal output by the first beam combiner / splitter unchanged, and rotate the polarization direction of the optical signal output by the second or third beam combiner / splitter by 90°, outputting it to the first end of the optical delay line. The second PSR is used to keep the polarization direction of the delayed optical signal corresponding to the first beam combiner / splitter unchanged, outputting it to the mixer in the first frequency modulation group, and rotating the polarization direction of the delayed optical signal corresponding to the second or third beam combiner / splitter by 90°, outputting it to the mixer in the second frequency modulation group.

[0025] Based on the above example, the characteristics of PSR in transmitting optical signals in the first and second frequency modulation groups separately and rotating the polarization direction of the optical signal in the second frequency modulation group by 90° can be utilized to enable at least three frequency modulation optoelectronic circuits in the two frequency modulation groups to reuse the same optical delay line and transmit the delayed signals in at least three frequency modulation optoelectronic circuits in the same direction.

[0026] In another possible design of Structure 1, the polarization control element includes a first polarization element and a second polarization element. The first polarization element is connected between the first end of the optical delay line, the first beam combiner / splitter in the first frequency modulation group, and the mixer in the second frequency modulation group. The second polarization element is connected between the second end of the optical delay line, the mixer in the first frequency modulation group, and the second beam combiner / splitter in the second frequency modulation group. Alternatively, the first polarization element is connected between the first end of the optical delay line, the first beam combiner / splitter in the first frequency modulation group, and the mixer in the third frequency modulation optoelectronic circuit. The second polarization element is connected between the second end of the optical delay line, the mixer in the first frequency modulation group, and the third beam splitter in the third frequency modulation optoelectronic circuit. The first polarization element is used to maintain the polarization direction of the optical signal output by the first beam combiner / splitter unchanged and output it to the first end of the optical delay line, and to output the delayed optical signal corresponding to the second beam combiner / splitter or the third beam splitter to the mixer in the second frequency modulation group with the original polarization direction in the second frequency modulation group; the second polarization element is used to make the polarization direction of the optical signal output by the second beam combiner / splitter or the third beam splitter or the first beam combiner / splitter orthogonal to the polarization direction of the optical signal output by the first beam combiner / splitter, output it to the second end of the optical delay line, and to maintain the polarization direction of the delayed optical signal corresponding to the first beam combiner / splitter unchanged and output it to the mixer in the first frequency modulation group.

[0027] Based on the above design, at least three optical signals from two frequency modulation groups can be transmitted in reverse on the same optical delay line using two polarization elements. Under the same delay duration, the number of optical delay lines in the signal processing device can be reduced by at least two, which can greatly simplify the architecture of the signal processing device and reduce the hardware cost of the signal processing device.

[0028] In one example of the above design, the optical signal output by the first beam combiner / splitter has an orthogonal polarization direction to the optical signal output by the second beam combiner / splitter or the third beam splitter. The first polarization element is a first polarization polarization element (PBS), and the second polarization element is a second polarization polarization element (PBS). The first PBS is used to maintain the polarization direction of the optical signal output by the first beam combiner / splitter unchanged and output it to the first end of the optical delay line. It also maintains the polarization direction of the delayed optical signal corresponding to the second beam combiner / splitter unchanged and outputs it to the mixer in the second frequency modulation group. The second PBS is used to maintain the polarization direction of the optical signal output by the second beam combiner / splitter or the third beam splitter unchanged and output it to the second end of the optical delay line. It also maintains the polarization direction of the delayed optical signal corresponding to the first beam combiner / splitter unchanged and outputs it to the mixer in the first frequency modulation group.

[0029] Based on the above example, the optical signal in the first frequency modulation group can be transmitted through the PBS and the optical signal in the second frequency modulation group can be reflected through the PBS. At least three frequency modulation optoelectronic circuits in the two frequency modulation groups can be multiplexed using the same optical delay line to transmit the delayed signals in at least three frequency modulation optoelectronic circuits in reverse.

[0030] In another example of the above design, the optical signal output by the first beam combiner / splitter has the same polarization direction as the optical signal output by the second or third beam combiner / splitter. The first polarization element is a first PSR, and the second polarization element is a second PSR. The first PSR is used to keep the polarization direction of the optical signal output by the first beam combiner / splitter unchanged and output it to the first end of the optical delay line. It also rotates the polarization direction of the delayed optical signal corresponding to the second or third beam combiner / splitter by 90° and outputs it to the mixer in the second frequency modulation group. The second PSR is used to rotate the polarization direction of the optical signal output by the second or third beam combiner / splitter by 90° and output it to the second end of the optical delay line. It also keeps the polarization direction of the delayed optical signal corresponding to the first beam combiner / splitter unchanged and outputs it to the mixer in the first frequency modulation group.

[0031] Based on the above example, the characteristic of PSR to separately transmit optical signals in the first and second frequency modulation groups and rotate the polarization direction of the optical signal in the second frequency modulation group by 90° can be utilized to enable at least three frequency modulation optoelectronic circuits in the two frequency modulation groups to reuse the same optical delay line through two PSRs, so as to transmit the delayed signals in at least three frequency modulation optoelectronic circuits in reverse.

[0032] Structure 2: The polarization control elements in the first frequency modulation group include a first polarization element, a second polarization element, a first optical transmission element, and a second optical transmission element. The first optical transmission element is connected between the first beam splitter in the first frequency modulation optoelectronic circuit, the mixer in the second frequency modulation optoelectronic circuit, and the first end of the first polarization element. The second end of the first polarization element is connected to the first beam splitter in the third frequency modulation optoelectronic circuit, and the third end of the first polarization element is connected to the first end of the optical delay line. The second optical transmission element is connected between the mixer in the first frequency modulation optoelectronic circuit, the first beam splitter in the second frequency modulation optoelectronic circuit, and the first end of the second polarization element. The second end of the second polarization element is connected to the mixer in the third frequency modulation optoelectronic circuit, and the third end of the second polarization element is connected to the second end of the optical delay line. The first optical transmission element is used to transmit the first optical signal, split by the first beam splitter in the first frequency-modulated optoelectronic circuit, to the first polarization element, and to transmit the delayed second optical signal to the mixer in the second frequency-modulated optoelectronic circuit; the first polarization element is used to keep the polarization direction of the first optical signal unchanged, to make the polarization direction of the third optical signal, split by the first beam splitter in the third frequency-modulated optoelectronic circuit, orthogonal to the polarization direction of the first optical signal, and output it to the first end of the optical delay line, and to keep the polarization direction of the delayed second optical signal unchanged, and output it to the first optical transmission element; the second optical transmission element is used for The second optical signal after being split by the first beam splitter in the second frequency-modulated optoelectronic circuit is transmitted to the second polarization element, and the first optical signal after delay processing is transmitted to the mixer in the first frequency-modulated optoelectronic circuit; the second polarization element is used to keep the polarization direction of the second optical signal unchanged and output it to the second end of the optical delay line, keep the polarization direction of the first optical signal after delay processing unchanged and output it to the second optical transmission element, and make the polarization direction of the third optical signal after delay processing in the third frequency-modulated optoelectronic circuit the same as the original polarization direction in the third frequency-modulated optoelectronic circuit, and output it to the mixer in the third frequency-modulated optoelectronic circuit.

[0033] Based on the above structure two, only one third frequency-modulated optoelectronic circuit can be set in the second frequency-modulated group, so that the three frequency-modulated optoelectronic circuits can share the same optical delay line. Furthermore, the optical signals in the two frequency-modulated optoelectronic circuits in the first frequency-modulated group have opposite transmission directions in the optical delay line, while the optical signals in the third frequency-modulated optoelectronic circuit have the same transmission direction as the optical signals in the first frequency-modulated optoelectronic circuit.

[0034] In one possible design of Structure 2, the second frequency modulation group further includes a fourth frequency modulation optoelectronic circuit, a third optical transmission element, and a fourth optical transmission element. The third optical transmission element is connected between the first beam splitter in the third frequency modulation optoelectronic circuit, the mixer in the fourth frequency modulation optoelectronic circuit, and the polarization control element. The fourth optical transmission element is connected between the first beam splitter in the fourth frequency modulation optoelectronic circuit, the mixer in the third frequency modulation optoelectronic circuit, and the polarization control element. The third optical transmission element is used to transmit the third optical signal split by the first beam splitter in the third frequency modulation optoelectronic circuit to the polarization control element, and to transmit the fourth optical signal after delay processing to the mixer in the fourth frequency modulation optoelectronic circuit. The fourth optical transmission element is used to transmit the fourth optical signal split by the first beam splitter in the fourth frequency modulation optoelectronic circuit to the polarization control element, and to transmit the third optical signal after delay processing to the mixer in the third frequency modulation optoelectronic circuit.

[0035] Based on the above design, two frequency-modulated photoelectric circuits can be set in the second frequency-modulated group, thereby achieving the effect that the four frequency-modulated photoelectric circuits—two in the first frequency-modulated group and two in the second frequency-modulated group—share the same optical delay line. Furthermore, the optical signals in the two frequency-modulated photoelectric circuits of the second frequency-modulated group propagate in opposite directions along the optical delay line.

[0036] In one example of the above design, the polarization control element in the first frequency modulation group includes a first polarization element, a second polarization element, a first optical transmission element, and a second optical transmission element. The first optical transmission element is connected between the first beam splitter in the first frequency modulation optoelectronic circuit, the mixer in the second frequency modulation optoelectronic circuit, and the first end of the first polarization element. The second end of the first polarization element is connected to the third optical transmission element, and the third end of the first polarization element is connected to the first end of the optical delay line. The second optical transmission element is connected between the mixer in the first frequency modulation optoelectronic circuit, the first beam splitter in the second frequency modulation optoelectronic circuit, and the first end of the second polarization element. The second end of the second polarization element is connected to the fourth optical transmission element, and the third end of the second polarization element is connected to the second end of the optical delay line. The first optical transmission element is used to transmit the first optical signal after being split by the first beam splitter in the first frequency modulation optoelectronic circuit to the first polarization element, and to transmit the second optical signal after delay processing to the mixer in the second frequency modulation optoelectronic circuit; the first polarization element is used to keep the polarization direction of the first optical signal unchanged, make the polarization direction of the third optical signal output by the third optical transmission element orthogonal to the polarization direction of the first optical signal, output to the first end of the optical delay line, keep the polarization direction of the second optical signal after delay processing unchanged, output to the first optical transmission element, and output the polarization direction of the fourth optical signal after delay processing to the third optical transmission element with the original polarization direction in the fourth frequency modulation optoelectronic circuit; The second optical transmission element is used to transmit the second optical signal split by the first beam splitter in the second frequency modulation optoelectronic circuit to the second polarization element, and to transmit the first optical signal after delay processing to the mixer in the first frequency modulation optoelectronic circuit; the second polarization element is used to keep the polarization direction of the second optical signal unchanged, so that the polarization direction of the fourth optical signal output by the fourth optical transmission element is orthogonal to the polarization direction of the second optical signal and output to the second end of the optical delay line, and to keep the polarization direction of the first optical signal after delay processing unchanged and output to the second optical transmission element, and to make the polarization direction of the third optical signal after delay processing be the same as the original polarization direction in the third frequency modulation optoelectronic circuit and output to the fourth optical transmission element.

[0037] Based on the above example, the optical signals in the two frequency-modulated photoelectric circuits in the first frequency-modulated group propagate in opposite directions in the optical delay line, and the optical signals in the two frequency-modulated photoelectric circuits in the second frequency-modulated group also propagate in opposite directions in the optical delay line. This allows two groups of frequency-modulated photoelectric circuits that propagate in opposite directions to share the same optical delay line.

[0038] In a further possible example, the first optical signal, the second optical signal, the third optical signal, and the fourth optical signal have orthogonal polarization directions. The first polarization element is a first polarization polarization element (PBS), and the second polarization element is a second polarization polarization element (PBS). The first PBS is used to maintain the polarization direction of the first optical signal unchanged, maintain the polarization direction of the third optical signal unchanged, and output to the first end of the optical delay line. It also maintains the polarization direction of the delayed second optical signal unchanged and outputs to the first optical transmission element, and maintains the polarization direction of the delayed fourth optical signal unchanged and outputs to the third optical transmission element. The second PBS is used to maintain the polarization direction of the second optical signal unchanged, maintain the polarization direction of the fourth optical signal unchanged, and output to the second end of the optical delay line. It also maintains the polarization direction of the delayed first optical signal unchanged and outputs to the second optical transmission element, and maintains the polarization direction of the delayed third optical signal unchanged and outputs to the fourth optical transmission element.

[0039] Based on the above example, the optical signal in the first frequency modulation group can be transmitted in the PBS and the optical signal in the second frequency modulation group can be reflected in the PBS. By using two PBSs, the four frequency modulation optoelectronic circuits in the two frequency modulation groups can reuse the same optical delay line, and the two frequency modulation optoelectronic circuits in each frequency modulation group can transmit the signal to be delayed in reverse in the optical delay line.

[0040] In a further possible example, the first optical signal, the second optical signal, the third optical signal, and the fourth optical signal have the same polarization direction. The first polarization element is a first PSR, and the second polarization element is a second PSR. The first PSR is used to keep the polarization direction of the first optical signal unchanged, rotate the polarization direction of the third optical signal by 90°, and output it to the first end of the optical delay line. It also keeps the polarization direction of the second optical signal after delay processing unchanged and outputs it to the first optical transmission element. Furthermore, it rotates the polarization direction of the fourth optical signal after delay processing by 90° and outputs it to the third optical transmission element. The second PSR is used to keep the polarization direction of the second optical signal unchanged, rotate the polarization direction of the fourth optical signal by 90°, and output it to the second end of the optical delay line. It also keeps the polarization direction of the first optical signal after delay processing unchanged and outputs it to the second optical transmission element. Finally, it rotates the polarization direction of the third optical signal after delay processing by 90° and outputs it to the fourth optical transmission element.

[0041] Based on the above example, the characteristics of PSR in transmitting optical signals in the first and second frequency modulation groups separately and rotating the polarization direction of the optical signal in the second frequency modulation group by 90° can be utilized. Through two PSRs, four frequency modulation optoelectronic circuits in the two frequency modulation groups can reuse the same optical delay line, and the two frequency modulation optoelectronic circuits in each frequency modulation group can transmit the signal to be delayed in opposite directions in the optical delay line.

[0042] In one possible design of Structure 2, in each frequency-modulated optoelectronic circuit, the first beam-splitting element includes a first beam splitter and a second beam splitter. The first output terminal of the first beam splitter is connected to the input terminal of the second beam splitter, and the second output terminal of the first beam splitter is connected to the target measurement path. The first output terminal of the second beam splitter is connected to a polarization control element, and the second output terminal of the second beam splitter is connected to a mixer. The first beam splitter is used to split the optical signal generated by the light source to obtain a probe signal and an intermediate optical signal. It outputs the intermediate optical signal through its first output terminal and the probe signal through its second output terminal. The second beam splitter is used to split the intermediate optical signal to obtain a local oscillator signal and a signal to be delayed. It outputs the signal to be delayed through its first output terminal and the local oscillator signal through its second output terminal. The mixer is used to mix the local oscillator signal and the delayed signal. The target measurement path is used to perform target measurement using the probe signal.

[0043] Based on the above design, the function of the first beam splitting element can be achieved through two beam splitters. The beam splitters are low in cost and small in size, which helps to achieve small size and low cost of signal processing device.

[0044] In one possible design of Structure 2, the optical transmission element is a circulator. Circulators have lower cost and simpler structure.

[0045] In one possible design of Structure 1 or Structure 2, there are N pairs of first and second frequency modulation groups, where N is an integer greater than or equal to 2. The signal processing device further includes a third beam combiner and a fourth beam combiner. The third beam combiner is connected between the first polarization element of each of the N pairs of first frequency modulation groups and the first end of the optical delay line, and the fourth beam combiner is connected between the second polarization element of each of the N pairs of first frequency modulation groups and the second end of the optical delay line.

[0046] Based on the above design, at least two first frequency modulation groups and at least two second frequency modulation groups can share the same optical delay line, further reducing the number of optical delay lines required in the signal processing device and greatly reducing the structure and cost of the signal processing device.

[0047] In one possible design, each frequency-modulated optoelectronic circuit also includes an amplifier and / or an analog-to-digital converter (ADC), connected between the mixer and the light source. Taking an amplifier and ADC as an example, the amplifier amplifies the intermediate frequency (IF) signal obtained by the mixer; the ADC performs analog-to-digital conversion on the amplified IF signal to obtain a digital signal.

[0048] Based on the above design, the power of the intermediate frequency signal is amplified by an amplifier, which ensures that the intermediate frequency signal is successfully transmitted to the analog-to-digital converter. The intermediate frequency signal is then sampled into a digital signal by the analog-to-digital converter, which facilitates subsequent software analysis.

[0049] In one possible design, each frequency-modulated optoelectronic circuit also includes a photodetector, a processing element, and a driving circuit. The photodetector is used to detect the intermediate frequency signal obtained by the mixer; the processing element is used to generate a feedback signal based on the intermediate frequency signal detected by the photodetector; and the driving circuit is used to calibrate the linearity between the modulation signal output to the light source and the light signal output by the light source based on the feedback signal generated by the processing element.

[0050] Optionally, when the device includes both an amplifier and an analog-to-digital converter, as well as a photodetector, a processing element, and a driving circuit, the amplifier and the analog-to-digital converter are connected between the photodetector and the processing element.

[0051] In one possible design, the optical delay line is either an optical fiber delay line or a waveguide delay line integrated on a chip.

[0052] Based on the above design, the signal processing device can be applied to a variety of optical delay lines, thus possessing universality.

[0053] Secondly, this application provides a detection device, including the signal processing device in the first aspect or any of the designs in the first aspect.

[0054] Thirdly, this application provides a terminal device that includes the signal processing device in the first aspect or any of the designs in the first aspect, or includes the detection device in the second aspect.

[0055] The technical effects that can be achieved by the second or third aspect mentioned above can be referred to the description of the beneficial effects in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0056] Figure 1a illustrates an exemplary schematic diagram of the linear relationship between the emitted beam and the modulated signal;

[0057] Figure 1b illustrates an exemplary schematic diagram of the nonlinear relationship between the emitted beam and the modulated signal;

[0058] Figure 2 illustrates a possible application scenario to which this application applies;

[0059] Figure 3a illustrates an exemplary schematic diagram of a mainstream direct-modulation FMCWLiDAR architecture;

[0060] Figure 3b illustrates a schematic diagram of the structure of a single-laser direct-modulated FMCWLiDAR provided in the industry.

[0061] Figure 3c illustrates a schematic diagram of the structure of a direct-modulation FMCWLiDAR with multiple lasers provided in the industry.

[0062] Figure 4 illustrates a schematic diagram of the structure of a signal processing device provided in this application;

[0063] Figure 5 illustrates a schematic diagram of another signal processing device provided in this application;

[0064] Figure 6 illustrates a schematic diagram of the structure of a signal processing device provided in Embodiment 1;

[0065] Figure 7a illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 1;

[0066] Figure 7b illustrates a schematic diagram of another signal processing device provided in Embodiment 1;

[0067] Figure 8 illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 1;

[0068] Figure 9a illustrates a possible structural diagram of a PBS provided in Implementation Scheme 1;

[0069] Figure 9b illustrates an exemplary schematic diagram of another possible structure of the PBS provided in Implementation Scheme 1;

[0070] Figure 9c illustrates a possible structural diagram of another PBS provided in Implementation Scheme 1;

[0071] Figure 10 illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 1;

[0072] Figure 11 illustrates a possible structural diagram of a PSR provided in Implementation Scheme 1;

[0073] Figure 12a illustrates a schematic diagram of another signal processing device provided in Embodiment 1;

[0074] Figure 12b illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 1;

[0075] Figure 12c exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in Embodiment 1;

[0076] Figure 13a illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 1;

[0077] Figure 13b illustrates a schematic diagram of another signal processing device provided in Embodiment 1;

[0078] Figure 13c exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in Embodiment 1;

[0079] Figure 14 illustrates a schematic diagram of a signal processing device provided in Embodiment 2;

[0080] Figure 15a illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 2;

[0081] Figure 15b illustrates a schematic diagram of another signal processing device provided in Embodiment 2;

[0082] Figure 16a illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 2;

[0083] Figure 16b illustrates a schematic diagram of another signal processing device provided in Embodiment 2;

[0084] Figure 16c exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in Embodiment 2;

[0085] Figure 16d exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in Embodiment 2;

[0086] Figure 17a illustrates a schematic diagram of a signal processing apparatus provided in Embodiment 3;

[0087] Figure 17b illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 3;

[0088] Figure 18 illustrates a schematic diagram of another signal processing device provided in Embodiment 3;

[0089] Figure 19a exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in Embodiment 3;

[0090] Figure 19b illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 3;

[0091] Figure 20a illustrates a schematic diagram of another signal processing device provided in Embodiment 3;

[0092] Figure 20b exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in Embodiment 3;

[0093] Figure 20c exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in Embodiment 3;

[0094] Figure 20d exemplarily illustrates a structural schematic diagram of another signal processing device provided in Embodiment 3;

[0095] Figure 21a illustrates a schematic diagram of another signal processing apparatus provided in this application;

[0096] Figure 21b illustrates a schematic diagram of another signal processing device provided in this application;

[0097] Figure 22a illustrates a schematic diagram of another signal processing apparatus provided in this application;

[0098] Figure 22b illustrates a schematic diagram of another signal processing apparatus provided in this application;

[0099] Figure 23 illustrates a schematic diagram of the structure of a detection device provided in this application;

[0100] Figure 24 illustrates a schematic diagram of the structure of a terminal device provided in this application. Detailed Implementation

[0101] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0102] The following provides explanations for some of the terms used in this application. It should be noted that these explanations are for the convenience of those skilled in the art and do not constitute a limitation on the scope of protection claimed in this application.

[0103] I. Interference Properties and Independence of Light

[0104] The interference property of light refers to the phenomenon that when two or more beams of light meet in space, a stable distribution of intensity is formed in the overlapping region. However, since the beams of light are independent during propagation, as long as the two or more beams of light leave the overlapping region, they will return to their original state of motion. In other words, the interfering light can be separated into the two or more beams of light that were not interfering with each other, and each beam of light will continue to propagate with the original frequency, direction, and phase.

[0105] II. Linear Polarization State

[0106] Linear polarization is a mode of light propagation. Light exhibiting linear polarization is called linearly polarized light, also known as plane-polarized light. In the direction of light propagation, the electric vector at each point lies within a defined plane. Since the trajectory of the endpoints of the electric vector is a straight line, it is called linearly polarized light. The plane of vibration of linearly polarized light is fixed and does not deflect. The plane of vibration refers to the plane formed by the direction of the light vector and the direction of light propagation.

[0107] Common linearly polarized light includes P-waves, S-waves, TE-waves, and TM-waves. P-waves and S-waves represent light with different polarization directions in space. Simply put, in space, the light vector is decomposed into two mutually perpendicular vibration directions. The light with the vibration direction within the plane of incidence is called the parallel component of the light vector, or simply P-wave, while the light with the vibration direction perpendicular to the plane of incidence is called the perpendicular component, or simply S-wave. TE-waves and TM-waves represent light with different polarization directions from a chip integration perspective, and are often used to describe the propagation characteristics of electromagnetic waves. TE-waves are also called transverse electric waves, where the electric field component is perpendicular to the propagation direction of the electromagnetic wave; that is, the electric field component is parallel to the plane of incidence. TM-waves are also called transverse magnetic waves, where the magnetic field component is perpendicular to the propagation direction of the electromagnetic wave; that is, the electric field direction is perpendicular to the plane of incidence.

[0108] III. Polarizing Beam Splitter (PBS)

[0109] A polarization beam splitter (PBS) is an optical device used to couple orthogonally linearly polarized light from a single-mode fiber or polarization-maintaining fiber into two separate polarization-maintaining fibers for output. For example, it can split a beam of light synthesized from TE and TM light into TE and TM light for separate output. PBS implementations include, but are not limited to, polarization beam splitters.

[0110] PBS can also be used in reverse, that is, to couple two orthogonally linearly polarized beams input from a polarization-maintaining fiber into a single-mode fiber or a polarization-maintaining fiber for output, such as combining TE light and TM light into a single beam for output. In this case, PBS becomes a polarizing beam combiner (PBC).

[0111] IV. Polarization Rotating Beam Splitter (PSR)

[0112] A PSR is an optical device that integrates the functions of a PBS and a polarization rotator (PR). It can separate two linearly polarized lights and convert the polarization direction of one of the linearly polarized lights into the other polarization direction. For example, it can separate TM light and TE light and convert the TM light into TE light.

[0113] PSR can also be used in reverse, that is, the polarization direction of one linearly polarized light is converted to another polarization direction and then combined with another linearly polarized light to output a single beam. For example, one of two TE beams can be converted into a TM beam, and then combined with the other TE beam to output a single beam.

[0114] V. Frequency mixing.

[0115] Frequency mixing, also known as coherent demodulation, refers to the process of subtracting the frequency and phase of two signals.

[0116] In FMCW LiDAR, the probe signal is typically a linear frequency modulated (LFM) signal. After this LFM signal interacts with the target object, the reflected echo signal (i.e., the received signal) also exhibits the same frequency variation characteristics. However, depending on the target distance, the echo signal will have a certain phase and frequency difference relative to the probe signal. Therefore, after receiving the echo signal, the echo signal and the probe signal can be mixed; that is, the frequency and phase difference between the probe signal and the echo signal is calculated to obtain a low-frequency beat signal, also known as a beat frequency signal or intermediate frequency (IF) signal. The IF signal contains information about the frequency difference between the two signals, which is related to the target distance. For example, in a static state, the absolute value of the frequency difference is proportional to the target distance. In a dynamic state, the IF signal also contains information about the Doppler effect caused by target movement; based on this Doppler effect information, the target's velocity can be calculated.

[0117] The preceding text introduced some of the terms used in this application. The following text introduces the possible application scenarios of this application.

[0118] In one possible implementation, the signal processing device provided in this application can be integrated into a detection device, which can be installed on a vehicle, including but not limited to: vehicles, ships, airplanes, drones, trains, subways, automated guided vehicles (AGVs), or unmanned vehicles. For example, please refer to Figure 2, which illustrates a possible application scenario of this application. In this scenario, the detection device is installed on the front bumper of a vehicle. This detection device can serve as an information source for path planning, assisting the driver in achieving or automatically achieving safe driving. It is understood that the detection device can also be installed in other locations on the vehicle, such as around the headlights, around the rearview mirrors, near the doors, on the rear bumper, behind the windshield, or on the roof, to capture information about the vehicle's surrounding environment. When the detection device is installed behind the windshield, the requirement for no gravel collision risk is lower, and it does not affect the vehicle's appearance. Furthermore, the windshield itself has window heating and defogging functions as well as wiper cleaning functions.

[0119] It should be understood that the above application scenarios are merely examples, and the detection device provided in this application can also be applied to other possible scenarios, not limited to those listed above. For example, the detection device can also be installed in a roadside unit (RSU) as a roadside traffic detection device to realize intelligent vehicle-road cooperative communication. For example, the detection device can also be installed in the cabin of a vehicle as a liveness detection device to detect and alert the user to children or pets left behind in the cabin. Furthermore, the detection device can also be applied to terminal devices or components of terminal devices, such as smartphones, smart home devices, smart manufacturing equipment, medical devices, industrial equipment, and robots. These will not be listed exhaustively here. Moreover, the detection device can also be applied to…

[0120] It should be noted that the application scenarios described in this application are for the purpose of more clearly illustrating the technical solutions of this application, and do not constitute a limitation on the technical solutions provided in this application.

[0121] In addition, the above-mentioned application scenarios can be applied to fields such as autonomous driving, assisted driving, intelligent driving, autonomous driving, connected vehicles, optical communication, security monitoring, biomedicine, surveying and mapping (such as 3D mapping and remote sensing mapping), meteorological research, biomass and vegetation research, air quality monitoring, and aviation and aerospace applications.

[0122] The detection devices mentioned above may include, but are not limited to, LiDAR, such as a direct-modulation FMCW LiDAR, or simply direct-modulation FMCW LiDAR. Before introducing the specific solution provided in this application, the relevant content of direct-modulation FMCW LiDAR will be introduced below.

[0123] Figure 3a shows a schematic diagram of a mainstream direct-modulation FMCWLiDAR architecture. This direct-modulation FMCWLiDAR includes a light source, a beam splitter, a target measurement path, a reference calibration path, and a driving circuit. The reference calibration path is connected to one output terminal of the beam splitter, and the target measurement path is connected to the other output terminal. When the direct-modulation FMCWLiDAR is working, the driving circuit generates a modulation signal (L1) and inputs it to the light source. This modulation signal L1 drives the light source to emit a light signal S whose frequency changes linearly with time. The beam splitter separates the light signal S into a probe signal and a calibration signal. The probe signal is output to the target measurement path, and the calibration signal is output to the reference calibration path. The target measurement path performs target measurement based on the probe signal to obtain information such as the target's distance and velocity. The reference calibration path generates a feedback signal (P) based on the calibration signal and outputs the feedback signal P to the driving circuit. The driving circuit calibrates the output modulation signal L1 based on the feedback signal P, ensuring that the frequency change of the light signal S emitted by the light source is linear with the modulation signal L1 input to the light source.

[0124] For example, taking a laser as the light source and beam splitter 1 as the beam splitter element, please refer to Figure 3b, which shows a specific structural schematic diagram of a direct-modulated FMCWLiDAR with a single laser. In this example, the reference calibration path may include beam splitter 2, optical delay line, mixer, photodetector, and processing element. The laser emits a laser signal S according to the modulation signal L1 input to the driving circuit. Beam splitter 1 splits the laser signal S into a detection signal and a calibration signal. The detection signal is input to the target measurement path for target measurement, and the calibration signal is input to beam splitter 2. Beam splitter 2 splits the calibration signal into a signal light to be delayed and a local oscillator light of the calibration path. The local oscillator light of the calibration path is directly input to the mixer, and the signal light to be delayed is also input to the mixer after being delayed by the optical delay line. The mixer mixes the local oscillator light of the calibration path and the delayed signal light to obtain an intermediate frequency (IF) signal. The photodetector detects the IF signal and inputs the detected IF signal to the processing element. The processing element processes the IF signal to obtain a feedback signal P, and inputs the feedback signal P to the driving circuit. The driving circuit adjusts the modulation signal L1 output to the laser based on the input feedback signal P.

[0125] Based on the single-laser direct-modulation FMCWLiDAR architecture shown in Figure 3b, the structure is extended to a multi-laser scenario, as shown in Figure 3c. It can be seen that in a multi-laser direct-modulation FMCWLiDAR, multiple optical delay lines are required, and the number of delay lines corresponds one-to-one with the number of lasers. Therefore, if extended to a P (P≥2) laser direct-modulation FMCWLiDAR, the length of the optical delay line needs to be P times the length of the delay line in a single-laser direct-modulation FMCWLiDAR. In a single-laser direct-modulation FMCWLiDAR, the length of the optical delay line is related to the required delay time, typically on the order of meters. This length is already quite long; if extended to P lasers, multiplying the meter-level delay line by P times results in a very large size and high hardware cost, occupying a significant amount of space within the FMCWLiDAR.

[0126] In view of this, this application provides a signal processing device that transmits two or more optical signals with orthogonal polarization directions in the same optical delay line through a polarization control element, thereby multiplexing the same optical delay line to delay the two or more optical signals. When applied to a direct-modulated FMCWLiDAR with multiple lasers, the multiple reference calibration paths corresponding to the multiple lasers can share the same optical delay line, which greatly reduces the number of optical delay lines, reduces the size and hardware cost of the optical delay lines, and correspondingly reduces the space occupied by the optical delay lines in the direct-modulated FMCWLiDAR.

[0127] The signal processing device and related scheme proposed in this application will be described in detail below with reference to Figures 4 to 24.

[0128] It should be noted that in the accompanying drawings of this application, two devices are connected by a "dashed line," indicating that the two devices are connected through an optical medium, such as an optical fiber, waveguide, or any medium capable of transmitting optical signals. In short, two devices connected by a "dashed line" can transmit optical signals. Similarly, two devices are connected by a "solid line," indicating that the two devices are connected through an electrical medium (also called an electrical connection), such as a cable, wire, or any medium capable of transmitting electrical signals. In short, two devices connected by a "solid line" can transmit electrical signals.

[0129] Please refer to Figure 4, which shows a schematic diagram of the structure of a signal processing device provided in this application. The signal processing device includes a first frequency modulation group 11, a second frequency modulation group 21, and an optical delay line 400. The first frequency modulation group 11 includes a first frequency modulation photoelectric circuit 110, a second frequency modulation photoelectric circuit 210, and a polarization control element 300. The second frequency modulation group 21 includes a third frequency modulation photoelectric circuit 310. Each frequency modulation photoelectric circuit from the first frequency modulation photoelectric circuit 110 to the third frequency modulation photoelectric circuit 310 includes a light source, a first beam splitter, a mixer, a photodetector, a processing element, and a driving circuit. For example, the first frequency-modulated photoelectric circuit 110 includes a light source 111, a first beam splitter 112, a mixer 114, a photodetector 115, a processing element 116, and a driving circuit 117; the second frequency-modulated photoelectric circuit 210 includes a light source 211, a first beam splitter 212, a mixer 214, a photodetector 215, a processing element 216, and a driving circuit 217; and the third frequency-modulated photoelectric circuit 310 includes a light source 311, a first beam splitter 312, a mixer 314, a photodetector 315, a processing element 316, and a driving circuit 317.

[0130] As shown in Figure 4, the polarization control element 300 is connected between the optical delay line 400, the first beam splitter in each frequency-modulated optoelectronic circuit, and the mixer in each frequency-modulated optoelectronic circuit. For example, it is connected between the optical delay line 400, the first beam splitter 112, the first beam splitter 212, the first beam splitter 312, the mixer 114, the mixer 214, and the mixer 314. Based on this connection, the first optical signal S after being split by the first beam splitter 112 in the first frequency-modulated optoelectronic circuit 110... 11 The second optical signal S after being split by the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210 21 The third optical signal S after being split by the first beam splitter 312 in the third frequency-modulated photoelectric circuit 310 31Both can be input to the polarization control element 300. The polarization control element 300 will input the first optical signal S... 11 Second optical signal S 21 and the third optical signal S 31 The optical signal is output to the optical delay line 400 with two orthogonal polarization directions for delay processing, and the first optical signal S after delay processing is then processed. 11 The output is sent to the mixer 114 in the first frequency modulation photoelectric circuit 110, which will then process the second optical signal S after delay. 21 The output is sent to the mixer 214 in the second frequency modulation photoelectric circuit 210, which will then process the delayed third optical signal S. 31 The output is sent to mixer 314 in the third frequency-modulated photoelectric circuit 310. Thus, the optical signal S in the three frequency-modulated photoelectric circuits 110-310... 11 ~S 31 The same optical delay line 400 can be used to transmit signals on the same optical delay line 400, thereby enabling delay processing of optical signals in three frequency-modulated optoelectronic circuits. This reduces the number of optical delay lines required in the signal processing device, thus reducing the cost and space occupied by optical delay lines.

[0131] In the above signal processing device, the frequency modulation photoelectric circuit can be understood as a loop formed by the signal transmission between the various internal components. For example, taking the first frequency modulation photoelectric circuit 110 as an example, as shown in Figure 4, the signal transmission process of this circuit is as follows: the optical signal S1 output by the light source 111 enters the first beam splitter 112; the first beam splitter 112 splits the optical signal S into the first optical signal S1. 11 Other optical signals (not shown in the figure, see Figure 5 below for details); First optical signal S 11 The signal is transmitted through polarization control element 300 to optical delay line 400 for delay processing, and then through polarization control element 300 to mixer 114 for mixing with other signals (not shown in the figure, see Figure 5 below) to obtain intermediate frequency signal Z1. Intermediate frequency signal Z1 is detected by photodetector element 115 and output to processing element 116. Processing element 116 sends feedback signal P1 to driving circuit 117 according to the detected intermediate frequency signal Z1. Driving circuit 117 adjusts modulation signal L1 output to light source 111 according to feedback signal P1 to calibrate the linearity between modulation signal L1 and optical signal S1 output by light source 111.

[0132] Optionally, in each frequency-modulated photoelectric circuit, the first beam splitter can perform beam splitting processing on the optical signal output from the light source to obtain the local oscillator signal and the signal to be delayed (i.e., the first optical signal S). 11 Second optical signal S 21 Or the third optical signal S 23The local oscillator signal is directly input to the mixer for mixing, while the signal to be delayed is first delayed by the optical delay line 400 before being input to the mixer. For example, please refer to Figure 5, which shows a schematic diagram of another signal processing device provided in this application. Taking the first frequency modulation photoelectric circuit 110 as an example, as shown in Figure 5, the first beam splitter 112 may have an input terminal and a first output terminal c. 11 Second output terminal c 12 The mixer 114 may have an output terminal and a first input terminal d. 11 Second input terminal d 12 The polarization control element 300 is connected to the first output terminal c of the first beam splitter 112. 11 The first input terminal d of mixer 114 11 Between the optical delay line 400 and the second output terminal c of the first beam splitter 112 12 Connect to the second input terminal d of mixer 114 12 .

[0133] Based on this connection, after the light source 111 outputs the optical signal S1, the first beam splitter 112 can perform beam splitting processing on the optical signal S1 to obtain the first optical signal S. 11 And the calibration path local oscillator signal, the first beam splitter 112 through its first output terminal c 11 Output the first optical signal S 11 And through its second output terminal c 12 The output calibration path local oscillator signal is directly input to the second input terminal d of mixer 114. 12 The first optical signal S 11 The signal first passes through the polarization control element 300 to the optical delay element 400 for delay processing, and then passes through the polarization control element 300 again to enter the first input terminal d of the mixer 114. 11 Mixer 114 connects to its first input terminal d. 11 Receive the first optical signal S after delay processing 11 ', and through its second input terminal d 12 Upon receiving the calibration path local oscillator signal, the first optical signal S after delay processing... 11 The intermediate frequency signal Z1 is obtained by mixing the local oscillator signal with the calibration signal.

[0134] Optionally, each frequency-modulated photoelectric circuit may also include a target measurement path. For example, as shown in Figure 5, the first frequency-modulated photoelectric circuit 110 may also include a target measurement path 113, the second frequency-modulated photoelectric circuit 210 may also include a target measurement path 213, and the third frequency-modulated photoelectric circuit 310 may also include a target measurement path 313. Target measurement paths 113 to 313 may be the same target measurement path or different target measurement paths, without limitation. Taking target measurement path 113 as an example, as shown in Figure 5, the first beam splitter 112 may also have a third output terminal (c 13 ), third output terminal c 13 Connected to target measurement path 113. The first beam splitter 112 splits the optical signal S1 output from the light source 111, and can also obtain a detection signal. The detection signal passes through the third output terminal c of the first beam splitter 112. 13 The output is sent to the target measurement path 113, which performs target measurement based on the received detection signal to determine the target's speed and / or distance.

[0135] Further, optionally, as shown in Figure 5, each frequency-modulated optoelectronic circuit may also include an amplifier and / or an analog-to-digital converter (ADC). For example, the first frequency-modulated optoelectronic circuit 110 may also include an amplifier 118 and / or an ADC 119, the second frequency-modulated optoelectronic circuit 210 may also include an amplifier 218 and / or an ADC 219, and the third frequency-modulated optoelectronic circuit 310 may also include an amplifier 318 and / or an ADC 319. Taking the first frequency-modulated optoelectronic circuit 110 as an example, as shown in Figure 5, when an amplifier 118 is included, the amplifier 118 can be connected between the photodetector element 115 and the processing element 116 to amplify the intermediate frequency signal Z1 detected by the photodetector element 115. When an ADC 119 is included, the ADC 119 can be connected between the photodetector element 115 and the processing element 116 to perform analog-to-digital conversion on the intermediate frequency signal Z1 detected by the photodetector element 115 to obtain a digital signal. When both amplifier 118 and analog-to-digital converter 119 are included, amplifier 118 and analog-to-digital converter 119 can be connected in series between photodetector 115 and processing element 116. Amplifier 118 can amplify the intermediate frequency signal Z1 detected by photodetector 115, and then input the amplified intermediate frequency signal Z1 to analog-to-digital converter 119. Analog-to-digital converter 119 performs analog-to-digital conversion on the amplified intermediate frequency signal Z1 to obtain a digital signal, and then inputs the digital signal to processing element 116.

[0136] Based on the signal processing device shown in Figure 4 or Figure 5, the three optical signals from the three frequency-modulated photoelectric loops are input to the same optical delay line 400 for delay processing. These three optical signals can be transmitted in the same direction or in opposite directions within the same optical delay line 400. For example, all three optical signals can be transmitted in the same direction; or, two optical signals in the first frequency-modulated group can be transmitted in the same direction, and the optical signal in the second frequency-modulated group can be transmitted in opposite directions; or, one optical signal in the first frequency-modulated group and the optical signal in the second frequency-modulated group can be transmitted in the same direction, and the other optical signal in the first frequency-modulated group can be transmitted in opposite directions. The specific implementation is not limited. For ease of understanding, the following uses the structure of the signal processing device shown in Figure 5 as an example, and introduces three possible implementation methods based on implementation schemes one to three.

[0137] Implementation Plan 1

[0138] Here, Scheme 1 corresponds to the scheme in which optical signals from two frequency modulation groups are transmitted in the same direction on the same optical delay line 400.

[0139] Optionally, please refer to Figure 6, which shows a schematic diagram of a signal processing device provided in Embodiment 1. Referring to Figure 6 and Figure 5 above, in the first frequency modulation group 11, the first frequency modulation photoelectric circuit 110 and the second frequency modulation photoelectric circuit 210 share the same mixer 114, the same photodetector element 115, and the same processing element 116. Optionally, they also share the same amplifier 118 and analog-to-digital converter element 119. That is, the mixers 114 and 214 in Figure 5 above are the same mixer, the photodetectors 115 and 215 are the same photodetector element, the processing elements 116 and 216 are the same processing element, the amplifiers 118 and 218 are the same amplifier, and the analog-to-digital converter elements 119 and 219 are the same analog-to-digital converter element.

[0140] As shown in Figure 6, the first beam splitting element in both the first frequency-modulated optoelectronic circuit 110 and the second frequency-modulated optoelectronic circuit 120 includes a first beam splitter and a first beam combiner / splitter. For example, the first beam splitting element 112 includes a first beam splitter 1121 and a first beam combiner / splitter 1122, and the first beam splitting element 212 includes a first beam splitter 2121 and a first beam combiner / splitter 1122. The first frequency-modulated optoelectronic circuit 110 and the second frequency-modulated optoelectronic circuit 210 also share the same first beam combiner / splitter 1122. This first beam combiner / splitter 1122 is connected between the first beam splitter 1121, the first beam splitter 2121, the shared mixer 114, and the polarization control element 300.

[0141] Based on this structure and connection, after receiving the optical signal S1 output by the light source 111, the first beam splitter 1121 performs beam splitting processing on the optical signal S1 to obtain the detection signal and the intermediate optical signal S. 10The detection signal is output to the target measurement path 113, so that it participates in the target measurement in the first frequency modulation photoelectric circuit 110, and the intermediate optical signal S is output to the target measurement path 113. 10 The signal is output to the first beam combiner / splitter 1122. Similarly, after receiving the optical signal S2 output by the light source 211, the first beam splitter 2121 performs beam splitting on the optical signal S2 to obtain the detection signal and the intermediate optical signal S. 20 The detection signal is output to the target measurement path 213, so that it participates in the target measurement in the second frequency modulation photoelectric circuit 210, and the intermediate optical signal S is output to the target measurement path 213. 20 It is also output to the first beam combiner / splitter 1122.

[0142] Furthermore, the first beam combiner / splitter 1122 combines the two received intermediate optical signals S 10 S 20 Perform beam combining and splitting processing, such as combining two intermediate optical signals S 10 S 20 The components of each signal are mixed in equal parts to obtain a calibration path local oscillator signal and a signal to be delayed. The calibration path local oscillator signal is output to a shared mixer 114, and the signal to be delayed is output to a polarization control element 300. Since both the calibration path local oscillator signal and the signal to be delayed are obtained by mixing components of two intermediate optical signals, the calibration path local oscillator signal includes the calibration path local oscillator signal in the first frequency modulation optoelectronic circuit 110, and the signal to be delayed includes the first optical signal S to be delayed in the first frequency modulation optoelectronic circuit 110. 11 The second optical signal S to be delayed in the second frequency modulation photoelectric circuit 210 21 The polarization control element 300 inputs the signal to be delayed to the optical delay line 400 for delay processing, and then outputs the delayed signal to the shared mixer 114. The delayed signal also includes the delayed first optical signal S from the first frequency modulation optoelectronic circuit 110. 11 The second optical signal S after delay processing in the second frequency modulation photoelectric circuit 210 21 '.

[0143] Mixer 114 processes the received calibration path local oscillator signal from the first frequency modulation calibration path 110 and the delayed first optical signal S. 11 'Perform frequency mixing processing to obtain the intermediate frequency signal Z1 in the first frequency modulation calibration path 110, and process the received calibration path local oscillator signal and the delayed second optical signal S in the second frequency modulation calibration path 210.' 21The intermediate frequency (IF) signal Z2 in the second frequency modulation (FM) calibration circuit 210 is obtained through mixing. IF signals Z1 and Z2 are detected by the photodetector 115 and output to the amplifier 118. After amplification by the amplifier 118, they are output to the analog-to-digital converter 119, converted into digital signals, and input to the processing element 116. The processing element 116 generates a feedback signal P1 in the first FM photoelectric circuit 110 based on the IF signal Z1 and sends it to the drive circuit 117 in the first FM photoelectric circuit 110. It also generates a feedback signal P2 in the second FM photoelectric circuit 210 based on the IF signal Z2 and sends it to the drive circuit 217 in the second FM photoelectric circuit 210. The drive circuit 117 in the first FM photoelectric circuit 110 adjusts the modulation signal L1 output to the light source 111 based on the feedback signal P1 to calibrate the linearity between the modulation signal L1 and the optical signal S1 output by the light source 111. The driving circuit 217 in the second frequency modulation photoelectric circuit 210 adjusts the modulation signal L2 output to the light source 211 according to the feedback signal P2, so as to calibrate the linearity between the modulation signal L2 and the light signal S2 output by the light source 211.

[0144] Based on the above structure, the signals to be delayed in the first frequency-modulated photoelectric circuit 110 and the second frequency-modulated photoelectric circuit 210 need to be combined into one path and passed through the same optical delay line 400, and then mixed separately in the same mixer 114 before their respective drive signals can be separated in the processing element 116. To achieve the accuracy of each mixing, the optical signals in the two frequency-modulated photoelectric circuits need to have differences in wavelength or frequency sweep.

[0145] For example, in one example, the optical signals in the two frequency-modulated optoelectronic circuits have different wavelengths. For instance, the optical signal S1 output from the light source 111 in the first frequency-modulated optoelectronic circuit 110 has a first wavelength, while the optical signal S2 output from the light source 211 in the second frequency-modulated optoelectronic circuit 210 has a second wavelength; the first wavelength and the second wavelength are different. In this case, the two optical signals of different wavelengths are first split by a first beam splitter into signals to be delayed at different wavelengths, and then combined by a first beam combiner into a dual-wavelength signal to be delayed and a dual-wavelength calibration path local oscillator signal. The dual-wavelength calibration path local oscillator signal directly enters the mixer 114, while the dual-wavelength signal to be delayed is delayed by an optical delay line 400 and then also enters the mixer 114. The mixer 114 mixes the calibration path local oscillator signal and the delayed signal at different wavelengths to obtain intermediate frequency signals of different wavelengths, which are the intermediate frequency signals of different frequency-modulated optoelectronic circuits. In this example, by setting the optical signal wavelengths in the two frequency-modulated optoelectronic circuits to be different, a larger range can be scanned at once using signals of at least two wavelengths.

[0146] For example, in another example, the two frequency-modulated photoelectric circuits have different sweep frequencies, such as opposite sweep directions or the same sweep direction but different sweep slopes. Frequency sweep is also known as frequency modulation, specifically manifested as a linear change in the light signal output by the light source over time, as shown in Figure 1a above. Optionally, if the light signal S1 output by the light source 111 in the first frequency-modulated photoelectric circuit 110 exhibits a linear change pattern of first increasing and then decreasing over time, then the light signal S2 output by the light source 211 in the second frequency-modulated photoelectric circuit 210 can be configured to exhibit a linear change pattern of first decreasing and then increasing over time. Alternatively, the light signal S2 output by the light source 211 in the second frequency-modulated photoelectric circuit 210 can also be configured to first increase and then decrease over time, but with different slopes for the increase or decrease. In this case, the mixer 114 can distinguish the calibration path local oscillator signal and the delayed signal of the two frequency-modulated photoelectric circuits according to different frequency modulation directions or slopes, and mix the signals of the two frequency-modulated photoelectric circuits separately to obtain the intermediate frequency signals of each of the two frequency-modulated photoelectric circuits.

[0147] It is understandable that as long as the two frequency modulation photoelectric circuits differ in either wavelength or frequency sweep, they can be mixed to produce intermediate frequency signals from different frequency modulation photoelectric circuits. However, it is also possible to configure different wavelengths and frequency sweeps simultaneously to facilitate more accurate mixing. This application does not make any specific limitations on this.

[0148] It should be noted that Figure 6 above only illustrates an example of two frequency-modulated photoelectric circuits in the first frequency modulation group 11. However, the first frequency modulation group 11 can also have three or more frequency-modulated photoelectric circuits. For example, it can have one first frequency-modulated photoelectric circuit and at least two second frequency-modulated photoelectric circuits, or multiple first frequency-modulated photoelectric circuits and one second frequency-modulated photoelectric circuit, or multiple first frequency-modulated photoelectric circuits and multiple second frequency-modulated photoelectric circuits. In this case, the first beam combiner / splitter 1122 includes at least three input terminals. The intermediate optical signals from all the first and second frequency-modulated photoelectric circuits are input to the first beam combiner / splitter 1122. The first beam combiner / splitter 1122 combines the relevant components of the intermediate optical signals from at least three frequency-modulated photoelectric circuits to split the calibration path local oscillator signal and the signal to be delayed. Optionally, the optical signals in the at least three frequency-modulated photoelectric circuits can also be configured to have differences in wavelength and / or frequency sweep, so that the signals in the at least three frequency-modulated photoelectric circuits can be mixed separately in the shared mixer 114.

[0149] The structure of the first frequency modulation group 11 has been introduced above. The structure of the second frequency modulation group 21 will be explained below.

[0150] In one example, the second frequency modulation group 21 may include only one frequency modulation photoelectric circuit, namely the third frequency modulation photoelectric circuit 310. In this case, referring to Figure 7a, the first beam splitting element 312 may specifically include a second beam splitter 3121 and a third beam splitter 3123. The input end of the second beam splitter 3121 is connected to the light source 311, one output end is connected to the input end of the third beam splitter 3123, and the other output end is connected to the target measurement path 313. One output end of the third beam splitter 3123 is connected to the polarization control element 300, and the other output end is connected to the mixer 314. Based on this structure, after the second beam splitter 3121 receives the optical signal S3 output by the light source 311, it performs beam splitting processing on the optical signal S3 to obtain the intermediate optical signal S. 30 The detection signal is output to the target measurement path 313, and the intermediate optical signal S is transmitted to the target measurement path 313. 30 The output is sent to the third beam splitter 3123. The third beam splitter 3123 splits the intermediate optical signal S... 30 The optical signal is split to obtain the local oscillator signal of the calibration path and the third optical signal S. 31 The calibration path local oscillator signal is output to mixer 314, and the third optical signal S is output to mixer 314. 31 The signal is output to the polarization control element 300. The polarization control element 300 converts the third optical signal S... 31 The signal is input to the optical delay line 400 for delay processing, and then the delayed third optical signal S is input to the optical delay line 400 for delay processing. 21 The output is sent to mixer 314. Mixer 114 processes the received calibration path local oscillator signal and the delayed third optical signal S. 21 The intermediate frequency signal Z3 in the third frequency modulation calibration path 110 is obtained by performing frequency mixing. The processing flow of subsequent components is described above and will not be repeated here.

[0151] In another example, the second frequency modulation group 21 may also include a fourth frequency modulation optoelectronic circuit 410, as shown in Figure 7b. The first beam splitting element in both the third and fourth frequency modulation optoelectronic circuits 310 and 410 includes a second beam splitter and a second beam combiner / splitter. For example, the first beam splitting element 312 includes a second beam splitter 3121 and a second beam combiner / splitter 3122, and the first beam splitting element 412 includes a second beam splitter 4121 and a second beam combiner / splitter 3122. The third and fourth frequency modulation optoelectronic circuits 310 and 410 share the same second beam combiner / splitter 3122, the same mixer 314, the same photodetector element 315, and the same processing element 316. Optionally, they also share the same amplifier 318 and analog-to-digital converter 319. The second beam combiner / splitter 3122 is connected between the second beam splitter 3121, the second beam splitter 4121, the shared mixer 314, and the polarization control element 300.

[0152] Based on this structure and connection, after receiving the optical signal S3 output by the light source 311, the second beam splitter 3121 performs beam splitting processing on the optical signal S3 to obtain the detection signal and the intermediate optical signal S. 30 The detection signal is output to the target measurement path 313, and the intermediate optical signal S is output to the target measurement path 313. 30 The signal is output to the second beam combiner / splitter 3122. After receiving the optical signal S4 output from the light source 411, the second beam splitter 4121 performs beam splitting on the optical signal S4 to obtain the detection signal and the intermediate optical signal S. 40 The detection signal is output to the target measurement path 413, and the intermediate optical signal S is output to the target measurement path 413. 40 The output is sent to the second beam combiner / splitter 3122. The second beam combiner / splitter 3122 processes the two received intermediate optical signals S 30 S 40 The components in the signal are mixed and split to obtain the calibration path local oscillator signal and the signal to be delayed. The calibration path local oscillator signal is output to a common mixer 314, and the signal to be delayed is output to the polarization control element 300. The polarization control element 300 inputs the signal to be delayed to the optical delay line 400 for delay processing, and then outputs the delayed signal to the common mixer 314.

[0153] The calibration path local oscillator signal output by the second beam combiner / splitter 3122 includes the calibration path local oscillator signal from the third frequency-modulated optoelectronic circuit 310 and the calibration path local oscillator signal from the fourth frequency-modulated optoelectronic circuit 410. The signal to be delayed includes the third optical signal S to be delayed from the third frequency-modulated optoelectronic circuit 310. 31 and the fourth optical signal S to be delayed in the fourth frequency-modulated photoelectric circuit 410 41 Therefore, the delayed signal also includes the delayed third optical signal S from the third frequency-modulated photoelectric circuit 310. 31 The fourth optical signal S after delay processing in the fourth frequency modulation photoelectric circuit 410 41 The mixer 314 processes the received calibration path local oscillator signal from the third frequency modulation calibration path 310 and the delayed third optical signal S. 31 'Perform frequency mixing processing to obtain the intermediate frequency signal Z3 in the third frequency modulation calibration path 310, and process the received calibration path local oscillator signal and the delayed fourth optical signal S in the fourth frequency modulation calibration path 410.' 41 'Perform frequency mixing processing to obtain the intermediate frequency signal Z4 in the fourth frequency modulation calibration channel 410.'

[0154] Intermediate frequency (IF) signals Z3 and Z4 are detected by photodetector 315 and output to amplifier 318. After amplification by amplifier 318, they are output to analog-to-digital converter 319, converted into digital signals, and input to processing element 316. Processing element 316 generates feedback signal P3 in the third frequency modulation photoelectric circuit 310 based on IF signal Z3 and sends it to drive circuit 317 in the third frequency modulation photoelectric circuit 310. It also generates feedback signal P4 in the fourth frequency modulation photoelectric circuit 410 based on IF signal Z4 and sends it to drive circuit 417 in the fourth frequency modulation photoelectric circuit 410. Drive circuit 317 in the third frequency modulation photoelectric circuit 310 adjusts the modulation signal L3 output to light source 311 based on feedback signal P3 to calibrate the linearity between modulation signal L3 and optical signal S3 output by light source 311. Drive circuit 417 in the fourth frequency modulation photoelectric circuit 410 adjusts the modulation signal L4 output to light source 411 based on feedback signal P4 to calibrate the linearity between modulation signal L4 and optical signal S4 output by light source 411.

[0155] Similar to the first frequency modulation group 11, in the second frequency modulation group 21, the optical signals in the third frequency modulation photoelectric circuit 310 and the fourth frequency modulation photoelectric circuit 410 also need to have differences in wavelength and / or frequency sweep. Furthermore, the second frequency modulation group 21 may also include three or more frequency modulation photoelectric circuits, such as one third frequency modulation photoelectric circuit 310 and at least two fourth frequency modulation photoelectric circuits 410, or at least two third frequency modulation photoelectric circuits 310 and one fourth frequency modulation photoelectric circuit 410, or at least two third frequency modulation photoelectric circuits 310 and at least two fourth frequency modulation photoelectric circuits 410. The optical signals in these three or more frequency modulation photoelectric circuits also need to have differences in wavelength and / or frequency sweep. Further details will not be repeated here.

[0156] Taking the structure shown in Figure 7b as an example, in the optical delay line 400, the polarization direction of the optical signal in the first frequency modulation group 11 is orthogonal to the polarization direction of the optical signal in the second frequency modulation group 21. That is to say, the polarization direction of the first optical signal S 11 Second optical signal S 21 Having the same polarization direction, while the third optical signal S 31 and the fourth optical signal S 41 The polarization direction of the first optical signal S 11 Second optical signal S 21 The polarization directions are orthogonal. Thus, for both frequency modulation groups 11 and 21, although the optical signals will be transmitted along the same optical delay line 400, the optical signals (S1, S2, S3) in the two frequency modulation groups will be different. 11 and S 21 It is a group, S 31 and S 41(The other group) transmits in orthogonal polarization directions. Therefore, the optical signals in the two frequency modulation groups after delay processing can also be separated based on polarization direction and return to their respective frequency modulation groups.

[0157] Based on this, for any two frequency modulation photoelectric circuits in the first frequency modulation group 11 and the second frequency modulation group 21, such as the first optical signal S in the first frequency modulation photoelectric circuit 110 11 and the third optical signal S in the third frequency modulation photoelectric circuit 310 31 Or, the first optical signal S in the first frequency-modulated photoelectric circuit 110 11 and the fourth optical signal S in the fourth frequency-modulated photoelectric circuit 410 41 Or, the second optical signal S in the second frequency-modulated photoelectric circuit 210 21 and the third optical signal S in the third frequency modulation photoelectric circuit 310 31 Or, the second optical signal S in the second frequency-modulated photoelectric circuit 210 21 and the fourth optical signal S in the fourth frequency-modulated photoelectric circuit 410 41 It can be an optical signal with completely identical characteristics, such as an optical signal with the same frequency, wavelength, phase, and emission time, or it can be an optical signal with at least one different characteristic, such as an optical signal with different wavelength, different phase, different frequency, or different emission time. This will not affect the functional realization of each frequency modulation optoelectronic circuit in the two frequency modulation groups.

[0158] Optionally, there are many ways to achieve orthogonal polarization of optical signals in two frequency modulation groups. As an example, taking the structure shown in Figure 7b above, the polarization control element 300 may include a first polarization element 301 and a second polarization element 302. The first polarization element 301 is connected between the first beam combiner / splitter 1122 in the first frequency modulation group 11, the second beam combiner / splitter 3122 in the second frequency modulation group 21 (or the third beam splitter 3123 if it is the structure shown in Figure 7a), and the first end a1 of the optical delay line 400. The second polarization element 302 is connected between the mixer 114 shared in the first frequency modulation group 11, the mixer 314 shared in the second frequency modulation group 21, and the second end a2 of the optical delay line 400.

[0159] Based on this structure, assuming the optical signal in the first frequency modulation group 11 has a first linear polarization state and the optical signal in the second frequency modulation group 21 has a second linear polarization state, then the first polarization element 301 can receive the delayed signal S from the first frequency modulation group sent by the first beam combiner / splitter 1122. 11 +S 21 The delayed signal S in the second frequency modulation group 21 transmitted by the first beam combiner / splitter 3122 31 +S 41The delay signal S in the first frequency modulation group 11 +S 21 The signal S to be delayed in the second frequency modulation group 21 has a first linear polarization state. 31 +S 41 It has a second linear polarization state. The first polarization element 301 holds the signal S to be delayed in the first frequency modulation group 11. 11 +S 21 The polarization direction remains unchanged, so that the signal S to be delayed in the second frequency modulation group 21 remains unchanged. 31 +S 41 The polarization direction is orthogonal to the delay signal S in the first frequency modulation group 11 11 +S 21 The polarization direction is determined, and the two sets of signals to be delayed are output together to the first end a1 of the optical delay line 400. After being delayed by the optical delay line 400, the two sets of signals are output from the second end a2 of the optical delay line 400 and enter the second polarization element 302. The second polarization element 302 maintains the delayed optical signal S in the first frequency modulation group 11. 11 '+S 21 The polarization direction of the signal remains unchanged, so that it is still output to the mixer 114 in the first frequency modulation group 11 in the form of the first linear polarization state, and the delayed optical signal S in the second frequency modulation group 21 is converted into the signal. 31 '+S 41 The output is in the form of a second linear polarization state to the mixer 314 in the second frequency modulation group 21.

[0160] Based on this, the two sets of optical signals in the two frequency modulation groups are input to the same end of the optical delay line 400 in orthogonal linear polarization state. After being transmitted in the same direction in the optical delay line 400, they return to the mixer in their respective frequency modulation groups in their original linear polarization state. Therefore, without affecting their respective mixing operations, the mutual interference between the two sets of optical signals in the two frequency modulation groups during the delay processing can be reduced, so that the optical signal output to the mixer in the two frequency modulation groups after delay processing can have better signal quality, and the signal calibration effect in each frequency modulation optoelectronic circuit can be improved.

[0161] In the above content, the first linear polarization state and the second linear polarization state can be the same linear polarization state or orthogonal linear polarization states. For example, when the first linear polarization state and the second linear polarization state are the same linear polarization state, spatially speaking, the optical signal S of the first linear polarization state... 11 +S 21 The optical signal S in the second linear polarization state 31 +S 41 Both can be P-type light or both can be S-type light; from the perspective of chip integration, the first linearly polarized optical signal S... 11 +S 21 The optical signal S in the second linear polarization state31 +S 41 Both can be TE light, or both can be TM light. Conversely, when the first and second linear polarization states are orthogonal linear polarization states, spatially speaking, the light signal S of the first linear polarization state... 11 +S 21 It is a P-ray, and the optical signal S is in the second linear polarization state. 31 +S 41 It is S-light, or the light signal in the first linear polarization state. 11 +S 21 It is S-light, and the light signal S in the second linear polarization state. 31 +S 41 It is P-light; from the perspective of chip integration, the first linearly polarized optical signal S... 11 +S 21 It is TE light, and the light signal S is in the second linear polarization state. 31 +S 41 It is TM light, or the light signal S in the first linear polarization state. 11 +S 21 It is TM light, and the light signal S is in the second linear polarization state. 31 +S 41 It's TE light. And so on. There are many possible implementations, such as different but not orthogonal linear polarization states, which will not be listed here.

[0162] The following sections will separately describe the two cases where the first and second linear polarization states are the same linear polarization state or orthogonal linear polarization states.

[0163] The first linear polarization state and the second linear polarization state are orthogonal linear polarization states.

[0164] Optionally, when the first linear polarization state and the second linear polarization state are orthogonal linear polarization states, as shown in FIG7b, the first polarization element 301 can maintain the signal S to be delayed in the first frequency modulation group 11. 11 +S 21 The polarization direction remains unchanged, and the signal S to be delayed in the second frequency modulation group 21 is kept constant. 31 +S 41 With the polarization direction unchanged, the two sets of signals to be delayed are input together to the first end a1 of the optical delay line 400. The second polarization element 302 can maintain the delayed optical signal S in the first frequency modulation group 11. 11 '+S 21 The polarization direction remains unchanged, and it is output to the mixer 114 in the first frequency modulation group 11, and the delayed S in the second frequency modulation group 21 is maintained. 31 '+S 41 The polarization direction remains unchanged, and it is output to the mixer 314 in the second frequency modulation group 21.

[0165] Based on this, the first polarization element 301 and the second polarization element 302 can be any polarization processing device or combination thereof that can maintain the polarization direction of the two sets of input signals unchanged. For example, it can be a PBS as shown in Figure 8. In this case, the first polarization element 301 can specifically be a first PBS, i.e., PBS3011, and the second polarization element 302 can specifically be a second PBS, i.e., PBS3021. Both PBS3011 and PBS3021 have a first end, a second end, and a third end, i.e., “1”, “2”, and “3” as shown in Figure 8. P-light or TE-light is transmitted between the first end and the third end, and S-light or TM-light is reflected between the second end and the third end.

[0166] Assuming the first linearly polarized light signal is TE light and the second linearly polarized light signal is TM light, as shown in Figure 8, the first end of PBS3011 is connected to the first beam combiner / splitter 1122, the second end is connected to the second beam combiner / splitter 3122, and the third end is connected to the first end a1 of the optical delay line 400. The first end of PBS3021 is connected to the mixer 114, the second end is connected to the mixer 314, and the third end is connected to the second end a2 of the optical delay line 400. Referring to Figures 8 and 7b, in the first frequency modulation group 11, the light sources in both the first frequency modulation photoelectric circuit 110 and the second frequency modulation photoelectric circuit 210 output TE light. After this TE light is split by the first beam splitter, the resulting intermediate light signal S... 10 S 20 Both are TE beams. The two TE beams enter the first beam combiner / splitter 1122 for beam combining and splitting. The resulting calibration path local oscillator signal and the signal to be delayed S 11 +S 12 Both are TE optical signals, and the delayed signal S of the TE optical signal is... 11 +S 21 The light enters the first end of PBS3011. In the second frequency modulation group 21, the light sources in the third frequency modulation photoelectric circuit 310 and the fourth frequency modulation photoelectric circuit 410 both output TM light. This TM light is then split by the second beam splitter, resulting in the intermediate light signal S. 30 S 40 Both are TM beams. The two TM beams enter the second beam combiner / splitter 3122 for beam combining and splitting. The resulting calibration path local oscillator signal and the signal to be delayed S 31 +S 41 Both are TM light, and the delayed signal S of the TM light is... 31 +S 41 Enter the second end of PBS3011.

[0167] PBS3011 transmits the TE light from the first frequency modulation group 11 input at the first end to the third end, and reflects the TM light from the second frequency modulation group 21 input at the second end to the third end, so that the TE light from the first frequency modulation group 11 and the TM light from the second frequency modulation group 21 are output together to the first end a1 of the optical delay line 400. The time-delayed TE light from the first frequency modulation group 11 and the time-delayed TM light from the second frequency modulation group 21 output from the second end a2 of the optical delay line 400 enter the third end of PBS3021 together. PBS3021 transmits the TE light input from the third terminal to the first terminal, so that the delayed TE light in the first frequency modulation group 11 enters the mixer 114 in the first frequency modulation group 11 and performs a mixing operation with the local oscillator signal of the calibration path of the TE light in the first frequency modulation group 11; and reflects the TM light input from the third terminal to the second terminal, so that the delayed TM light in the second frequency modulation group 21 enters the mixer 314 in the second frequency modulation group 21 and performs a mixing operation with the local oscillator signal of the calibration path of the TM light in the second frequency modulation group 21.

[0168] Optionally, there are many implementations of the above PBS, including chip-integrated PBS and non-chip-integrated PBS.

[0169] For example, please refer to Figure 9a, which shows a schematic diagram of a PBS structure provided in Implementation Scheme 1. This structure is a chip-integrated PBS. Figure 9a(A) shows the external structure of the PBS, and Figure 9a(B) shows the internal structure of the PBS. Combining Figures 9a(A) and (B), the PBS includes a top oxide layer, a bottom buried oxide layer, and a waveguide structure sandwiched between these two layers. The waveguide structure includes a straight waveguide and a curved waveguide, which are sandwiched between the top oxide layer and the bottom buried oxide layer. The top oxide layer and the bottom buried oxide layer are made of the same material, such as SiO2. The straight waveguide and the curved waveguide are of equal width and are partially parallel. The length of the parallel region needs to be carefully designed so that when TM light couples from the straight waveguide to the curved waveguide, almost no or only a small portion of the TE light couples to the curved waveguide. It can be considered that the output on the curved waveguide is relatively pure TM light.

[0170] Based on the structure shown in Figure 9a, the end of the straight waveguide furthest from the curved waveguide is the first end of the PBS, the end of the straight waveguide closest to the curved waveguide is the third end of the PBS, and the end of the curved waveguide furthest from the straight waveguide is the second end of the PBS. When TE and TM light are input to the third end of the straight waveguide, the TM light rapidly couples from the straight waveguide to the curved waveguide during transmission, while the TE light couples very little or almost nothing. Therefore, the light output from the first end of the straight waveguide is entirely TE light, and the light output from the second end of the curved waveguide is almost entirely TM light. Even if it is a mixture of TM and TE light, since the TE light is very small, it can be considered relatively pure TM light. Conversely, when TM light is input to the second end of the curved waveguide, the TM light rapidly couples from the curved waveguide to the straight waveguide during transmission, and the polarization direction of the TM light does not change during coupling. Therefore, the light output from the third end of the straight waveguide is still TM light. When TE light is input to the first end of the straight waveguide, the TE light will be transmitted from the first end of the straight waveguide to the third end of the straight waveguide. The polarization direction does not change during the transmission process. Therefore, the light output from the third end of the straight waveguide is still TE light.

[0171] In one example, considering that a small amount of TE light may also couple into the curved waveguide when the TM light couples from the straight waveguide to the curved waveguide, potentially causing a small amount of TE light to be mixed into the TM light output from the second end of the curved waveguide, multiple structures as shown in Figure 9a can be cascaded to further improve the purity of the TM light output from the second end of the PBS. For example, the second end of the curved waveguide in the previous stage structure can be used as the third end of the straight waveguide in the next stage structure. In this way, even if a small amount of TE light is mixed into the TM light and output from the second end of the curved waveguide in the previous stage structure, a very small portion of this TE light will couple into the curved waveguide in the next stage structure during the coupling process from the straight waveguide to the curved waveguide. Therefore, the TM light output from the second end of the curved waveguide in the next stage structure will be much purer than the TM light output from the second end of the curved waveguide in the previous stage structure. Generally, cascading two structures is sufficient, effectively improving the purity of the TM light output from the PBS without significantly increasing structural complexity.

[0172] Based on the PBS structure shown in Figure 9a, since the PBS can be entirely located on the buried oxide layer (above the substrate), it can be integrated into the chip. In other words, using the structure shown in Figure 9a to implement the PBS not only allows for the sharing of optical delay lines based on polarization multiplexing, but also enables the chip integration of the entire signal processing device, resulting in a high degree of integration.

[0173] For example, please refer to Figure 9b, which shows a schematic diagram of another PBS structure provided in Implementation Scheme 1. This structure is a non-chip integrated PBS, specifically a polarizing beam splitter prism. When the PBS is a non-chip integrated structure, the TE light in Figure 8 above can be replaced with the P light, and the TM light can be replaced with the S light. Optionally, as shown in Figure 9b, this PBS is a cubic structure formed by depositing a multilayer film structure on the inclined surface of a right-angle prism and then synthesizing it with an adhesive layer (also known as gluing, bonding, lamination, or bonding, which refers to the operation method of laminating the glued surfaces after coating or proper drying). Utilizing the property that the P light transmittance is 1 and the S light transmittance is less than 1 when the beam is incident at the Brewster angle, after the beam passes through the multilayer film structure multiple times at the Brewster angle, the P polarization component is completely transmitted, while the vast majority of the S polarization component is reflected (at least 90%), making it an optical element. For example, the PBS can separate the incident light (P-beam and S-beam) at the third end into horizontally polarized light and vertically polarized light, i.e., P-beam and S-beam. The P-beam passes through completely and exits from the first end, while the S-beam is reflected at a 45° angle and exits from the second end, with the exit direction of the S-beam forming a 90° angle with the exit direction of the P-beam. Furthermore, the PBS can also allow the incident light (P-beam) at the first end to pass through completely, reflect the incident light (S-beam) at the second end at a 45° angle, with the exit direction of the S-beam being the same as that of the P-beam. The S-beam and P-beam are then combined into a single beam and exit from the third end.

[0174] For example, please refer to Figure 9c, which shows a schematic diagram of another PBS structure provided in Implementation Scheme 1. This structure also belongs to the non-chip integrated PBS. The PBS consists of two parts: a first part located at the top and a second part located at the bottom. The surface in contact between the first part and the second part is a reflective surface. If horizontally polarized light and vertically polarized light, i.e., P-light and S-light, are input from the upper left of the first part (corresponding to the third end), the S-light will be reflected by the reflective surface to the upper right of the first part (corresponding to the second end), while the P-light will pass through the reflective surface into the second part. After transmission in the second part, it will exit from the lower right of the second part (corresponding to the first end). Conversely, if P-light is input from the lower right of the second part (i.e., the first end) and S-light is input from the upper right of the first part (i.e., the second end), the P-light will pass through the reflective surface into the first part and exit from the upper left of the first part (i.e., the third end). The S-light will be reflected by the reflective surface and also exit from the upper left of the first part (i.e., the third end). The S-light and P-light are combined into a single beam and exit from the third end.

[0175] Understandably, PBS can also be implemented in other ways, such as through fiber optic devices, other polarization beam splitters, or on-chip structures different from those in Figure 9a, etc., without specific limitations here.

[0176] Based on the above scheme, the transmission of P-light or TE-light in PBS and the reflection of S-light or TM-light in PBS can be utilized to enable at least three frequency-modulated optoelectronic circuits in two frequency-modulated groups to reuse the same optical delay line through two PBSs, so as to transmit the delayed signals in at least three frequency-modulated optoelectronic circuits in the same direction. Therefore, under the same delay duration, the number of optical delay lines in the signal processing device can be reduced by at least 2, which can greatly simplify the architecture of the signal processing device and reduce the hardware cost of the signal processing device.

[0177] The first linear polarization state and the second linear polarization state are the same linear polarization state.

[0178] Optionally, when the first linear polarization state and the second linear polarization state are the same linear polarization state, as shown in FIG7b, the first polarization element 301 can maintain the signal S to be delayed in the first frequency modulation group 11. 11 +S 21 With the polarization direction unchanged, the signal S to be delayed in the second frequency modulation group 21 is... 31 +S 41 The polarization direction is rotated by 90° so that it is aligned with the delay signal S in the first frequency modulation group 11. 11 +S 21 The polarization directions are orthogonal, and then these two sets of signals to be delayed are input together to the first end a1 of the optical delay line 400. The second polarization element 302 can maintain the delayed optical signal S in the first frequency modulation group 11. 11 '+S 21 The polarization direction remains unchanged, and it is output to the mixer 114 shared by the first frequency modulation group 11, and the delayed S in the second frequency modulation group 21 is used. 31 '+S 41 The polarization direction of the signal is rotated by 90° to return it to its original linear polarization state, and then output to the mixer 314 shared by the second frequency modulation group 21. Alternatively, the first polarization element 301 holds the signal S to be delayed in the second frequency modulation group 21. 31 +S 41 With the polarization direction unchanged, the signal S to be delayed in the first frequency modulation group 11 is... 11 +S 21 The polarization direction is rotated by 90° and input together to the first end a1 of the optical delay line 400. The second polarization element 302 holds the delayed optical signal S from the second frequency modulation group 21. 31 '+S 41 The polarization direction remains unchanged, and it is output to the mixer 314 shared by the second frequency modulation group 21, and the S after delay processing in the first frequency modulation group 11 is also output to the mixer 314 shared by the second frequency modulation group 21. 11 '+S 21 The polarization direction of ' is rotated by 90° and output to the mixer 114 shared by the first frequency modulation group 11.

[0179] Taking the former as an example, the first polarization element 301 and the second polarization element 302 can be any polarization processing device or combination thereof that can maintain the polarization direction of one set of input signals unchanged and rotate the polarization direction of another set of input signals by 90°. For example, it can be a PSR as shown in Figure 10. In this case, the first polarization element 301 can specifically be a first PSR, namely PSR3012, and the second polarization element 302 can specifically be a second PSR, namely PSR3022. Both PSR3012 and PSR3022 have a first end, a second end, and a third end, namely “1”, “2”, and “3” as shown in Figure 10. The P-light or TE-light is transmitted between the first end and the third end in the original polarization direction, while the signal is transmitted between the second end and the third end in the polarization direction after being rotated by 90°. For example, the P-light or TE-light is converted into S-light or TM-light and then output, and the returned S-light or TM-light is converted into P-light or TE-light and then output.

[0180] Assuming that both the first and second linearly polarized light signals are TE light, as shown in Figure 10, the first end of PSR3012 is connected to the first beam combiner / splitter 1122, the second end is connected to the second beam combiner / splitter 3122, and the third end is connected to the first end a1 of the optical delay line 400. The first end of PSR3022 is connected to the mixer 114, the second end is connected to the mixer 314, and the third end is connected to the second end a2 of the optical delay line 400. Referring to Figures 10 and 7b, in the first frequency modulation group 11, the light sources in both the first frequency modulation photoelectric circuit 110 and the second frequency modulation photoelectric circuit 210 output TE light. After this TE light is split by the first beam splitter, the resulting intermediate light signal S... 10 S 20 Both are TE beams. The two TE beams enter the first beam combiner / splitter 1122 for beam combining and splitting. The resulting calibration path local oscillator signal and the signal to be delayed S 11 +S 12 Both are TE optical signals, and the delayed signal S of the TE optical signal is... 11 +S 12 The light enters the first terminal of PSR3012. In the second frequency modulation group 21, the light sources in the third frequency modulation photoelectric circuit 310 and the fourth frequency modulation photoelectric circuit 410 also output TE light. After the TE light is split by the second beam splitter, the intermediate optical signal S is obtained. 30 S 40 Both are TE beams. The two TE beams enter the second beam combiner / splitter 3122 for beam combining and splitting. The resulting calibration path local oscillator signal and the signal to be delayed S 31 +S 41 Both are TE optical signals, and the delayed signal S of the TE optical signal is... 31 +S 41 Enter the second end of PSR3012.

[0181] PSR3012 maintains the polarization direction of the TE light in the first frequency modulation group 11 input at its first terminal unchanged, and rotates the polarization direction of the TE light in the first frequency modulation group 11 input at its second terminal by 90° to convert it into TM light. Then, it outputs both light through its third terminal to the first terminal a1 of the optical delay line 400. The delayed TE light from the first frequency modulation group 11 and the delayed TM light from the second frequency modulation group 21 output from the second terminal a2 of the optical delay line 400 enter the third terminal of PSR3022 together. PSR3022 maintains the transmission direction of the TE light input at its third terminal unchanged and outputs it from its first terminal, so that the delayed TE light from the first frequency modulation group 11 still enters the mixer 114 in the first frequency modulation group 11 as TE light. It also rotates the polarization direction of the TM light input at its third terminal by 90° to convert it into TE light and outputs it from its second terminal, so that the delayed TM light from the second frequency modulation group 21 becomes TE light again and enters the mixer 314 in the second frequency modulation group 21.

[0182] Optionally, there are many ways to implement the above PSR, including chip-integrated PSR and non-chip-integrated PSR.

[0183] For example, please refer to Figure 11, which shows a schematic diagram of a PSR structure provided in Implementation Scheme 1. This structure belongs to a chip-integrated PSR. As shown in Figure 11, the PSR includes a straight waveguide and a curved waveguide. The straight waveguide and curved waveguide are similar to the straight waveguide and curved waveguide in the PBS shown in Figure 9a above, but there are some differences, mainly including the following two points: 1. The widths of the straight waveguide and the curved waveguide are different. For example, the straight waveguide is wider, while the curved waveguide is relatively narrower; 2. The upper and lower sides of the straight waveguide and the curved waveguide need to be made of different materials. For example, if the bottom is made of a buried oxide layer composed of SiO2, then the top must be a non-SiO2 material. For example, it can be directly exposed to the air, or it can be covered by a layer composed of other materials, without limitation.

[0184] Based on the structure shown in Figure 11, the end of the straight waveguide furthest from the curved waveguide is the first end of the PSR, the end of the straight waveguide closest to the curved waveguide is the third end of the PSR, and the end of the curved waveguide furthest from the straight waveguide is the second end of the PSR. When TE light is input to the first end of the straight waveguide, it propagates from the first end to the third end along the straight waveguide without changing its polarization direction. Therefore, the light output from the third end of the straight waveguide is still TE light. When TE light is input to the second end of the curved waveguide, it gradually couples from the curved waveguide to the straight waveguide during propagation. During coupling, the polarization direction of the TE light rotates by 90°, transforming it into TM light. Therefore, the light output from the third end of the straight waveguide is TM light. Conversely, when TE light is input to the third end of the straight waveguide, it propagates from the third end to the first end along the straight waveguide without changing its polarization direction. Therefore, the light output from the first end of the straight waveguide is still TE light. When TM light is input to the third end of the straight waveguide, the TM light will gradually couple from the straight waveguide to the curved waveguide during transmission. During the coupling process, the polarization direction of the TM light rotates by 90°, and the TM light becomes TE light. Therefore, the light output from the second end of the curved waveguide is TE light.

[0185] Based on the PSR structure shown in Figure 11, since the PSR can be entirely located on the buried oxide layer (above the substrate), the PSR can be integrated into the chip. In other words, using this structure to implement the PSR not only allows for the sharing of optical delay lines based on polarization multiplexing, but also enables the chip integration of the entire signal processing device, resulting in a high degree of integration.

[0186] However, it should be understood that PSR can also be implemented in other ways, such as through fiber optic devices, or through devices such as prisms combined with waveplates, or through a chip-integratable structure different from that shown in Figure 11, and so on. For example, in another example, the top and bottom sides of the straight waveguide and the curved waveguide in Figure 11 can be made of the same material, but the straight waveguide and the curved waveguide can be made into asymmetrical waveguides, such as ridge waveguides, which can also achieve the function of PSR. There are many other possible implementations, which will not be listed here.

[0187] Based on the above scheme, the characteristics of PSR in transmitting P-light and S-light separately and converting P-light to S-light, or in transmitting TM-light and TE-light separately and converting TE-light to TM-light, can be utilized to enable at least three frequency modulation optoelectronic circuits in two frequency modulation groups to reuse the same optical delay line through two PSRs, so as to transmit the delayed signals in at least three frequency modulation optoelectronic circuits in the same direction. Under the same delay duration, the number of optical delay lines in the signal processing device can be reduced by at least 2, which can greatly simplify the architecture of the signal processing device and reduce the hardware cost of the signal processing device.

[0188] Figures 6, 7a, 7b, 8, and 10 above illustrate signal processing devices with two frequency modulation groups as examples. However, this structure can also be extended to signal processing devices with three or more frequency modulation groups, allowing all frequency modulation optoelectronic circuits in the three or more frequency modulation groups to share the same optical delay line 400 to transmit the delayed signals of all frequency modulation optoelectronic circuits in the three or more frequency modulation groups in the same direction. For example, based on the signal processing device shown in Figure 7b, two possible implementation methods are introduced through the following scenario one and scenario two.

[0189] In scenario one, the signal processing device has multiple second frequency modulation groups.

[0190] Please refer to Figure 12a, which shows a schematic diagram of another signal processing device provided in Embodiment 1. In this example, the signal processing device may include a first frequency modulation group and N second frequency modulation groups, where N is an integer greater than or equal to 2. The structures of the N second frequency modulation groups may be the same or different. Each second frequency modulation group may include only one third frequency modulation photoelectric circuit, or it may include one third frequency modulation photoelectric circuit and one fourth frequency modulation photoelectric circuit, or it may include one third frequency modulation photoelectric circuit and multiple fourth frequency modulation photoelectric circuits, or multiple third frequency modulation photoelectric circuits and one fourth frequency modulation photoelectric circuit, or multiple third frequency modulation photoelectric circuits and multiple fourth frequency modulation photoelectric circuits; the specific configuration is not limited.

[0191] For example, Figure 12a shows an example where each second frequency modulation group includes a third frequency modulation photoelectric circuit and a fourth frequency modulation photoelectric circuit. From top to bottom, the first frequency modulation group includes a first frequency modulation photoelectric circuit 110 and a second frequency modulation photoelectric circuit 210. The first second frequency modulation group includes a third frequency modulation photoelectric circuit 310 and a fourth frequency modulation photoelectric circuit 410. The structures of these two frequency modulation groups are the same as those shown in Figure 7b above, and will not be described again. The second frequency modulation group includes a third frequency modulation optoelectronic circuit 320 and a fourth frequency modulation optoelectronic circuit 420. The third frequency modulation optoelectronic circuit 320 includes a light source 321, a second beam splitter 3221, a second beam combiner / splitter 3222, a mixer 324, a photodetector 325, an amplifier 328, an analog-to-digital converter 329, a processing element 326, and a drive circuit 327. The fourth frequency modulation optoelectronic circuit 420 includes a light source 421, a second beam splitter 4221, a second beam combiner / splitter 3222, a mixer 324, a photodetector 325, an amplifier 328, an analog-to-digital converter 329, a processing element 326, and a drive circuit 427. The third frequency modulation optoelectronic circuit 320 and the fourth frequency modulation optoelectronic circuit 420 share the same second beam combiner / splitter 3222, the same mixer 324, the same photodetector 325, the same amplifier 328, the same analog-to-digital converter 329, and the same processing element 326.

[0192] Similarly, the Nth second frequency modulation group includes a third frequency modulation optoelectronic circuit 3N0 and a fourth frequency modulation optoelectronic circuit 4N0. The third frequency modulation optoelectronic circuit 3N0 includes a light source 3N1, a second beam splitter 3N21, a second beam combiner / splitter 3N22, a mixer 3N4, a photodetector 3N5, an amplifier 3N8, an analog-to-digital converter 3N9, a processing element 3N6, and a drive circuit 3N7. The fourth frequency modulation optoelectronic circuit 4N0 includes a light source 4N1, a second beam splitter 4N21, a second beam combiner / splitter 3N22, a mixer 3N4, a photodetector 3N5, an amplifier 3N8, an analog-to-digital converter 3N9, a processing element 3N6, and a drive circuit 4N7. The third frequency modulation optoelectronic circuit 3N0 and the fourth frequency modulation optoelectronic circuit 4N0 share the same second beam combiner / splitter 3N22, the same mixer 3N4, the same photodetector 3N5, the same amplifier 3N8, the same analog-to-digital converter 3N9, and the same processing element 3N6. The connection relationships of the various components are shown in Figure 12a, and will not be described in detail here.

[0193] In addition to the components mentioned above, as shown in Figure 12a, the signal processing device also includes a beam combiner 510 and a beam splitter 520. The beam combiner 510 has N input terminals and one output terminal, and the beam splitter 520 has N output terminals and one input terminal. One input terminal of the beam combiner 510 is connected to the output terminal of the first polarization element 301 in the first frequency modulation group, and the other N-1 input terminals are connected one-to-one to the N-1 second beam combiners / splitters 3222 to 3N22 in the second to Nth second frequency modulation groups. The output terminal of the beam combiner 510 is connected to the first end a1 of the optical delay line 400. The input terminal of the second beam splitter 520 is connected to the second end a2 of the optical delay line 400, and one output terminal is connected to the input terminal of the second polarization element 302 in the first frequency modulation group. The other N-1 output terminals are connected one-to-one to the N-1 mixers 324 to 3N4 in the second to Nth second frequency modulation groups.

[0194] Based on this structure and connection relationship, the first beam combiner / splitter 1122 in the first frequency modulation group outputs a set of delay signals S 11 +S 21 A set of delayed signals S output by the second combiner / splitter 3122 in the first second frequency modulation group 31 +S 41 Both signals enter the first polarization element 301, which outputs the two sets of signals to be delayed to the combining element 510 with orthogonal polarization directions. In the second to the Nth second frequency modulation group, the N-1 sets of signals S output by the N-1 second combining and splitting elements 3222 to 3N22 are... 32 +S 42 ~S 3N +S 4NThe signal is directly output to the optical combiner 510. The optical combiner 510 combines the received N sets of signals to be delayed into a single optical signal and inputs it to the first end a1 of the optical delay line 400. After the N sets of signals to be delayed are transmitted and delayed in the optical delay line 400, they become N sets of delayed optical signals S. 11 '+S 21 '+S 31 '+S 41 '、S 32 '+S 42 '、……、S 3N '+S 4N It is output from the second end a2 of the optical delay line 400 and enters the second beam splitter 520.

[0195] Optionally, the wavelength of the optical signal in the first second frequency modulation group can be the same as the wavelength of the optical signal in the first frequency modulation group, because they can be separated by polarization multiplexing using polarization elements (having orthogonal polarization directions in the optical delay line). However, for each of the second to Nth second frequency modulation groups, no polarization elements are provided between them and the other frequency modulation groups. Therefore, in order to separate the delayed optical signal from each of the second to Nth second frequency modulation groups from the N delayed optical signals, the wavelength of the optical signal in each of the second to Nth second frequency modulation groups needs to be different from the wavelengths of the optical signals in the other frequency modulation groups. In other words, the wavelength of the optical signal in each of the second to Nth second frequency modulation groups is different from the wavelength of the optical signal in the first frequency modulation group, and also different from the wavelengths of the optical signals in the other N-1 second frequency modulation groups.

[0196] Based on this, the second beam splitter 520 can separate the delayed optical signal from each of the second to Nth second frequency modulation groups from the N groups of delayed optical signals based on the wavelength, and then split the delayed optical signal S in the second second frequency modulation group. 32 '+S 42 The output is sent to mixer 324 in the second second frequency modulation group, ..., to process the delayed optical signal S in the Nth second frequency modulation group. 3N '+S 4N The output is sent to mixer 3N4 in the Nth second frequency modulation group so that mixers 324 to 3N4 in the second to Nth second frequency modulation groups can successfully complete the mixing operation. Additionally, the second beam splitter 520 splits the delayed optical signal S from the first frequency modulation group and the first second frequency modulation group. 11 '+S 21 '+S 31 '+S 41The signal is sent to the second polarization element 302, which separates the delayed optical signals in the two frequency modulation groups based on orthogonal polarization directions, and separates the delayed optical signal S from the first frequency modulation group. 11 '+S 21 The output is sent to mixer 114 in the first frequency modulation group in the original polarization direction, and the delayed optical signal S from the first second frequency modulation group is used as the input. 31 '+S 32 The original polarization direction is output to the mixer 314 in the first second frequency modulation group so that the mixers 114 and 314 in the first and second frequency modulation groups can also successfully complete the mixing operation.

[0197] For example, in one instance, referring to Figure 12b, when both the first polarization element 301 and the second polarization element 302 are PBS, if the signal S to be delayed in the first frequency modulation group... 11 +S 21 For TE light, the delay signal S in the first second frequency modulation group 31 +S 41 Configured as TM light, and the delay signal S in the second to Nth second frequency modulation groups. 32 +S 42 ~S 3N +S 4N It can be configured as either TE or TM light, but the wavelength of the signal to be delayed must be different from that of the other FM groups. The signal to be delayed, S... 32 +S 42 ~S 3N +S 4N Taking TM light as an example, as shown in Figure 12b, the signal S to be delayed in the first frequency modulation group... 11 +S 21 Using TE light and the delayed signal S in the first second frequency modulation group 31 +S 41 The TM light is input to the PBS3011 in the form of light TM. The PBS3011 transmits the TE light to the light combining element 510 and reflects the TM light to the light combining element 510. The delay signal S in the second to Nth second frequency modulation group. 32 +S 42 ~S 3N +S 4NThe TM light is also input to the beam combiner 510. The beam combiner 510 combines the TE light and TM light input from PBS3011 with the N-1 TM lights from the subsequent N-1 second frequency modulation groups into a single optical signal, which is then input to the optical delay line 400. The delayed optical signal enters the second beam splitter 520, which splits the beam based on wavelength, separating the delayed TM light from the second second frequency modulation group and outputting it to the mixer 324 in the second second frequency modulation group, and so on. The delayed TM light from the Nth second frequency modulation group is then separated and output to the mixer 3N4 in the Nth second frequency modulation group, from which the delayed TE light and TM light from the first frequency modulation group and the first second frequency modulation group are separated and output to PBS3021. PBS3021 transmits the TE light to mixer 114 in the first frequency modulation group, so that it is mixed with the local oscillator signal of the calibration path of the TE light in the first frequency modulation group, and reflects the TM light to mixer 314 in the first second frequency modulation group, so that it is mixed with the local oscillator signal of the calibration path of the TM light in the first second frequency modulation group.

[0198] Alternatively, in another example, referring to Figure 12c, when both the first polarization element 301 and the second polarization element 302 are PSRs, if the signal to be delayed S in the first frequency modulation group... 11 +S 21 For TE light, the delay signal S in the first second frequency modulation group 31 +S 41 It is also configured as TE light, and the delay signal S in the second to Nth second frequency modulation groups 32 +S 42 ~S 3N +S 4N It can be configured as either TE or TM light, but the wavelength of the optical signal must be different from that in other frequency modulation groups. The delay signal S is to be used. 32 +S 42 ~S 3N +S 4N Taking TE optical configuration as an example, as shown in Figure 12c, the signal to be delayed S in the first frequency modulation group 11 +S 21 And the delayed signal S in the first second frequency modulation group 31 +S 41 All signals are input to the PSR3012 in the form of TE light. The PSR3012 will then output the signal to be delayed, S. 11 +S 21 The signal S to be delayed is transmitted to the light combining element 510 in the form of TE light. 31 +S 41 The polarization direction is rotated by 90° to convert it into TM light, which is then reflected to the optical combining element 510. The signals S to be delayed in the second to Nth second frequency modulation groups...32 +S 42 ~S 3N +S 4N The TE light is also input to the beam combiner 510. The beam combiner 510 combines the TE and TM light input from PSR3012 with the N-1 TE lights from the subsequent N-1 second frequency modulation groups into a single optical signal, which is then input to the optical delay line 400. The delayed optical signal enters the second beam splitter 520, which splits the beam based on wavelength, separating the delayed TE light from the second second frequency modulation group and outputting it to the mixer 324 in the second second frequency modulation group, and so on. The delayed TE light from the Nth second frequency modulation group is then separated and output to the mixer 3N4 in the Nth second frequency modulation group, from which the delayed TE and TM light from the first frequency modulation group and the first second frequency modulation group are separated and output to PSR3022. PSR3022 transmits the TE light to mixer 114 in the first frequency modulation group, mixing it with the local oscillator signal of the calibration path of the TE light in the first frequency modulation group. It also rotates the polarization direction of the TM light by 90°, turning it into TE light, and then reflects it to mixer 314 in the first second frequency modulation group, mixing it with the local oscillator signal of the calibration path of the TE light in the first second frequency modulation group.

[0199] Using the structure shown in Figure 12a above, the optical signals in one first frequency modulation group and multiple second frequency modulation groups are transmitted in the same direction in the same optical delay line. Therefore, one first frequency modulation group and multiple second frequency modulation groups can share the same optical delay line for delay processing based on polarization multiplexing. In this way, the number of optical delay lines that need to be set in the signal processing device can be further reduced, and the delay time of the optical signal by one first frequency modulation group and multiple second frequency modulation groups is not reduced. Thus, a very simple architecture and extremely low cost of signal processing device can be achieved.

[0200] Scenario 2: The signal processing device has multiple first frequency modulation groups and multiple second frequency modulation groups.

[0201] Please refer to Figure 13a, which shows a structural diagram of another possible signal processing device provided in Embodiment 1. In this example, the signal processing device may include N first frequency modulation groups and N second frequency modulation groups, with each pair corresponding to one another, also referred to as N pairs of frequency modulation groups, where N is an integer greater than or equal to 2. The structures of the N pairs of frequency modulation groups may be identical or different. The second frequency modulation group in each pair may include only one third frequency modulation photoelectric circuit, or it may include one third frequency modulation photoelectric circuit and one fourth frequency modulation photoelectric circuit, or it may include multiple third frequency modulation photoelectric circuits and / or multiple fourth frequency modulation photoelectric circuits; the specifics are not limited.

[0202] For example, Figure 13a shows an example where each pair of frequency modulation groups has the structure shown in Figure 7b. From top to bottom, the first pair of frequency modulation groups includes a first first frequency modulation group and a first second frequency modulation group. The first first frequency modulation group includes a first frequency modulation photoelectric circuit 110 and a second frequency modulation photoelectric circuit 210. The first second frequency modulation group includes a third frequency modulation photoelectric circuit 310 and a fourth frequency modulation photoelectric circuit 410. The structures of these two frequency modulation groups are the same as those in Figure 7b above and will not be repeated. Similarly, the Nth frequency modulation group includes an Nth first frequency modulation group and an Nth second frequency modulation group. The Nth second frequency modulation group includes a third frequency modulation photoelectric circuit 3N0 and a fourth frequency modulation photoelectric circuit 4N0, with the structure shown in Figure 12a above, and will not be repeated. The Nth first frequency modulation group includes a first frequency modulation photoelectric circuit 1N0, a second frequency modulation photoelectric circuit 2N0, a first polarization element 301N, and a second polarization element 302N. The first frequency-modulated optoelectronic circuit 1N0 includes a light source 1N1, a second beam splitter 1N21, a first beam combiner / splitter 1N22, a mixer 1N4, a photodetector 1N5, an amplifier 1N8, an analog-to-digital converter 1N9, a processing element 1N6, and a drive circuit 1N7. The second frequency-modulated optoelectronic circuit 2N0 includes a light source 2N1, a second beam splitter 2N21, a first beam combiner / splitter 1N22, a mixer 1N4, a photodetector 1N5, an amplifier 1N8, an analog-to-digital converter 1N9, a processing element 1N6, and a drive circuit 2N7. The first frequency-modulated optoelectronic circuit 1N0 and the second frequency-modulated optoelectronic circuit 2N0 share the same first beam combiner / splitter 1N22, the same mixer 1N4, the same photodetector 1N5, the same amplifier 1N8, the same analog-to-digital converter 1N9, and the same processing element 1N6. The connection relationship of each component is shown in Figure 13a, and will not be described in detail here.

[0203] In addition to the components mentioned above, as shown in Figure 13a, the signal processing device also includes a beam combiner element 510 and a beam splitter element 520. The beam combiner element 510 has N input terminals and one output terminal, and the beam splitter element 520 has N output terminals and one input terminal. The N input terminals of the beam combiner element 510 are connected one-to-one to the output terminals of the N first polarization elements 301 to 301N in the N first frequency modulation groups, and the output terminals of the beam combiner element 510 are connected to the first terminal a1 of the optical delay line 400. The input terminal of the second beam splitter element 520 is connected to the second terminal a2 of the optical delay line 400, and the N output terminals of the second beam splitter element 520 are connected one-to-one to the input terminals of the N second polarization elements 302 to 302N in the N first frequency modulation groups.

[0204] Based on this structure and connection, in each pair of frequency modulation groups, one set of delayed signals output from the first beam combiner and the second set of delayed signals output from the second beam combiner enter the first polarization element. The first polarization element outputs these two sets of delayed signals to the optical combining element 510 with orthogonal polarization directions. The optical combining element 510 receives the N sets of delayed signals S from the N pairs of frequency modulation groups. 11 +S 21 +S 31 +S 41 ~S 1N +S 2N +S 3N +S 4N The N sets of signals to be delayed are combined into a single optical signal and input to the first end a1 of the optical delay line 400. After being transmitted and delayed in the optical delay line 400, these N sets of signals to be delayed become N sets of delayed optical signals S. 11 '+S 21 '+S 31 '+S 41 '~S 1N '+S 2N '+S 3N '+S 4N It is output from the second end a2 of the optical delay line 400 and enters the second beam splitter 520.

[0205] Optionally, in each pair of frequency modulation groups, the wavelength of the optical signal in the second frequency modulation group can be the same as that in the first frequency modulation group, because the two can be separated by polarization multiplexing (having orthogonal polarization directions in the optical delay line) using polarization elements. However, for N pairs of frequency modulation groups, there are no polarization elements between them. Therefore, to accurately separate the delayed signals of different pairs of frequency modulation groups, the wavelengths of the optical signals in the N pairs of frequency modulation groups need to be different. For example, the wavelengths of the optical signals in the N first frequency modulation groups in the N pairs of frequency modulation groups are different, and the wavelengths of the optical signals in the N second frequency modulation groups in the N pairs of frequency modulation groups are also different.

[0206] Based on this, the second beam splitter 520 can separate the delayed optical signal from each pair of frequency-modulated groups from the N groups of delayed optical signals based on the wavelength, and split the delayed optical signal S from the first pair of frequency-modulated groups. 11 '+S 21 '+S 31 '+S 41 The output is sent to the second polarization element 302 in the first pair of frequency modulation groups, ..., and the delayed optical signal S in the Nth pair of frequency modulation groups is... 1N '+S 2N '+S 3N '+S 4NThe output is sent to the second polarization element 302N in the Nth pair of frequency modulation groups. In each pair of frequency modulation groups, the second polarization element separates the delayed optical signals in the first and second frequency modulation groups based on orthogonal polarization directions. The delayed optical signal in the first frequency modulation group is output to the mixer in the first frequency modulation group with its original polarization direction, and the delayed optical signal in the second frequency modulation group is output to the mixer in the second frequency modulation group with its original polarization direction.

[0207] For example, in one instance, referring to Figure 13b, when both the first and second polarization elements are PBS, N delay signals S of the first frequency modulation group can be configured. 11 +S 21 ~S 1N +S 2N All signals are TE light with different wavelengths, and there are N second frequency modulation groups of signals S to be delayed. 31 +S 41 ~S 3N +S 4N All signals are TM light with different wavelengths. In each pair of frequency modulation groups, the signal to be delayed in the first frequency modulation group is input to the left PBS in the form of TE light, and the signal to be delayed in the second frequency modulation group is input to TM light. The PBS transmits the TE light to the beam combiner 510 and reflects the TM light to the beam combiner 510. The beam combiner 510 combines the N sets of TE and TM light from the N pairs of frequency modulation groups into a single optical signal, which is input to the optical delay line 400. The delayed optical signal enters the second beam splitter 520, which splits the beam based on wavelength, separating the delayed TE and TM light from each pair of frequency modulation groups, and outputs it to the right PBS in each pair of frequency modulation groups. The PBS on the right outputs the TE light to the mixer in the first frequency modulation group, so that it is mixed with the local oscillator signal of the calibration path of the TE light in the first frequency modulation group, and outputs the TM light to the mixer in the second frequency modulation group, so that it is mixed with the local oscillator signal of the calibration path of the TM light in the second frequency modulation group.

[0208] Alternatively, in another example, referring to Figure 13c, when both the first and second polarization elements are PSRs, the signals S to be delayed in N first frequency modulation groups can be configured. 11 +S 21 ~S 1N +S 2N All are TE light with different wavelengths, and the signals to be delayed are S in N second frequency modulation groups. 31 +S 41 ~S 3N +S 4NThe light beams are all TE (transient optical) beams with different wavelengths. In each pair of frequency modulation (FM) groups, the signal to be delayed in the first FM group is input as TE light, and the signal to be delayed in the second FM group is also input as TE light to the left-hand PSR (Pressure Separator). The PSR keeps the polarization direction of the TE light in the first FM group unchanged, rotates the polarization direction of the TE light in the second FM group by 90° to make it TM (transient optical) light, and outputs the TE light and TM light together to the beam combiner 510. The beam combiner 510 combines the N sets of TE light and TM light from the N pairs of FM groups into a single optical signal, which is then input to the optical delay line 400. The delayed optical signal enters the second beam splitter 520, which splits the beam based on wavelength, separating the delayed TE light and TM light from each pair of FM groups, and outputs them to the right-hand PSR of each pair of FM groups. The PSR on the right outputs the TE light to the mixer in the first frequency modulation group, where it mixes with the local oscillator signal of the calibration path of the TE light in the first frequency modulation group. It also rotates the polarization direction of the TM light by 90°, turning it into TE light, and outputs it to the mixer in the second frequency modulation group, where it mixes with the local oscillator signal of the calibration path of the TE light in the second frequency modulation group.

[0209] Using the structure shown in Figure 13a above, the optical signals in multiple first frequency modulation groups and multiple second frequency modulation groups are transmitted in the same direction in the same optical delay line. Therefore, multiple first frequency modulation groups and multiple second frequency modulation groups can share the same optical delay line for delay processing based on polarization multiplexing. In this way, the number of optical delay lines that need to be set in the signal processing device can be further reduced, and the delay time of the optical signals by multiple first frequency modulation groups and multiple second frequency modulation groups is not reduced. Thus, a very simple architecture and extremely low cost of signal processing device can be achieved.

[0210] It should be noted that the above scenarios one and two are both based on wavelength-based beam splitting using the second beam splitter 520 as an example. In this scenario, the second beam splitter 520 can specifically be a wavelength division multiplexer. Based on wavelength-based beam splitting, the second beam splitter 520 can separate clean, time-delayed optical signals of different wavelengths. These time-delayed optical signals of different wavelengths are output to their respective frequency modulation groups and mixed with the local oscillator signal of the calibration path of the same wavelength, resulting in a good mixing effect.

[0211] However, in other examples, the second beam splitter 520 can also be other types of beam splitters, such as power beam splitters, mode beam splitters, resonant beam splitters, etc. When it is another type of beam splitter, although the second beam splitter 520 may split each path of delayed optical signals with multiple wavelengths (for example, each delayed optical signal is a mixed optical signal with each wavelength equally divided), during mixing in the mixer, the wavelength of the calibration path local oscillator signal will be used for mixing, and other wavelengths will not be used. Therefore, power beam splitting or other information beam splitting can also realize subsequent mixing and processing functions. Based on this, this application does not specifically limit the beam splitting type of the second beam splitter 520.

[0212] Furthermore, each frequency-modulated photoelectric circuit in Situations 1 and 2 above has its own separate target measurement path, but this is only an example. In other examples, the frequency-modulated photoelectric circuits may share the same target measurement path, or some of the frequency-modulated photoelectric circuits may share the same target measurement path, while other frequency-modulated photoelectric circuits have their own separate target measurement paths, etc. This application does not make specific limitations in this regard.

[0213] Furthermore, other scenarios can be derived by combining scenarios one and two above. For example, in another scenario, multiple first frequency modulation groups and multiple second frequency modulation groups can be set up, but the number of first frequency modulation groups is less than the number of second frequency modulation groups. This is equivalent to setting up multiple pairs of first and second frequency modulation groups based on the scheme in scenario two, and then connecting one or more second frequency modulation groups from scenario one to any first frequency modulation group. The relevant content can be directly deduced by analogy, and will not be elaborated here.

[0214] Implementation Plan 2

[0215] Here, implementation scheme two corresponds to the scheme in which optical signals from two frequency modulation groups are transmitted in reverse on the same optical delay line 400.

[0216] In Implementation Scheme 2, the structures of the components in the first frequency modulation group 11 and the second frequency modulation group 21 are the same as in Implementation Scheme 1, only the connection relationships are different. For example, taking the structure shown in Figure 7b above as an example, please refer to Figure 14, which shows a schematic diagram of the structure of a signal processing device provided in Implementation Scheme 2. Referring to Figure 14 and Figure 7b above:

[0217] In Implementation Scheme 1, the first beam combiner / splitter 1122 in the first frequency modulation group 11 and the second beam combiner / splitter 3122 in the second frequency modulation group 21 are both connected to the first polarization element 301, and the mixer 114 shared by the first frequency modulation group 11 and the mixer 314 shared by the second frequency modulation group 21 are both connected to the second polarization element 301. In Implementation Scheme 2, the first beam combiner / splitter 1122 in the first frequency modulation group 11 and the mixer 314 shared by the second frequency modulation group 21 are connected to the first polarization element 301, while the second beam combiner / splitter 3122 in the second frequency modulation group 21 and the mixer 114 shared by the first frequency modulation group 11 are connected to the second polarization element 301.

[0218] Based on this structure, as shown in Figure 14, the delay signal S in the first frequency modulation group 11 output by the first beam combiner / splitter 1122 is... 11 +S 21 The signal S to be delayed enters the first polarization element 301, while the second frequency modulation group 21 output by the second beam combiner / splitter 3122... 31 +S 41 Then it enters the second polarization element 302. Assuming the optical signal in the first frequency modulation group 11 has a first linear polarization state and the optical signal in the second frequency modulation group 21 has a second linear polarization state, then: from left to right, the first polarization element 301 can maintain the delayed signal S in the first frequency modulation group 11. 11 +S 21 With its polarization direction unchanged, it is output to the first end a1 of the optical delay line 400, to be delayed signal S. 11 +S 21 The signal is transmitted from left to right in the optical delay line 400 and output at the second end a2 of the optical delay line 400, entering the second polarization element 302. The second polarization element 302 holds the delayed optical signal S from the first frequency modulation group 11. 11 '+S 21 The polarization direction of the signal remains unchanged, so that it is still output to the mixer 114 in the first frequency modulation group 11 in the form of the first linear polarization state. Viewed from right to left, the second polarization element 302 causes the delayed signal S in the second frequency modulation group 21 to remain in the first linear polarization state. 31 +S 41 Orthogonal to the delay signal S 11 +S 21 The polarization direction is output to the second end a2 of the optical delay line 400, and the signal to be delayed S 31 +S 41 The optical signal S is transmitted from right to left in the optical delay line 400 and outputs at the first end a1 of the optical delay line 400, entering the first polarization element 301. The first polarization element 301 then converts the delayed optical signal S from the second frequency modulation group 21 into a signal that has been transmitted from right to left in the optical delay line 400. The signal outputs from the first end a1 of the optical delay line 400 and enters the first polarization element 301 31 '+S 41The output is in the form of a second linear polarization state to the mixer 314 in the second frequency modulation group 21.

[0219] Based on this, the two sets of optical signals in the two frequency modulation groups are input to different ends of the optical delay line 400 in orthogonal linear polarization state. After being transmitted in reverse in the optical delay line 400, they return to the mixer in their respective frequency modulation groups in their original linear polarization state. Therefore, without affecting their respective mixing operations, the mutual interference between the two sets of optical signals in the two frequency modulation groups during the delay processing can be reduced, so that the optical signal output to the mixer in the two frequency modulation groups after delay processing can have better signal quality, and the signal calibration effect in each frequency modulation optoelectronic circuit can be improved.

[0220] It should be noted that, based on the interference properties of light, two beams of light from different directions will couple and transmit when they meet in the same area. However, after leaving the area, the two beams of light can continue to transmit while maintaining their original characteristics. Based on this, the characteristics of the optical signals in the first and second frequency modulation groups can be exactly the same, such as the same wavelength, the same frequency, etc., or there may be at least one different characteristic. This will not affect the functional implementation of the first and second frequency modulation groups.

[0221] In the above content, the first linear polarization state and the second linear polarization state can be the same linear polarization state or they can be orthogonal linear polarization states.

[0222] For example, when the first linear polarization state and the second linear polarization state are orthogonal linear polarization states, the first polarization element 301 and the second polarization element 302 can be any polarization processing device or combination thereof that can keep the polarization directions of the two sets of input signals unchanged. For example, they can be PBS3011 and PBS3021 as shown in Figure 15a. Both PBS3011 and PBS3021 have a first end, a second end, and a third end. P-light or TE-light is transmitted between the first end and the third end, and S-light or TM-light is reflected between the second end and the third end. The first end of PBS3011 is connected to the first beam combiner / splitter 1122, the second end is connected to the mixer 314, and the third end is connected to the first end a1 of the optical delay line 400. The first end of PBS3021 is connected to the second beam combiner / splitter 3122, the second end is connected to the mixer 114, and the third end is connected to the second end a2 of the optical delay line 400.

[0223] Referring to Figures 15a and 14, in the first frequency modulation group 11, the light sources in both the first frequency modulation photoelectric circuit 110 and the second frequency modulation photoelectric circuit 210 output TE light. After the TE light is split by the first beam splitter, the resulting intermediate optical signal S... 10 S 20 Both are TE beams. The two TE beams enter the first beam combiner / splitter 1122 for beam combining and splitting. The resulting calibration path local oscillator signal and the signal to be delayed S 11+S 21 Both are TE optical signals, and the delayed signal S of the TE optical signal is... 11 +S 21 The light enters the first end of PBS3011, is transmitted through PBS3011 to the third end, and is output to the first end a1 of optical delay line 400. After being transmitted from left to right in optical delay line 400, it is output from the second end a2 of optical delay line 400, enters the third end of PBS3021, is transmitted through PBS3021 to the first end, and enters the mixer 114 in the first frequency modulation group 11 to perform a mixing operation with the local oscillator signal of the calibration path of TE light in the first frequency modulation group 11.

[0224] In the second frequency modulation group 21, the light sources in the third frequency modulation photoelectric circuit 310 and the fourth frequency modulation photoelectric circuit 410 both output TM light. After the TM light is split by the second beam splitter, the resulting intermediate optical signal S 30 S 40 Both are TM beams. The two TM beams enter the second beam combiner / splitter 3122 for beam combining and splitting. The resulting calibration path local oscillator signal and the signal to be delayed S 31 +S 41 Both are TM light, and the delayed signal S of the TM light is... 31 +S 41 The light enters the second end of PBS3021, is reflected by PBS3021 to the third end, enters the second end a2 of optical delay line 400, is transmitted from right to left in optical delay line 400, is output from the first end a1 of optical delay line 400, enters the third end of PBS3011, is reflected by PBS3011 to the second end, enters the mixer 314 in the second frequency modulation group 21, and is mixed with the local oscillator signal of the calibration path of TM light in the second frequency modulation group 21.

[0225] Based on the above scheme, the transmission of P-light or TE-light in the PBS and the reflection of S-light or TM-light in the PBS can be utilized to enable at least three frequency-modulated optoelectronic circuits in two frequency-modulated groups to multiplex the same optical delay line through two PBSs, thereby transmitting the delayed signals in at least three frequency-modulated optoelectronic circuits in reverse. There are many ways to implement the PBS, including chip-integrated PBS and non-chip-integrated PBS, or it can be implemented using fiber optic devices, or other polarization beam splitters, etc., which will not be repeated here.

[0226] For example, when the first linear polarization state and the second linear polarization state are the same linear polarization state, the first polarization element 301 and the second polarization element 302 can be any polarization processing device or combination thereof that can keep the polarization direction of one set of input signals unchanged and rotate the polarization direction of another set of input signals by 90°. For example, it can be PSR3012 and PSR3022 as shown in Figure 15b. PSR3012 and PSR3022 both have a first end, a second end and a third end. P-light or TE light is transmitted between the first end and the third end in the original polarization direction, while the signal is transmitted between the second end and the third end in the polarization direction after being rotated by 90°. For example, P-light or TE light is converted into S-light or TM light and then output, and the returned S-light or TM light is converted into P-light or TE light and then output. The first end of PSR3012 is connected to the first beam combiner / splitter 1122, the second end is connected to the mixer 314, and the third end is connected to the first end a1 of the optical delay line 400. The first end of PSR3022 is connected to the second beam combiner / splitter 3122, the second end is connected to the mixer 114, and the third end is connected to the second end a2 of the optical delay line 400.

[0227] Referring to Figures 15b and 14, in the first frequency modulation group 11, the light sources in both the first frequency modulation photoelectric circuit 110 and the second frequency modulation photoelectric circuit 210 output TE light. After the TE light is split by the first beam splitter, the resulting intermediate optical signal S... 10 S 20 Both are TE beams. The two TE beams enter the first beam combiner / splitter 1122 for beam combining and splitting. The resulting calibration path local oscillator signal and the signal to be delayed S 11 +S 21 Both are TE optical signals, and the delayed signal S of the TE optical signal is... 11 +S 21 The TE light input at the first terminal of PSR3012 is transmitted through the first terminal. PSR3012 maintains the polarization direction of the TE light input at the first terminal and outputs it from the third terminal, allowing it to enter the first terminal a1 of the optical delay line 400. After propagating from left to right within the optical delay line 400, the light is output from the second terminal a2 of the optical delay line 400 and enters the third terminal of PSR3022. PSR3022 maintains the polarization direction of the TE light input at the third terminal and outputs it from the first terminal, allowing it to enter the mixer 114 in the first frequency modulation group 11, where it is mixed with the local oscillator signal of the calibration path of the TE light in the first frequency modulation group 11.

[0228] In the second frequency modulation group 21, the light sources in the third frequency modulation photoelectric circuit 310 and the fourth frequency modulation photoelectric circuit 410 also output TE light. After the TE light is split by the second beam splitter, the resulting intermediate optical signal S 30 S 40 Both are TE beams. The two TE beams enter the second beam combiner / splitter 3122 for beam combining and splitting. The resulting calibration path local oscillator signal and the signal to be delayed S31 +S 41 Both are TE optical signals, and the delayed signal S of the TE optical signal is... 31 +S 41 The light enters the second terminal of PSR3022. PSR3022 rotates the polarization direction of the TE light input at the second terminal by 90°, converting it into TM light, and outputs it from the third terminal. This light then enters the second terminal a2 of the optical delay line 400. After propagating from right to left in the optical delay line 400, it exits from the first terminal a1 of the optical delay line 400 and enters the third terminal of PSR3012. PSR3012 rotates the polarization direction of the TM light input at the third terminal by 90°, converting it into TE light, and outputs it from the second terminal. This light then enters the mixer 314 in the second frequency modulation group 21, where it is mixed with the local oscillator signal of the calibration path of the TE light in the second frequency modulation group 21.

[0229] Based on the above scheme, the characteristics of PSRs (Pressure Separator) in separately transmitting P-light and S-light and converting P-light to S-light, or separately transmitting TM-light and TE-light and converting TE-light to TM-light, can be utilized. Two PSRs can be used to multiplex at least three frequency modulation (FM) optoelectronic circuits in two frequency modulation groups using the same optical delay line, thereby transmitting the delayed signals in at least three FM optoelectronic circuits in reverse. There are many ways to implement the above PSRs, including chip-integrated PSRs and non-chip-integrated PSRs, or they can be implemented using fiber optic devices, or using devices such as prisms combined with waveplates, etc., etc., which will not be repeated here.

[0230] Similar to Implementation Scheme 1, the signal processing device structure in Implementation Scheme 2 can also be extended to a signal processing device with three or more frequency modulation groups, so that all frequency modulation photoelectric circuits in the three or more frequency modulation groups share the same optical delay line 400 to transmit the delayed signals of all frequency modulation photoelectric circuits in the three or more frequency modulation groups in the same direction.

[0231] For example, in one example, based on the signal processing device shown in Figure 14, and referring to Figure 12a in the first embodiment above, please refer to Figure 16a, which shows a schematic diagram of another signal processing device provided in the second embodiment. In this example, the signal processing device includes a first frequency modulation group and N second frequency modulation groups, where N is an integer greater than or equal to 2. The details of the first frequency modulation group and the N second frequency modulation groups are described in the first embodiment above and will not be repeated here.

[0232] Unlike implementation scheme one, as shown in Figure 16a, in this example, the signal processing device may further include two optical combining / splitting elements, namely optical combining / splitting element 530 and optical combining / splitting element 540. Optical combining / splitting element 530 has two communication terminals (communication terminals are terminals that serve as both inputs and outputs) and N-1 output terminals, while optical combining / splitting element 540 has two communication terminals and N-1 input terminals. One communication terminal of optical combining / splitting element 530 is connected to the first polarization element 301 in the first frequency modulation group, and the other communication terminal is connected to the first end a1 of the optical delay line 400. The other N-1 output terminals are connected one-to-one to the N-1 mixers 324 to 3N4 in the second to Nth second frequency modulation groups. One communication terminal of the beam combiner / splitter 540 is connected to the second polarization element 302 in the first frequency modulation group, and the other communication terminal is connected to the second end a2 of the optical delay line 400. The other N-1 input terminals are connected one-to-one to the N-1 second beam combiners / splitters 3222 to 3N22 in the second to Nth second frequency modulation groups.

[0233] Based on this structure and connection relationship, the first beam combiner / splitter 1122 in the first frequency modulation group outputs a set of delay signals S 11 +S 21 The signal will enter the first polarization element 301, and the first polarization element 301 will delay the group of signals S. 11 +S 21 The signal is output to the beam combiner / splitter 530 in its original polarization direction. This set of signals to be delayed, S... 11 +S 21 The signal S is transmitted via the combiner / splitter 530 to the first end a1 of the optical delay line 400. After a delay from left to right, it is output at the second end a2 of the optical delay line 400, enters the combiner / splitter 540, and is output by the combiner / splitter 540 to the second polarization element 302. The second polarization element 302 then outputs the delayed signal S. 11 '+S 21 The signal is output to mixer 114 in its original polarization direction. In the N second frequency modulation groups, the second beam combiner / splitter 3122 in the first second frequency modulation group outputs a set of delayed signals S. 31 +S 41 The signal enters the second polarization element 302, which then transmits the set of signals to be delayed, S. 31 +S 41 Orthogonal to the delay signal S 11 +S 21 The polarization direction is output to the combining and splitting element 540. The N-1 groups of delayed signals S output by the second combining and splitting elements 3222~3N22 in the second to Nth second frequency modulation groups... 32 +S 42 ~S 3N +S 4NThe signal is directly output to the beam combiner / splitter 530. The beam combiner / splitter 530 converts the received N sets of delayed signals S... 31 +S 41 ~S 3N +S 4N The signals are combined into a single optical signal and input to the second end a1 of the optical delay line 400. After propagating from right to left within the optical delay line 400, the signal is output from the second end a2 of the optical delay line 400 and enters the combining / splitting element 530. Optionally, the combining / splitting element 530 is based on the wavelength of the N-group delayed optical signal S. 31 '+S 41 '~S 3N '+S 4N The delayed optical signal from each second frequency modulation group is separated, and the delayed optical signals from the second to the Nth second frequency modulation groups are output to the mixer in each second frequency modulation group. The delayed optical signal from the first second frequency modulation group is output to the first polarization element 301. The first polarization element 301 causes the delayed optical signal from the first second frequency modulation group to be output to the mixer 314 in the first second frequency modulation group with its original polarization direction.

[0234] For example, in another example, based on the signal processing device shown in Figure 14, and referring to Figure 13a in Implementation Scheme 1, please refer to Figure 16b, which shows a schematic diagram of another signal processing device provided in Implementation Scheme 2. In this example, the signal processing device includes N first frequency modulation groups and N second frequency modulation groups in a one-to-one correspondence, where N is an integer greater than or equal to 2. The relevant details of the N first frequency modulation groups and N second frequency modulation groups are described in Implementation Scheme 1 above, and will not be repeated here.

[0235] Unlike implementation scheme one, as shown in Figure 16b, in implementation scheme two, the signal processing device may further include two optical combining / splitting elements, namely optical combining / splitting element 530 and optical combining / splitting element 540. Both optical combining / splitting element 530 and optical combining / splitting element 540 have N+1 communication terminals. One communication terminal of optical combining / splitting element 530 is connected to the first terminal a1 of optical delay line 400, and the other N communication terminals are connected one-to-one to the N first polarization elements 301 to 301N in N pairs of frequency modulation groups. One communication terminal of optical combining / splitting element 540 is connected to the second terminal a2 of optical delay line 400, and the other N communication terminals are connected one-to-one to the N second polarization elements 302 to 302N in N pairs of frequency modulation groups.

[0236] Based on this structure and connection, from left to right, in each first frequency modulation group, a set of signals to be delayed output from the first beam combiner / splitter enters the first polarization element. The first polarization element outputs the signals to be delayed in their original polarization direction to the beam combiner / splitter 530. The beam combiner / splitter 530 takes the N sets of signals S to be delayed input from the N first polarization elements 301 to 301N in the N first frequency modulation groups. 11 +S 21 ~S 1N +S 2N The signals are combined into a single optical signal and input to the first end a1 of the optical delay line 400. After being delayed and transmitted from left to right within the optical delay line 400, the signal becomes N sets of delayed optical signals S. 11 '+S 21 '~S 1N '+S 2N The optical signal is output from the second end a2 of the optical delay line 400 and enters the optical combining and splitting element 540. Optionally, in order to separate the delayed optical signals from the N first frequency modulation groups, the wavelengths of the optical signals in the N first frequency modulation groups can be configured to be different. In this way, the N groups of delayed optical signals S 11 '+S 21 '~S 1N '+S 2N The wavelengths of the N groups of optical signals S will also differ. Based on this, the combining and splitting element 540 can determine the wavelength based on the N groups of optical signals S after delay processing. 11 '+S 21 '~S 1N '+S 2N The delayed optical signal S is separated from N first frequency modulation groups. 11 '+S 21 '、……、S 1N '+S 2N ', the delayed optical signal S in the first frequency modulation group 11 '+S 21 The output is sent to the second polarization element 302 in the first frequency modulation group, ..., and the delayed optical signal S in the Nth frequency modulation group is... 1N '+S 2N The signal is output to the second polarization element 302N in the Nth first frequency modulation group. In each first frequency modulation group, the second polarization element keeps the polarization direction of the delayed optical signal in the first frequency modulation group unchanged and outputs it to the mixer in the first frequency modulation group.

[0237] Looking from right to left, in each second frequency modulation group, a set of delayed signals output from the second combiner / splitter enters the second polarization element. The second polarization element outputs the delayed signals in a polarization direction orthogonal to the optical signals in the first frequency modulation group to the combiner / splitter 540. The combiner / splitter 540 takes the N sets of delayed signals S input from the N second polarization elements 302 to 302N in the N second frequency modulation groups. 31 +S 41 ~S 3N +S 4N The signals are combined into a single optical signal and input to the second end a2 of the optical delay line 400. After being transmitted and delayed from right to left within the optical delay line 400, the signal becomes N sets of delayed optical signals S. 31 '+S 41 '~S 3N '+S 4N The optical signal is output from the first end a1 of the optical delay line 400 and enters the optical combining and splitting element 530. Optionally, in order to separate the delayed optical signals from the N second frequency modulation groups, the wavelengths of the optical signals in the N second frequency modulation groups can be configured to be different. In this way, the N groups of delayed optical signals S 31 '+S 41 '~S 3N '+S 4N The wavelengths of the N groups of optical signals S will also differ. Based on this, the combining and splitting element 530 can determine the wavelength based on the N groups of optical signals S after delay processing. 31 '+S 41 '~S 3N '+S 4N The delayed optical signal S is separated from N second frequency modulation groups. 31 '+S 41 '、……、S 3N '+S 4N ', the delayed optical signal S from the first second frequency modulation group 31 '+S 41 The output is sent to the first polarization element 301 in the first second frequency modulation group, ..., and the delayed optical signal S in the Nth second frequency modulation group is... 3N '+S 4N The output is sent to the first polarization element 301N in the Nth second frequency modulation group. In each second frequency modulation group, the first polarization element outputs the delayed optical signal in the second frequency modulation group to the mixer in the second frequency modulation group with the original polarization direction in the second frequency modulation group.

[0238] For example, in one instance, referring to Figure 16b and Figure 15a above, and referring to Figure 16c, when the N first polarizing elements 301-301N and the N second polarizing elements 302-302N are all PBS, the optical signals of the N first frequency modulation groups can be configured as TE light, and the optical signals of the N second frequency modulation groups can be configured as TM light. At the same time, the optical wavelengths in the N first frequency modulation groups are all different, and the optical signal wavelengths in the N second frequency modulation groups are all different. The optical signal wavelengths in any first frequency modulation group and any second frequency modulation group can be the same or different.

[0239] As shown in Figure 16c, in each first frequency modulation group, the signal to be delayed is input to the left PBS in the form of TE light. The PBS transmits the TE light to the combining / splitting element 530. The combining / splitting element 530 combines the N groups of TE light from the N first frequency modulation groups into a large TE light beam, which is then input to the optical delay line 400. After being delayed from left to right, it enters the combining / splitting element 540. The combining / splitting element 540 splits the beam based on wavelength, separating the delayed TE light from each first frequency modulation group and outputting it to the right PBS in each first frequency modulation group. The PBS transmits the received delayed TE light to the mixer in the first frequency modulation group, mixing it with the calibration path local oscillator signal of the TE light in the first frequency modulation group. In each second frequency modulation group, the signal to be delayed is input to the right PBS in the form of TM light. The PBS reflects the TM light to the combining / splitting element 540. The beam combiner / splitter 540 combines the N groups of TM light from the N second frequency modulation groups into a large TM light beam, which is then input to the optical delay line 400. After a right-to-left transmission delay, the beam combines / splitter 530. The beam combiner / splitter 530 splits the beam based on wavelength, separating the delayed TM light from each second frequency modulation group and outputting it to the left-hand PBS in each second frequency modulation group. The PBS reflects the received delayed TM light to the mixer in the second frequency modulation group, where it is mixed with the calibration path local oscillator signal of the TM light in the second frequency modulation group.

[0240] For example, in another example, referring to Figure 16d in conjunction with Figure 16b and Figure 15b above, when all N first polarization elements 301-301N and N second polarization elements 302-302N are PSRs, the optical signals of the N first frequency modulation groups and the N second frequency modulation groups can be configured to be TE light. At the same time, the optical wavelengths in the N first frequency modulation groups are different, and the optical signal wavelengths in the N second frequency modulation groups are different. The optical signal wavelengths in any one first frequency modulation group and any one second frequency modulation group can be the same or different.

[0241] As shown in Figure 16d, in each first frequency modulation group, the signal to be delayed is input to the left-hand PSR in the form of TE light. The PSR maintains the polarization direction of the TE light and outputs it to the combiner / splitter 530. The combiner / splitter 530 combines the N groups of TE light from the N first frequency modulation groups into a large TE light beam and inputs it to the optical delay line 400. After being delayed from left to right, it enters the combiner / splitter 540. The combiner / splitter 540 splits the beam based on wavelength, separating the delayed TE light from each first frequency modulation group and outputting it to the right-hand PSR in each first frequency modulation group. This PSR maintains the polarization direction of the received TE light and outputs it to the mixer in the first frequency modulation group, where it is mixed with the calibration path local oscillator signal of the TE light in the first frequency modulation group. In each second frequency modulation group, the signal to be delayed is input to the right-hand PSR in the form of TE light. The PSR rotates the polarization direction of the TE light by 90°, converting it into TM light, and outputs it to the combiner / splitter 540. The combiner / splitter 540 combines the N groups of TM light from the N second frequency modulation groups into a large TM beam, which is then input to the optical delay line 400. After being delayed from right to left, it enters the combiner / splitter 530. The combiner / splitter 530 splits the beam based on wavelength, separating the delayed TM light from each second frequency modulation group and outputting it to the left-hand PSR in each second frequency modulation group. The PSR rotates the polarization direction of the received delayed TM light by 90°, converting it into TE light, and outputs it to the mixer in the second frequency modulation group, where it is mixed with the calibration path local oscillator signal of the TE light in the second frequency modulation group.

[0242] It should be noted that the relevant content in Implementation Scheme 1 also applies to Implementation Scheme 2. For example, the above description uses wavelength-based beam splitting of beam combining and splitting elements 530 and 540 as an example. However, in other examples, beam combining and splitting elements 530 and 540 can also be used for beam splitting based on other features, such as power multiplexers, mode multiplexers, or resonant multiplexers. This application does not limit the beam splitting type of beam combining and splitting elements 530 and 540. For another example, multiple first frequency modulation groups and multiple second frequency modulation groups can be set, but the number of first frequency modulation groups is less than the number of second frequency modulation groups, equivalent to connecting one or more second frequency modulation groups to N pairs of first and second frequency modulation groups. Furthermore, each frequency modulation optoelectronic circuit can have its own separate target measurement path, or they can share the same target measurement path, or some of the frequency modulation optoelectronic circuits can share the same target measurement path, while other frequency modulation optoelectronic circuits have their own separate target measurement paths. These will not be elaborated further here.

[0243] Implementation Plan 3

[0244] Here, Scheme 3 corresponds to the scheme in which two sets of optical signals in the same frequency modulation group are transmitted in reverse on the same optical delay line 400.

[0245] Please refer to Figure 17a, which shows a schematic diagram of a signal processing device provided in Embodiment 3. In this example, the light source, first beam splitter, mixer, photodetector, amplifier, analog-to-digital converter, processing element, and drive circuit in the first frequency modulation photoelectric circuit 110, the second frequency modulation photoelectric circuit 210, and the third frequency modulation photoelectric circuit 310 are all independent, and there are no shared components.

[0246] Similar to embodiments one and two, the polarization control element 300 in embodiment three may also include a first polarization element 301 and a second polarization element 302. Both the first polarization element 301 and the second polarization element 302 have a first end, a second end, and a third end. The second end of the first polarization element 301 is the input end, while the first and third ends can both input and output signals. Similarly, the second end of the second polarization element 302 is the output end, while the first and third ends can both input and output signals. The third end of the first polarization element 301 is connected to the first end a1 of the optical delay line 400, and the third end of the second polarization element 302 is connected to the second end a2 of the optical delay line 400.

[0247] Optionally, as shown in FIG17a, the polarization control element 300 may further include a first optical transmission element 611 and a second optical transmission element 612. The first optical transmission element 611 is connected between the first beam splitter 112 in the first frequency modulation optoelectronic circuit 110, the mixer 214 in the second frequency modulation optoelectronic circuit 210, and the first end of the first polarization element 301. The second optical transmission element 612 is connected between the first beam splitter 212 in the second frequency modulation optoelectronic circuit 210, the mixer 114 in the first frequency modulation optoelectronic circuit 110, and the first end of the second polarization element 302. For example, as shown in FIG17a, both the first optical transmission element 611 and the second optical transmission element 612 have three ends, and the transmission between the first end and the second end and the third end is unidirectional. The first end of the first optical transmission element 611 is connected to the first beam splitter 112, the second end is connected to the first end of the first polarization element 301, and the third end is connected to the mixer 214. The first end of the second optical transmission element 612 is connected to the first beam splitter 212, the second end is connected to the first end of the second polarization element 302, and the third end is connected to the mixer 114.

[0248] Based on this structure and connection, in the first frequency-modulated photoelectric circuit 110, after the first beam splitter 112 receives the optical signal S1 output by the light source 111, it performs beam splitting processing on the optical signal S1 to obtain the detection signal, the calibration path local oscillator signal, and the first optical signal S. 11The detection signal is output to the target measurement path 113, the local oscillator signal of the calibration path is output to the mixer 114, and the first optical signal S is output to the mixer 114. 11 The signal is output to the first end of the first optical transmission element 611. The first optical transmission element 611 outputs the first optical signal S from its second end. 11 This allows the light to enter the first end of the first polarization element 301, and the first polarization element 301 maintains the first optical signal S. 11 The polarization direction remains unchanged, and the signal is output from the third end, entering the first end a1 of the optical delay line 400. After propagating from left to right in the optical delay line 400, it is output from the second end a2 of the optical delay line 400 and enters the third end of the second polarization element 302. The second polarization element 302 holds the first optical signal S after the delay processing. 11 The polarization direction of ' remains unchanged, and it is output from the first end, so that the first optical signal S after delay processing is... 11 The signal enters the second terminal of the second optical transmission element 612. The second optical transmission element 612 outputs the delayed first optical signal S from the third terminal. 11 This allows it to enter the mixer 114 and be mixed with the local oscillator signal of the calibration circuit in the first frequency modulation photoelectric circuit 110.

[0249] Similarly, in the second frequency-modulated photoelectric circuit 210, after the first beam splitter 212 receives the optical signal S2 output by the light source 211, it performs beam splitting processing on the optical signal S2 to obtain the detection signal, the calibration path local oscillator signal, and the second optical signal S. 21 The detection signal is output to the target measurement path 213, the local oscillator signal of the calibration path is output to the mixer 214, and the second optical signal S is output to the mixer 214. 21 The output is sent to the first end of the second optical transmission element 621. The second optical transmission element 621 outputs the second optical signal S from its second end. 21 This allows the light to enter the first end of the second polarization element 302, and the second polarization element 302 maintains the second optical signal S. 21 The polarization direction remains unchanged, and the signal is output from the third end, entering the second end a2 of the optical delay line 400. After propagating from right to left in the optical delay line 400, it is output from the first end a1 of the optical delay line 400 and enters the third end of the first polarization element 301. The first polarization element 301 holds the second optical signal S after the delay processing. 21 The polarization direction of ' remains unchanged, and it is output from the first end, so that the second optical signal S after delay processing is... 21 The signal enters the second terminal of the first optical transmission element 611. The first optical transmission element 611 outputs the delayed second optical signal S from the third terminal. 21 This allows it to enter mixer 214 and be mixed with the local oscillator signal of the calibration path in the second frequency modulation photoelectric circuit 210.

[0250] Optionally, the second frequency modulation group 21 may include only one third frequency modulation photoelectric circuit 310, or it may include both the third frequency modulation photoelectric circuit 310 and other frequency modulation photoelectric circuits, which will be explained below.

[0251] In one example, when only the third frequency-modulated optoelectronic circuit 310 is included, as shown in Figure 17a, the second end of the first polarizing element 301 is connected to the first beam splitter 312 in the third frequency-modulated optoelectronic circuit 310, and the second end of the second polarizing element 302 is connected to the mixer 314 in the third frequency-modulated optoelectronic circuit 310. Based on this connection, in the third frequency-modulated optoelectronic circuit 310, after the first beam splitter 312 receives the optical signal S3 output by the light source 311, it performs beam splitting processing on the optical signal S3 to obtain the detection signal, the calibration path local oscillator signal, and the third optical signal S. 31 The detection signal is output to the target measurement path 313, the local oscillator signal of the calibration path is output to the mixer 314, and the third optical signal S is output to the mixer 314. 31 The signal is output to the second terminal of the first polarization element 301. The first polarization element 301 converts the third optical signal S... 31 Orthogonal to the first optical signal S 11 The polarization direction is output from its third end, making the third optical signal S 31 The light enters the first end a1 of the optical delay line 400, propagates from left to right within the optical delay line 400, and exits from the second end a2 of the optical delay line 400, entering the third end of the second polarization element 302. The second polarization element 302 then outputs the delayed third optical signal S. 31 The original polarization direction of the third frequency-modulated photoelectric circuit 310 is output from its second end, so that the delayed third optical signal S 31 The signal enters mixer 314 and is mixed with the local oscillator signal of the calibration path in the third frequency-modulated optoelectronic circuit 310. Based on this connection, the optical signals in the third frequency-modulated optoelectronic circuit 310 and the first frequency-modulated optoelectronic circuit 110 are transmitted in the same direction in the optical delay line 400, while the optical signal in the second frequency-modulated optoelectronic circuit 210 is transmitted in the opposite direction in the optical delay line 400.

[0252] Understandably, the connection can also be reversed. For example, referring to Figure 17b, the second end of the first polarizing element 301 is connected to the mixer 314 in the third frequency-modulated optoelectronic circuit 310, and the second end of the second polarizing element 302 is connected to the first beam-splitting element 312 in the third frequency-modulated optoelectronic circuit 310. Based on this connection, in the third frequency-modulated optoelectronic circuit 310, the third optical signal S after being split by the first beam-splitting element 312... 31 The signal is output to the second terminal of the second polarization element 302. The second polarization element 302 converts the third optical signal S... 31 Orthogonal to the first optical signal S 11The polarization direction is output from its third end, making the third optical signal S 31 The light enters the second end a2 of the optical delay line 400, propagates from right to left, and then exits from the first end a1 of the optical delay line 400, entering the third end of the first polarization element 301. The first polarization element 301 then delays the third optical signal S. 31 The original polarization direction of the third frequency-modulated photoelectric circuit 310 is output from its second end, so that the delayed third optical signal S 31 The signal enters mixer 314 and is mixed with the local oscillator signal of the calibration path in the third frequency-modulated photoelectric circuit 310. With this connection, the optical signals in the third frequency-modulated photoelectric circuit 310 and the second frequency-modulated photoelectric circuit 210 are transmitted in the same direction in the optical delay line 400, while the optical signal in the first frequency-modulated photoelectric circuit 110 is transmitted in the opposite direction in the optical delay line 400.

[0253] When the second frequency modulation group 21 includes both the third frequency modulation optoelectronic circuit 310 and other frequency modulation optoelectronic circuits, as shown in FIG18, it may also include a fourth frequency modulation optoelectronic circuit 410, a third optical transmission element 711, and a fourth optical transmission element 712. The fourth frequency modulation optoelectronic circuit 410 includes a light source 411, a first beam splitter 412, a mixer 414, a photodetector 412, an amplifier 418, an analog-to-digital converter 419, a processing element 416, and a driving circuit 417. The third optical transmission element 711 is connected between the first beam splitter 312 in the third frequency modulation optoelectronic circuit 310, the mixer 414 in the fourth frequency modulation optoelectronic circuit 410, and the second end of the first polarization element 301. The fourth optical transmission element 712 is connected between the first beam splitter 412 in the fourth frequency modulation optoelectronic circuit 410, the mixer 314 in the third frequency modulation optoelectronic circuit 310, and the second end of the second polarization element 302. For example, as shown in Figure 18, both the third optical transmission element 711 and the fourth optical transmission element 712 have three ends, with unidirectional transmission between the first end and the second end, and between the second end and the third end. The first end of the third optical transmission element 711 is connected to the first beam splitter 312, the second end of the third optical transmission element 711 is connected to the second end of the first polarization element 301, and the third end of the third optical transmission element 711 is connected to the mixer 414. The first end of the fourth optical transmission element 712 is connected to the first beam splitter 412, the second end of the fourth optical transmission element 712 is connected to the second end of the second polarization element 302, and the third end of the fourth optical transmission element 712 is connected to the mixer 314.

[0254] Based on this structure and connection, the first beam splitter 112 in the first frequency-modulated photoelectric circuit 110 splits the first optical signal S1 from the optical signal S1 output by the light source 111. 11 And output to the first optical transmission element 611, the first optical transmission element 611 transmits the first optical signal S11 The signal is transmitted to the first end of the first polarization element 301. The first beam splitter 312 in the third frequency-modulated photoelectric circuit 310 splits the third optical signal S3 from the optical signal S3 output from the light source 311, thus separating the third optical signal S. 31 The signal is then output to the third optical transmission element 711, which transmits the third optical signal S. 31 The signal is transmitted to the second end of the first polarization element 301. The first polarization element 301 holds the first optical signal S input at the first end. 11 The polarization direction remains unchanged, so that the third optical signal S input at the second end remains unchanged. 31 The polarization direction is orthogonal to the first optical signal S 11 The two optical signals are output together from the third end to the first end a1 of the optical delay line 400, allowing them to propagate from left to right within the optical delay line 400. They are then output from the second end a2 of the optical delay line 400 and enter the third end of the second polarization element 302. The second polarization element 302 holds the delayed first optical signal S. 11 The polarization direction remains unchanged, and the signal is output from its first end to the second optical transmission element 612, then transmitted to the mixer 114 via the second optical transmission element 612, and the third optical signal S after delay processing is... 31 The original polarization direction of the third frequency-modulated photoelectric circuit 310 is output to the fourth optical transmission element 712, and then transmitted to the mixer 314 via the fourth optical transmission element 712.

[0255] Conversely, in the second frequency-modulated photoelectric circuit 210, the first beam-splitting element 212 splits the second optical signal S from the optical signal S2 output from the light source 211. 21 The signal is transmitted to the second optical transmission element 612, which then transmits the second optical signal S. 21 The signal is transmitted to the first end of the second polarization element 302. The first beam splitter 412 in the fourth frequency-modulated photoelectric circuit 410 splits the fourth optical signal S4 from the optical signal S4 output from the light source 411. 41 And output to the fourth optical transmission element 712, the fourth optical transmission element 712 transmits the fourth optical signal S 41 The signal is transmitted to the second end of the second polarization element 302. The second polarization element 302 holds the second optical signal S input from the first end. 21 The polarization direction remains unchanged, so that the fourth optical signal S input at the second end remains unchanged. 41 The polarization direction is orthogonal to the second optical signal S 21 The two optical signals are output together from the third end to the second end a2 of the optical delay line 400, so that they are transmitted from right to left in the optical delay line 400 and output from the first end a1 of the optical delay line 400, entering the third end of the first polarization element 301. The first polarization element 301 holds the second optical signal S after the delay processing. 21The polarization direction of the signal remains unchanged, and it is output to the first optical transmission element 611 through its first end. The signal is then transmitted to the mixer 214 via the first optical transmission element 611, and the delayed fourth optical signal S... 41 The original polarization direction of the fourth frequency-modulated photoelectric circuit 410 is output to the third optical transmission element 711, and then transmitted to the mixer 414 via the third optical transmission element 711.

[0256] Understandably, in the structure shown in Figure 18, the transmission directions of the optical signals in the first frequency-modulated photoelectric circuit 110 and the third frequency-modulated photoelectric circuit 310 are opposite to those in the second frequency-modulated photoelectric circuit 210 and the fourth frequency-modulated photoelectric circuit 410. Based on the interference characteristics and independence of light, the two or more optical signals transmitted in opposite directions can be directly separated after leaving the common transmission area. Therefore, the correlation characteristics of the optical signals in the first frequency-modulated photoelectric circuit 110 and the third frequency-modulated photoelectric circuit 310 can be exactly the same as those in the second frequency-modulated photoelectric circuit 210 and the fourth frequency-modulated photoelectric circuit 410, such as the same wavelength, the same frequency modulation direction, the same frequency modulation slope, etc. This will not affect the signal flow process between the frequency-modulated photoelectric circuits transmitting in opposite directions.

[0257] Conversely, for two frequency-modulated photoelectric circuits transmitting in the same direction, such as the first frequency-modulated photoelectric circuit 110 and the third frequency-modulated photoelectric circuit 310, or the second frequency-modulated photoelectric circuit 210 and the fourth frequency-modulated photoelectric circuit 410, although two sets of optical signals will transmit in the same direction in the optical delay line 400, since the two frequency-modulated photoelectric circuits belong to two different frequency-modulation groups, and the optical signals in the two frequency-modulation groups have orthogonal polarization directions in the optical delay line 400, the delayed optical signals can also be separated in the polarization control element based on the orthogonal polarization directions. Based on this, the relevant characteristics of the optical signals in the two frequency-modulated photoelectric circuits transmitting in the same direction can also be completely identical. For example, the optical signals in the first frequency-modulated photoelectric circuit 110 and the third frequency-modulated photoelectric circuit 310 have the same wavelength, the same frequency modulation direction, and the same frequency modulation slope, etc., and the optical signals in the second frequency-modulated photoelectric circuit 210 and the fourth frequency-modulated photoelectric circuit 410 have the same wavelength, the same frequency modulation direction, and the same frequency modulation slope, etc. This will not affect the signal flow process between the frequency-modulated photoelectric circuits transmitting in the same direction.

[0258] To better understand how the polarization direction of an optical signal changes during transmission in a signal processing device, two examples are given below.

[0259] In one example, assuming that the optical signals in the first frequency-modulated photoelectric circuit 110 and the second frequency-modulated photoelectric circuit 210 are configured as TE light, and the optical signals in the third frequency-modulated photoelectric circuit 310 and the fourth frequency-modulated photoelectric circuit 410 are configured as TM light, then, as shown in Figure 19a, the first polarization element 301 and the second polarization element 302 can specifically be PBS, for example, the first polarization element 301 is PBS3011 and the second polarization element 302 is PBS3021.

[0260] Viewed from left to right, the light source 111 in the first frequency-modulated photoelectric circuit 110 outputs TE light, which is then split by the first beam splitter 112 to obtain the first optical signal S. 11 That is, TE light, which enters the first end of the first optical transmission element 611, exits from the second end of the first optical transmission element 611, and enters the first end of PBS3011. The light source 311 in the third frequency-modulated photoelectric circuit 310 outputs TM light, which is then split by the first beam splitter 312 to obtain the third optical signal S. 31 That is, the TM light enters the first end of the third optical transmission element 711, exits from the second end of the third optical transmission element 711, and enters the second end of the PBS 3011. The PBS 3011 transmits the TE light input from the first end to the third end and reflects the TM light input from the second end to the third end, so that the TE light and TM light are output together from the third end to the optical delay line 400. After a left-to-right transmission delay in the optical delay line 400, it enters the third end of the PBS 3021. The PBS 3021 transmits the TE light to the first end and reflects the TM light to the second end. Therefore, the TE light enters the second end of the second optical transmission element 612, exits from the third end of the second optical transmission element 612, enters the mixer 114, and participates in the mixing operation in the first frequency modulation optoelectronic circuit 110. The TM light enters the second end of the fourth optical transmission element 712, exits from the third end of the fourth optical transmission element 712, enters the mixer 314, and participates in the mixing operation in the third frequency modulation optoelectronic circuit 310.

[0261] Conversely, the light source 211 in the second frequency-modulated photoelectric circuit 210 outputs TE light, which is then split by the first beam splitter 212 to obtain the second optical signal S. 21 That is, the TE light enters the first end of the second optical transmission element 612, exits from the second end of the second optical transmission element 612, and enters the first end of the PBS3021. The light source 411 in the fourth frequency-modulated photoelectric circuit 410 outputs TM light, which is split by the first beam splitter 412 to obtain the fourth optical signal S. 41That is, the TM light enters the first end of the fourth optical transmission element 712, exits from the second end of the fourth optical transmission element 712, and enters the second end of the PBS 3021. The PBS 3021 transmits the TE light input from the first end to the third end and reflects the TM light input from the second end to the third end, so that the TE light and TM light are output together from the third end to the optical delay line 400. After a right-to-left transmission delay in the optical delay line 400, it enters the third end of the PBS 3011. The PBS 3011 transmits the TE light to the first end and reflects the TM light to the second end. Therefore, the TE light enters the second end of the first optical transmission element 611, exits from the third end of the first optical transmission element 611, enters the mixer 214, and participates in the mixing operation in the second frequency modulation optoelectronic circuit 210. The TM light enters the second end of the third optical transmission element 711, exits from the third end of the third optical transmission element 711, enters the mixer 414, and participates in the mixing operation in the fourth frequency modulation optoelectronic circuit 410.

[0262] In another example, assuming that the optical signals in the first frequency-modulated photoelectric circuit 110 to the fourth frequency-modulated photoelectric circuit 410 are all configured as TE light, then, as shown in Figure 19b, the first polarization element 301 and the second polarization element 302 can specifically be PSRs, for example, the first polarization element 301 is PSR3012 and the second polarization element 301 is PSR3022.

[0263] Viewed from left to right, the light source 111 in the first frequency-modulated photoelectric circuit 110 outputs TE light, which is then split by the first beam splitter 112 to obtain the first optical signal S. 11 That is, TE light. This TE light enters the first end of the first optical transmission element 611, exits from the second end of the first optical transmission element 611, and enters the first end of the PSR3012. The light source 311 in the third frequency-modulated photoelectric circuit 310 also outputs TE light. This TE light is split by the first beam splitter 312 to obtain the third optical signal S. 31That is, the TE light enters the first end of the third optical transmission element 711, exits from the second end of the third optical transmission element 711, and enters the second end of PSR3012. PSR3012 keeps the polarization direction of the TE light input at the first end unchanged, rotates the polarization direction of the TE light input at the second end by 90° to make it TM light, and outputs the TE light and TM light together from the third end, so that the TE light and TM light enter the optical delay line 400 together. After a left-to-right transmission delay in the optical delay line 400, it enters the third end of PSR3022. PSR3022 keeps the polarization direction of the TE light input at the third end unchanged, makes it exit from the first end, enter the second end of the second optical transmission element 612, and exit from the third end of the second optical transmission element 612, enter the mixer 114, and participate in the mixing operation in the first frequency modulation optoelectronic circuit 110. PSR3022 rotates the polarization direction of the TM light input at the third end by 90°, turning it into TE light, and outputs it from the second end to the second end of the fourth optical transmission element 712, and outputs it from the third end of the fourth optical transmission element 712 to enter the mixer 314 to participate in the mixing operation in the third frequency modulation optoelectronic circuit 310.

[0264] Conversely, the light source 211 in the second frequency-modulated photoelectric circuit 210 outputs TE light, which is then split by the first beam splitter 212 to obtain the second optical signal S. 21 That is, TE light. This TE light enters the first end of the second optical transmission element 612, exits from the second end of the second optical transmission element 612, and enters the first end of the PSR3022. The light source 411 in the fourth frequency-modulated photoelectric circuit 410 also outputs TE light. This TE light is split by the first beam splitter 412 to obtain the fourth optical signal S. 41That is, the TE light enters the first end of the fourth optical transmission element 712, exits from the second end of the fourth optical transmission element 712, and enters the second end of PSR3022. PSR3022 keeps the polarization direction of the TE light input at the first end unchanged, rotates the polarization direction of the TE light input at the second end by 90° to make it TM light, and outputs the TE light and TM light together from the third end, so that the TE light and TM light enter the optical delay line 400 together. After a right-to-left transmission delay in the optical delay line 400, it enters the third end of PSR3012. PSR3012 keeps the polarization direction of the TE light input at the third end unchanged, outputs it from the first end, enters the second end of the first optical transmission element 611, and exits from the third end of the first optical transmission element 611 to enter the mixer 214, participating in the mixing operation in the second frequency modulation optoelectronic circuit 210. PSR3012 rotates the polarization direction of the TM light input at the third end by 90°, turning it into TE light, and outputs it from the second end to the second end of the third optical transmission element 711, and outputs it from the third end of the third optical transmission element 711 to the mixer 414, where it participates in the mixing operation in the fourth frequency modulation optoelectronic circuit 410.

[0265] Similar to the above implementation scheme one or two, the structure of the above signal processing device can also be extended to a signal processing device with three or more frequency modulation groups, so that all frequency modulation photoelectric circuits in the three or more frequency modulation groups share the same optical delay line 400 to transmit the delay signals of all frequency modulation photoelectric circuits in the three or more frequency modulation groups in the same direction.

[0266] For example, based on the signal processing device shown in Figure 18, please refer to Figure 20a, which shows a schematic diagram of another signal processing device provided in Embodiment 3. In this example, the signal processing device includes a first frequency modulation group and N second frequency modulation groups, where N is an integer greater than or equal to 2. The first frequency modulation group includes a first frequency modulation photoelectric circuit 110 and a second frequency modulation photoelectric circuit 210. The first second frequency modulation group includes a third frequency modulation photoelectric circuit 310 and a fourth frequency modulation photoelectric circuit 410. The specific structure is described above and will not be repeated here.

[0267] The second frequency modulation group includes a third frequency modulation photoelectric circuit 320 and a fourth frequency modulation photoelectric circuit 420. The third frequency modulation photoelectric circuit 320 includes a light source 321, a first beam splitter 322, a third optical transmission element 721, a fourth optical transmission element 722, a mixer 324, a photodetector 325, an amplifier 328, an analog-to-digital converter 329, a processing element 326, and a drive circuit 327. The fourth frequency modulation photoelectric circuit 420 includes a light source 421, a first beam splitter 422, a mixer 424, a photodetector 425, an amplifier 428, an analog-to-digital converter 429, a processing element 426, and a drive circuit 427. ...and so on, the Nth second frequency modulation group includes a third frequency modulation photoelectric circuit 3N0 and a fourth frequency modulation photoelectric circuit 4N0. The third frequency modulation photoelectric circuit 3N0 includes a light source 3N1, a first beam splitter 3N2, a third optical transmission element 7N1, a fourth optical transmission element 7N2, a mixer 3N4, a photodetector 3N5, an amplifier 3N8, an analog-to-digital converter 3N9, a processing element 3N6, and a drive circuit 3N7. The fourth frequency modulation photoelectric circuit 4N0 includes a light source 4N1, a first beam splitter 4N2, a mixer 4N4, a photodetector 4N5, an amplifier 4N8, an analog-to-digital converter 4N9, a processing element 4N6, and a drive circuit 4N7. The connection relationships of each component are shown in Figure 20a, and will not be repeated here.

[0268] In addition to the components mentioned above, as shown in Figure 20a, the signal processing device may also include two optical combining / splitting elements, namely optical combining / splitting element 530 and optical combining / splitting element 540. Optical combining / splitting element 530 has two communication terminals (communication terminals are terminals that function as both inputs and outputs) and N-1 output terminals. Optical combining / splitting element 540 has two communication terminals and N-1 input terminals. One communication terminal of optical combining / splitting element 530 is connected to the first polarization element 301 in the first frequency modulation group, and the other communication terminal is connected to the first end a1 of the optical delay line 400. The other N-1 output terminals are connected one-to-one with the N third optical transmission elements 721 to 7N1 in the N second frequency modulation groups. One communication terminal of optical combining / splitting element 540 is connected to the second polarization element 302 in the first frequency modulation group, and the other communication terminal is connected to the second end a2 of the optical delay line 400. The other N-1 input terminals are connected one-to-one with the N fourth optical transmission elements 722 to 7N2 in the N second frequency modulation groups.

[0269] Based on this structure and connection, viewed from left to right, in the first frequency modulation group, the delay signal S output by the first beam splitter 112 in the first frequency modulation photoelectric circuit 110 is... 11 The light enters the first optical transmission element 611 and is transmitted to the first polarization element 301. Meanwhile, in the first second frequency modulation group, the delay signal S output by the first beam splitter 312 in the third frequency modulation optoelectronic circuit 310... 31The signal enters the third optical transmission element 711 and is also transmitted to the first polarization element 301. The first polarization element 301 transmits the signal S to be delayed. 11 and the delay signal S 31 The signal S is transmitted to the beam combiner / splitter 530 with orthogonal polarization directions. In the second to Nth second frequency modulation groups, the delay signal S output by the first beam splitter 322 to 3N2 in the N-1 third frequency modulation photoelectric circuits 320 to 3N0 is... 32 ~S 3N The light enters the third optical transmission elements 721-7N1 and is also transmitted to the combining and splitting optical element 530. The combining and splitting optical element 530 converts these N sets of delayed signals S 11 +S 31 S 32 ... S 3N After being combined into a single optical signal, the signal is output to the first end a1 of the optical delay line 400. After being transmitted from left to right, the signal is output at the second end a2 of the optical delay line 400 and enters the combining and splitting element 540.

[0270] Optionally, the optical signal wavelengths of the N third frequency-modulated optoelectronic circuits 310 to 3N0 are all different. Based on this, the combining and splitting element 540 separates the delayed optical signals S from the N groups of delayed optical signals into N-1 delayed optical signals S from the third frequency-modulated optoelectronic circuits 320 to 3N0. 32 '~S 3N Each of these signals is sent to the fourth optical transmission elements 722-7N2 in the second to Nth second frequency modulation groups, and then transmitted via the fourth optical transmission elements 722-7N2 to the mixers 324-3N4 in the N-1 third frequency modulation optoelectronic circuits 320-3N0, as well as to the delayed optical signal S in the first frequency modulation optical circuit 110 and the third frequency modulation optoelectronic circuit 310. 11 '+S 31 The signal is sent to the second polarization element 302. The second polarization element 302 then transmits the delayed optical signal S from the first frequency modulation optical circuit 110. 11 The optical signal S, after being output in the polarization direction of the first frequency-modulated photoelectric circuit 110, is transmitted to the second optical transmission element 612 via the second optical transmission element 612 to the mixer 114, and is also transmitted to the third frequency-modulated optical circuit 310 after delay processing. 31 The light is output to the fourth optical transmission element 712 in the polarization direction of the third frequency modulation photoelectric circuit 310, and then transmitted to the mixer 314 via the fourth optical transmission element 712.

[0271] Conversely, in the first frequency modulation group, the delay signal S output by the first beam splitter 212 in the second frequency modulation photoelectric circuit 210 is... 21The light enters the second optical transmission element 612 and is transmitted to the second polarization element 302. Meanwhile, in the first second frequency modulation group, the delay signal S output by the first beam splitter 412 in the fourth frequency modulation photoelectric circuit 410... 41 The signal enters the fourth optical transmission element 712 and is also transmitted to the second polarization element 302. The second polarization element 302 then transmits the signal S to be delayed. 21 and the delay signal S 41 The signal S is transmitted to the beam splitter 540 with orthogonal polarization directions. In the second to Nth second frequency modulation groups, the delay signal S output by the first beam splitter 422 to 4N2 in the N-1 fourth frequency modulation photoelectric circuits 420 to 4N0 is... 42 ~S 4N The light enters the fourth optical transmission elements 722-7N2 and is also transmitted to the combining and splitting optical element 540. The combining and splitting optical element 540 converts these N sets of delayed signals S 21 +S 41 S 42 ... S 4N After being combined into a single optical signal, the signal is output to the second end a2 of the optical delay line 400. After a delay from right to left, the signal is output at the first end a1 of the optical delay line 400 and enters the combining and splitting element 530.

[0272] Optionally, the optical signal wavelengths of the N fourth frequency-modulated photoelectric circuits 410 to 4N0 are all different. Based on this, the combining and splitting element 530 separates the delayed optical signal S from the N groups of delayed optical signals into N-1 delayed optical signals S from the fourth frequency-modulated photoelectric circuits 420 to 4N0. 42 '~S 4N Each of these signals is sent to the third optical transmission elements 721 to 7N1 in the second to Nth second frequency modulation groups, and then transmitted via the third optical transmission elements 721 to 7N1 to the mixers 424 to 4N4 in the N-1 fourth frequency modulation optoelectronic circuits 420 to 4N0, and the delayed optical signal S in the second frequency modulation optical circuit 210 and the fourth frequency modulation optoelectronic circuit 410 is processed. 21 '+S 41 The signal is sent to the first polarization element 301. The first polarization element 301 transmits the delayed optical signal S from the second frequency modulation optical circuit 210. 21 The optical signal S, output in the polarization direction of the second frequency-modulated photoelectric circuit 210, is transmitted to the first optical transmission element 611 via the first optical transmission element 611 to the mixer 214, and the delayed optical signal S in the fourth frequency-modulated optical circuit 410 is also transmitted. 41 The light is output to the third optical transmission element 711 in the polarization direction of the fourth frequency modulation photoelectric circuit 410, and then transmitted to the mixer 414 via the third optical transmission element 711.

[0273] For example, in another example, based on the signal processing device shown in Figure 18, please refer to Figure 20b, which shows a schematic diagram of another signal processing device provided in Embodiment 3. In this example, the signal processing device includes N first frequency modulation groups and N second frequency modulation groups in a one-to-one correspondence, where N is an integer greater than or equal to 2. Each first frequency modulation group includes a first frequency modulation photoelectric circuit and a second frequency modulation photoelectric circuit, and each second frequency modulation group includes a third frequency modulation photoelectric circuit and a frequency modulation photoelectric circuit.

[0274] For example, the Nth first frequency modulation group includes a first frequency modulation optoelectronic circuit 1N0, a second frequency modulation optoelectronic circuit 2N0, a first polarization element 301N, a second polarization element 302N, a first optical transmission element 6N1, and a second optical transmission element 6N2. The first frequency modulation optoelectronic circuit 1N0 includes a light source 1N1, a first beam splitter 1N2, a mixer 1N4, a photodetector 1N5, an amplifier 1N8, an analog-to-digital converter 1N9, a processing element 1N6, and a drive circuit 1N7. The second frequency modulation optoelectronic circuit 2N0 includes a light source 2N1, a first beam splitter 2N2, a mixer 2N4, a photodetector 2N5, an amplifier 2N8, an analog-to-digital converter 2N9, a processing element 2N6, and a drive circuit 2N7. The Nth second frequency modulation group includes a third frequency modulation optoelectronic circuit 3N0, a fourth frequency modulation optoelectronic circuit 4N0, a third optical transmission element 7N1, and a fourth optical transmission element 7N2. The third frequency-modulated optoelectronic circuit 3N0 includes a light source 3N1, a first beam splitter 3N2, a mixer 3N4, a photodetector 3N5, an amplifier 3N8, an analog-to-digital converter 3N9, a processing element 3N6, and a driver circuit 3N7. The fourth frequency-modulated optoelectronic circuit 4N0 includes a light source 4N1, a first beam splitter 4N2, a mixer 4N4, a photodetector 4N5, an amplifier 4N8, an analog-to-digital converter 4N9, a processing element 4N6, and a driver circuit 4N7. The connection relationships of each component are shown in Figure 20b, and will not be repeated here.

[0275] In addition to the components mentioned above, as shown in Figure 20b, the signal processing device may also include two optical combiner / splitter elements, namely optical combiner / splitter element 530 and optical combiner / splitter element 540. Both optical combiner / splitter element 530 and optical combiner / splitter element 540 have N+1 communication terminals. One communication terminal of optical combiner / splitter element 530 is connected to the first terminal a1 of optical delay line 400, and the remaining N communication terminals are connected one-to-one to the N first polarization elements 301 to 301N in the N first frequency modulation groups. One communication terminal of optical combiner / splitter element 540 is connected to the second terminal a2 of optical delay line 400, and the other N communication terminals are connected one-to-one to the N second polarization elements 302 to 302N in the N first frequency modulation groups.

[0276] Based on this structure and connection relationship, viewed from left to right, in the N first frequency modulation groups, the delay signal S output by the N first beam splitting elements 112~1N2 in the N first frequency modulation photoelectric circuits 110 is... 11 ~S 1N The signals are respectively transmitted to N first optical transmission elements 611-6N1 and then to N first polarization elements 301-301N. Meanwhile, in the N second frequency modulation groups, the delayed signal S output from the N first beam splitters 312-3N2 in the N third frequency modulation optoelectronic circuits 310... 31 ~S 3N The signals are respectively transmitted to N third optical transmission elements 711-7N1 and also to N first polarization elements 301-301N. The N first polarization elements 301-301N respectively transmit the N signals S to be delayed. 11 ~S 1N and N signals S to be delayed 31 ~S 3N The outputs are orthogonally polarized to the combining / splitting element 530. Optionally, the optical signals from N first frequency-modulated photoelectric circuits 110 to 1N0 have different wavelengths, and the optical signals from N third frequency-modulated photoelectric circuits 320 to 3N0 have different wavelengths. Based on this, the combining / splitting element 540 separates N pairs of delayed optical signals S from the 2N groups of delayed optical signals based on wavelength. 11 '+S 31 '~S 1N '+S 3N The signals are respectively sent to N second polarization elements 302 to 302N in the first and second frequency modulation groups. Each second polarization element outputs the delayed optical signal received from the first frequency modulation optical circuit to the connected second optical transmission element in the polarization direction of the first frequency modulation optoelectronic circuit, and then transmits it to the mixer in the first frequency modulation optoelectronic circuit via the second optical transmission element. It also outputs the delayed optical signal from the third frequency modulation optical circuit to the fourth optical transmission element in the polarization direction of the third frequency modulation optoelectronic circuit, and then transmits it to the mixer in the third frequency modulation optoelectronic circuit via the fourth optical transmission element.

[0277] Conversely, in the N first frequency modulation groups, the delay signal S output by the first beam splitter 212 to 2N2 in the N second frequency modulation photoelectric circuits 210 to 2N0 is... 21 ~S 2N The light enters the second optical transmission elements 612-6N2 and is transmitted to N second polarization elements 302-302N. Meanwhile, in the N second frequency modulation groups, the delayed signal S output from the first beam splitter 412-4N2 of the N fourth frequency modulation optoelectronic circuits 410-4N0... 41 ~S 4NThe light enters the fourth optical transmission element 712-7N2 and is also transmitted to N second polarization elements 302-302N. The N second polarization elements 302-302N then transmit the N signals S to be delayed. 21 ~S 2N and N signals S to be delayed 41 ~S 4N The signals are transmitted to the combiner / splitter 540 with orthogonal polarization directions. The combiner / splitter 540 combines these 2N groups of signals to be delayed into a single optical signal and outputs it to the second end a2 of the optical delay line 400. After being delayed from right to left, the signal is output from the first end a1 of the optical delay line 400 and enters the combiner / splitter 530. Optionally, the optical signal wavelengths of the N second frequency-modulated photoelectric circuits 210–2N0 are all different, and the optical signal wavelengths of the N fourth frequency-modulated photoelectric circuits 420–4N0 are all different. Based on this, the combiner / splitter 530 separates N pairs of delayed optical signals S from the 2N groups of delayed optical signals based on wavelength. 21 '+S 41 '~S 2N '+S 4N The signals are respectively sent to N first polarization elements 301 to 301N in the first and second frequency modulation groups. Each first polarization element outputs the delayed optical signal received from the second frequency modulation optical circuit to the connected first optical transmission element in the polarization direction of the second frequency modulation optoelectronic circuit, and then transmits it to the mixer in the second frequency modulation optoelectronic circuit via the first optical transmission element. It also outputs the delayed optical signal from the fourth frequency modulation optical circuit to the third optical transmission element in the polarization direction of the fourth frequency modulation optoelectronic circuit, and then transmits it to the mixer in the fourth frequency modulation optoelectronic circuit via the third optical transmission element.

[0278] For example, in one instance, when N first polarizing elements 301–301N and N second polarizing elements 302–302N are all PBS, as shown in Figure 20c, the signal S to be delayed in the N first frequency-modulated photoelectric circuits 110–1N0 can be... 11 ~S 1N and the delay signal S in N second frequency-modulated photoelectric circuits 210~2N0 21 ~S 2N Configured as TE light, the signal S to be delayed in N third frequency-modulated photoelectric circuits 310 to 3N0 is... 31 ~S 3N and the delay signal S in N fourth frequency-modulated photoelectric circuits 410~4N0 41 ~S 4NThe optical signal is configured as TM light, and the wavelengths of the optical signals in any two first frequency-modulated photoelectric circuits, any two second frequency-modulated photoelectric circuits, any two third frequency-modulated photoelectric circuits, and any two fourth frequency-modulated photoelectric circuits are different.

[0279] Based on this, the N TE beams output from the first beam splitters 112-1N2 in the N first frequency-modulated optoelectronic circuits 110-1N0 are transmitted by the first optical transmission elements 611-6N1 to the left-hand PBS in the N pairs of frequency-modulated groups. Similarly, the TM beams output from the first beam splitters 312-3N2 in the N third frequency-modulated optoelectronic circuits 310-3N0 are also transmitted by the third optical transmission elements 711-7N1 to the left-hand PBS in the N pairs of frequency-modulated groups. The left-hand PBS in the N pairs of frequency-modulated groups transmits the N TE beams to the combining and splitting element 530 and reflects the N TM beams to the combining and splitting element 530. The combining and splitting element 530 combines the N TE beams and N TM beams into a single optical signal and outputs it to the first end a1 of the optical delay line 400. After a left-to-right transmission delay, it outputs at the second end a2 of the optical delay line 400 and enters the combining and splitting element 540. The beam splitter 540, based on wavelength, separates N delayed TE and TM beams from 2N delayed TE and TM beams from the first frequency-modulated optoelectronic circuits 110-1N0 and N delayed TM beams from the third frequency-modulated optoelectronic circuits 310-3N0. The delayed TE and TM beams from the first frequency-modulated optoelectronic circuit 110 and the third frequency-modulated optoelectronic circuit 310 are then sent to the rightmost PBS in the first pair of frequency-modulated groups, and so on. The delayed TE and TM beams from the first frequency-modulated optoelectronic circuit 1N0 and the third frequency-modulated optoelectronic circuit 3N0 are sent to the rightmost PBS in the Nth pair of frequency-modulated groups. Each rightmost PBS transmits the TE beam to the connected second optical transmission element, allowing the TE beam to be transmitted through the second optical transmission element to the mixer in the connected first frequency-modulated optoelectronic circuit for mixing with the calibration path local oscillator signal of the TE beam in the first frequency-modulated optoelectronic circuit. Furthermore, the TM light is reflected to the connected fourth optical transmission element, so that the TM light is transmitted through the fourth optical transmission element to the mixer in the connected third frequency modulation optoelectronic circuit, and mixed with the calibration path local oscillator signal of the TM light in the third frequency modulation optoelectronic circuit.

[0280] Conversely, the N TE beams output from the first beam splitters 212-2N2 in the N second frequency-modulated optoelectronic circuits 210-2N0 are transmitted by the second optical transmission elements 612-6N2 to the right-hand PBS in the N pairs of frequency-modulated groups. Similarly, the TM beams output from the first beam splitters 412-4N2 in the N fourth frequency-modulated optoelectronic circuits 410-4N0 are also transmitted by the fourth optical transmission elements 712-7N2 to the right-hand PBS in the N pairs of frequency-modulated groups. The right-hand PBS in the N pairs of frequency-modulated groups transmits the N TE beams to the combining and splitting element 540 and reflects the N TM beams to the combining and splitting element 540. The combining and splitting element 540 combines the N TE beams and N TM beams into a single optical signal and outputs it to the second end a2 of the optical delay line 400. After a right-to-left transmission delay, it outputs at the first end a1 of the optical delay line 400 and enters the combining and splitting element 530. The beam combiner / splitter 530, based on wavelength, separates the delayed TE light from 2N delayed TM light sources from the second frequency-modulated optoelectronic circuits 210–2N0 and the delayed TM light from the fourth frequency-modulated optoelectronic circuits 410–4N0. The delayed TE light from the second frequency-modulated optoelectronic circuit 210 and the delayed TM light from the fourth frequency-modulated optoelectronic circuit 410 are then sent to the left-hand PBS in the first pair of frequency-modulated groups, and so on. The delayed TE light from the second frequency-modulated optoelectronic circuit 2N0 and the delayed TM light from the fourth frequency-modulated optoelectronic circuit 4N0 are sent to the left-hand PBS in the Nth pair of frequency-modulated groups. Each left-hand PBS transmits the TE light to the connected first optical transmission element, allowing the TE light to pass through the first optical transmission element to the mixer in the connected second frequency-modulated optoelectronic circuit for mixing with the calibration path local oscillator signal of the TE light in the second frequency-modulated optoelectronic circuit. Furthermore, the TM light is reflected to the connected third optical transmission element, so that the TM light is transmitted through the third optical transmission element to the mixer in the connected fourth frequency modulation optoelectronic circuit, and mixed with the calibration path local oscillator signal of the TM light in the fourth frequency modulation optoelectronic circuit.

[0281] For example, in another example, when both the first polarization element 301 and the second polarization element 302 are PSRs, as shown in Figure 20d, the signals S to be delayed in the N first frequency-modulated photoelectric circuits 110 can be... 11 ~S 1N The delay signal S in N second frequency modulation photoelectric circuits 210 21 ~S 2N The delay signal S in N third frequency-modulated photoelectric circuits 310 to 3N0 31 ~S 3N and the delay signal S in N fourth frequency-modulated photoelectric circuits 410~4N0 41 ~S 4NAll are configured with TE light, and the optical signals in any two first frequency-modulated photoelectric circuits, any two second frequency-modulated photoelectric circuits, any two third frequency-modulated photoelectric circuits, and any two fourth frequency-modulated photoelectric circuits have different wavelengths.

[0282] Based on this, the N TE beams output from the first beam splitters 112-1N2 in the N first frequency-modulated optoelectronic circuits 110-1N0 are transmitted by the first optical transmission elements 611-6N1 to the left PSR in the N pairs of frequency-modulated groups. Similarly, the TE beams output from the first beam splitters 312-3N2 in the N third frequency-modulated optoelectronic circuits 310-3N0 are also transmitted by the third optical transmission elements 711-7N1 to the left PSR in the N pairs of frequency-modulated groups. The left PSR in the N pairs of frequency-modulated groups maintains the polarization direction of the TE beams in the N first frequency-modulated optoelectronic circuits 110-1N0 unchanged, rotates the polarization direction of the TE beams in the N third frequency-modulated optoelectronic circuits 310-3N0 by 90° to convert them into TM beams, and outputs the N TE beams and N TM beams to the combining and splitting element 530. The beam combiner / splitter 530 combines N TE beams and N TM beams into a single optical signal and outputs it to the first end a1 of the optical delay line 400. After a left-to-right transmission delay, it outputs at the second end a2 of the optical delay line 400 and enters the beam combiner / splitter 540. Based on wavelength, the beam combiner / splitter 540 separates N delayed TE beams from the 2N delayed TE beams and TM beams from the first frequency-modulated photoelectric circuits 110 to 1N0 and N delayed TM beams from the third frequency-modulated photoelectric circuits 310 to 3N0. The delayed TE beam from the first frequency-modulated photoelectric circuit 110 and the delayed TM beam from the third frequency-modulated photoelectric circuit 310 are sent to the right PSR in the first pair of frequency-modulated groups, and so on. The delayed TE beam from the first frequency-modulated photoelectric circuit 1N0 and the delayed TM beam from the third frequency-modulated photoelectric circuit 3N0 are sent to the right PSR in the Nth pair of frequency-modulated groups. Each right-hand PSR maintains the polarization direction of the TE light and transmits it to the connected second optical transmission element. The TE light then passes through the second optical transmission element to the mixer 114 in the connected first frequency-modulated optoelectronic circuit, where it is mixed with the calibration path local oscillator signal of the TE light in the first frequency-modulated optoelectronic circuit. Additionally, the polarization direction of the TM light is rotated by 90° to become TE light, which is then transmitted to the connected fourth optical transmission element. The TE light then passes through the fourth optical transmission element to the mixer in the connected third frequency-modulated optoelectronic circuit, where it is mixed with the calibration path local oscillator signal of the TE light in the third frequency-modulated optoelectronic circuit.

[0283] Conversely, the N TE beams output from the first beam-splitting elements 212-2N2 of the N second frequency-modulated optoelectronic circuits 210-2N0 are transmitted by the second optical transmission elements 612-6N2 to the right-hand PSR of the N pairs of frequency-modulated groups. Similarly, the TE beams output from the first beam-splitting elements 412-4N2 of the N fourth frequency-modulated optoelectronic circuits 410-4N0 are also transmitted by the fourth optical transmission elements 712-7N2 to the right-hand PSR of the N pairs of frequency-modulated groups. The right-hand PSR of the N pairs of frequency-modulated groups maintains the polarization direction of the TE beams in the N second frequency-modulated optoelectronic circuits 210-2N0 unchanged, rotates the polarization direction of the TE beams in the N fourth frequency-modulated optoelectronic circuits 210-2N0 by 90°, transforming them into TM beams, and outputs the N TE beams and N TM beams to the combining and splitting element 540. The beam combiner / splitter 540 combines N TE beams and N TM beams into a single optical signal and outputs it to the second end a2 of the optical delay line 400. After a right-to-left transmission delay, it outputs at the first end a1 of the optical delay line 400 and enters the beam combiner / splitter 530. Based on wavelength, the beam combiner / splitter 530 separates N delayed TE beams from the 2N delayed TE beams and TM beams from the second frequency modulation optoelectronic circuits 210 to 2N0 and N delayed TM beams from the fourth frequency modulation optoelectronic circuits 410 to 4N0. The delayed TE beams from the second frequency modulation optoelectronic circuit 210 and the delayed TM beams from the fourth frequency modulation optoelectronic circuit 410 are sent to the left PSR in the first pair of frequency modulation groups, and so on. The delayed TE beams from the second frequency modulation optoelectronic circuit 2N0 and the delayed TM beams from the fourth frequency modulation optoelectronic circuit 4N0 are sent to the left PSR in the Nth pair of frequency modulation groups. Each left-hand PSR maintains the polarization direction of the TE light and transmits it to the connected first optical transmission element. The TE light then passes through the first optical transmission element to the mixer in the connected second frequency-modulated optoelectronic circuit, where it is mixed with the calibration path local oscillator signal of the TE light in the second frequency-modulated optoelectronic circuit. Additionally, the polarization direction of the TM light is rotated by 90° to become TE light, which is then transmitted to the connected third optical transmission element. The TE light then passes through the third optical transmission element to the mixer in the connected fourth frequency-modulated optoelectronic circuit, where it is mixed with the calibration path local oscillator signal of the TE light in the fourth frequency-modulated optoelectronic circuit.

[0284] It should be noted that the relevant content in Implementation Scheme 1 also applies to Implementation Scheme 3. For example, the above description uses wavelength-based beam splitting of the beam combining and splitting elements 530 and 540 as an example. However, in other examples, the beam combining and splitting elements 530 and 540 can also be used for beam splitting based on other features, such as power multiplexers, mode multiplexers, etc. Furthermore, multiple first frequency modulation groups and multiple second frequency modulation groups can be set, but the number of first frequency modulation groups is less than the number of second frequency modulation groups, equivalent to connecting one or more second frequency modulation groups to N pairs of first and second frequency modulation groups. Moreover, each frequency modulation optoelectronic circuit can have its own separate target measurement path, or they can share the same target measurement path, or some of the frequency modulation optoelectronic circuits can share the same target measurement path, while other frequency modulation optoelectronic circuits have their own separate target measurement paths. These will not be elaborated further here.

[0285] Furthermore, the above three implementation schemes are merely illustrative examples of three possible ways to achieve the transmission of three or more optical signals in the same optical delay line in the same direction or in the opposite direction using polarization control elements. In actual signal processing devices, there may be other implementation schemes. Any scheme that can reuse one or more optical delay lines to transmit three or more optical signals in the same direction or in the opposite direction is within the scope of protection of this application, and this application does not make any specific limitations on it.

[0286] The above content introduces the specific implementation scheme of at least two frequency-modulated optoelectronic circuits sharing the same optical delay line. The following section will introduce the specific structure and function of each component and assembly in the above scheme to provide an exemplary implementation scheme.

[0287] 1. Target measurement route

[0288] In this application, the target measurement path refers to a path used for detecting a target. The target measurement path can send detection signals into the detection space and receive signals reflected back from the target in the detected space, and then detect relevant information about the target based on the signals.

[0289] For example, taking the target measurement path 113 in Figure 7b as an example, as shown in Figure 21a, the target measurement path 113 may include a beam splitter 1131, an optical transmission element 1132, a mixer 1133, a photodetector 1134, an amplifier 1135, an analog-to-digital converter 1136, and a processing element 1137. The optical transmission element 1132 has a first end (b) 51 ), second end (b) 52 ) and the third end (b 53 ), first end b 51 To the second end b 52 Second end b 52 To the third end b53 It is unidirectional transmission. The input terminal of the beam splitter 1131 is connected to the detection signal output terminal of the first beam splitter 1121, and one output terminal of the beam splitter 1131 is connected to the first terminal b of the optical transmission element 1132. 51 The other output is connected to one input of mixer 1133. The second terminal b of optical transmission element 1132... 52 Towards the probe space, the third end b of the optical transmission element 1132 53 Connect to the other input terminal of mixer 1133. Mixer 1133, photodetector 1134, amplifier 1135, analog-to-digital converter 1136 and processing element 1137 are connected in series.

[0290] Based on the above structure and connection relationship, as shown in Figure 21a, in the target measurement path 113, the beam splitter 1131 can receive the third output terminal c of the first beam splitter 1121. 13 The output detection signal is split into a transmission signal and a target path local oscillator signal. The target path local oscillator signal is directly input to mixer 1133. The transmission signal originates from the first terminal b of optical transmission element 1132. 51 Input, from the second end b of the optical transmission element 1132 52 The output illuminates the target in the detection space, and is then reflected back to the second end b of the optical transmission element 1132 after being reflected by the target. 52 and from the third end b of the optical transmission element 1132 53 The signal is output to mixer 1133 (referred to as the received signal or echo signal). Mixer 1133 mixes the input target path local oscillator signal and the received signal to obtain an intermediate frequency (IF) signal for target measurement. Optical detection element 1134 detects this IF signal and inputs it to amplifier 1135. After amplification by amplifier 1135, the signal is input to analog-to-digital converter 1136. Analog-to-digital converter 1136 performs analog-to-digital conversion on the input IF signal to obtain a digital signal, which is then input to processing element 1137. Processing element 1137 processes the input digital signal to obtain relevant target information.

[0291] For example, processing element 1137 can perform a Fast Fourier Transform (FFT) on the digital signal to extract the target's distance and motion state information. Processing element 1137 can also analyze the temporal variation trend of the frequency difference in the digital signal to obtain the change in the target's position within different time intervals, and thus calculate the target's velocity. Furthermore, processing element 1137 can output data such as the target object's distance and velocity, and further convert it into position information in three-dimensional space for subsequent scene modeling, obstacle recognition, or other application requirements.

[0292] Optionally, the target measurement path in different frequency-modulated optoelectronic circuits can be separate or shared. For example, Figure 21a shows a scheme where three frequency-modulated optoelectronic circuits have different target measurement paths. Please refer to Figure 21b, which shows a scheme where two frequency-modulated optoelectronic circuits in the first frequency-modulated group share the same target measurement path 113. In the case of sharing, the beam splitting element 1131 in the target measurement path 113 shown in Figure 21a can be replaced by a beam combining and splitting element 1138 (for example, it can be a beam combiner / splitter, or a combination of a beam combiner and a beam splitter, or a combination of other components, etc., without limitation). The beam combining and splitting element 1138 has two input terminals and two output terminals. One input terminal is connected to the detection signal output terminal of the first beam splitter 1121 in the first frequency-modulated optoelectronic circuit 110, and the other input terminal is connected to the detection signal output terminal of the first beam splitter 2121 in the second frequency-modulated optoelectronic circuit 210. One output terminal is connected to the first end b of the optical transmission element 1132. 51 The other output is connected to one input of mixer 1133.

[0293] Based on the structure and connection relationship shown in Figure 21b, the beam combining and splitting element 1138 can receive the detection signal split by the first beam splitter 1121 in the first frequency-modulated photoelectric circuit 110 and the detection signal split by the first beam splitter 2121 in the second frequency-modulated photoelectric circuit 210 through its two input terminals. The beam combining and splitting element 1138 mixes the components of these two detection signals, for example, by taking half the power of each and mixing them to obtain two signals. One signal is used as the transmission signal, and the other signal is used as the target path local oscillator signal. The transmission signal is sent to the detection space to detect the target, while the target path local oscillator signal is input to the mixer 1133 to wait for mixing with the returned echo signal. In this way, by sharing a single target measurement path, the detection signals after splitting the optical signals modulated by the two frequency-modulated photoelectric circuits can be combined into a single signal for measuring the target. This not only saves the number of target measurement paths that need to be set up, but also saves the cost and space of components, and increases the power of the detection signal for measuring the target.

[0294] It is understandable that at least two frequency modulation photoelectric circuits from different frequency modulation groups may share the same target measurement path. For example, the first frequency modulation photoelectric circuit 110 and the third frequency modulation photoelectric circuit 310 may share the same target measurement path, or the first frequency modulation photoelectric circuit 110, the second frequency modulation photoelectric circuit 210 and the third frequency modulation photoelectric circuit 310 may share the same target measurement path, or the first frequency modulation photoelectric circuit 110, the second frequency modulation photoelectric circuit 210, the third frequency modulation photoelectric circuit 310 and the fourth frequency modulation photoelectric circuit 410 may share the same target measurement path, or the second frequency modulation photoelectric circuit 210 and the third frequency modulation photoelectric circuit 310, etc., and so on. They will not be listed here one by one.

[0295] 2. Light source

[0296] Alternatively, the light source can be any device capable of emitting light, such as a laser, including but not limited to: vertical cavity surface emitting laser (VCSEL), edge emitting laser (EEL), diode pumped solid state laser (DPSS), or fiber laser.

[0297] In one example, the light source can emit a frequency-modulated continuous wave. In other words, the signal processing device can be a component of the FMCWLiDAR.

[0298] 3. Spectrometer

[0299] Optionally, the beam splitting element can be any device or combination of devices with beam splitting function, such as a beam splitter, a beam combiner, a combination of beam splitters, or a combination of beam splitters and beam combiners.

[0300] For example, taking the beam splitter 112 in Figure 18 as an example (see Figure 22a), the beam splitter 112 may specifically include a first beam splitter 1121 and a second beam splitter 1122. The input terminal of the first beam splitter 1121 is connected to the output terminal of the light source 111. One output terminal of the first beam splitter 1121 is connected to the input terminal of the second beam splitter 1122. The other output terminal of the first beam splitter 1121 is connected to the target measurement path 113. One output terminal of the second beam splitter 1122 is connected to the mixer 114. The other output terminal of the second beam splitter 1122 is connected to the first terminal of the first optical transmission element 611. Based on this structure and connection relationship, the optical signal output by the light source 111 enters the first beam splitter 1121. The first beam splitter 1121 performs beam splitting processing on the optical signal to obtain a detection signal and an intermediate optical signal. The detection signal is output to the target measurement path 113 to participate in the target measurement, and the intermediate optical signal is output to the second beam splitter 1122. The second beam splitter 1122 performs beam splitting on the intermediate optical signal to obtain the calibration path local oscillator signal and the first optical signal S. 11 The calibration path local oscillator signal is output to mixer 114, and the first optical signal S is output to mixer 114. 11 The output is sent to the first optical transmission element 611, so that the first optical signal S 11 After passing through the first optical transmission element 611, the first polarization element 301, the optical delay line 400, the second polarization element 302, and the second optical transmission element 612 in sequence, the light enters the mixer 114.

[0301] It should be noted that the above beam splitters can be any type of beam splitter, including but not limited to: wavelength beam splitters, power beam splitters, mode multiplexers, and other types of beam splitters, etc., without specific limitations here.

[0302] 4. Polarization control element

[0303] Here, the polarization control element 300 may include the aforementioned first polarization element and second polarization element. The first and second polarization elements may be PBS (Polarization Particulate Components), as shown in Figures 8, 12b, 13b, 15a, 16c, 19a, and 20c, or PSR (Polarization Particulate Components), as shown in Figures 10, 12c, 13c, 15b, 16d, 19b, and 20d. In some scenarios, a combination of PSB (Polarization Particulate Component) and PSR may also be used. For example, the PBS 3011 in Figure 8 may be replaced by two PSRs. The two PSRs rotate the polarization direction of one of the input signals twice by 90° to restore the original polarization direction, thus achieving the function of the PBS. Many other possible implementations exist, which will not be repeated here.

[0304] Optionally, the polarization control element 300 may further include an optical transmission element, as shown in Figures 17a, 17b, 18, 19a, 19b, and 20a-20d above. The optical transmission element can be any device with at least three ports and unidirectional transmission between ports, such as a circulator, an isolator, or a coupler. Although a coupler cannot completely transmit the received signal to the mixer, by setting the interference parameters of each port on the coupler, the input and output signals of each port can be proportionally adjusted, thereby ensuring that most of the received signal is transmitted to the mixer. Of course, the optical transmission element may also be other devices, which are not specifically limited here.

[0305] 5. Optical Delay Line

[0306] Optionally, an optical delay line can be a component capable of delaying the transmission of optical signals, such as, but not limited to, fiber optic delay lines or integrated waveguide delay lines. Fiber optic delay lines utilize the propagation of optical signals within optical fibers to achieve signal delay and typically have a relatively long length. Integrated waveguide delay lines are waveguide devices fabricated on semiconductor chips. Their working principle involves controlling the propagation path length of electromagnetic waves in a dielectric waveguide, silicon, or other materials to achieve signal delay. The semiconductor materials used in integrated waveguide delay lines can be, for example, silicon (Si) or silicon nitride (SiN), and they transmit optical signals internally. Integrated waveguide delay lines offer numerous advantages, including, but not limited to, high integration density, good programmability, high delay accuracy, ease of integration with other circuits, and smaller size.

[0307] 6. Mixer

[0308] In a frequency modulation optoelectronic circuit, the mixer can perform frequency mixing on the input signal and output an intermediate frequency signal.

[0309] Optionally, the mixer can be any type of optical mixer, including but not limited to a 180° optical mixer or a 90° optical mixer. For example, taking the mixer 114 in Figure 18 above as an example, as shown in Figure 22a, mixer 114 can be a 180° optical mixer, which can process the local oscillator signal of the calibration path and the first optical signal S after delay processing in the first frequency modulation optoelectronic circuit 110. 11 Coherent mixing is performed so that the relative phase difference between the two output signals is 0° and 180°, respectively. For example, in another example, as shown in Figure 22b, mixer 114 can be a 90° optical mixer with four outputs, which can process the local oscillator signal of the calibration path and the first optical signal S after delay processing in the first frequency-modulated optoelectronic circuit 110. 11 Perform coherent mixing so that the relative phase differences between the four outputs are 0°, 90°, 180°, and 270°, respectively. And so on, not listed here.

[0310] 7. Optical detection element

[0311] A photodetector, also known as a photoreceiver, is an electronic device used to detect optical signals and convert them into electrical signals. Photodetectors are typically located after a mixer, thus enabling them to detect the intermediate frequency (IF) signal output from the mixer and convert it into an electrical signal. Optionally, examples of photodetectors include, but are not limited to: phototubes, photomultiplier tubes, photodiodes (PDs), avalanche photodiodes (APDs), and single-photon avalanche diodes (SPADs).

[0312] Taking a photodetector (PD) as an example, the photodetector element can include at least one PD, and the number of at least one PD can be the same as the number of output terminals of the mixer located in front of it. For example, taking the photodetector element 115 in Figure 18 as an example, and referring to Figures 18 and 22a, when the mixer 114 is a 180° optical mixer, the photodetector element 115 can specifically include two PDs, namely PD11 and PD12. The input terminals of PD11 and PD12 are both connected to the output terminals of the 180° optical mixer, and the output terminals of PD11 and PD12 are connected to the input terminals of amplifier 118. PD11 and PD12 can be used to detect signals with a relative phase difference of 0° and 180° output from the 180° optical mixer, convert them into electrical signals, and then combine them on a single line for transmission to amplifier 118. For example, referring to Figures 18 and 22b, when mixer 114 is a 90° optical mixer, the optical detection element 115 may specifically include four photodetectors (PDs), namely PD11a, PD11b, PD12a, and PD12b. The input terminals of the four PDs are respectively connected to the four output terminals of the 90° optical mixer, and the output terminals of every two PDs are connected to the input terminal of an amplifier. The four PDs can be used to detect signals with relative phase differences of 0°, 90°, 180°, and 270° output from the four output terminals of the 90° optical mixer, convert them into electrical signals, and then combine them in pairs before transmitting them to the subsequent amplifier.

[0313] 8. Amplifier

[0314] Optionally, the amplifier can be a component or combination of components with signal amplification function. For example, it can include a trans-impedance amplifier (TIA). A TIA can amplify the input signal with a certain intensity of low noise, that is, amplify the useful signal in the input signal while suppressing the amplification of noise signals, so as to improve the optical signal-to-noise ratio (OSNR).

[0315] Taking a TIA as an example, an amplifier may include at least one TIA. The number of TIAs can be related to the number of photodetectors (PDs) contained in the photodetector element positioned in front of it, for example, it can be half the number of PDs. For example, taking amplifier 118 in Figure 18 as an example, and referring to Figures 18 and 22a, when the photodetector element 115 includes two PDs, namely PD11 and PD12, amplifier 118 may include one TIA, namely TIA 1180. The output terminals of PD11 and PD12 are combined and connected to the input terminal of TIA 1180. Therefore, the two intermediate frequency signals detected by PD11 and PD12 are combined into one and sent to TIA 1180. TIA 1180 can perform low-noise amplification on the combined intermediate frequency signal Z1 with a certain intensity. For example, referring to Figures 18 and 22b, when the photodetector 115 includes four photodetectors (PDs), namely PD11a, PD11b, PD12a, and PD12b, the amplifier 118 can include two intermediate frequency amplifiers (TIAs), namely TIA 1181 and TIA 1182. The outputs of PD11a and PD11b are combined and connected to the input of TIA 1181, and the outputs of PD12a and PD12b are combined and connected to the input of TIA 1182. Therefore, the two intermediate frequency signals detected by PD11a and PD11b are combined into one signal and sent to TIA 1181 (referred to as the first intermediate frequency signal Z). 11 The two intermediate frequency signals detected by PD12a and PD12b are combined into one signal and sent to TIA 1182 (referred to as the second intermediate frequency signal Z). 12 TIA 1181 and TIA 1182 respectively process the first intermediate frequency signal Z... 11 Second intermediate frequency signal Z 12 Perform low-noise amplification at a certain intensity.

[0316] 9. Analog-to-digital converter

[0317] Analog-to-digital converters can sample received analog signals that are continuous in time and amplitude, and convert them into digital signals that are discrete in time and amplitude, thereby simplifying the software processing operations of subsequent processing components.

[0318] Optionally, the analog-to-digital conversion element may include at least one analog-to-digital converter (ADC), and the number of at least one ADC may be the same as the number of TIAs contained in the amplifier preceding it. For example, taking the analog-to-digital conversion element 119 in Figure 7b as an example, in conjunction with Figures 18 and 22a, when the amplifier 118 includes only one TIA, namely TIA 1180, the analog-to-digital conversion element 119 may include only one ADC, namely ADC 1190. The input terminal of ADC 1190 is connected to the output terminal of TIA 1180, and is used to perform analog-to-digital conversion on the amplified intermediate frequency signal Z1 output by TIA 1180 to obtain a digital signal. For example, referring to Figures 18 and 22b, when amplifier 118 includes two TIAs, namely TIA 1181 and TIA 1182, analog-to-digital converter element 119 can also include two ADCs, namely ADC 1191 and ADC 1192. The input terminal of ADC 1191 is connected to the output terminal of TIA 1181, and the input terminal of ADC 1192 is connected to the output terminal of TIA 1182. The output terminals of ADC 1191 and ADC 1192 are connected together to the input terminal of processing element 116. ADC 1191 is used to process the amplified first intermediate frequency signal Z output from TIA 1181. 11 Analog-to-digital conversion is performed to obtain the first digital signal. The ADC 1192 is used to amplify the second intermediate frequency signal Z output from the TIA 1182. 12 An analog-to-digital conversion is performed to obtain a second digital signal. The first and second digital signals are then input together to the processing element 116.

[0319] 10. Processing Components

[0320] A processing element refers to a device with signal processing capabilities, such as a digital signal processor (DSP). Taking the processing element 116 in Figure 18 as an example, as shown in Figure 22a or Figure 22b, the processing element 116 may specifically include a DSP 1160. The DSP 1160 can process one or more digital signals output by the analog-to-digital converter 119 to obtain a feedback signal P1, and input the feedback signal P1 into the drive circuit 117.

[0321] The feedback signal can be used to calibrate the linearity between the modulation signal output from the driver circuit to the light source and the optical signal output from the light source; this is referred to as nonlinear calibration. There are various ways to achieve nonlinear calibration, including but not limited to frequency sweep monitoring and frequency modulation signal pre-distortion. Frequency sweep monitoring involves calculating the frequency sweep curve by monitoring changes in the modulation signal and determining whether the curve is linear. If it is not linear, it is calibrated to be linear. Frequency modulation signal pre-distortion refers to pre-compensating for modulation signals that will produce nonlinearity, ensuring that the compensated modulation signal is not distorted, i.e., maintaining linearity. Of course, other nonlinear calibration methods are possible, but specific limitations are not discussed here.

[0322] 11. Drive circuit

[0323] In each frequency-modulated photoelectric circuit, the driving circuit can generate a modulation signal based on the feedback signal output by the processing element, and input the modulation signal into the light source. The modulation signal is used to drive the light source to output a light signal whose frequency changes linearly with time, such as a light signal whose frequency changes linearly with time in the form of a triangular wave or a sawtooth wave. In some cases, the driving circuit also needs to be responsible for timing control functions, such as controlling the time window for the light source to emit light signals, and synchronizing with the receiving end (i.e., the receiving operation of the target measurement path) in order to accurately demodulate the information in the echo signal (i.e., the received signal).

[0324] It should be noted that Figures 22a and 22b above are only examples of the components in the calibration path of the first frequency modulation optoelectronic circuit 110 (referring to the path containing the first beam splitter 112, the first polarization element 301, the optical delay line 400, the second polarization element 302, the mixer 114, the photodetector 115, the amplifier 118, the analog-to-digital converter 119, and the processing element 116). However, the relevant content of these components also applies to the target measurement path 113 of the first frequency modulation optoelectronic circuit 110 (referring to the beam splitter 1131 shown in Figure 21a or the beam combiner / splitter 1138, optical transmission element 1132, mixer 1133, photodetector 1134, amplifier 1135, and analog-to-digital converter 116 shown in Figure 21b). The calibration path in the second frequency-modulated optoelectronic circuit 210 (which includes the first beam splitter 212, optical delay line 400, mixer 214, photodetector 215, amplifier 218, analog-to-digital converter 219, and processing element 216), the target measurement path 213 in the second frequency-modulated optoelectronic circuit 210, the calibration path in the third frequency-modulated optoelectronic circuit 310 (which includes the first beam splitter 312, optical delay line 400, mixer 314, photodetector 315, amplifier 318, analog-to-digital converter 319, and processing element 316), the target measurement path 313 in the second frequency-modulated optoelectronic circuit 310, and the calibration and target measurement paths in other frequency-modulated optoelectronic circuits.

[0325] Furthermore, within the same first frequency-modulated photoelectric circuit, or the same second frequency-modulated photoelectric circuit, or the same third frequency-modulated photoelectric circuit, the mixer in the target measurement path and the mixer in the calibration path can be of the same type or different types. Similarly, within different first frequency-modulated photoelectric circuits, or different second frequency-modulated photoelectric circuits, or different third frequency-modulated photoelectric circuits, the mixer in the calibration path can be of the same type or different types, and the mixer in the target measurement path can be of the same type or different types; this application does not impose specific limitations in this regard.

[0326] Based on the structure and functional principles of the signal processing device described above, this application can also provide a detection device, as shown in FIG23. The detection device 2300 includes a signal processing device 2310, which can be the signal processing device in any of the above embodiments, such as the signal processing device described in any of FIG4 to FIG22b.

[0327] Alternatively, the detection device 2300 can be a lidar, such as an FMCW LiDAR.

[0328] Optionally, as shown in Figure 23 above, the detection device 2300 may further include a window 2320, which is used to protect the internal signal processing device 2310 and can transmit the light signal emitted by the signal processing device 2310.

[0329] It should be noted that the detection device architecture shown in Figure 23 is only an example. In other examples, the detection device may include more, fewer, or different structures, and each structure may include more, fewer, or different components. This application does not make any specific limitations in this regard.

[0330] Based on the structure and functional principles of the detection device described above, this application can also provide a terminal device, as shown in Figure 24. This terminal device 2400 may include the signal processing device described above, or it may include a detection device 2410. The detection device 2410 may be a detection device from any of the above embodiments, such as the detection device 2300 in Figure 23.

[0331] Optionally, as shown in Figure 24 above, the terminal device 2400 may further include a processor 2420, which is used to call programs or instructions to control the operation of the detection device 2410. Furthermore, the processor 2420 may also receive target-related information from the detection device 2410. When the terminal device 2400 is a vehicle, the processor 2420 may also perform vehicle path planning, braking, or starting based on the acquired information. For example, the vehicle's position can be determined using latitude and longitude, or the vehicle's direction of travel and destination in the future can be determined using speed and orientation, or the number and density of obstacles around the vehicle can be determined using the distance to surrounding objects.

[0332] Furthermore, optionally, the terminal device 2400 may also include a memory 2430 for storing programs or instructions. Of course, the terminal device 2400 may also include other devices, such as wireless communication devices.

[0333] Processor 2420 may include one or more processing units. For example, processor 2420 may include an application processor (AP), an image signal processor (ISP), a controller, a DSP, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. Different processing units may be independent devices or integrated into one or more processors.

[0334] The memory 2430 includes, but is not limited to, random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. Exemplarily, the storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can reside within an ASIC.

[0335] For example, the terminal device 2400 may be a vehicle (e.g., unmanned vehicle, intelligent vehicle, electric vehicle, or digital car), robot, surveying equipment, drone, smart home device (e.g., television, robot vacuum cleaner, smart lamp, audio system, smart lighting system, electrical control system, home background music, home theater system, intercom system, or video surveillance), smart manufacturing equipment (e.g., industrial equipment), smart transportation equipment (e.g., AGV, unmanned transport vehicle, or truck), or smart terminal (mobile phone, computer, tablet, PDA, desktop computer, headphones, audio equipment, wearable device, in-vehicle device, virtual reality device, augmented reality device, etc.).

[0336] It is understandable that, unless otherwise specified or logically conflicting, the terminology and / or descriptions of the various implementation schemes described above are consistent and can be referenced from each other. The technical features of different implementation schemes can be combined to form new implementation schemes based on their inherent logical relationships.

[0337] Furthermore, the above implementation schemes are merely examples of FMCW LiDAR to illustrate the internal structure of the signal processing device. It should be understood that the aforementioned signal processing device can also be applied to other applications requiring linear frequency modulation. For instance, in other scenarios, the above signal processing device can also be applied to optical frequency domain reflectometry (OFDR) systems. The structure of an OFDR system is similar to that of an FMCW LiDAR, except that the devices on its target measurement path are connected via optical fibers, while the calibration path is the same as that of an FMCW LiDAR. In this case, the structure of the above signal processing device can also be used to achieve the multiplexing of delay elements (such as optical delay lines). In addition, with the development of detection technology, the signal processing device structure provided in this application is also applicable to the same technical problems, and this application does not specifically limit its application in this regard.

[0338] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0339] Additionally, in this application, the terms "optionally" or "exemplary" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design described as "optional" or "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or design options. Alternatively, it can be understood that the use of the terms "exemplary" or "optional" is intended to present concepts in a specific manner and does not constitute a limitation of this application.

[0340] It is understood that the various numerical designations used in this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and inherent logic. Terms such as "first," "second," and "third," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or device is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

Claims

1. A signal processing apparatus, characterized in that, include: The system comprises a first frequency modulation group, a second frequency modulation group, and an optical delay line. The first frequency modulation group includes a first frequency modulation optoelectronic circuit, a second frequency modulation optoelectronic circuit, and a polarization control element. The second frequency modulation group includes a third frequency modulation optoelectronic circuit. Each frequency modulation optoelectronic circuit from the first to the third frequency modulation optoelectronic circuit includes a light source, a first beam splitter, and a mixer. The polarization control element is connected between the optical delay line, the first beam splitter in each frequency-modulated optoelectronic circuit, and the mixer in each frequency-modulated optoelectronic circuit. The polarization control element is used to receive a first optical signal, a second optical signal, and a third optical signal after they have been split by the first beam splitter in the first frequency-modulated optoelectronic circuit to the third frequency-modulated optoelectronic circuit, and to output the first optical signal, the second optical signal, and the third optical signal to the optical delay line in two orthogonal polarization directions. The element also outputs the delayed first optical signal to the mixer in the first frequency-modulated optoelectronic circuit, the delayed second optical signal to the mixer in the second frequency-modulated optoelectronic circuit, and the delayed third optical signal to the mixer in the third frequency-modulated optoelectronic circuit.

2. The apparatus as claimed in claim 1, characterized in that, In the optical delay line, the first optical signal and the second optical signal have the same polarization direction, and the polarization direction of the third optical signal is orthogonal to the polarization directions of the first optical signal and the second optical signal.

3. The apparatus as described in claim 1 or 2, characterized in that, The first optical signal and the second optical signal satisfy at least one of the following conditions: Different wavelengths result in different frequency modulation directions and different frequency modulation slopes.

4. The apparatus according to any one of claims 1 to 3, characterized in that, In the first frequency modulation group: The first beam splitting element in both the first and second frequency-modulated optoelectronic circuits includes a first beam splitter and a first beam combiner / splitter. The first and second frequency-modulated optoelectronic circuits share the same first beam combiner / splitter and the same mixer. The first beam combiner / splitter is connected between the first beam splitter in the first frequency-modulated optoelectronic circuit, the first beam splitter in the second frequency-modulated optoelectronic circuit, the mixer, and the polarization control element; The first beam splitter is used to split the intermediate optical signal from the optical signal output by the light source in the frequency modulation optoelectronic circuit. The first beam combiner / splitter is used to perform beam combining and splitting processing on the intermediate optical signals in the first frequency-modulated optoelectronic circuit and the second frequency-modulated optoelectronic circuit to obtain the calibration path local oscillator signal and the signal to be delayed. The calibration path local oscillator signal is output to the mixer, and the signal to be delayed is output to the polarization control element. The signal to be delayed includes the first optical signal and the second optical signal.

5. The apparatus as described in claim 4, characterized in that, In the third frequency-modulated photoelectric circuit: The first beam splitting element includes a second beam splitter and a third beam splitter, wherein the third beam splitter is connected between the second beam splitter, the mixer and the polarization control element; The second beam splitter is used to split the intermediate light signal from the light signal output by the light source; The third beam splitter is used to split the calibration path local oscillator signal and the third optical signal from the intermediate optical signal, output the calibration path local oscillator signal to the mixer, and output the third optical signal to the polarization control element.

6. The apparatus as claimed in claim 4, characterized in that, In the second frequency modulation group: It also includes a fourth frequency-modulated optoelectronic circuit; The first beam splitting element in both the third and fourth frequency-modulated optoelectronic circuits includes a second beam splitter and a second beam combiner / splitter. The third and fourth frequency-modulated optoelectronic circuits share the same second beam combiner / splitter and the same mixer. The second beam combiner / splitter is connected between the second beam splitter in the third frequency-modulated optoelectronic circuit, the second beam splitter in the fourth frequency-modulated optoelectronic circuit, the mixer, and the polarization control element; The second beam splitter is used to split the intermediate optical signal from the optical signal output by the light source in the frequency modulation optoelectronic circuit. The second beam combiner / splitter is used to combine and split the intermediate optical signals in the third and fourth frequency-modulated optoelectronic circuits to obtain a calibration path local oscillator signal and a delay signal. The calibration path local oscillator signal is output to the mixer, and the delay signal is output to the polarization control element. The delay signal includes the third optical signal and the fourth optical signal, and the fourth optical signal is the delay signal in the fourth frequency-modulated optoelectronic circuit.

7. The apparatus as described in claim 5 or 6, characterized in that, The polarization control element includes a first polarization element and a second polarization element. The first polarization element is connected between the first end of the optical delay line, the first beam combiner / splitter in the first frequency modulation group, and the second beam combiner / splitter in the second frequency modulation group. The second polarization element is connected between the second end of the optical delay line, the mixer in the first frequency modulation group, and the mixer in the second frequency modulation group. Alternatively, the first polarization element is connected between the first end of the optical delay line, the first beam combiner / splitter in the first frequency modulation group, and the third beam splitter in the third frequency modulation optoelectronic circuit. The second polarization element is connected between the second end of the optical delay line, the mixer in the first frequency modulation group, and the mixer in the third frequency modulation optoelectronic circuit. The first polarization element is used to keep the polarization direction of the optical signal output by the first beam combiner unchanged, so that the polarization direction of the optical signal output by the second beam combiner or the third beam splitter is orthogonal to the polarization direction of the optical signal output by the first beam combiner, and output the two sets of optical signals to the first end of the optical delay line. The second polarization element is used to keep the polarization direction of the delayed optical signal corresponding to the first beam combiner / splitter unchanged and output it to the mixer in the first frequency modulation group, and to output the delayed optical signal corresponding to the second beam combiner / splitter or the third beam splitter to the mixer in the second frequency modulation group with the original polarization direction in the second frequency modulation group.

8. The apparatus as claimed in claim 7, characterized in that, The optical signal output by the first beam combiner / splitter has an orthogonal polarization direction to the optical signal output by the second beam combiner / splitter or the third beam splitter. The first polarization element is a first polarization beam splitter (PBS), and the second polarization element is a second PBS. The first PBS is used to keep the polarization direction of the optical signal output by the first beam combiner / splitter unchanged, and to keep the polarization direction of the optical signal output by the second beam combiner / splitter or the third beam splitter unchanged, and outputs it to the first end of the optical delay line; The second PBS is used to maintain the polarization direction of the delayed optical signal corresponding to the first beam combiner / splitter unchanged and output it to the mixer in the first frequency modulation group, and to maintain the polarization direction of the delayed optical signal corresponding to the second beam combiner / splitter or the third beam splitter unchanged and output it to the mixer in the second frequency modulation group.

9. The apparatus as claimed in claim 7, characterized in that, The optical signal output by the first beam combiner / splitter has the same polarization direction as the optical signal output by the second beam combiner / splitter or the third beam splitter. The first polarization element is a first polarization rotating beam splitter (PSR), and the second polarization element is a second PSR. The first PSR is used to keep the polarization direction of the optical signal output by the first beam combiner / splitter unchanged, rotate the polarization direction of the optical signal output by the second beam combiner / splitter or the third beam splitter by 90°, and output it to the first end of the optical delay line; The second PSR is used to keep the polarization direction of the delayed optical signal corresponding to the first beam combiner / splitter unchanged and output it to the mixer in the first frequency modulation group, and to rotate the polarization direction of the delayed optical signal corresponding to the second beam combiner / splitter or the third beam splitter by 90° and output it to the mixer in the second frequency modulation group.

10. The apparatus as claimed in claim 5 or 6, characterized in that, The polarization control element includes a first polarization element and a second polarization element. The first polarization element is connected between a first end of the optical delay line, a first beam combiner / splitter in the first frequency modulation group, and a mixer in the second frequency modulation group. The second polarization element is connected between a second end of the optical delay line, a mixer in the first frequency modulation group, and a second beam combiner / splitter in the second frequency modulation group. Alternatively, the first polarization element is connected between a first end of the optical delay line, a first beam combiner / splitter in the first frequency modulation group, and a mixer in the third frequency modulation optoelectronic circuit. The second polarization element is connected between a second end of the optical delay line, a mixer in the first frequency modulation group, and a third beam splitter in the third frequency modulation optoelectronic circuit. The first polarization element is used to keep the polarization direction of the optical signal output by the first beam combiner unchanged, output to the first end of the optical delay line, and cause the delayed optical signal corresponding to the second beam combiner or the third beam splitter to be output to the mixer in the second frequency modulation group with the original polarization direction in the second frequency modulation group. The second polarization element is used to make the polarization direction of the optical signal output by the second beam combiner or the third beam splitter orthogonal to the polarization direction of the optical signal output by the first beam combiner or splitter, and output it to the second end of the optical delay line; and to keep the polarization direction of the optical signal after delay processing corresponding to the first beam combiner or splitter unchanged, and output it to the mixer in the first frequency modulation group.

11. The apparatus as claimed in claim 10, characterized in that, The optical signal output by the first beam combiner / splitter has an orthogonal polarization direction to the optical signal output by the second beam combiner / splitter or the third beam splitter. The first polarization element is a first polarization beam splitter (PBS), and the second polarization element is a second PBS. The first PBS is used to keep the polarization direction of the optical signal output by the first beam combiner unchanged and output it to the first end of the optical delay line, and to keep the polarization direction of the optical signal after delay processing corresponding to the second beam combiner or the third beam splitter unchanged and output it to the mixer in the second frequency modulation group. The second PBS is used to maintain the polarization direction of the optical signal output by the second beam combiner or the third beam splitter unchanged and output it to the second end of the optical delay line, and to maintain the polarization direction of the optical signal after delay processing corresponding to the first beam combiner unchanged and output it to the mixer in the first frequency modulation group.

12. The apparatus as claimed in claim 10, characterized in that, The optical signal output by the first beam combiner / splitter has the same polarization direction as the optical signal output by the second beam combiner / splitter or the third beam splitter. The first polarization element is a first polarization rotating beam splitter (PSR), and the second polarization element is a second PSR. The first PSR is used to keep the polarization direction of the optical signal output by the first beam combiner unchanged and output it to the first end of the optical delay line, and to rotate the polarization direction of the delayed optical signal corresponding to the second beam combiner or the third beam splitter by 90° and output it to the mixer in the second frequency modulation group. The second PSR is used to rotate the polarization direction of the optical signal output by the second beam combiner or the third beam splitter by 90° and output it to the second end of the optical delay line, and to keep the polarization direction of the optical signal after delay processing corresponding to the first beam combiner unchanged and output it to the mixer in the first frequency modulation group.

13. The apparatus according to any one of claims 1 to 3, characterized in that, In the first frequency modulation group: The polarization control element includes a first polarization element, a second polarization element, a first optical transmission element, and a second optical transmission element; The first optical transmission element is connected between the first beam splitter in the first frequency-modulated optoelectronic circuit, the mixer in the second frequency-modulated optoelectronic circuit, and the first end of the first polarization element. The second end of the first polarization element is connected to the first beam splitter in the third frequency-modulated optoelectronic circuit, and the third end of the first polarization element is connected to the first end of the optical delay line. The second optical transmission element is connected between the mixer in the first frequency-modulated optoelectronic circuit, the first beam splitter in the second frequency-modulated optoelectronic circuit, and the first end of the second polarization element. The second end of the second polarization element is connected to the mixer in the third frequency-modulated optoelectronic circuit, and the third end of the second polarization element is connected to the second end of the optical delay line. The first optical transmission element is used to transmit the first optical signal after being split by the first beam splitter in the first frequency-modulated optoelectronic circuit to the first polarization element, and to transmit the second optical signal after delay processing to the mixer in the second frequency-modulated optoelectronic circuit. The first polarization element is used to keep the polarization direction of the first optical signal unchanged, so that the polarization direction of the third optical signal after being split by the first beam splitter in the third frequency modulation optoelectronic circuit is orthogonal to the polarization direction of the first optical signal, and output to the first end of the optical delay line; and to keep the polarization direction of the second optical signal after the delay processing unchanged, and output to the first optical transmission element. The second optical transmission element is used to transmit the second optical signal after it has been split by the first beam splitter in the second frequency-modulated optoelectronic circuit to the second polarization element, and to transmit the first optical signal after delay processing to the mixer in the first frequency-modulated optoelectronic circuit. The second polarization element is used to keep the polarization direction of the second optical signal unchanged and output it to the second end of the optical delay line, keep the polarization direction of the first optical signal after delay processing unchanged and output it to the second optical transmission element, and make the polarization direction of the third optical signal after delay processing in the third frequency modulation optoelectronic circuit be the same as the original polarization direction in the third frequency modulation optoelectronic circuit and output it to the mixer in the third frequency modulation optoelectronic circuit.

14. The apparatus according to any one of claims 1 to 3, characterized in that, In the second frequency modulation group: It also includes a fourth frequency-modulated optoelectronic circuit, a third optical transmission element, and a fourth optical transmission element; The third optical transmission element is connected between the first beam splitter in the third frequency-modulated optoelectronic circuit, the mixer in the fourth frequency-modulated optoelectronic circuit, and the polarization control element; the fourth optical transmission element is connected between the first beam splitter in the fourth frequency-modulated optoelectronic circuit, the mixer in the third frequency-modulated optoelectronic circuit, and the polarization control element. The third optical transmission element is used to transmit the third optical signal after being split by the first beam splitter in the third frequency modulation optoelectronic circuit to the polarization control element, and to transmit the fourth optical signal after delay processing to the mixer in the fourth frequency modulation optoelectronic circuit. The fourth optical transmission element is used to transmit the fourth optical signal after being split by the first beam splitter in the fourth frequency-modulated optoelectronic circuit to the polarization control element, and to transmit the third optical signal after delay processing to the mixer in the third frequency-modulated optoelectronic circuit.

15. The apparatus as claimed in claim 14, characterized in that, In the first frequency modulation group: The polarization control element includes a first polarization element, a second polarization element, a first optical transmission element, and a second optical transmission element; The first optical transmission element is connected between the first beam splitter in the first frequency-modulated optoelectronic circuit, the mixer in the second frequency-modulated optoelectronic circuit, and the first end of the first polarization element. The second end of the first polarization element is connected to the third optical transmission element, and the third end of the first polarization element is connected to the first end of the optical delay line. The second optical transmission element is connected between the mixer in the first frequency modulation optoelectronic circuit, the first beam splitter in the second frequency modulation optoelectronic circuit, and the first end of the second polarization element. The second end of the second polarization element is connected to the fourth optical transmission element, and the third end of the second polarization element is connected to the second end of the optical delay line. The first optical transmission element is used to transmit the first optical signal after being split by the first beam splitter in the first frequency-modulated optoelectronic circuit to the first polarization element, and to transmit the second optical signal after delay processing to the mixer in the second frequency-modulated optoelectronic circuit. The first polarization element is used to keep the polarization direction of the first optical signal unchanged, make the polarization direction of the third optical signal output by the third optical transmission element orthogonal to the polarization direction of the first optical signal, and output it to the first end of the optical delay line; and keep the polarization direction of the second optical signal after delay processing unchanged and output it to the first optical transmission element; and output the polarization direction of the fourth optical signal after delay processing to the third optical transmission element with the original polarization direction in the fourth frequency modulation photoelectric circuit. The second optical transmission element is used to transmit the second optical signal after it has been split by the first beam splitter in the second frequency-modulated optoelectronic circuit to the second polarization element, and to transmit the first optical signal after delay processing to the mixer in the first frequency-modulated optoelectronic circuit. The second polarization element is used to keep the polarization direction of the second optical signal unchanged, so that the polarization direction of the fourth optical signal output by the fourth optical transmission element is orthogonal to the polarization direction of the second optical signal and output to the second end of the optical delay line, and to keep the polarization direction of the first optical signal after delay processing unchanged and output to the second optical transmission element, and to make the polarization direction of the third optical signal after delay processing be the original polarization direction in the third frequency modulation optoelectronic circuit and output to the fourth optical transmission element.

16. The apparatus as claimed in claim 15, characterized in that, The first optical signal, the second optical signal, the third optical signal, and the fourth optical signal have orthogonal polarization directions. The first polarization element is a first polarization beam splitter (PBS), and the second polarization element is a second PBS. The first PBS is used to maintain the polarization direction of the first optical signal unchanged, maintain the polarization direction of the third optical signal unchanged, and output to the first end of the optical delay line; maintain the polarization direction of the second optical signal after delay processing unchanged and output to the first optical transmission element; and maintain the polarization direction of the fourth optical signal after delay processing unchanged and output to the third optical transmission element. The second PBS is used to maintain the polarization direction of the second optical signal unchanged, maintain the polarization direction of the fourth optical signal unchanged, and output to the second end of the optical delay line; maintain the polarization direction of the first optical signal after delay processing unchanged and output to the second optical transmission element; and maintain the polarization direction of the third optical signal after delay processing unchanged and output to the fourth optical transmission element.

17. The apparatus as claimed in claim 15, characterized in that, The first optical signal, the second optical signal, the third optical signal, and the fourth optical signal have the same polarization direction. The first polarization element is a first polarization rotating beam splitter (PSR), and the second polarization element is a second PSR. The first PSR is used to keep the polarization direction of the first optical signal unchanged, rotate the polarization direction of the third optical signal by 90° and output it to the first end of the optical delay line, keep the polarization direction of the second optical signal after delay processing unchanged and output it to the first optical transmission element, and rotate the polarization direction of the fourth optical signal after delay processing by 90° and output it to the third optical transmission element. The second PSR is used to keep the polarization direction of the second optical signal unchanged, rotate the polarization direction of the fourth optical signal by 90° and output it to the second end of the optical delay line, keep the polarization direction of the first optical signal after delay processing unchanged and output it to the second optical transmission element, and rotate the polarization direction of the third optical signal after delay processing by 90° and output it to the fourth optical transmission element.

18. The apparatus as claimed in any one of claims 4 to 17, characterized in that, The first frequency modulation group and the second frequency modulation group have N pairs, where N is an integer greater than or equal to 2. The signal processing device further includes a third beam combiner and a fourth beam combiner. The third beam combiner / splitter is connected between the first polarization element of each of the N pairs of first frequency modulation groups and the first end of the optical delay line, and the fourth beam combiner / splitter is connected between the second polarization element of each of the N pairs of first frequency modulation groups and the second end of the optical delay line.

19. The apparatus as claimed in any one of claims 13 to 17, characterized in that, In each of the frequency-modulated photoelectric circuits: The first beam splitting element includes a first beam splitter and a second beam splitter. The first output terminal of the first beam splitter is connected to the input terminal of the second beam splitter, the second output terminal of the first beam splitter is connected to the target measurement path, the first output terminal of the second beam splitter is connected to the polarization control element, and the second output terminal of the second beam splitter is connected to the mixer. The first beam splitter is used to split the light signal generated by the light source to obtain the detection signal and the intermediate light signal, output the intermediate light signal through its first output terminal, and output the detection signal through its second output terminal. The second beam splitter is used to split the intermediate optical signal to obtain the local oscillator signal and the signal to be delayed. It outputs the signal to be delayed through its first output terminal and the local oscillator signal through its second output terminal. The mixer is used to perform mixing processing on the local oscillator signal and the delayed signal; The target measurement path is used to perform target measurement using the detection signal.

20. The apparatus according to any one of claims 1 to 19, characterized in that, In each of the frequency-modulated photoelectric circuits: It also includes an amplifier and an analog-to-digital converter, the amplifier and the analog-to-digital converter being connected between the mixer and the light source; The amplifier is used to amplify the intermediate frequency signal obtained by the mixer. The analog-to-digital converter is used to perform analog-to-digital conversion on the amplified intermediate frequency signal to obtain a digital signal.

21. The apparatus according to any one of claims 1 to 20, characterized in that, The optical delay line is either an optical fiber delay line or an on-chip integrated waveguide delay line.

22. A detection device, characterized in that, Includes the signal processing apparatus as described in any one of claims 1 to 21.

23. A terminal device, characterized in that, It includes the signal processing apparatus as described in any one of claims 1 to 21, or the detection apparatus as described in claim 22.

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