Signal processing device, detection device and terminal equipment

Abstract

The invention discloses a signal processing device, a detection device and terminal equipment, relates to the technical field of detection, and is used for reducing the cost and occupied space of an optical delay line. The signal processing device comprises a first frequency modulation photoelectric loop and a second frequency modulation photoelectric loop which share a polarization regulation and control element and an optical delay line. The polarization regulation and control element outputs an optical signal in a first linear polarization state in the first frequency modulation photoelectric loop and an optical signal in a second linear polarization state in the second frequency modulation photoelectric loop to the optical delay line in an orthogonal polarization direction, and outputs the optical signals subjected to respective delay processing to respective mixers in an original linear polarization state form. The optical signals of the two frequency modulation photoelectric loops are transmitted in the same optical delay line, so that the two frequency modulation photoelectric loops can share the same optical delay line, the number of the optical delay lines needing to be arranged in the signal processing device is reduced, and the cost and the occupied space of the optical delay lines are reduced.

Description

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

[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.

[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.

[0005] Summary of the Invention

[0006] 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.

[0007] In a first aspect, this application provides a signal processing apparatus, including a first frequency-modulated (FM) optoelectronic circuit and a second FM optoelectronic circuit. Each FM optoelectronic circuit includes a light source, a first beam splitter, a polarization control element, an optical delay line, a mixer, a photodetector, a processing element, and a driving circuit. The first and second FM optoelectronic circuits share the polarization control element and the optical delay line. The polarization control element is used to receive a first linearly polarized optical signal from the first beam splitter in the first FM optoelectronic circuit and a second linearly polarized optical signal from the first beam splitter in the second FM optoelectronic circuit, causing the first and second linearly polarized optical signals to be output to the optical delay line with orthogonal polarization directions. It also outputs the delayed optical signal from the first FM optoelectronic circuit in the form of a first linearly polarized state to the mixer in the first FM optoelectronic circuit, and outputs the delayed optical signal from the second FM optoelectronic circuit in the form of a second linearly polarized state to the mixer in the second FM optoelectronic circuit.

[0008] Based on the above structure, by using a polarization control element to output the optical signals of the two frequency-modulated optoelectronic circuits to the same optical delay line, the two frequency-modulated optoelectronic circuits can share the same optical delay line, reducing the number of optical delay lines required in the signal processing device, lowering the size and space occupied by the optical delay lines, and saving hardware costs for the signal processing device. Furthermore, by using the polarization control element to input the optical signals of the two frequency-modulated optoelectronic circuits into the optical delay line with orthogonal polarization directions and outputting them to their respective mixers in their original linear polarization state, interference between the optical signals of the two frequency-modulated optoelectronic circuits during the delay process can be reduced without affecting their respective mixing operations, resulting in better signal quality for the delayed optical signals output to the mixers of the two frequency-modulated optoelectronic circuits. Thus, when the above signal processing device is applied to a detection device (such as an FMCW LiDAR), it can not only reduce the length and cost of the optical delay line that needs to be set in the FMCW LiDAR, simplify the system architecture of the FMCW LiDAR, and reduce the system cost of the FMCW LiDAR, but also enable the delayed optical signal of each frequency-modulated photoelectric circuit to have better signal quality and improve the calibration effect of the frequency-modulated photoelectric circuit.

[0009] It should be noted that although the optical signals from the two frequency-modulated optoelectronic circuits propagate along the same optical delay line, they can be separated based on their polarization directions because they propagate in orthogonal polarization directions. That is, the optical signals from the two frequency-modulated optoelectronic circuits can be identical in characteristics, such as having the same frequency, wavelength, phase, and emission time, or they can differ in at least one characteristic, such as having different wavelengths, phases, or frequencies. This does not affect the functionality of the two frequency-modulated optoelectronic circuits.

[0010] In one possible design, the first linear polarization state is the same as the second linear polarization state, or the first linear polarization state is orthogonal to the second linear polarization state. For example, when the first linear polarization state and the second linear polarization state are the same, the optical signals of both the first and second linear polarization states are either P-type light, TE-type light, S-type light, or TM-type light. When the first linear polarization state and the second linear polarization state are orthogonal, the optical signal of the first linear polarization state is P-type light and the optical signal of the second linear polarization state is S-type light; or, the optical signal of the first linear polarization state is TE-type light and the optical signal of the second linear polarization state is TM-type light; or, the optical signal of the first linear polarization state is S-type light and the optical signal of the second linear polarization state is P-type light; or, the optical signal of the first linear polarization state is TM-type light and the optical signal of the second linear polarization state is TE-type light.

[0011] Based on the above design, the signal processing device can be applied to scenarios where the linear polarization states of the emitted beams from two light sources are the same or orthogonal, and the signal processing device has good versatility.

[0012] In one possible design, the polarization control element can have either structure one or structure two as follows:

[0013] 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 beam splitter in the first frequency-modulated optoelectronic circuit, the first beam splitter in the second frequency-modulated optoelectronic circuit, and the first end of the optical delay line. The second polarization element is connected between the mixer in the first frequency-modulated optoelectronic circuit, the mixer in the second frequency-modulated optoelectronic circuit, and the second end of the optical delay line. The first polarization element receives the first linearly polarized optical signal from the first beam splitter in the first frequency-modulated optoelectronic circuit and the second linearly polarized optical signal from the first beam splitter in the second frequency-modulated optoelectronic circuit, causing the first and second linearly polarized optical signals to be output to the optical delay line with orthogonal polarization directions. The second polarization element receives the delayed optical signal from both the first and second frequency-modulated optoelectronic circuits, outputs the delayed optical signal from the first frequency-modulated optoelectronic circuit in the first linearly polarized state to the mixer in the first frequency-modulated optoelectronic circuit, and outputs the delayed optical signal from the second frequency-modulated optoelectronic circuit in the second linearly polarized state to the mixer in the second frequency-modulated optoelectronic circuit.

[0014] Based on structure one, the polarization control element can output the optical signals in the two frequency-modulated optoelectronic circuits to the same end of the optical delay line, that is, make the two optical signals transmit in the same direction in the same optical delay line, so as to realize the multiplexing of the same optical delay line.

[0015] Structure 2 includes a polarization control element comprising a first polarization element and a second polarization element. The first polarization 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 optical delay line. The second polarization 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 second end of the optical delay line. The first polarization element receives the first linearly polarized optical signal from the first beam splitter in the first frequency-modulated optoelectronic circuit and the delayed optical signal from the second frequency-modulated optoelectronic circuit, outputs the first linearly polarized optical signal to the optical delay line, and outputs the delayed optical signal from the second frequency-modulated optoelectronic circuit in the second linearly polarized form to the mixer in the second frequency-modulated optoelectronic circuit. The second polarization element is used to receive the second linearly polarized optical signal after it has been split by the first beam splitter in the second frequency-modulated optoelectronic circuit and the delayed optical signal in the first frequency-modulated optoelectronic circuit. It outputs the second linearly polarized optical signal to the optical delay line in a polarization direction perpendicular to the first linearly polarized optical signal, and outputs the delayed optical signal in the first frequency-modulated optoelectronic circuit to the mixer in the first frequency-modulated optoelectronic circuit in the form of the first linearly polarized optical signal.

[0016] Based on structure two, the polarization control element can output the optical signals in the two frequency-modulated optoelectronic circuits to different ends of the optical delay line, that is, to make the two optical signals transmit in opposite directions in the same optical delay line, so as to realize the multiplexing of the same optical delay line.

[0017] In one possible design of the above structure one, the first linear polarization state is the same as the second linear polarization state. Both the first and second polarization elements have a first end, a second end, and a third end. Signals are transmitted between the third end and the first end in the original polarization direction, and between the third end and the second end in the polarization direction after a 90° rotation. The first end of the first polarization element is connected to the first beam splitter in the first frequency-modulated optoelectronic circuit, the second end of the first polarization element is connected to the first beam splitter in the second 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 first end of the second polarization element is connected to the mixer in the first frequency-modulated optoelectronic circuit, the second end of the second polarization element is connected to the mixer in the second frequency-modulated optoelectronic circuit, and the third end of the second polarization element is connected to the second end of the optical delay line.

[0018] Based on the above design, the first polarization element can acquire two optical signals with the same polarization direction, keep the polarization direction of one optical signal unchanged, and rotate the polarization direction of the other optical signal by 90°, thereby obtaining two optical signals with orthogonal polarization directions. These signals are then input into the optical delay line in the same direction to reduce mutual interference during the delay processing. The second polarization element can acquire two delayed optical signals with orthogonal polarization directions, keep the polarization direction of one delayed optical signal unchanged, and rotate the polarization direction of the other delayed optical signal by 90°, thereby obtaining two delayed optical signals with the same polarization direction. These signals are then input into their respective mixers to ensure that the mixer receives the delayed signal with the original polarization direction, thus ensuring the accuracy of the mixing operation.

[0019] In one example of the above design, both the first and second polarization elements are polarization rotator splitters (PSRs). Based on this, the first polarization element can maintain the polarization direction of the first linearly polarized optical signal unchanged and rotate the polarization direction of the second linearly polarized optical signal by 90° to obtain a third linearly polarized optical signal. After combining the third linearly polarized optical signal and the first linearly polarized optical signal, the result is output to the optical delay line. The second polarization element can split the delayed optical signal to obtain a delayed first linearly polarized optical signal and a delayed third linearly polarized optical signal. Maintaining the polarization direction of the delayed first linearly polarized optical signal unchanged, the result is output to the mixer in the first frequency-modulated optoelectronic circuit. The second polarization element can rotate the polarization direction of the delayed third linearly polarized optical signal by 90° to obtain a delayed second linearly polarized optical signal, which is then output to the mixer in the second frequency-modulated optoelectronic circuit.

[0020] Based on the above examples, PSR can be integrated into a chip. Therefore, implementing polarization control elements based on PSR can not only achieve the sharing of optical delay lines through polarization multiplexing, but also realize the chip integration of the entire signal processing device, resulting in a high degree of integration.

[0021] In another possible design of the above structure one, the first linear polarization state and the second linear polarization state are orthogonal. Both the first and second polarization elements have a first end, a second end, and a third end. Signals are transmitted between the third end and the first end in the original polarization direction, and between the third end and the second end in the original polarization direction. The first end of the first polarization element is connected to the first beam splitter in the first frequency-modulated optoelectronic circuit, the second end of the first polarization element is connected to the first beam splitter in the second 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 first end of the second polarization element is connected to the mixer in the first frequency-modulated optoelectronic circuit, the second end of the second polarization element is connected to the mixer in the second frequency-modulated optoelectronic circuit, and the third end of the second polarization element is connected to the second end of the optical delay line.

[0022] Based on the above design, the first polarization element can acquire two optical signals with orthogonal polarization directions, maintain the polarization directions of these two optical signals unchanged, and input them to the optical delay line, thereby reducing mutual interference during the delay processing. The second polarization element can acquire two delayed optical signals with orthogonal polarization directions, maintain the polarization directions of these two delayed optical signals unchanged, and input them to their respective mixers, ensuring that the mixers receive the delayed signals with the original polarization directions, thus ensuring the accuracy of the mixing operation.

[0023] In one example of the above design, both the first polarizing element and the second polarizing element are polarizing beam splitters (PBS). Based on this, the first polarizing element can combine the first linearly polarized optical signal and the second linearly polarized optical signal and output them to the optical delay line; the second polarizing element can split the delayed optical signal to obtain the delayed first linearly polarized optical signal and the delayed second linearly polarized optical signal. The delayed first linearly polarized optical signal is output to the mixer in the first frequency-modulated optoelectronic circuit, and the delayed second linearly polarized optical signal is output to the mixer in the second frequency-modulated optoelectronic circuit.

[0024] Based on the above examples, PBS can be integrated into a chip. Therefore, implementing polarization control elements based on PBS can not only achieve the sharing of optical delay lines through polarization multiplexing, but also realize the chip integration of the entire signal processing device, resulting in a high degree of integration.

[0025] In one possible design of the above structure one, there are N first frequency-modulated photoelectric circuits, where N is an integer greater than or equal to 2. In this case, the signal processing device also includes a first beam combining element and a second beam splitting element. The N input terminals of the first beam combining element are connected one-to-one to the N first beam splitting elements in the N first frequency-modulated photoelectric circuits. The output terminal of the first beam combining element is connected to the first end of the first polarization element. The input terminal of the second beam splitting element is connected to the first end of the second polarization element. The N output terminals of the second beam splitting element are connected one-to-one to the N mixers in the N first frequency-modulated photoelectric circuits.

[0026] Based on the above design, multiple first frequency-modulated optoelectronic circuits and one second frequency-modulated optoelectronic circuit can share the same optical delay line, which can further reduce the number of optical delay lines that need to be set in the signal processing device, and realize the extremely simple architecture and extremely low cost of the signal processing device.

[0027] In one possible design of the above structure one, there are M second frequency-modulated optoelectronic circuits, where M is an integer greater than or equal to 2. The signal processing device also includes a second beam combiner and a third beam splitter. The M input terminals of the second beam combiner are connected one-to-one to the M first beam splitters in the M second frequency-modulated optoelectronic circuits. The output terminal of the second beam combiner is connected to the second terminal of the first polarization element. The input terminal of the third beam splitter is connected to the second terminal of the second polarization element. The M output terminals of the third beam splitter are connected one-to-one to the M mixers in the M second frequency-modulated optoelectronic circuits.

[0028] Based on the above design, multiple second frequency-modulated optoelectronic circuits and one first frequency-modulated optoelectronic circuit can share the same optical delay line, which can further reduce the number of optical delay lines that need to be set in the signal processing device, and realize the extremely simple architecture and extremely low cost of the signal processing device.

[0029] In one possible design of the above structure two, the first linear polarization state is the same as the second linear polarization state. Both the first and second polarization elements have a first end, a second end, and a third end. Signals are transmitted between the third end and the first end in the original polarization direction, and between the third end and the second end in the polarization direction after a 90° rotation. The first end of the first polarization element is connected to the first beam splitter in the first frequency-modulated optoelectronic circuit, the second end of the first polarization element is connected to the mixer in the second 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 first end of the second polarization element is connected to the mixer in the first frequency-modulated optoelectronic circuit, the second end of the second polarization element is connected to the first beam splitter in the second frequency-modulated optoelectronic circuit, and the third end of the second polarization element is connected to the second end of the optical delay line.

[0030] Based on the above design, the first polarization element can acquire an un-delayed optical signal and a delayed optical signal with the same polarization direction. It maintains the polarization direction of the un-delayed optical signal and inputs it to the optical delay line, while rotating the polarization direction of the delayed optical signal by 90° and inputting it to the corresponding mixer. Similarly, the second polarization element can acquire an un-delayed optical signal and a delayed optical signal with the same polarization direction, rotate the polarization direction of the un-delayed optical signal by 90° and input it to the optical delay line, while maintaining the polarization direction of the delayed optical signal and inputting it to the corresponding mixer. Thus, by combining the first and second polarization elements, the polarization directions of the two optical signals input to the optical delay line can be made orthogonal, reducing mutual interference during the delay process. Simultaneously, it ensures that the optical signal input to the mixer maintains its original polarization direction, guaranteeing the accuracy of the mixing operation.

[0031] In one example of the above design, both the first polarization element and the second polarization element are PSRs. Based on this, the first polarization element can maintain the polarization direction of the first linearly polarized optical signal unchanged and output it to the optical delay line. It can also rotate the polarization direction of the third linearly polarized optical signal after the optical delay line delay processing by 90° to obtain the second linearly polarized optical signal after the delay processing. The second linearly polarized optical signal after the delay processing is then output to the mixer of the second frequency-modulated optoelectronic circuit. The second polarization element can rotate the polarization direction of the second linearly polarized optical signal by 90° to obtain the third linearly polarized optical signal and output it to the optical delay line. It can also maintain the polarization direction of the first linearly polarized optical signal after the delay processing unchanged and output it to the mixer of the first frequency-modulated optoelectronic circuit.

[0032] Based on the above examples, PSR can be integrated into a chip. Therefore, implementing polarization control elements based on PSR can not only achieve the sharing of optical delay lines through polarization multiplexing, but also realize the chip integration of the entire signal processing device, resulting in a high degree of integration.

[0033] In another possible design of the above structure two, the first linear polarization state and the second linear polarization state are orthogonal. Both the first polarization element and the second polarization element have a first end, a second end, and a third end. The third end transmits signals with the first end in the original polarization direction, and the third end transmits signals with the second end in the original polarization direction. The first end of the first polarization element is connected to the first beam splitter in the first frequency-modulated optoelectronic circuit, the second end of the first polarization element is connected to the mixer in the second 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 first end of the second polarization element is connected to the mixer in the first frequency-modulated optoelectronic circuit, the second end of the second polarization element is connected to the first beam splitter in the second frequency-modulated optoelectronic circuit, and the third end of the second polarization element is connected to the second end of the optical delay line.

[0034] Based on the above design, the first polarization element can acquire an un-delayed optical signal and a delayed optical signal with orthogonal polarization directions, keeping the polarization direction of the un-delayed optical signal unchanged before inputting it to the optical delay line, and keeping the polarization direction of the delayed optical signal unchanged before inputting it to the corresponding mixer. Similarly, the second polarization element can acquire an un-delayed optical signal and a delayed optical signal with orthogonal polarization directions, keeping the polarization direction of the un-delayed optical signal unchanged before inputting it to the optical delay line, and keeping the polarization direction of the delayed optical signal unchanged before inputting it to the corresponding mixer. Thus, by combining the first and second polarization elements, the polarization directions of the two optical signals input to the optical delay line can be made orthogonal, reducing mutual interference during the delay process. Simultaneously, it ensures that the optical signal input to the mixer maintains its original polarization direction, ensuring the accuracy of the mixing operation.

[0035] In one example of the above design, both the first polarization element and the second polarization element are polarized beam splitters (PBS). Based on this, the first polarization element can maintain the polarization direction of the first linearly polarized optical signal unchanged and output it to the optical delay line, and maintain the polarization direction of the delayed second linearly polarized optical signal unchanged and output it to the mixer of the second frequency-modulated optoelectronic circuit. The second polarization element can maintain the polarization direction of the second linearly polarized optical signal unchanged and output it to the optical delay line, and maintain the polarization direction of the delayed first linearly polarized optical signal unchanged and output it to the mixer of the first frequency-modulated optoelectronic circuit.

[0036] Based on the above examples, PBS can be integrated into a chip. Therefore, implementing polarization control elements based on PBS can not only achieve the sharing of optical delay lines through polarization multiplexing, but also realize the chip integration of the entire signal processing device, resulting in a high degree of integration.

[0037] In one possible design of the above structure two, there are N first frequency-modulated photoelectric circuits, where N is an integer greater than or equal to 2. The signal processing device also includes a first beam combining element and a second beam splitting element. The N input terminals of the first beam combining element are connected one-to-one to the N first beam splitting elements in the N first frequency-modulated photoelectric circuits. The output terminal of the first beam combining element is connected to the first end of the first polarization element. The input terminal of the second beam splitting element is connected to the first end of the second polarization element. The N output terminals of the second beam splitting element are connected one-to-one to the N mixers in the N first frequency-modulated photoelectric circuits.

[0038] Based on the above design, multiple first frequency-modulated optoelectronic circuits and one second frequency-modulated optoelectronic circuit can share the same optical delay line, which can further reduce the number of optical delay lines that need to be set in the signal processing device, and realize the extremely simple architecture and extremely low cost of the signal processing device.

[0039] In one possible design of the above structure two, there are M second frequency-modulated optoelectronic circuits, where M is an integer greater than or equal to 2. The signal processing device also includes a second beam combiner and a third beam splitter. The M input terminals of the second beam combiner are connected one-to-one to the M first beam splitters in the M second frequency-modulated optoelectronic circuits. The output terminal of the second beam combiner is connected to the second end of the second polarization element. The input terminal of the third beam splitter is connected to the second end of the first polarization element. The M output terminals of the third beam splitter are connected one-to-one to the M mixers in the M second frequency-modulated optoelectronic circuits.

[0040] Based on the above design, multiple second frequency-modulated optoelectronic circuits and one first frequency-modulated optoelectronic circuit can share the same optical delay line, which can further reduce the number of optical delay lines that need to be set in the signal processing device, and realize the extremely simple architecture and extremely low cost of the signal processing device.

[0041] In one possible design of Structure 1 or Structure 2 above, the signal processing device satisfies any one of the following conditions 1 to 4:

[0042] Scenario 1: When both the first polarization element and the second polarization element are PSRs, the optical signals input to the first polarization element are TE light and TE light, and the optical signals output from the first polarization element are TE light and TM light. The optical signals input to the second polarization element are TE light and TM light, and the optical signals output from the second polarization element are TE light and TE light.

[0043] Scenario 2: When both the first polarizing element and the second polarizing element are PBS, the optical signals input to the first polarizing element are TE light and TM light, the optical signals output from the first polarizing element are TE light and TM light, the optical signals input to the second polarizing element are TE light and TM light, and the optical signals output from the second polarizing element are TE light and TM light.

[0044] Scenario 3: When both the first polarization element and the second polarization element are PSRs, the optical signals input to the first polarization element are P-light and P-light, and the optical signals output from the first polarization element are P-light and S-light. The optical signals input to the second polarization element are P-light and S-light, and the optical signals output from the second polarization element are P-light and P-light.

[0045] Scenario 4: When both the first polarizing element and the second polarizing element are PBS, the optical signals input to the first polarizing element are P-light and S-light, the optical signals output from the first polarizing element are P-light and S-light, the optical signals input to the second polarizing element are P-light and S-light, and the optical signals output from the second polarizing element are P-light and S-light.

[0046] Based on the above design, the signal processing device can be applied to optical signal calibration in space, such as in scenario three or four, and can also be applied to optical signal calibration on a chip, such as in scenario one or two. Therefore, the signal processing device has good versatility.

[0047] In one possible design, the optical delay line is either an optical fiber delay line or a waveguide delay line integrated on a chip.

[0048] Based on the above design, the signal processing device can be applied to a variety of optical delay lines, thus possessing universality.

[0049] In one possible design, each frequency-modulated optoelectronic circuit further includes a target measurement path. A polarization control element and an optical delay line are connected between the first output of the first beam splitter and the first input of the mixer. The second output of the first beam splitter is connected to the second input of the mixer, and the third output of the first beam splitter is connected to the target measurement path. Based on this, the first beam splitter can split the optical signal generated by the light source to obtain a local oscillator signal, a signal to be delayed, and a probe signal. It outputs the signal to be delayed through its first output, the local oscillator signal through its second output, and the probe signal through its third output. The mixer can mix the local oscillator signal and the delayed signal, and the target measurement path can use the probe signal for target measurement.

[0050] Based on the above design, the signal processing device can not only calibrate the modulation signal output by the drive circuit, but also perform target measurement. By calibrating the frequency modulation signal output by the drive circuit, the frequency of the light signal emitted by the light source can change linearly with time, thereby making the detection signal obtained based on the light signal meet the preset requirements, thus improving the accuracy of target detection in the target measurement path.

[0051] In one possible design, 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, 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. Based on this, the first beam splitter can perform beam splitting processing on the optical signal generated by the light source to obtain a probe signal and an intermediate optical signal, outputting the intermediate optical signal through its first output terminal and the probe signal through its second output terminal; the second beam splitter can perform beam splitting processing on the intermediate optical signal to obtain a local oscillator signal and a signal to be delayed, outputting the signal to be delayed through its first output terminal and the local oscillator signal through its second output terminal.

[0052] 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.

[0053] In one possible design, each frequency-modulated optoelectronic circuit also includes an amplifier and an analog-to-digital converter (ADC). The amplifier and ADC are connected between the photodetector and the processing element. The amplifier is used to amplify the intermediate frequency (IF) signal from the photodetector, and the ADC is used to convert the amplified IF signal to a digital signal.

[0054] Based on the above design, amplifying the power of the intermediate frequency (IF) signal through an amplifier ensures that the IF signal is successfully transmitted to the analog-to-digital (ADC) converter. Furthermore, sampling the IF signal into a digital signal through the ADC facilitates software analysis by subsequent processing components.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] Figure 1a illustrates an exemplary schematic diagram of the linear relationship between the emitted beam and the modulated signal;

[0059] Figure 1b illustrates an exemplary schematic diagram of the nonlinear relationship between the emitted beam and the modulated signal;

[0060] Figure 2 illustrates a possible application scenario to which this application applies;

[0061] Figure 3a illustrates an exemplary architecture diagram of a mainstream direct-modulation FMCW LiDAR;

[0062] Figure 3b illustrates, exemplarily, a schematic diagram of the structure of a single-laser direct-modulated FMCW LiDAR provided in the industry;

[0063] Figure 3c illustrates a schematic diagram of a direct-modulated FMCW LiDAR with multiple lasers provided in the industry.

[0064] Figure 4 illustrates a schematic diagram of the structure of a signal processing device provided in this application;

[0065] Figure 5 illustrates a schematic diagram of another signal processing device provided in this application;

[0066] Figure 6 illustrates a schematic diagram of the structure of a signal processing apparatus provided in Embodiment 1;

[0067] Figure 7 illustrates, by way of example, a schematic diagram of the flow of linear polarization state of an optical signal provided in Implementation Scheme 1;

[0068] Figure 8a illustrates a possible structural diagram of a PSR provided in Implementation Scheme 1;

[0069] Figure 8b illustrates a schematic diagram of the signal transmission process of a PSR provided in Implementation Scheme 1.

[0070] Figure 8c illustrates a schematic diagram of a single-channel signal transmission process for a PSR provided in Implementation Scheme 1.

[0071] Figure 9 illustrates, by way of example, another linear polarization state transition of an optical signal provided in Implementation Scheme 1;

[0072] Figure 10a illustrates an exemplary schematic diagram of the external structure of a PBS provided in Embodiment 1;

[0073] Figure 10b illustrates an exemplary internal structure diagram of a PBS provided in Implementation Scheme 1;

[0074] Figure 10c illustrates a schematic diagram of a signal transmission process of a PBS provided in Implementation Scheme 1.

[0075] Figure 10d illustrates an exemplary structural diagram of another PBS provided in Implementation Scheme 1;

[0076] Figure 11a illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 1;

[0077] Figure 11b illustrates a schematic diagram of another signal processing device provided in Embodiment 1;

[0078] Figure 11c exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in Embodiment 1;

[0079] Figure 12 illustrates a schematic diagram of a signal processing apparatus provided in Embodiment 2;

[0080] Figure 13 illustrates, by way of example, a schematic diagram of the flow of linear polarization state of an optical signal provided in Implementation Scheme 2;

[0081] Figure 14 illustrates, by way of example, another linear polarization state flow of an optical signal provided in Implementation Scheme 2;

[0082] Figure 15a illustrates a schematic diagram of another signal processing apparatus provided in Embodiment 2;

[0083] Figure 15b illustrates a schematic diagram of the structure of yet another signal processing device provided in Embodiment 2;

[0084] Figure 15c exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in Embodiment 2;

[0085] Figure 16a illustrates a schematic diagram of another signal processing apparatus provided in this application;

[0086] Figure 16b illustrates a schematic diagram of another signal processing apparatus provided in this application;

[0087] Figure 17a illustrates a schematic diagram of another signal processing apparatus provided in this application;

[0088] Figure 17b illustrates a schematic diagram of another signal processing apparatus provided in this application;

[0089] Figure 18a illustrates a schematic diagram of another signal processing apparatus provided in this application;

[0090] Figure 18b illustrates a schematic diagram of another signal processing device provided in this application;

[0091] Figure 18c exemplarily illustrates a structural schematic diagram of another signal processing apparatus provided in this application;

[0092] Figure 18d illustrates a schematic diagram of another signal processing apparatus provided in this application;

[0093] Figure 19 illustrates a schematic diagram of the structure of a detection device provided in this application;

[0094] Figure 20 illustrates a schematic diagram of the structure of a terminal device provided in this application.

[0095] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0096] 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.

[0097] I. Mixing

[0098] Frequency mixing, also known as coherent demodulation, refers to the process of subtracting the frequency and phase of two signals.

[0099] For example, in FMCW LiDAR, the detection 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) will also have the same frequency variation characteristics. However, depending on the distance to the target, the echo signal will have a certain phase difference and frequency difference relative to the detection signal. Therefore, after receiving the echo signal, the echo signal and the detection signal can be mixed, that is, the frequency and phase difference between the detection signal and the echo signal can be 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 proportional to the target distance. It also contains information about the Doppler effect caused by the target's movement, based on which the target's velocity can be calculated.

[0100] II. Interference Properties and Independence of Light

[0101] 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.

[0102] III. Polarizing Beam Splitter (PBS)

[0103] 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.

[0104] 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).

[0105] IV. Polarization Rotating Beam Splitter (PSR)

[0106] 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.

[0107] 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.

[0108] The preceding text introduced some of the terms used in this application. The following text introduces the possible application scenarios of this application.

[0109] 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.

[0110] 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…

[0111] 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.

[0112] 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.

[0113] 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.

[0114] Figure 3a shows a schematic diagram of a mainstream direct-modulation FMCW LiDAR architecture. This direct-modulation FMCW LiDAR 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 FMCW LiDAR 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.

[0115] 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 FMCW LiDAR 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 probe signal and a calibration signal. The probe 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.

[0116] Based on the single-laser direct-modulation FMCW LiDAR 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 FMCW LiDAR, 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 FMCW LiDAR, the length of the optical delay line needs to be P times the length of the delay line in a single-laser direct-modulation FMCW LiDAR. In a single-laser direct-modulation FMCW LiDAR, 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 FMCW LiDAR.

[0117] 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. Thus, when applied to a direct-modulated FMCW LiDAR with multiple lasers, the multiple reference calibration paths corresponding to the multiple lasers can share the same optical delay line, significantly reducing the number of optical delay lines, lowering the size and hardware cost of the optical delay lines, and correspondingly reducing the space occupied by the optical delay lines in the direct-modulated FMCW LiDAR.

[0118] The signal processing apparatus proposed in this application will be described in detail below with reference to Figures 4 to 18d.

[0119] 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.

[0120] 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-modulated photoelectric circuit 110 and a second frequency-modulated photoelectric circuit 210. Each frequency-modulated photoelectric circuit in the first frequency-modulated photoelectric circuit 110 and the second frequency-modulated photoelectric circuit 210 includes a light source, a first beam splitter, a polarization control element 300, an optical delay line 400, a mixer, a photodetector, a processing element, and a driving circuit. Furthermore, the first frequency-modulated photoelectric circuit 110 and the second frequency-modulated photoelectric circuit 210 share the same polarization control element 300 and the same optical delay line 400. For example, the first frequency-modulated photoelectric circuit 110 includes a light source 111, a first beam splitter 112, a polarization control element 300, an optical delay line 400, a mixer 114, a photodetector 115, a processing element 116, and a driving circuit 117, and the second frequency-modulated photoelectric circuit 210 includes a light source 211, a first beam splitter 212, a polarization control element 300, an optical delay line 400, a mixer 214, a photodetector 215, a processing element 216, and a driving circuit 217.

[0121] Based on the structure of this signal processing device, as shown in Figure 4, the first linearly polarized optical signal (S) after being split by the first beam splitting element 112 in the first frequency modulation photoelectric circuit 110 11 The optical signal in the second linearly polarized state (S) after being split by the first beam-splitting element 212 in the second frequency-modulated photoelectric circuit 210. 21 All signals are input to the polarization control element 300, which converts the first linearly polarized optical signal S... 11 The optical signal S in the second linear polarization state 21 The optical signal S is output to the optical delay line 400 with orthogonal polarization directions for delay processing, and the delayed optical signal S in the first frequency-modulated photoelectric circuit 110 is then processed. 11 The optical signal S, output in the form of a first linear polarization state, is then fed to the mixer 114 in the first frequency-modulated photoelectric circuit 110, and the delayed optical signal S in the second frequency-modulated photoelectric circuit 210 is converted into a signal. 21 The output is in the form of a second linear polarization state to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0122] Thus, the optical signal S in the first frequency-modulated photoelectric circuit 110 11 The optical signal S in the second frequency modulation photoelectric circuit 210 21 The signals will be transmitted on the same optical delay line 400, meaning that the same optical delay line 400 can be reused to transmit the optical signals S in the two frequency-modulated optoelectronic circuits. 11 and S 21 The delay processing reduces the number of optical delay lines required in the signal processing device, thereby reducing the cost and space occupied by optical delay lines. Furthermore, due to the optical signal S in the two frequency-modulated optoelectronic circuits...11 and S 21 The optical signal S in the two frequency-modulated optoelectronic circuits is reduced without affecting their respective mixing operations, as the orthogonal linearly polarized states are input to the optical delay line 400 and output to their respective mixers in the original linearly polarized states. 11 and S 21 The mutual interference during the delay processing results in the delayed optical signal S output to the mixers in the two frequency modulation optoelectronic circuits. 11 'and S 21 It can have better signal quality, which can improve the signal calibration effect in each frequency modulation optoelectronic circuit.

[0123] It is understandable that, although the optical signal S in the first frequency modulation photoelectric circuit 110 11 The optical signal S in the second frequency modulation photoelectric circuit 210 21 They will be transmitted in the same optical delay line 400, but due to the two optical signals S 11 and S 21 It is transmitted in orthogonal polarization directions; therefore, the two optical signals S after delay processing 11 'and S 21 Separation can also be based on polarization direction. That is to say, the optical signal S in the first frequency-modulated photoelectric circuit 110 11 The optical signal S in the second frequency modulation photoelectric circuit 210 21 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 the first frequency modulation photoelectric circuit 110 and the second frequency modulation photoelectric circuit 210.

[0124] In the above signal processing device, the frequency-modulated photoelectric circuit can be understood as a loop formed by the signal transmission between the various internal components. For example, taking the first frequency-modulated photoelectric circuit 110 as an example, as shown in Figure 4, the signal transmission process of this circuit is as follows: the light signal S output by the light source 111 enters the first beam splitter 112; the first beam splitter 112 splits the light signal S into light signals Si in the first linear polarization state. 11 Other optical signals (not shown in the figure, see Figure 5 below for details); the optical signal S in the first linearly polarized state 11The 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 Z. The intermediate frequency signal Z is detected by photodetector element 115 and output to processing element 116. Processing element 116 sends feedback signal P to driving circuit 117 according to the detected intermediate frequency signal Z. Driving circuit 117 adjusts modulation signal L1 output to light source 111 according to feedback signal P to calibrate the linearity between modulation signal L1 and optical signal S output by light source 111.

[0125] Optionally, in each frequency-modulated photoelectric circuit, the first beam-splitting element 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 optical signal S in the first linear polarization state). 11 Or the second linearly polarized optical signal S 21 The local oscillator signal is directly input to the mixer, 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 ) and second output terminal (c 12 The mixer 114 may have an output terminal and a first input terminal (d). 11 ) and 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 and the first input terminal d of mixer 114 11 Between, the second output terminal c of the first beam splitter 112 12 Connect to the second input terminal d of mixer 114 12 .

[0126] Based on this structure, after the light source 111 outputs the optical signal S, the first beam splitting element 112 can perform beam splitting processing on the optical signal S to obtain the optical signal S in the first linear polarization state. 11 And the calibration path local oscillator signal, the first beam splitter 112 through its first output terminal c 11 Output the first linearly polarized 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 linearly polarized light signal S 11The 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 in its original linear polarization state (i.e., the first linear polarization state). 11 Mixer 114 connects to its first input terminal d. 11 Received optical signal S in the first linearly polarized state after delay processing 11 ', and through its second input terminal d 12 Upon receiving the calibration path local oscillator signal, the optical signal S of the first linearly polarized state after delay processing... 11 The intermediate frequency signal Z is obtained by mixing the calibrator signal with the local oscillator signal.

[0127] 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, and the second frequency-modulated optoelectronic circuit 210 may also include an amplifier 218 and / or an ADC 219. Taking the first frequency-modulated optoelectronic circuit 110 as an example, as shown in Figure 5, when the 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 Z detected by the photodetector element 115. When the 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 Z 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 Z detected by photodetector 115, and then input the amplified intermediate frequency signal Z to analog-to-digital converter 119. Analog-to-digital converter 119 performs analog-to-digital conversion on the amplified intermediate frequency signal Z to obtain a digital signal, and then inputs the digital signal to processing element 116.

[0128] Furthermore, optionally, as shown in Figure 5, each frequency-modulated photoelectric circuit may also include a target measurement path. For example, the first frequency-modulated photoelectric circuit 110 may also include a target measurement path 113, and the second frequency-modulated photoelectric circuit 210 may also include a target measurement path 213. Target measurement path 113 and target measurement path 213 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 13Connected to the target measurement path 113. The first beam splitter 112 performs beam splitting processing on the optical signal S output from the light source 111, in addition to obtaining the optical signal S in the first linearly polarized state. 11 In addition to the calibration local oscillator signal, a detection signal can also be obtained. The first beam splitter 112 outputs the signal through its third output terminal c. 13 Output detection signal. Due to the third output terminal c 13 Connected to the target measurement path 113, the detection signal can be received by the target measurement path 113, which then performs target measurement based on the received detection signal. The specific implementation of the target measurement path will be described below and will not be discussed here.

[0129] Based on the signal processing device shown in Figure 4 or Figure 5, the optical signals in the first frequency-modulated photoelectric circuit 110 and the second frequency-modulated photoelectric circuit 210 are both input to the same optical delay line 400 for delay processing. These two optical signals can be transmitted in the same direction or in opposite directions within the same optical delay line 400; no specific limitation is imposed. For ease of understanding, the following uses the structure of the signal processing device shown in Figure 5 as an example, and describes the possible implementation methods of unidirectional and reverse transmission based on Scheme 1 and Scheme 2, respectively.

[0130] Implementation Plan 1

[0131] Here, implementation scheme one corresponds to the scheme in which the optical signals in the first frequency modulation optoelectronic circuit 110 and the second frequency modulation optoelectronic circuit 210 are transmitted in the same direction in the same optical delay line 400.

[0132] 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 this example, the polarization control element 300 may include a first polarization element 310 and a second polarization element 320. The first polarization element 310 is connected between the first beam splitter 112 in the first frequency-modulated optoelectronic circuit 110, the first beam splitter 212 in the second frequency-modulated optoelectronic circuit 210, and the first end (a1) of the optical delay line 400. The second polarization element 320 is connected between the mixer 114 in the first frequency-modulated optoelectronic circuit 110, the mixer 214 in the second frequency-modulated optoelectronic circuit 210, and the second end (a2) of the optical delay line 400.

[0133] Based on this structure, when the signal processing device is working, the first polarization element 310 can receive the first linearly polarized optical signal S from the first beam splitter 112 in the first frequency modulation photoelectric circuit 110. 11 The second linearly polarized optical signal S after being split by the first beam-splitting element 212 in the second frequency-modulated photoelectric circuit 210 21 And can make the light signal S in the first linear polarization state 11The optical signal S in the second linear polarization state 21 The two optical signals are output to the first end a1 of the optical delay line 400 with orthogonal polarization directions. After being delayed by the optical delay line 400, they are output from the second end a2 of the optical delay line 400 and enter the second polarization element 320. The second polarization element 320 can decelerate the delayed optical signal S in the first frequency-modulated photoelectric circuit 110. 11 The optical signal S, after being delayed in the second frequency-modulated optoelectronic circuit 210, is output to the mixer 114 in the first frequency-modulated optoelectronic circuit 110 in the form of a first linear polarization state. 21 The output is in the form of a second linear polarization state to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0134] To achieve the above functionality, in one example, as shown in Figure 6, the first polarization element 310 may have a first end b. 11 Second end b 12 and the third end b 13 The first end b 11 The first output terminal c of the first beam splitter 112 connected in the first frequency modulation photoelectric circuit 110 11 The second end b 12 The first output terminal i of the first beam splitter 212 connected in the second frequency modulation photoelectric circuit 210 11 The third end b 13 Connect the first end a1 of the optical delay line 400. In the first frequency-modulated photoelectric circuit 110, the optical signal output from the light source 111 is processed by the first beam splitter 112 to obtain the detection signal, the calibration path local oscillator signal, and the optical signal S of the first linear polarization state. 11 The detection signal originates from the third output terminal c of the first beam splitter 112. 13 The output is sent to the target measurement path 113 for target detection, and the local oscillator signal of the calibration path is output from the second output terminal c of the first beam splitter 112. 12 The output is sent to mixer 114, and the first linearly polarized optical signal S 11 Then from the first output terminal c of the first beam splitter 112 11 Output to the first terminal b of the first polarization element 310 11 In the second frequency-modulated photoelectric circuit 210, the optical signal output from the light source 211 is processed by the first beam splitter 212 to obtain the detection signal, the calibration path local oscillator signal, and the optical signal S of the second linear polarization state. 21 The detection signal originates from the third output terminal i of the first beam splitter 212. 13 The output is sent to the target measurement path 213 for target detection, and the local oscillator signal of the calibration path is output from the second output terminal i of the first beam splitter 212. 12 The output is sent to mixer 214, while the second linearly polarized optical signal S21 Then from the first output terminal i of the first beam splitter 212 11 Output to the second end b of the first polarization element 310 12 The first polarizing element 310 passes through its first end b 11 Acquire the optical signal S in the first linearly polarized state 11 , through its second end b 12 Acquire the optical signal S in the second linearly polarized state 21 Then the first linearly polarized optical signal S 11 The optical signal S in the second linear polarization state 21 With orthogonal polarization directions from its third end b 13 Output. Due to the third terminal b of the first polarization element 310 13 Connecting the first end a1 of the optical delay line 400, therefore, the optical signal S in the first linearly polarized state... 11 The optical signal S in the second linear polarization state 21 It will enter the optical delay line 400 from the first end a1 with orthogonal polarization direction, and then be transmitted in the same direction to the second end a2 of the optical delay line 400 before being output.

[0135] Similarly, as shown in Figure 6, the second polarization element 320 may have a first end b 21 Second end b 22 and the third end b 23 The first end b 21 The first input terminal d of the mixer 114 in the first frequency modulation optoelectronic circuit 110 is connected to... 11 The second end b 22 The first input terminal d of the mixer 214 in the second frequency modulation optoelectronic circuit 210 is connected. 21 The third end b 23 Connect the second end a2 of the optical delay line 400. The delayed optical signal output from the second end a2 of the optical delay line 400 will exit from the third end b of the second polarization element 320. 23 The signal enters the second polarization element 320, which performs beam splitting on the delayed optical signal to obtain the delayed optical signal S in the first frequency-modulated photoelectric circuit 110. 11 The delayed optical signal S in the second frequency-modulated photoelectric circuit 210 21 The second polarization element 320 can polarize the delayed optical signal S in the first frequency-modulated photoelectric circuit 110. 11 'From its first end b in the form of the first linear polarization state' 21The output is transmitted to the mixer 114 in the first frequency-modulated photoelectric circuit 110, where it is mixed with the calibration path signal in the first frequency-modulated photoelectric circuit 110. The second polarization element 320 can also convert the delayed optical signal S in the second frequency-modulated photoelectric circuit 210 into a frequency-modulated signal. 21 'From its second end b in the form of a second linear polarization state' 22 The output is transmitted to the mixer 214 in the second frequency modulation photoelectric circuit 210, and then mixed with the calibration path signal in the second frequency modulation photoelectric circuit 210 itself.

[0136] Optionally, the first linear polarization state and the second linear polarization state mentioned above 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 The optical signal S in the second linear polarization state 21 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 The optical signal S in the second linear polarization state 21 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 It is a P-ray, and the optical signal S is in the second linear polarization state. 21 It is S-light, or the light signal in the first linear polarization state. 11 It is S-light, and the light signal S in the second linear polarization state. 21 It is P-light; from the perspective of chip integration, the first linearly polarized optical signal S... 11 It is TE light, and the light signal S is in the second linear polarization state. 21 It is TM light, or the light signal S in the first linear polarization state. 11 It is TM light, and the light signal S is in the second linear polarization state. 21 It's TE light. And so on. There are many possible implementations, such as different but non-orthogonal linear polarization states, which will not be listed here.

[0137] The following sections will separately introduce the two cases where the first and second linear polarization states are the same linear polarization state or orthogonal linear polarization states.

[0138] The first linear polarization state and the second linear polarization state are the same linear polarization state.

[0139] In one possible implementation, when the first linear polarization state and the second linear polarization state are the same linear polarization state, as shown in Figure 6, the first end b of the first polarization element 310... 11With the third end b 13 Signals are transmitted between them in the original polarization direction, and the second end b 12 With the third end b 13 Signals are transmitted between them in the polarization direction after a 90° rotation. Similarly, the first end b of the second polarization element 320... 21 With the third end b 23 Signals are transmitted between them in the original polarization direction, and the second end b 22 With the third end b 23 Signals are transmitted between them in the polarization direction after a 90° rotation. Or, conversely, that is, the first end b of the first polarization element 310... 11 With the third end b 13 Signals are transmitted between them in the polarization direction after a 90° rotation, and the second end b 12 With the third end b 13 Signals are transmitted between them in the original polarization direction. Similarly, the first end b of the second polarization element 320... 21 With the third end b 23 Signals are transmitted between them in the polarization direction after a 90° rotation, and the second end b 22 With the third end b 23 Signals are transmitted between them in the original polarization direction.

[0140] Taking the former as an example, as shown in Figure 6, due to the first end b of the first polarization element 310 11 The connection is to the first beam splitter 112 in the first frequency modulation photoelectric circuit 110, and the second terminal b 12 The first polarization element 310 is connected to the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210. Therefore, the first polarization element 310 can maintain the first linearly polarized optical signal S output by the first beam splitter 112 in the first frequency-modulated photoelectric circuit 110. 11 The polarization direction remains unchanged, and the second linearly polarized optical signal S output from the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210 can be converted into a single signal. 21 The polarization direction is rotated by 90° to obtain the optical signal in the third linear polarization state. Then, it is transmitted through its third end b. 13 The optical signal in the third linearly polarized state and the optical signal in the first linearly polarized state are output together to the first end a1 of the optical delay line 400. The delayed optical signal is output from the second end a2 of the optical delay line 400 and then enters the second polarization element 320. The second polarization element 320 performs beam splitting on the delayed optical signal to obtain the delayed third linearly polarized optical signal and the delayed first linearly polarized optical signal. Because the first end b of the second polarization element 320... 21 The connection is to the mixer 113 in the first frequency modulation photoelectric circuit 110, and the second terminal b 22Connected to the mixer 214 in the second frequency-modulated optoelectronic circuit 210, the second polarization element 320 can maintain the polarization direction of the first linearly polarized optical signal after the delay processing unchanged, so that it exits from its first end b in the original form of the first linearly polarized state. 21 The output is sent to the mixer 114 in the first frequency modulation optoelectronic circuit 110, which can rotate the polarization direction of the delayed third linearly polarized optical signal by 90° to obtain the delayed second linearly polarized optical signal, so that the delayed second linearly polarized optical signal is transmitted from its second end b in the form of the original second linearly polarized state. 22 The output is sent to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0141] For example, suppose the light signal S in the first linearly polarized state... 11 The optical signal S in the second linear polarization state 21 All are TE light. Please refer to Figure 7, which shows a schematic diagram of the linear polarization state transition of an optical signal provided in Embodiment 1. Referring to Figure 7 and Figure 6 above, in the first frequency-modulated photoelectric circuit 110, the light source 111 outputs TE light. This TE light is split and processed by the first beam splitter 112, and then exits from its first output terminal c. 11 The output optical signal S in the first linear polarization state 11 That is, the TE light, which enters the first end b of the first polarization element 310. 11 In the second frequency-modulated photoelectric circuit 210, the light source 211 outputs TE light, which is then split and processed by the first beam splitter 212, and outputs from its first output terminal i. 11 The output optical signal S in the second linear polarization state 21 That is, the TE light, which enters the second end b of the first polarizing element 310. 11 The first polarizing element 310 maintains its first end b. 11 The polarization direction of the TE light in the first frequency-modulated photoelectric circuit 110 remains unchanged, and its second end b... 12 The polarization direction of the TE light in the input second frequency-modulated photoelectric circuit 210 is rotated by 90° to become TM light, which is then transmitted through its third terminal b. 13 Both are output to the optical delay line 400. The delayed TE light from the first frequency-modulated optoelectronic circuit 110 and the delayed TM light from the second frequency-modulated optoelectronic circuit 210, output from the optical delay line 400, enter the second polarization element 320 together. The second polarization element 320 maintains the polarization direction of the delayed TE light from the first frequency-modulated optoelectronic circuit 110 unchanged, causing it to exit from its first end b in the form of TE light. 21The output is sent to the mixer 114 in the first frequency-modulated optoelectronic circuit 110, and the polarization direction of the delayed TM light in the second frequency-modulated optoelectronic circuit 210 is rotated by 90° to turn it back into TE light, which is then emitted from its second end b in the form of TE light. 22 The output is sent to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0142] Optionally, the first polarization element 310 and the second polarization element 320 described above can be any polarization processing device or combination thereof capable of maintaining the polarization direction of one input signal unchanged and rotating the polarization direction of another input signal by 90°. For example, it can be a PSR as shown in Figure 7. There are many ways to implement a PSR, such as chip-integrated PSR and non-chip-integrated PSR.

[0143] Taking a chip-integrated PSR as an example, please refer to Figure 8a, which shows a possible structural schematic diagram of a PSR provided in Implementation Scheme 1. Figures 8b and 8c show the complete signal transmission flowchart and the single-channel signal transmission flowchart of the PSR, respectively. It should be noted that Figure 8c is only a functional schematic diagram shown for the purpose of illustrating the scheme, and not an actual structural diagram. In the actual structure, the broken lines in Figure 8c should be curved, corresponding to the curved part in Figure 8a. This application will not elaborate on this further.

[0144] First, referring to Figure 8a, the PSR can include two waveguides, such as a straight waveguide and a curved waveguide. The straight waveguide and the curved waveguide have different widths; for example, the straight waveguide is wider, while the curved waveguide is relatively narrower. The top and bottom 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; there are no restrictions.

[0145] Next, as shown in Figure 8a, the straight waveguide and the curved waveguide are positioned with one end close to the other and the other end far apart. The end close to the other end of the straight waveguide is called end 3, the end far apart is called end 1, and the end far apart in the curved waveguide is called end 2. Referring to Figures 8a, 8b, and 8c (A), when TE light is input to end 3 of the straight waveguide, the TE light will propagate from end 3 along the straight waveguide to end 1. The polarization direction does not change during propagation; therefore, the light output from end 1 of the straight waveguide is still TE light. Referring to Figures 8a, 8b, and 8c (B), when TE light is input to end 1 of the straight waveguide, the TE light will propagate from end 1 along the straight waveguide to end 3. The polarization direction does not change during propagation; therefore, the light output from end 3 of the straight waveguide is still TE light. Referring to Figures 8a, 8b, and 8c (C), when TM light is input at end 3 of the straight waveguide, it gradually couples from the straight waveguide to the curved waveguide during transmission. During this coupling process, the polarization direction of the TM light rotates by 90°, transforming it into TE light. Therefore, the light output from end 2 of the curved waveguide is TE light. Referring to Figures 8a, 8b, and 8c (D), when TE light is input at end 2 of the curved waveguide, it gradually couples from the curved waveguide to the straight waveguide during transmission. During this coupling process, the polarization direction of the TE light rotates by 90°, transforming it into TM light. Therefore, the light output from end 3 of the straight waveguide is TM light.

[0146] Based on this, referring to Figures 7 and 8a to 8c, when the PSR is PSR 311 in Figure 7, the 3rd terminal corresponds to the third terminal b of PSR 311. 13 Terminal 1 corresponds to the first terminal b of PSR 311. 11 The second end (b) corresponds to the second end of the PSR 311. 12 In the first frequency-modulated optoelectronic circuit 110, the TE light split by the first beam splitter 112 enters the PSR from end 1 and then propagates along the straight waveguide to end 3. During propagation, the polarization direction of the TE light remains unchanged, i.e., it is always horizontal. Therefore, the optical signal in the first frequency-modulated optoelectronic circuit 110 still enters the optical delay line 400 in the form of TE light. This signal transmission process corresponds to diagram (B) in Figure 8c. In the second frequency-modulated optoelectronic circuit 210, the TE light split by the first beam splitter 212 enters the PSR from end 2 and then gradually couples from the curved waveguide to the straight waveguide, propagating along the straight waveguide to end 3. During coupling, the polarization direction of the TE light changes, gradually shifting from horizontal to vertical, and the TE light becomes TM light. Therefore, the optical signal in the second frequency-modulated optoelectronic circuit 210 enters the optical delay line 400 in the form of TM light. This signal transmission process corresponds to diagram (D) in Figure 8c.

[0147] Similarly, referring to Figures 7 and 8a to 8c, when the PSR is PSR 321 in Figure 7, the 3rd terminal corresponds to the third terminal b of PSR 321. 23 Terminal 1 corresponds to terminal b of PSR 321. 21 The second end (b) corresponds to the second end of the PSR 321. 22 The TE light in the first frequency-modulated optoelectronic circuit 110, after being delayed by the optical delay line 400, enters the PSR from end 3 and then propagates to end 1 of the PSR on the straight waveguide. During the propagation, the polarization direction of the TE light does not change, that is, it is always a horizontal polarization direction. Therefore, the delayed optical signal in the first frequency-modulated optoelectronic circuit 110 still enters the mixer 114 in the first frequency-modulated optoelectronic circuit 110 in the form of TE light. This signal transmission process corresponds to Figure (A) in Figure 8c. The TM light in the second frequency-modulated optoelectronic circuit 210, after being delayed by the optical delay line 400, enters the PSR from end 3, and then couples from the straight waveguide to the curved waveguide, and is transmitted to end 2 of the PSR on the curved waveguide. During the coupling process, the polarization direction of the TM light changes, gradually deflecting from the vertical polarization direction to the horizontal polarization direction, and the TM light becomes TE light. Therefore, the delayed optical signal in the second frequency-modulated optoelectronic circuit 210 enters the mixer 214 in the second frequency-modulated optoelectronic circuit 210 in the form of TE light. This signal transmission process corresponds to Figure (C) in Figure 8c.

[0148] Based on the structure of the PSR described above, since the PSR can be entirely disposed on the buried oxide layer (located above the substrate), it can be integrated into the chip. In other words, using the PSR to implement polarization control elements 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.

[0149] 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 8a, and so on. For example, in another example, the top and bottom sides of the straight waveguide and the curved waveguide in Figure 8a 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.

[0150] The first linear polarization state and the second linear polarization state are orthogonal linear polarization states.

[0151] In one possible implementation, when the first linear polarization state and the second linear polarization state are orthogonal linear polarization states, as shown in Figure 6, the first end b of the first polarization element 310... 11 With the third end b 13Signals are transmitted between them in the original polarization direction, and the second end b 12 With the third end b 13 Signals are also transmitted between them in the original polarization direction. Similarly, the first end b of the second polarization element 320... 21 With the third end b 23 Signals are transmitted between them in the original polarization direction, and the second end b 22 With the third end b 23 Signals are transmitted between them in the original polarization direction.

[0152] Based on this, the first polarization element 310 can maintain the first linearly polarized optical signal S output by the first beam splitter 112 in the first frequency modulation photoelectric circuit 110. 11 The polarization direction remains unchanged, and the second linearly polarized optical signal S output by the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210 can be maintained. 21 The polarization direction remains unchanged, and then it passes through its third end b. 13 The optical signal S in the first frequency-modulated photoelectric circuit 110 with unchanged polarization direction 11 The optical signal S in the second frequency modulation photoelectric circuit 210 21 Both signals are output to the optical delay line 400. The optical signal, after being delayed by the optical delay line 400, is output from the second end a2 of the optical delay line 400 and enters the second polarization element 320. The second polarization element 320 performs beam splitting on the delayed optical signal to obtain the delayed first linearly polarized optical signal S. 11 'and the second linearly polarized optical signal S after time delay processing 21 The second polarization element 320 can maintain the optical signal S in the first linearly polarized state after the delay processing. 11 The polarization direction of ' remains unchanged, so that it remains in its original first linear polarization state from its first end b. 21 The output is sent to the mixer 114 in the first frequency-modulated photoelectric circuit 110, and can maintain the second linearly polarized optical signal S after delay processing. 21 The polarization direction of ' remains unchanged, so that it remains in its original second linear polarization state from its second end b. 22 The output is sent to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0153] For example, suppose the light signal S in the first linearly polarized state... 11 For TE light, the optical signal S in the second linearly polarized state 21 For TM light, please refer to Figure 9, which shows a schematic diagram of the linear polarization state transition of another optical signal provided in Embodiment 1. Referring to Figure 9 and Figure 6 above, in the first frequency-modulated photoelectric circuit 110, the light source 111 outputs TE light. This TE light is split by the first beam splitter 112 and then outputs from its first output terminal c. 11The output optical signal S in the first linear polarization state 11 That is, the TE light, which enters the first end b of the first polarization element 310. 11 In the second frequency-modulated photoelectric circuit 210, the light source 211 outputs TM light, which is then split and processed by the first beam splitter 212 before exiting from its first output terminal i. 11 The output optical signal S in the second linear polarization state 21 That is, the TM light, which enters the second end b of the first polarizing element 310. 12 The first polarizing element 310 maintains its first end b. 11 The polarization direction of the TE light in the first frequency-modulated photoelectric circuit 110 remains unchanged, and its second end b is maintained. 12 The polarization direction of the TM light in the second frequency-modulated photoelectric circuit 210 remains unchanged. The TE light and the TM light are combined into a single beam, which then passes through its third terminal b. 13 The light is output to the optical delay line 400. The delayed TE light from the first frequency-modulated optoelectronic circuit 110 and the delayed TM light from the second frequency-modulated optoelectronic circuit 210, both output from the optical delay line 400, enter the second polarization element 320. The second polarization element 320 maintains the polarization direction of the delayed TE light from the first frequency-modulated optoelectronic circuit 110 unchanged, causing it to exit from its first end b in the form of TE light. 21 The output is sent to the mixer 114 in the first frequency modulation optoelectronic circuit 110, and the polarization direction of the delayed TM light in the second frequency modulation optoelectronic circuit 210 remains unchanged, so that it exits from its second end b in the form of TM light. 22 The output is sent to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0154] Optionally, the first polarization element 310 and the second polarization element 320 described above can be any polarization device or combination thereof capable of combining or splitting two input signals with different polarization directions. For example, it can be a PBS as shown in Figure 9. There are many ways to implement a PBS, such as a chip-integrated PBS and a non-chip-integrated PBS.

[0155] Taking a chip-integrated PBS as an example, please refer to Figures 10a, 10b and 10c. Figure 10a shows a schematic diagram of the appearance of a PBS provided in Embodiment 1, Figure 10b shows a schematic diagram of the internal structure of the PBS, and Figure 10c shows a flowchart of the signal transmission of the PBS.

[0156] First, referring to Figures 10a and 10b, the structure includes a top oxide layer, a bottom buried oxide layer, and a waveguide structure enclosed by these two layers. The waveguide structure comprises a straight waveguide and a curved waveguide. These straight and curved waveguides are similar to those in the PSR shown in Figure 8a, but with some differences, mainly the following three points: 1. The straight and curved waveguides in the PBS are set to have equal widths, i.e., the widths of the straight and curved waveguides are the same; 2. The top and bottom sides of the straight and curved waveguides in the PBS need to be... The same material is used. For example, if the bottom is made of buried oxide layer composed of SiO2, then the top must also be made of oxide layer composed of SiO2. The straight waveguide and the curved waveguide are sandwiched between the bottom buried oxide layer and the top oxide layer. 3. Some areas of the straight waveguide and the curved waveguide in the PBS are parallel. The length of the parallel area needs to be carefully designed so that when the TM light is coupled from the straight waveguide to the curved waveguide, the TE light can hardly or only a small part can be coupled to the curved waveguide. It can be considered that the output of the two ends of the curved waveguide is relatively pure TM light.

[0157] Next, referring to Figures 10a, 10b, and 10c, when TE and TM light are input to end 3 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 end 1 of the straight waveguide is entirely TE light, and the light output from end 2 of the curved waveguide is almost entirely TM light. Even the mixed light of TM and TE light can be considered relatively pure TM light because the amount of TE light is very small. Conversely, when TM light is input to end 2 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 end 3 of the straight waveguide is still TM light. When TE light is input to end 1 of the straight waveguide, the TE light propagates from end 1 of the straight waveguide along the straight waveguide to end 3 of the straight waveguide, and the polarization direction does not change during transmission. Therefore, the light output from end 3 of the straight waveguide is still TE light.

[0158] Based on this, and referring to Figures 7, 10a to 10c, when the PBS is PBS 312 in Figure 7, the 3-end corresponds to the third end b of PBS 312. 13 End 1 corresponds to the first end b of PBS 312. 11 The two ends correspond to the second end b of PBS 312. 12The TE light, split by the first beam splitter 112 in the first frequency-modulated optoelectronic circuit 110 input to end 1 of the PBS, is horizontal. The TM light, split by the first beam splitter 212 in the second frequency-modulated optoelectronic circuit 210 input to end 2 of the PBS, is vertical. The horizontal TE light is transmitted along the straight waveguide to end 3 of the PBS, and its polarization direction does not change during the transmission. Meanwhile, the vertical TM light is rapidly coupled from the curved waveguide to the straight waveguide and then transmitted to end 3 of the PBS. Its polarization direction also does not change during the transmission. Therefore, both lights are output from end 3 of the PBS to the optical delay line 400 with their original polarization direction, thus achieving the beam combining function.

[0159] Similarly, referring to Figures 7, 10a to 10c, when the PBS is PBS 322 in Figure 7, the 3-end corresponds to the third end b of PBS 322. 23 End 1 corresponds to the first end b of PBS 322. 21 The 2nd end corresponds to the second end b of PBS 322. 22 The TE light in the first frequency-modulated optoelectronic circuit 110 and the TM light in the second frequency-modulated optoelectronic circuit 210, after being delayed by the optical delay line 400, both enter the PBS from end 3. The horizontal TE light propagates along the straight waveguide to end 1 of the PBS, and its polarization direction does not change during propagation. The vertical TM light is rapidly coupled from the straight waveguide to the curved waveguide and propagates to end 2 of the PBS, and its polarization direction also does not change during propagation. Therefore, the delayed optical signal in the first frequency-modulated optoelectronic circuit 110 still enters the mixer 114 in the first frequency-modulated optoelectronic circuit 110 in the form of TE light, and the delayed optical signal in the second frequency-modulated optoelectronic circuit 210 enters the mixer 214 in the form of TM light, thus realizing the beam splitting function.

[0160] 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 two ends of the curved waveguide, multiple structures as shown in Figure 10b can be cascaded to further improve the purity of the TM light output from the two ends of the PBS. In this way, even if a small amount of TE light is mixed into the TM light output from the two ends of the curved waveguide of the first structure, a very small portion of this TE light can couple into the curved waveguide of the next structure during the coupling process from the straight waveguide to the curved waveguide. Therefore, the TM light output from the two ends of the curved waveguide of the next structure will be much purer than the TM light output from the two ends of the curved waveguide of the first structure. Generally, cascading two structures is sufficient, effectively improving the purity of the PSR output TM light without significantly increasing structural complexity.

[0161] Based on the structure of the PBS described above, 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 PBS to implement polarization control elements 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.

[0162] However, it should be understood that PBS can also have other implementations. For example, please refer to Figure 10d, which shows another possible implementation structure of PBS. This structure can split and combine P-beams (corresponding to TE beams) and S-beams (corresponding to TM beams) in space. Specifically, the S-beam in the beam input to this structure can be reflected by the structure, while the P-beam is transmitted through it. Whether transmitted or reflected, the polarization direction does not change during transmission. For example, if P-beams and S-beams are input from end 3 of the structure, the P-beam will be transmitted to end 1, while the S-beam will be reflected to end 2, thus splitting the P-beams and S-beams. Conversely, if P-beams are input from end 1 and S-beams from end 2, the structure will transmit the P-beam to end 3 and reflect the S-beam to end 3. Both P-beams and S-beams will be output from end 3, thus combining the P-beams and S-beams. Therefore, this structure can also realize the function of PBS.

[0163] Of course, PBS can also be implemented in other ways, such as through fiber optic devices, or through prisms (such as polarizing beam splitters), or through a chip-integratable structure different from that in Figure 10b, etc., without specific limitations here.

[0164] It should be noted that Figures 6, 7, and 9 above all illustrate signal processing devices with two frequency-modulated photoelectric loops. However, this structure can also be extended to signal processing devices with three or more frequency-modulated photoelectric loops, allowing the three or more frequency-modulated photoelectric loops to share the same optical delay line 400 to transmit the delayed signals in the three or more frequency-modulated photoelectric loops in the same direction. For example, based on the signal processing device shown in Figure 6, please refer to Figures 11a to 11c, which show the structural diagrams of three other possible signal processing devices provided in Scheme 1. These three structures are described in Schemes 1 to 3 below.

[0165] In scenario one, the signal processing device has multiple first frequency modulation optoelectronic circuits.

[0166] In scenario one, referring to Figure 11a, the signal processing device may include N first frequency-modulated photoelectric circuits, namely first frequency-modulated photoelectric circuit 110, first frequency-modulated photoelectric circuit 120, ..., first frequency-modulated photoelectric circuit 1N0, where N is an integer greater than or equal to 2. The structures of the N first frequency-modulated photoelectric circuits 110 to 1N0 are all identical, and the structure of each first frequency-modulated photoelectric circuit can be seen in Figures 6, 7, or 9 above.

[0167] For example, Figure 11a uses the structure shown in Figure 6 as an example. The first frequency-modulated photoelectric circuit 110 includes the light source 111, the first beam splitter 112, the first polarization element 310, the optical delay line 400, the second polarization element 320, the mixer 114, the photodetector 115, the amplifier 118, the analog-to-digital converter 119, the processing element 116, the drive circuit 117, and the target measurement path 113, as described above. Similarly, the first frequency-modulated photoelectric circuit 120 includes the light source 121, the first beam splitter 122, the first polarization element 310, the optical delay line 400, the second polarization element 320, the mixer 124, the photodetector 125, the amplifier 128, the analog-to-digital converter 129, the processing element 126, the drive circuit 127, and the target measurement path 123. ... The first frequency-modulated optoelectronic circuit 1N0 includes a light source 1N1, a first beam splitter 1N2, a first polarization element 310, an optical delay line 400, a second polarization element 320, a mixer 1N4, a photodetector 1N5, an amplifier 1N8, an analog-to-digital converter 1N9, a processing element 1N6, a drive circuit 1N7, and a target measurement circuit 1N3.

[0168] In addition to the components mentioned above, as shown in Figure 11a, the signal processing device may also include a first beam combining element 510 and a second beam splitting element 520. The first beam combining element 510 has N input terminals, namely e1, e2, ..., e2. N The second beam splitter 520 has N output terminals, namely f1, f2, ..., f1. N And one input terminal. The N input terminals e1~e1 of the first optical combining element 510 N The first output terminals c of the N first beam splitting elements 112 to 1N2 in the N first frequency modulation optoelectronic circuits 110 to 1N0 are connected in a one-to-one correspondence. 11 ~c N1 The second output terminal c of the N first beam splitting elements 112 to 1N2 in the N first frequency modulation optoelectronic circuits 110 to 1N0 12 ~c N2 Connect one input terminal of each of the N mixers 114 to 1N4 in the N first frequency modulation optoelectronic circuits 110 to 1N0, and the third output terminal c of each of the N first beam splitting elements 112 to 1N2 in the N first frequency modulation optoelectronic circuits 110 to 1N0. 13 ~cN3 N target measurement paths 113 to 1N3 are respectively connected to N first frequency-modulated photoelectric circuits 110 to 1N0. The first polarization element 310 is connected to the output terminal of the first beam combining element 510 and the first output terminal of the first beam splitting element 212 in the second frequency-modulated photoelectric circuit 210. 11 Between the first end a1 of the optical delay line 400, the second polarization element 320 is connected to the second end a2 of the optical delay line 400, the input end of the second beam splitter 520, and the first input end d of the mixer 214 in the second frequency modulation optoelectronic circuit 210. 21 Between. The N output terminals f1 to f2 of the second beam splitter 520. N The other input terminal of each of the N mixers 114 to 1N4, which are connected to the N first frequency modulation optoelectronic circuits 110 to 1N0, is also connected in a one-to-one correspondence.

[0169] Based on the above structure and connection relationships, in each first frequency-modulated photoelectric circuit, the first beam splitter performs beam splitting processing on the optical signal generated by the light source to obtain a detection signal, a calibration path local oscillator signal, and a first linearly polarized optical signal. The first beam splitter inputs the detection signal to the target measurement path for target measurement through its third output terminal, inputs the calibration path local oscillator signal to the mixer through its second output terminal, and inputs the first linearly polarized optical signal to the first beam combiner 510 through its first output terminal. The first beam combiner 510 inputs through its N input terminals e1~e N Receives N first linearly polarized optical signals S output from N first beam splitting elements 112 to 1N2 in N first frequency-modulated photoelectric circuits 110 to 1N0. 11 ~S 1N For N optical signals S in the first linear polarization state 11 ~S 1N The optical signal is combined to obtain the total first linearly polarized optical signal, which is then input to the first polarization element 310. The first polarization element 310 maintains the polarization direction of the total first linearly polarized optical signal and outputs it to the optical delay line 400 for delay processing. The delayed optical signal then enters the second polarization element 320, which maintains the polarization direction of the delayed total first linearly polarized optical signal and outputs it to the second beam splitter 520. The second beam splitter 520 splits the delayed total first linearly polarized optical signal to obtain N delayed first linearly polarized sub-optical signals S. 11 '~S 1N ', and through its N output terminals f1 to f N The first linearly polarized sub-optical signal S after N delay processing 11 '~S 1NThe signals are respectively sent to N mixers 114 to 1N4 in N first frequency modulation photoelectric circuits 110 to 1N0. In each first frequency modulation photoelectric circuit, the mixer performs frequency mixing processing on the calibration path local oscillator signal input from the first beam splitter and the delayed first linearly polarized sub-light signal input from the second beam splitter 520 to obtain an intermediate frequency signal. The intermediate frequency signal is detected by the photodetector and converted into an electrical signal. The electrical signal is amplified by the amplifier and output to the analog-to-digital converter. After being converted into a digital signal by the analog-to-digital converter, it is output to the processing element. The processing element obtains a feedback signal based on the digital signal and inputs the feedback signal into the drive circuit. The drive circuit generates a modulation signal based on the feedback signal and inputs the modulation signal into the light source to calibrate the linearity between the modulation signal and the light signal output by the light source, so that the light source can output a light signal that conforms to the linear change law under the action of the modulation signal. The detection signal after the light signal is split enters the target measurement path, which can improve the detection accuracy of the target measurement path.

[0170] For example, referring to Figure 11a and Figure 7 above, when both the first polarization element 310 and the second polarization element 320 are PSR, if both the first linearly polarized light signal and the second linearly polarized light signal are TE light, then the N light signals output by the N light sources 111 to 1N1 in the N first frequency-modulated photoelectric circuits 110 to 1N0 and the light signal output by the light source 211 in the second frequency-modulated photoelectric circuit 210 are both TE light. The N TE light in the N first frequency-modulated photoelectric circuits 110 to 1N0 are still N TE light after being split by the N first beam splitters 112 to 1N2. These N TE light are combined into a beam of TE light by the first beam combiner 510 and then enter the first polarization element 310. The TE light split by the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210 also enters the first polarization element 310. The first polarization element 310 maintains the polarization direction of the TE light beam synthesized by the N first frequency-modulated photoelectric circuits 110 to 1N0 unchanged. It rotates the polarization direction of the TE light obtained by splitting in the second frequency-modulated photoelectric circuit 210 by 90° to become TM light. Then, it combines the TE light synthesized by the N first frequency-modulated photoelectric circuits 110 to 1N0 and the rotated TM light obtained by the second frequency-modulated photoelectric circuit 210 into a single optical signal with two polarization directions, and sends it to the optical delay line 400 for delay processing. The delayed optical signal still has two polarization directions. The second polarization element 320 separates these two polarization directions to obtain the delayed TE light and the delayed TM light. Maintaining the polarization direction of the delayed TE light unchanged, it outputs it to the second beam splitter 520. The second beam splitter 520 splits the delayed TE light into TE lights corresponding to the N first frequency-modulated photoelectric circuits, which are then transmitted to their respective mixers. The second polarization element 320 rotates the polarization direction of the delayed TM light by 90° to turn it back into TE light, and outputs it to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0171] For example, referring to Figure 11a and Figure 9 above, when both the first polarization element 310 and the second polarization element 320 are PBS, if the light signal in the first linear polarization state is TE light and the light signal in the second linear polarization state is TM light, then the N light signals output by the N light sources 111 to 1N1 in the N first frequency-modulated photoelectric circuits 110 to 1N0 are all TE light, and the light signal output by the light source 211 in the second frequency-modulated photoelectric circuit 210 is TM light. The N TE lights in the N first frequency-modulated photoelectric circuits 110 to 1N0 are still N TE lights after being split by the N first beam splitters 112 to 1N2. These N TE lights are combined into a beam of TE light by the first beam combiner 510, and then enter the first polarization element 310. The TM light split by the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210 also enters the first polarization element 310. The first polarization element 310 maintains the polarization direction of the TE light synthesized from the N first frequency-modulated optoelectronic circuits 110 to 1N0, and also maintains the polarization direction of the TM light obtained by the second frequency-modulated optoelectronic circuit 210. Then, it combines the TE light synthesized from the N first frequency-modulated optoelectronic circuits 110 to 1N0 and the TM light obtained by the second frequency-modulated optoelectronic circuit 210 into a single optical signal with two polarization directions, and sends it to the optical delay line 400 for delay processing. The delayed optical signal still has two polarization directions. The second polarization element 320 separates these two polarization directions to obtain the delayed TE light and the delayed TM light. Maintaining the polarization direction of the delayed TE light, it outputs it to the second beam splitter 520. The second beam splitter 520 splits the delayed TE light into TE lights corresponding to the N first frequency-modulated optoelectronic circuits, which are then transmitted to their respective mixers. The second polarization element 320 also keeps the polarization direction of the delayed TM light unchanged and outputs it to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0172] Using the structure shown in Figure 11a above, the optical signals of the first linear polarization state in multiple first frequency-modulated optoelectronic circuits and the optical signals of the second linear polarization state in a second frequency-modulated optoelectronic circuit are transmitted in the same direction on the same optical delay line. Therefore, multiple first frequency-modulated optoelectronic circuits and a second frequency-modulated optoelectronic circuit can share the same optical delay line for delay processing based on polarization multiplexing. This can save the number of optical delay lines that need to be set in the signal processing device, and does not reduce the delay time of the optical signals by multiple first frequency-modulated optoelectronic circuits and a second frequency-modulated optoelectronic circuit, thereby realizing a simplified architecture and extremely low cost of the signal processing device.

[0173] Scenario 2: The signal processing device has multiple second frequency-modulated optoelectronic circuits.

[0174] In scenario two, referring to Figure 11b, the signal processing device may include M second frequency-modulated photoelectric circuits, namely second frequency-modulated photoelectric circuit 210, second frequency-modulated photoelectric circuit 220, ..., second frequency-modulated photoelectric circuit 2M0, where M is an integer greater than or equal to 2. The structures of the M second frequency-modulated photoelectric circuits 210 to 2M0 are all identical, and the structure of each second frequency-modulated photoelectric circuit can be seen in Figures 6, 7, or 9 above.

[0175] For example, Figure 11b uses the structure shown in Figure 6 as an example. The second frequency-modulated photoelectric circuit 210 includes the light source 211, the first beam splitter 212, the first polarization element 310, the optical delay line 400, the second polarization element 320, the mixer 214, the photodetector 215, the amplifier 218, the analog-to-digital converter 219, the processing element 216, the drive circuit 217, and the target measurement path 213, as described above. Similarly, the second frequency-modulated photoelectric circuit 220 includes the light source 221, the first beam splitter 222, the first polarization element 310, the optical delay line 400, the second polarization element 320, the mixer 224, the photodetector 225, the amplifier 228, the analog-to-digital converter 229, the processing element 226, the drive circuit 227, and the target measurement path 223. ... The second frequency-modulated optoelectronic circuit 2M0 includes a light source 2M1, a first beam splitter 2M2, a first polarization element 310, an optical delay line 400, a second polarization element 320, a mixer 2M4, a photodetector 2M5, an amplifier 2M8, an analog-to-digital converter 2M9, a processing element 2M6, a drive circuit 2M7, and a target measurement circuit 2M3.

[0176] In addition to the components mentioned above, as shown in Figure 11b, the signal processing device may also include a second beam combining element 530 and a third beam splitting element 540. The second beam combining element 530 has M input terminals, namely g1, g2, ..., g M The third beam splitter 540 has M output terminals, namely h1, h2, ..., h1. M And one input terminal. The M input terminals g1 to g of the second optical combining element 530 M The first output terminals i of the M first beam splitting elements 212 to 2M2 of the M second frequency-modulated photoelectric circuits 210 to 2M0 are connected in a one-to-one correspondence. 11 ~i M1 The second output terminal i of the M first beam splitting elements 212 to 2M2 of the M second frequency-modulated optoelectronic circuits 210 to 2M0 12 ~i M2 The third output terminal i of each of the M mixers 214 to 2M4 connected to the M second frequency modulation optoelectronic circuits 210 to 2M0, and the M first beam splitting elements 212 to 2M2 of the M second frequency modulation optoelectronic circuits 210 to 2M0 are respectively connected to one input terminal. 13 ~iM3 M target measurement paths 213 to 2M3 are respectively connected to M second frequency-modulated photoelectric circuits 210 to 2M0. The first polarization element 310 is connected to the output terminal of the second beam combining element 530 and the first output terminal of the first beam splitting element 112 in the first frequency-modulated photoelectric circuit 110. 11 Between the first end a1 of the optical delay line 400, the second polarization element 320 is connected to the second end a2 of the optical delay line 400, the input end of the third beam splitter 540, and the first input end d of the mixer 114 in the first frequency modulation optoelectronic circuit 110. 11 Between. The M output terminals h1 to h2 of the third beam splitter 540. M The other input terminal of each of the M mixers 214 to 2M4 of the M second frequency modulation optoelectronic circuits 210 to 2M0 is connected in a one-to-one correspondence.

[0177] Based on the above structure and connection relationships, in each second frequency-modulated photoelectric circuit, the first beam splitter performs beam splitting processing on the optical signal generated by the light source to obtain a detection signal, a calibration path local oscillator signal, and a second linearly polarized optical signal. The first beam splitter inputs the detection signal to the target measurement path for target measurement through its third output terminal, inputs the calibration path local oscillator signal to the mixer through its second output terminal, and inputs the second linearly polarized optical signal to the second beam combiner 530 through its first output terminal. The second beam combiner 530 inputs through its M input terminals g1~g M Receives M second linearly polarized optical signals S output from M first beam splitting elements 212 to 2M2 in M ​​second frequency-modulated optoelectronic circuits 210 to 2M0. 21 ~S 2M For M optical signals S in the second linear polarization state 21 ~S 2M The beam is combined to obtain the total second linearly polarized optical signal, which is then input to the first polarization element 310. The first polarization element 310 outputs the total second linearly polarized optical signal in a polarization direction orthogonal to the first linearly polarized state to the optical delay line 400 for delay processing. The delayed optical signal then enters the second polarization element 320, which outputs the delayed optical signal in the form of a second linearly polarized state to the third beam splitter 540. The third beam splitter 540 splits the delayed total second linearly polarized optical signal to obtain M delayed second linearly polarized sub-light signals S. 21 '~S 2M ', and through its M output terminals h1 to h M The M-time-delayed sub-optical signals S of the second linearly polarized state 21 '~S 2MThe signals are respectively sent to M mixers 214 to 2M4 in M ​​second frequency-modulated photoelectric circuits 210 to 2M0. In each second frequency-modulated photoelectric circuit, the mixer performs frequency mixing processing on the calibration path local oscillator signal input from the first beam splitter and the delayed second linearly polarized sub-light signal input from the third beam splitter 540 to obtain an intermediate frequency signal. The intermediate frequency signal is detected by the photodetector and converted into an electrical signal. The electrical signal is amplified by the amplifier and output to the analog-to-digital converter. After being converted into a digital signal by the analog-to-digital converter, it is output to the processing element. The processing element obtains a feedback signal based on the digital signal and inputs the feedback signal into the drive circuit. The drive circuit generates a modulation signal based on the feedback signal and inputs the modulation signal into the light source to calibrate the linearity between the modulation signal and the light signal output by the light source, thereby improving the detection accuracy of the target measurement path.

[0178] For example, referring to Figure 11b and Figure 7 above, when both the first polarization element 310 and the second polarization element 320 are PSR, if both the first linearly polarized light signal and the second linearly polarized light signal are TE light, then the M light signals output by the M light sources 211 to 2M1 in the M second frequency-modulated photoelectric circuits 210 to 2M0 and the light signal output by the light source 111 in the first frequency-modulated photoelectric circuit 110 are all TE light. The M TE light in the M second frequency-modulated photoelectric circuits 210 to 2M0 is still M TE light after being split by the M first beam splitters 212 to 2M2. These M TE light are combined into a beam of TE light by the second beam combiner 530 and then enter the first polarization element 310. The TE light split by the first beam splitter 112 in the first frequency-modulated photoelectric circuit 110 also enters the first polarization element 310. The first polarization element 310 maintains the polarization direction of the TE light obtained from the first frequency-modulated photoelectric circuit 110, and rotates the polarization direction of the TE light synthesized by the M second frequency-modulated photoelectric circuits 210 to 2M0 by 90° to become TM light. Then, the TE light obtained from the first frequency-modulated photoelectric circuit 110 and the TM light obtained from the M second frequency-modulated photoelectric circuits 210 to 2M0 are combined into a light signal with two polarization directions and sent to the optical delay line 400 for delay processing. The delayed light signal still has two polarization directions. The second polarization element 320 separates these two polarization directions to obtain the delayed TE light and the delayed TM light. The polarization direction of the delayed TE light remains unchanged, and it is output to the mixer 114 in the first frequency-modulated photoelectric circuit 110. The polarization direction of the delayed TM light is rotated by 90° to become TE light again, and then output to the third beam splitter 540. The third beam splitter 540 splits the delayed TE light into M delayed TE lights corresponding to the second frequency modulation optoelectronic circuits 210 to 2M0, and then transmits them to their respective mixers.

[0179] For example, referring to Figure 11b and Figure 9 above, when both the first polarizing element 310 and the second polarizing element 320 are PBS, if the light signal in the first linearly polarized state is TE light and the light signal in the second linearly polarized state is TM light, then the light signal output by the light source 111 in the first frequency-modulated photoelectric circuit 110 is TE light, and the M light signals output by the M light sources 211 to 2M1 in the M second frequency-modulated photoelectric circuits 210 to 2M0 are all TM light. The TE light after being split by the first beam splitter 112 in the first frequency-modulated photoelectric circuit 110 enters the first polarizing element 310. The M TM lights in the M second frequency-modulated photoelectric circuits 210 to 2M0 are still M TM lights after being split by the M first beam splitters 212 to 2M2. These M TM lights are combined into a single TM light beam by the second beam combiner 530, and then also enter the first polarizing element 310. The first polarization element 310 maintains the polarization direction of the TE light obtained from the first frequency-modulated optoelectronic circuit 110 and the polarization direction of the TM light synthesized by the M second frequency-modulated optoelectronic circuits 210 to 2M0. Then, it combines the TE light from the first frequency-modulated optoelectronic circuit 110 and the TM light synthesized by the M second frequency-modulated optoelectronic circuits 210 to 2M0 into a single optical signal with two polarization directions, and sends it to the optical delay line 400 for delay processing. The delayed optical signal still has two polarization directions. The second polarization element 320 separates these two polarization directions to obtain the delayed TE light and the delayed TM light. The polarization direction of the delayed TE light remains unchanged, and it is output to the mixer 114 in the first frequency-modulated optoelectronic circuit 110. The polarization direction of the delayed TM light remains unchanged, and it is output to the third beam splitter 540. The third beam splitter 540 splits the delayed TM light into M delayed TM light beams corresponding to the second frequency modulation optoelectronic circuits 210 to 2M0, and then transmits them to their respective mixers.

[0180] Using the structure shown in Figure 11b above, the optical signals of the second linear polarization state in multiple second frequency-modulated optoelectronic circuits and the optical signals of the first linear polarization state in a first frequency-modulated optoelectronic circuit are transmitted in the same direction on the same optical delay line. Therefore, multiple second frequency-modulated optoelectronic circuits and a first frequency-modulated optoelectronic circuit can share the same optical delay line for delay processing based on polarization multiplexing. This can save the number of optical delay lines that need to be set in the signal processing device, and does not reduce the delay time of the optical signals by multiple second frequency-modulated optoelectronic circuits and a first frequency-modulated optoelectronic circuit. Thus, a simplified architecture and extremely low cost of signal processing device can be achieved.

[0181] Scenario 3: The signal processing device has multiple first frequency modulation optoelectronic circuits and multiple second frequency modulation optoelectronic circuits.

[0182] In scenario three, referring to Figure 11c, the signal processing device may include N first frequency-modulated photoelectric circuits 110 to 1N0 as described in scenario one, and M second frequency-modulated photoelectric circuits 210 to 2M0 as described in scenario two. Here, N and M are both integers greater than or equal to 2. The values ​​of N and M can be the same or different, and there is no specific limitation.

[0183] To achieve the reuse of the same optical delay line 400, as shown in Figure 11c, the signal processing device may further include the first beam combiner 510 and the second beam splitter 520 described in scenario one above, as well as the second beam combiner 530 and the third beam splitter 540 described in scenario two above. The first beam combiner 510 and the second beam splitter 520 can enable N first frequency-modulated optoelectronic circuits 110 to 1N0 to share the same optical delay line 400, and the second beam combiner 530 and the third beam splitter 540 can enable M second frequency-modulated optoelectronic circuits 210 to 2M0 to share the same optical delay line 400. Therefore, using the structure shown in Figure 11c, multiple first frequency-modulated optoelectronic circuits and multiple second frequency-modulated optoelectronic circuits can reuse the same optical delay line, which can further reduce the number of optical delay lines required in the signal processing device, achieving a simplified architecture and extremely low cost for the signal processing device.

[0184] It should be noted that the N first frequency-modulated photoelectric circuits and one second frequency-modulated photoelectric circuit in scenario one, the M second frequency-modulated photoelectric circuits and one first frequency-modulated photoelectric circuit in scenario two, and the N first frequency-modulated photoelectric circuits and M second frequency-modulated photoelectric circuits in scenario three are all described as having their own separate target measurement paths. However, in other examples, the N first frequency-modulated photoelectric circuits and one second frequency-modulated photoelectric circuit in scenario one, or the M second frequency-modulated photoelectric circuits and one first frequency-modulated photoelectric circuit in scenario two, or the N first frequency-modulated photoelectric circuits and M second frequency-modulated photoelectric circuits in scenario three may also share the same target measurement path, or some of the frequency-modulated photoelectric circuits may share the same target measurement path, while the other frequency-modulated photoelectric circuits have their own separate target measurement paths, etc. This application does not specifically limit this.

[0185] Furthermore, in scenarios one through three above, for multiple first frequency-modulated optoelectronic circuits or multiple second frequency-modulated optoelectronic circuits transmitting in the same direction, the corresponding multiple optical signals need to be combined into one path before being split into multiple paths. Therefore, to achieve accurate beam splitting, the multiple optical signals need to have wavelength differences. For example, in scenario one or three above, the N optical signals output by the N light sources in the N first frequency-modulated optoelectronic circuits can be optical signals of different wavelengths. These optical signals of different wavelengths are split into optical signals of different wavelengths in the first linear polarization state by the N first beam splitting elements, and then combined into one multi-wavelength optical signal by the first beam combining element 510. This multi-wavelength optical signal is delayed by the optical delay line 400, and then split into N delayed optical signals by the second beam splitting element 520. The N delayed optical signals enter their respective mixers and are mixed with the local oscillator signal of the calibration path of the corresponding wavelength. For example, in scenario two or three above, the M light signals output by the M light sources in the M second frequency-modulated photoelectric circuits can be light signals of different wavelengths. These light signals of different wavelengths are split into light signals of different wavelengths of second linear polarization state by the M first beam splitting elements, and then combined into a multi-wavelength light signal by the second beam combining element 530. The multi-wavelength light signal is delayed by the optical delay line 400, and then split into M delayed light signals by the third beam splitting element 540. The M delayed light signals enter their respective mixers and are mixed with the local oscillator signal of the calibration path of the corresponding wavelength.

[0186] The second beam splitter 520 or the third beam splitter 540 can be based on wavelength, power, or resonance, without specific limitations. For example, in wavelength-based beam splitting, the second beam splitter 520 or the third beam splitter 540 can separate clean, time-delayed optical signals of different wavelengths. These time-delayed optical signals of different wavelengths are output to their respective mixers and mixed with the local oscillator signal of the calibration path of the same wavelength. In power-based or resonance-based beam splitting, although the second beam splitter 520 or the third beam splitter 540 may separate time-delayed optical signals with multiple wavelengths in each path (e.g., each time-delayed optical signal is a uniformly mixed optical signal of various wavelengths), during mixing in the mixer, the wavelength of the calibration path local oscillator signal is used for mixing, and other wavelengths are not used. Therefore, power-based or resonance-based beam splitting can also achieve subsequent mixing and processing functions.

[0187] Implementation Plan 2

[0188] Here, implementation scheme two corresponds to the scheme in which the optical signals in the first frequency modulation optoelectronic circuit 110 and the second frequency modulation optoelectronic circuit 210 are transmitted in reverse on the same optical delay line 400.

[0189] Optionally, please refer to Figure 12, which shows a schematic diagram of a signal processing device provided in Embodiment 2. Referring to Figure 12 and Figure 5 above, in this example, the polarization control element 300 may include a first polarization element 310 and a second polarization element 320. The first polarization element 310 is connected between the first beam splitter 112 in the first frequency-modulated optoelectronic circuit 110, the mixer 214 in the second frequency-modulated optoelectronic circuit 210, and the first end a1 of the optical delay line 400. The second polarization element 320 is connected between the mixer 114 in the first frequency-modulated optoelectronic circuit 110, the first beam splitter 212 in the second frequency-modulated optoelectronic circuit 210, and the second end a2 of the optical delay line 400.

[0190] In one example (referred to as Example 1), when the signal processing device is operating, the first polarization element 310 can receive the first linearly polarized optical signal S from the first beam splitter 112 in the first frequency modulation photoelectric circuit 110 after beam splitting. 11 And the delayed optical signal S in the second frequency-modulated optoelectronic circuit 210 after being delayed by the optical delay line 400. 21 ', The optical signal S maintaining the first linear polarization state 11 The polarization direction remains unchanged, and it is directed to the optical delay line 400. The delayed optical signal S in the second frequency-modulated photoelectric circuit 210 is then... 21 The signal is output in a second linearly polarized state to the mixer 214 in the second frequency-modulated photoelectric circuit 210. Similarly, the second polarization element 320 can receive the second linearly polarized optical signal S from the first beam-splitting element 212 in the second frequency-modulated photoelectric circuit 210. 21 And the delayed optical signal S in the first frequency-modulated optoelectronic circuit 110 after being delayed by the optical delay line 400. 11 ', to convert the second linearly polarized optical signal S 21 The optical signal S, orthogonal to the first linear polarization state, is output to the optical delay line 400, and the delayed optical signal S in the first frequency-modulated photoelectric circuit 110 is then output. 11 The optical signal in the first frequency-modulated optoelectronic circuit 110 is output to the mixer 114 in the first linearly polarized state. Based on this, the optical signal in the first linearly polarized state in the first frequency-modulated optoelectronic circuit 110 is input from the first end a1 of the optical delay line 400 in the first linearly polarized state, and after being delayed by the optical delay line 400, it is output from the second end a2 of the optical delay line 400. Meanwhile, the optical signal in the second linearly polarized state in the second frequency-modulated optoelectronic circuit 110 is input from the second end a2 of the optical delay line 400 in a polarization direction orthogonal to the first linearly polarized state, and after being delayed by the optical delay line 400, it is output from the first end a1 of the optical delay line 400. Therefore, the optical signals in the two frequency-modulated optoelectronic circuits will propagate in opposite directions along the same optical delay line 400 with orthogonal polarization directions.

[0191] Alternatively, in another example (referred to as Example Two), when the signal processing device is operating, the first polarization element 310 receives the first linearly polarized optical signal S from the first beam splitter 112 in the first frequency-modulated photoelectric circuit 110. 11 And the delayed optical signal S in the second frequency-modulated optoelectronic circuit 210 after being delayed by the optical delay line 400. 21 Then, the first linearly polarized optical signal S 11 The optical signal S, orthogonal to the second linear polarization state, is output to the optical delay line 400, and the delayed optical signal S in the second frequency-modulated photoelectric circuit 210 is then used as the input. 21 The signal is output in a second linearly polarized state to the mixer 214 in the second frequency-modulated photoelectric circuit 210. Similarly, the second polarization element 320 receives the second linearly polarized optical signal S from the first beam-splitting element 212 in the second frequency-modulated photoelectric circuit 210. 21 And the delayed optical signal S in the first frequency-modulated optoelectronic circuit 110 after being delayed by the optical delay line 400. 11 Afterwards, the optical signal S maintains the second linear polarization state. 21 The polarization direction remains unchanged, and it is output to the optical delay line 400, and the delayed optical signal S in the first frequency-modulated photoelectric circuit 110 is converted into a signal. 11 The optical signal in the first frequency-modulated optoelectronic circuit 110 is output to the mixer 114 in the first linearly polarized state. Based on this, the optical signal in the first linearly polarized state in the first frequency-modulated optoelectronic circuit 110 is input from the first end a1 of the optical delay line 400 in a form orthogonal to the second linearly polarized state, and after being delayed by the optical delay line 400, is output from the second end a2 of the optical delay line 400. The optical signal in the second linearly polarized state in the second frequency-modulated optoelectronic circuit 110 is input from the second end a2 of the optical delay line 400 in the form of the second linearly polarized state, and after being delayed by the optical delay line 400, is output from the first end a1 of the optical delay line 400. Therefore, the optical signals in the two frequency-modulated optoelectronic circuits will also propagate in opposite directions along the same optical delay line 400 with orthogonal polarization directions.

[0192] To achieve the above solution, optionally, as shown in Figure 12, the first polarization element 310 may have a first end b 11 Second end b 12 and the third end b 13 The first end b 11 The first output terminal c of the first beam splitter 112 connected in the first frequency modulation photoelectric circuit 110 11 The second end b 12 The first input terminal d of the mixer 214 in the second frequency modulation optoelectronic circuit 210 is connected. 21 The third end b 13The first end a1 of the optical delay line 400 is connected. The second polarizing element 320 may have a first end b. 21 Second end b 22 and the third end b 23 The first end b 21 The first input terminal d of the mixer 114 in the first frequency modulation optoelectronic circuit 110 is connected to... 11 The second end b 22 The first output terminal i of the first beam splitter 212 connected in the second frequency modulation photoelectric circuit 210 11 The third end b 23 Connect the second end a2 of the optical delay line 400.

[0193] Taking the above example 1 as an example, in the first frequency-modulated photoelectric circuit 110, the optical signal output by the light source 111 is processed by the first beam splitter 112 to obtain the detection signal, the calibration path local oscillator signal, and the optical signal S of the first linear polarization state. 11 The detection signal originates from the third output terminal c of the first beam splitter 112. 13 The output is sent to the target measurement path 113 for target detection, and the local oscillator signal of the calibration path is output from the second output terminal c of the first beam splitter 112. 12 The output is sent to mixer 114, and the first linearly polarized optical signal S 11 Then from the first output terminal c of the first beam splitter 112 11 The signal is output to the first polarization element 310. The first polarization element 310 maintains the optical signal S in the first linear polarization state. 11 The polarization direction remains unchanged, and the optical signal S in the first linearly polarized state is... 11 From its third end b 13 Output. Due to the third terminal b of the first polarization element 310 13 Connecting the first end a1 of the optical delay line 400, therefore, the optical signal S in the first linearly polarized state... 11 The light signal S enters the optical delay line 400 at its first end a1 in a first linear polarization state. After being delayed within the optical delay line 400, it exits from the second end a2 and enters the second polarization element 320. The second polarization element 320 holds the delayed light signal S. 11 The polarization direction of ' remains unchanged, and the delayed optical signal S 11 'From its first end b in the form of the first linear polarization state' 21 The output enters the mixer 114 in the first frequency modulation photoelectric circuit 110, and is mixed with the calibration circuit signal in the first frequency modulation photoelectric circuit 110 itself.

[0194] Similarly, in the second frequency-modulated photoelectric circuit 210, the optical signal output from the light source 211 is processed by the first beam splitter 212 to obtain the detection signal, the calibration path local oscillator signal, and the optical signal S of the second linear polarization state. 21 The detection signal originates from the third output terminal i of the first beam splitter 212. 13 The output is sent to the target measurement path 213 for target detection, and the local oscillator signal of the calibration path is output from the second output terminal i of the first beam splitter 212. 12 The output is sent to mixer 214, while the second linearly polarized optical signal S 21 Then from the first output terminal i of the first beam splitter 212 11 Output to the second terminal b of the second polarization element 320 22 The second polarization element 320 causes the light signal S to be in the second linear polarization state. 21 Starting from its third end b, with a polarization direction orthogonal to the first linear polarization state. 23 Output. Due to the third terminal b of the second polarization element 320 23 Connecting the second end a2 of the optical delay line 400, therefore, the optical signal S in the second linearly polarized state... 21 The light signal S enters the second end a2 of the optical delay line 400 with a polarization direction orthogonal to the first linear polarization state. After being delayed within the optical delay line 400, it exits from the first end a1 and enters the first polarization element 310. The first polarization element 310 allows the delayed optical signal S to... 21 'From its second end b in the form of a second linear polarization state' 12 The output enters the mixer 214 in the second frequency modulation photoelectric circuit 210, and is mixed with the calibration path signal in the second frequency modulation photoelectric circuit 210 itself.

[0195] Optionally, the first linear polarization state and the second linear polarization state mentioned above 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, the optical signal S of the first linear polarization state... 11 The optical signal S in the second linear polarization state 21 The light can be all P-polarized light, or all S-polarized light, or all TE-polarized light, or all TM-polarized light. Conversely, when the first linear polarization state and the second linear polarization state are orthogonal linear polarization states, the light signal S of the first linear polarization state... 11 It is a P-ray, and the optical signal S is in the second linear polarization state. 21 It is S-light, or the light signal in the first linear polarization state. 11 It is S-light, and the light signal S in the second linear polarization state. 21 It is P-light, or S-light signal in the first linear polarization state. 11 It is TE light, and the light signal S is in the second linear polarization state. 21It is TM light, or the light signal S in the first linear polarization state. 11 It is TM light, and the light signal S is in the second linear polarization state. 21 It's TE light. And so on, I won't list them all here.

[0196] The following sections will separately introduce the two cases where the first and second linear polarization states are the same linear polarization state or orthogonal linear polarization states.

[0197] The first linear polarization state and the second linear polarization state are the same linear polarization state.

[0198] In one possible implementation, when the first linear polarization state and the second linear polarization state are the same linear polarization state, as shown in FIG12, the first end b of the first polarization element 310 11 With the third end b 13 Signals are transmitted between them in the original polarization direction, and the second end b 12 With the third end b 13 Signals are transmitted between them in the polarization direction after a 90° rotation. Similarly, the first end b of the second polarization element 320... 21 With the third end b 23 Signals are transmitted between them in the original polarization direction, and the second end b 22 With the third end b 23 Signals are transmitted between them in the polarization direction after a 90° rotation. Or, conversely, that is, the first end b of the first polarization element 310... 11 With the third end b 13 Signals are transmitted between them in the polarization direction after a 90° rotation, and the second end b 12 With the third end b 13 Signals are transmitted between them in the original polarization direction. Similarly, the first end b of the second polarization element 320... 21 With the third end b 23 Signals are transmitted between them in the polarization direction after a 90° rotation, and the second end b 22 With the third end b 23 Signals are transmitted between them in the original polarization direction.

[0199] Taking the former as an example, as shown in Figure 12, due to the first end b of the first polarization element 310 11 The first polarization element 310 is connected to the first beam splitter 112 in the first frequency-modulated photoelectric circuit 110. Therefore, the first polarization element 310 can maintain the first linearly polarized optical signal S output by the first beam splitter 112 in the first frequency-modulated photoelectric circuit 110. 11 The polarization direction remains unchanged, causing it to be output to the first end a1 of the optical delay line 400 in the form of a first linear polarization state. The delayed optical signal S in the first frequency-modulated photoelectric circuit 110... 11The light output from the second end a2 of the optical delay line 400 enters the second polarization element 320, due to the first end b of the second polarization element 320... 21 The second polarization element 320 is connected to the mixer 113 in the first frequency-modulated photoelectric circuit 110. Therefore, the second polarization element 320 maintains the delayed optical signal S in the first frequency-modulated photoelectric circuit 110. 11 The polarization direction of ' remains unchanged, so that it remains in its original first linear polarization state from its first end b. 21 The output is sent to the mixer 114 in the first frequency modulation photoelectric circuit 110.

[0200] Similarly, due to the second end b of the second polarization element 320 22 The second polarization element 320 is connected to the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210. Therefore, the second polarization element 320 can split the second linearly polarized optical signal S from the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210. 21 The polarization direction is rotated 90°, and then, through its third end b 23 The optical signal S after polarization direction rotation 21 The output is to the second terminal a2 of the optical delay line 400. The delayed optical signal S in the second frequency-modulated optoelectronic circuit 210... 21 The light output from the first end a1 of the optical delay line 400 enters the first polarization element 310, and due to the second end b of the first polarization element 310... 12 The first polarization element 310 is connected to the mixer 214 in the second frequency-modulated photoelectric circuit 210. Therefore, the first polarization element 310 can transmit the delayed optical signal S in the second frequency-modulated photoelectric circuit 210. 21 Rotate its polarization direction by 90° to return it to the second linear polarization state, and then pass it through its second end b. 22 The output enables the delayed optical signal S in the second frequency-modulated photoelectric circuit 210 to... 21 It is output to the mixer 214 in the second frequency modulation photoelectric circuit 210 in the form of the original second linear polarization state.

[0201] For example, suppose the light signal S in the first linearly polarized state... 11 The optical signal S in the second linear polarization state 21 All are TE light. Please refer to Figure 13, which shows a schematic diagram of the linear polarization state transition of an optical signal provided in Embodiment 2. Referring to Figure 13 and Figure 12 above, in the first frequency-modulated photoelectric circuit 110, the light source 111 outputs TE light. This TE light is split and processed by the first beam splitter 112, and then exits from its first output terminal c. 11 The output optical signal S in the first linear polarization state 11 That is, the TE light, which enters the first end b of the first polarization element 310. 11The first polarizing element 310 maintains its first end b. 11 The polarization direction of the TE light in the first frequency-modulated photoelectric circuit 110 remains unchanged, and it passes through its third terminal b. 13 The TE light is output to the optical delay line 400. The TE light after delay processing in the first frequency-modulated optoelectronic circuit 110 output from the optical delay line 400 enters the second polarization element 320. The second polarization element 320 maintains the polarization direction of the TE light after delay processing in the first frequency-modulated optoelectronic circuit 110 unchanged, so that it exits from the first end b in the form of TE light. 21 The output is sent to the mixer 114 in the first frequency modulation photoelectric circuit 110.

[0202] Similarly, in the second frequency-modulated photoelectric circuit 210, the light source 211 outputs TE light, which is then split and processed by the first beam splitter 212 before exiting from its first output terminal i. 11 The output optical signal S in the second linear polarization state 21 That is, the TE light, which enters the second end b of the second polarization element 320. 22 The second polarizing element 320 sets its second end b 22 The polarization direction of the TE light in the input second frequency-modulated photoelectric circuit 210 is rotated by 90° to become TM light, which is then transmitted through its third terminal b. 23 The TM light is output to the optical delay line 400. The time-delayed TM light from the second frequency-modulated optoelectronic circuit 210 output from the optical delay line 400 enters the first polarization element 310. The first polarization element 310 rotates the polarization direction of the TM light by 90°, turning it back into TE light, and causes it to exit from its second end b in the form of TE light. 12 The output is sent to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0203] Understandably, the first polarization element 310 and the second polarization element 320 described above can be any polarization processing device or combination thereof capable of maintaining the polarization direction of one input signal unchanged and rotating the polarization direction of another input signal by 90°. For example, it can be a PSR as shown in Figure 13. There are many ways to implement a PSR, such as chip-integrated PSR and non-chip-integrated PSR. The specific structure can be found in the description in Scheme 1 above, and will not be repeated here.

[0204] The first linear polarization state and the second linear polarization state are orthogonal linear polarization states.

[0205] In one possible implementation, when the first linear polarization state and the second linear polarization state are orthogonal linear polarization states, as shown in Figure 12, the first end b of the first polarization element 310... 11 With the third end b 13Signals are transmitted between them in the original polarization direction, and the second end b 12 With the third end b 13 Signals are also transmitted between them in the original polarization direction. Similarly, the first end b of the second polarization element 320... 21 With the third end b 23 Signals are transmitted between them in the original polarization direction, and the second end b 22 With the third end b 23 Signals are transmitted between them in the original polarization direction.

[0206] Based on this, the first polarization element 310 can maintain the first linearly polarized optical signal S after it has been split by the first beam splitter 112 in the first frequency modulation photoelectric circuit 110. 11 The polarization direction remains unchanged, causing it to exit from its third end b in the form of a first linear polarization state. 13 The output is sent to the optical delay line 400, and the delayed optical signal S in the second frequency-modulated optoelectronic circuit 210 can be maintained. 21 The polarization direction of ' remains unchanged, causing it to be in a second linear polarization state from its second end b. 12 The output is sent to mixer 214 in the second frequency-modulated optoelectronic circuit 210. Similarly, the second polarization element 320 can maintain the second linearly polarized optical signal S after it has been split by the first beam-splitting element 212 in the second frequency-modulated optoelectronic circuit 210. 21 The polarization direction remains unchanged, causing it to be in a second linear polarization state from its third end b. 23 The output is sent to the optical delay line 400, and the delayed optical signal S in the first frequency modulation optoelectronic circuit 110 can be maintained. 11 The polarization direction of ' remains unchanged, so that it is in the form of the first linear polarization state from its first end b. 11 The output is sent to the mixer 114 in the first frequency modulation photoelectric circuit 110.

[0207] For example, suppose the light signal S in the first linearly polarized state... 11 For TE light, the optical signal S in the second linearly polarized state 21 For TM light, please refer to Figure 14, which shows a schematic diagram of the linear polarization state transition of another optical signal provided in Embodiment 2. Referring to Figure 14 and Figure 12 above, in the first frequency-modulated photoelectric circuit 110, the light source 111 outputs TE light. This TE light is split by the first beam splitter 112 and then outputs from its first output terminal c. 11 The output optical signal S in the first linear polarization state 11 That is, the TE light, which enters the first end b of the first polarization element 310. 11 The first polarizing element 310 maintains its first end b. 11 The polarization direction of the TE light in the first frequency-modulated photoelectric circuit 110 remains unchanged, allowing it to pass through its third terminal b in the form of TE light. 13The output is sent to the optical delay line 400. The delayed TE light from the first frequency-modulated optoelectronic circuit 110 output from the optical delay line 400 enters the second polarization element 320. The second polarization element 320 maintains the polarization direction of the TE light, causing it to exit from its first end b in the form of TE light. 21 The output is sent to the mixer 114 in the first frequency modulation photoelectric circuit 110.

[0208] Similarly, in the second frequency-modulated photoelectric circuit 210, the light source 211 outputs TM light, which is then split and processed by the first beam splitter 212 before exiting from its first output terminal i. 11 The output optical signal S in the second linear polarization state 21 That is, the TM light, which enters the second end b of the second polarizing element 320. 22 The second polarizing element 320 maintains its second end b. 22 The polarization direction of the TM light in the input second frequency-modulated photoelectric circuit 210 remains unchanged, allowing it to pass through its third terminal b in the form of TM light. 23 The output is sent to the optical delay line 400. The time-delayed TM light from the second frequency-modulated optoelectronic circuit 210 output from the optical delay line 400 enters the first polarization element 310. The first polarization element 310 keeps the polarization direction of the TM light unchanged, so that it exits from its second end b in the form of TM light. 12 The output is sent to the mixer 214 in the second frequency modulation optoelectronic circuit 210.

[0209] Understandably, the first polarization element 310 and the second polarization element 320 mentioned above can be any polarization device or combination thereof capable of combining or splitting two input signals with different polarization directions. For example, it can be a PBS as shown in Figure 14. There are many ways to implement a PBS, such as chip-integrated PBS and non-chip-integrated PBS. The specific structure can be found in the description in Scheme 1 above, and will not be repeated here.

[0210] It should be noted that Figures 12 to 14 above all illustrate signal processing devices with two frequency-modulated photoelectric loops. However, this structure can also be extended to signal processing devices with three or more frequency-modulated photoelectric loops, allowing the three or more frequency-modulated photoelectric loops to share a single optical delay line 400 for reverse transmission of the signals to be delayed in the three or more frequency-modulated photoelectric loops. For example, based on the signal processing device shown in Figure 12, please refer to Figures 15a to 15c, which show structural diagrams of three other possible signal processing devices provided in Embodiment 2. These three structures are described in Scenarios 1 to 3, respectively.

[0211] In scenario one, the signal processing device has multiple first frequency modulation optoelectronic circuits.

[0212] In scenario one, referring to Figure 15a, the signal processing device may include N first frequency-modulated photoelectric circuits, namely first frequency-modulated photoelectric circuit 110, first frequency-modulated photoelectric circuit 120, ..., first frequency-modulated photoelectric circuit 1N0, where N is an integer greater than or equal to 2. The structures of the N first frequency-modulated photoelectric circuits 110 to 1N0 are all identical, and the structure of each first frequency-modulated photoelectric circuit can be seen in Figures 12 to 14 above.

[0213] For example, Figure 15a uses the structure shown in Figure 12 as an example. The first frequency-modulated photoelectric circuit 110 includes the light source 111, the first beam splitter 112, the first polarization element 310, the optical delay line 400, the second polarization element 320, the mixer 114, the photodetector 115, the amplifier 118, the analog-to-digital converter 119, the processing element 116, the drive circuit 117, and the target measurement path 113, as described above. Similarly, the first frequency-modulated photoelectric circuit 120 includes the light source 121, the first beam splitter 122, the first polarization element 310, the optical delay line 400, the second polarization element 320, the mixer 124, the photodetector 125, the amplifier 128, the analog-to-digital converter 129, the processing element 126, the drive circuit 127, and the target measurement path 123. ... The first frequency-modulated optoelectronic circuit 1N0 includes a light source 1N1, a first beam splitter 1N2, a first polarization element 310, an optical delay line 400, a second polarization element 320, a mixer 1N4, a photodetector 1N5, an amplifier 1N8, an analog-to-digital converter 1N9, a processing element 1N6, a drive circuit 1N7, and a target measurement circuit 1N3.

[0214] In addition to the components mentioned above, as shown in Figure 15a, the signal processing device may also include a first beam combining element 510 and a second beam splitting element 520. The first beam combining element 510 has N input terminals, namely e1, e2, ..., e2. N The second beam splitter 520 has N output terminals, namely f1, f2, ..., f1. N And one input terminal. The N input terminals e1~e1 of the first optical combining element 510 N The first output terminals c of the N first beam splitting elements 112 to 1N2 in the N first frequency modulation optoelectronic circuits 110 to 1N0 are connected in a one-to-one correspondence. 11 ~c N1 The second output terminal c of the N first beam splitting elements 112 to 1N2 in the N first frequency modulation optoelectronic circuits 110 to 1N0 12 ~c N2 The third output terminal c of each of the N mixers 114 to 1N4 connected to the N first frequency modulation optoelectronic circuits 110 to 1N0, and the third output terminal c of the N first beam splitting elements 112 to 1N2 in the N first frequency modulation optoelectronic circuits 110 to 1N0. 13 ~cN3 N target measurement paths 113 to 1N3 are respectively connected to N first frequency-modulated photoelectric circuits 110 to 1N0. A first polarization element 310 is connected between the output terminal of the first beam combiner 510, the first input terminal of the mixer 214 in the second frequency-modulated photoelectric circuit 210, and the first end a1 of the optical delay line 400. A second polarization element 320 is connected between the second end a2 of the optical delay line 400, the input terminal of the second beam splitter 520, and the first input terminal of the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210. The N output terminals f1 to f2 of the second beam splitter 520 are... N The other input terminal of each of the N mixers 114 to 1N4 in the N first frequency modulation optoelectronic circuits 110 to 1N0 is connected in a one-to-one correspondence.

[0215] Based on the above structure and connection relationships, in each first frequency-modulated photoelectric circuit, the first beam splitter performs beam splitting processing on the optical signal generated by the light source to obtain a detection signal, a calibration path local oscillator signal, and a first linearly polarized optical signal. The first beam splitter inputs the detection signal to the target measurement path for target measurement through its third output terminal, inputs the calibration path local oscillator signal to the mixer through its second output terminal, and inputs the first linearly polarized optical signal to the first beam combiner 510 through its first output terminal. The first beam combiner 510 inputs through its N input terminals e1~e N Receives N first linearly polarized optical signals S output from N first beam splitting elements 112 to 1N2 in N first frequency-modulated photoelectric circuits 110 to 1N0. 11 ~S 1N For N optical signals S in the first linear polarization state 11 ~S 1N The optical signal is combined to obtain the total first linearly polarized optical signal, which is then input to the first polarization element 310. The first polarization element 310 maintains the polarization direction of the total first linearly polarized optical signal and outputs it to the optical delay line 400 for delay processing. The delayed optical signal then enters the second polarization element 320, which maintains the polarization direction of the delayed total first linearly polarized optical signal and outputs it to the second beam splitter 520. The second beam splitter 520 splits the delayed total first linearly polarized optical signal to obtain N delayed first linearly polarized sub-optical signals S. 11 '~S 1N ', and through its N output terminals f1 to f N The first linearly polarized sub-optical signal S after N delay processing 11 '~S 1NThe signals are respectively sent to N mixers 114 to 1N4 in N first frequency modulation photoelectric circuits 110 to 1N0. In each first frequency modulation photoelectric circuit, the mixer performs frequency mixing processing on the calibration path local oscillator signal input from the first beam splitter and the delayed first linearly polarized sub-light signal input from the second beam splitter 520 to obtain an intermediate frequency signal. The intermediate frequency signal is detected by the photodetector and converted into an electrical signal. The electrical signal is amplified by the amplifier and output to the analog-to-digital converter. After being converted into a digital signal by the analog-to-digital converter, it is output to the processing element. The processing element obtains a feedback signal based on the digital signal and inputs the feedback signal into the drive circuit. The drive circuit generates a modulation signal based on the feedback signal and inputs the modulation signal into the light source to calibrate the linearity between the modulation signal and the light signal output by the light source, thereby improving the detection accuracy of the target measurement path.

[0216] For example, referring to Figure 15a and Figures 13 or 14 above, when both the first polarization element 310 and the second polarization element 320 are PSR or both are PBS, if the light signal of the first linearly polarized state is TE light, then the N light signals output by the N light sources 111 to 1N1 in the N first frequency-modulated photoelectric circuits 110 to 1N0 and the light signal output by the light source 211 in the second frequency-modulated photoelectric circuit 210 are both TE light. The N TE lights in the N first frequency-modulated photoelectric circuits 110 to 1N0 are still N TE lights after being split by the N first beam splitters 112 to 1N2. These N TE lights are combined into a beam of TE light by the first beam combiner 510, and then enter the first polarization element 310. The first polarization element 310 keeps the polarization direction of the beam of TE light combined by the N first frequency-modulated photoelectric circuits 110 to 1N0 unchanged, and sends the TE light combined by the N first frequency-modulated photoelectric circuits 110 to 1N0 to the optical delay line 400 for delay processing. The delayed TE light enters the second polarization element 320, which keeps the polarization direction of the delayed TE light unchanged and outputs it to the second beam splitter 520. The second beam splitter 520 splits the delayed TE light into N beams corresponding to the first frequency modulation optoelectronic circuits, and then transmits them to their respective mixers.

[0217] It should be noted that the signal flow process of the second frequency modulation photoelectric circuit 210 in scenario one is the same as that described in Figure 13 or Figure 14 above, and will not be repeated here.

[0218] Using the structure shown in Figure 15a above, the optical signals of the first linear polarization state in multiple first frequency-modulated optoelectronic circuits and the optical signals of the second linear polarization state in the second frequency-modulated optoelectronic circuit are transmitted in opposite directions on the same optical delay line. Therefore, multiple first frequency-modulated optoelectronic circuits and one second frequency-modulated optoelectronic circuit can share the same optical delay line for delay processing based on polarization multiplexing. This can save the number of optical delay lines that need to be set in the signal processing device, and does not reduce the delay time of the optical signals by multiple first frequency-modulated optoelectronic circuits and one second frequency-modulated optoelectronic circuit, thereby realizing a simplified architecture and extremely low cost of the signal processing device.

[0219] Scenario 2: The signal processing device has multiple second frequency-modulated optoelectronic circuits.

[0220] In scenario two, referring to Figure 15b, the signal processing device may include M second frequency-modulated photoelectric circuits, namely second frequency-modulated photoelectric circuit 210, second frequency-modulated photoelectric circuit 220, ..., second frequency-modulated photoelectric circuit 2M0, where M is an integer greater than or equal to 2. The structures of the M second frequency-modulated photoelectric circuits 210 to 2M0 are all identical, and the structure of each second frequency-modulated photoelectric circuit can be seen in Figures 12 to 14 above.

[0221] For example, Figure 15b uses the structure shown in Figure 12 as an example. The second frequency-modulated photoelectric circuit 210 includes the light source 211, the first beam splitter 212, the first polarization element 310, the optical delay line 400, the second polarization element 320, the mixer 214, the photodetector 215, the amplifier 218, the analog-to-digital converter 219, the processing element 216, the drive circuit 217, and the target measurement path 213, as described above. Similarly, the second frequency-modulated photoelectric circuit 220 includes the light source 221, the first beam splitter 222, the first polarization element 310, the optical delay line 400, the second polarization element 320, the mixer 224, the photodetector 225, the amplifier 228, the analog-to-digital converter 229, the processing element 226, the drive circuit 227, and the target measurement path 223. ... The second frequency-modulated optoelectronic circuit 2M0 includes a light source 2M1, a first beam splitter 2M2, a first polarization element 310, an optical delay line 400, a second polarization element 320, a mixer 2M4, a photodetector 2M5, an amplifier 2M8, an analog-to-digital converter 2M9, a processing element 2M6, a drive circuit 2M7, and a target measurement circuit 2M3.

[0222] In addition to the components mentioned above, as shown in Figure 15b, the signal processing device may also include a second beam combining element 530 and a third beam splitting element 540. The second beam combining element 530 has M input terminals, namely g1, g2, ..., g M The third beam splitter 540 has M output terminals, namely h1, h2, ..., h1. MAnd one input terminal. The M input terminals g1 to g of the second optical combining element 530 M The first output terminals i of the M first beam splitting elements 212 to 2M2 in the M second frequency-modulated photoelectric circuits 210 to 2M0 are connected in a one-to-one correspondence. 11 ~i M1 The second output terminal i of the M first beam splitting elements 212 to 2M2 in the M second frequency-modulated optoelectronic circuits 210 to 2M0 12 ~i M2 Connect one input terminal of each of the M mixers 214 to 2M4 in the M second frequency modulation optoelectronic circuits 210 to 2M0, and the third output terminal i of each of the M first beam splitting elements 212 to 2M2 in the M second frequency modulation optoelectronic circuits 210 to 2M0. 13 ~i M3 The M target measurement paths 213 to 2M3 of the M second frequency-modulated photoelectric circuits 210 to 2M0 are respectively connected. The second polarization element 320 is connected to the output terminal of the second light combining element 530 and the first input terminal d of the mixer 114 in the first frequency-modulated photoelectric circuit 110. 11 Between the second end a2 of the optical delay line 400, the first polarization element 310 is connected between the first end a1 of the optical delay line 400, the input end of the third beam splitter 540, and the first output end of the first beam splitter 112 in the first frequency modulation optoelectronic circuit 110. The M output ends h1~h2 of the third beam splitter 540 are connected between these points. M The other input terminal of each of the M mixers 214 to 2M4 in the M second frequency modulation optoelectronic circuits 210 to 2M0 is connected in a one-to-one correspondence.

[0223] Based on the above structure and connection relationships, in each second frequency-modulated photoelectric circuit, the first beam splitter performs beam splitting processing on the optical signal generated by the light source to obtain a detection signal, a calibration path local oscillator signal, and a second linearly polarized optical signal. The first beam splitter inputs the detection signal to the target measurement path for target measurement through its third output terminal, inputs the calibration path local oscillator signal to the mixer through its second output terminal, and inputs the second linearly polarized optical signal to the second beam combiner 530 through its first output terminal. The second beam combiner 530 inputs through its M input terminals g1~g M Receives M second linearly polarized optical signals S output from M first beam splitting elements 212 to 2M2 in M ​​second frequency-modulated optoelectronic circuits 210 to 2M0. 21 ~S 2M For M optical signals S in the second linear polarization state 21 ~S 2MThe beam is combined to obtain the total second linearly polarized optical signal, which is then input to the second polarization element 320. The second polarization element 320 outputs the total second linearly polarized optical signal in a form orthogonal to the first linearly polarized state to the optical delay line 400 for delay processing. The delayed optical signal then enters the first polarization element 310. The first polarization element 310 outputs the delayed total optical signal in the form of a second linearly polarized state to the third beam splitter 540. The third beam splitter 540 splits the delayed total second linearly polarized optical signal to obtain M delayed second linearly polarized sub-light signals S. 21 '~S 2M ', and through its M output terminals h1 to h M The M-time-delayed sub-optical signals S of the second linearly polarized state 21 '~S 2M The signals are respectively sent to M mixers 214 to 2M4 in M ​​second frequency-modulated photoelectric circuits 210 to 2M0. In each second frequency-modulated photoelectric circuit, the mixer performs frequency mixing processing on the calibration path local oscillator signal input from the first beam splitter and the delayed second linearly polarized sub-light signal input from the third beam splitter 540 to obtain an intermediate frequency signal. The intermediate frequency signal is detected by the photodetector and converted into an electrical signal. The electrical signal is amplified by the amplifier and output to the analog-to-digital converter. After being converted into a digital signal by the analog-to-digital converter, it is output to the processing element. The processing element obtains a feedback signal based on the digital signal and inputs the feedback signal into the drive circuit. The drive circuit generates a modulation signal based on the feedback signal and inputs the modulation signal into the light source to calibrate the linearity between the modulation signal and the light signal output by the light source, thereby improving the detection accuracy of the target measurement path.

[0224] For example, referring to Figure 15b and Figure 13 above, when both the first polarization element 310 and the second polarization element 320 are PSRs, if both the first linearly polarized light signal and the second linearly polarized light signal are TE light, then the M light signals output from the M light sources 211 to 2M1 in the M second frequency-modulated photoelectric circuits 210 to 2M0 and the light signal output from the light source 111 in the first frequency-modulated photoelectric circuit 110 are all TE light. After being split by the M first beam splitters 212 to 2M2, the M TE lights in the M second frequency-modulated photoelectric circuits 210 to 2M0 remain as M TE lights. These M TE lights are then combined into a single TE beam by the second beam combiner 530, and then enter the second polarization element 320. The second polarization element 320 rotates the polarization direction of the single TE beam synthesized by the M second frequency-modulated photoelectric circuits 210 to 2M0 by 90° to become TM light, and then sends the TM light to the optical delay line 400 for delay processing. The time-delayed TM light enters the first polarization element 310, which rotates the polarization direction of the time-delayed TM light by 90° to convert it back into TE light, and outputs it to the third beam splitter 540. The third beam splitter 540 splits the time-delayed TE light into M second frequency-modulated optoelectronic circuits 210 to 2M0, each corresponding to a time-delayed TE light, which is then transmitted to its corresponding mixer.

[0225] For example, referring to Figure 15b and Figure 14 above, when both the first polarizing element 310 and the second polarizing element 320 are PBS, if the light signal in the first linearly polarized state is TE light and the light signal in the second linearly polarized state is TM light, then the light signal output by the light source 111 in the first frequency-modulated photoelectric circuit 110 is TE light, and the M light signals output by the M light sources 211 to 2M1 in the M second frequency-modulated photoelectric circuits 210 to 2M0 are all TM light. The M TM lights in the M second frequency-modulated photoelectric circuits 210 to 2M0 are still M TM lights after being split by the M first beam splitters 212 to 2M2. These M TM lights are combined into a beam of TM light by the second beam combiner 530, and then enter the second polarizing element 320. The second polarizing element 320 keeps the polarization direction of the beam of TM light combined by the M second frequency-modulated photoelectric circuits 210 to 2M0 unchanged, and then sends the TM light to the optical delay line 400 for delay processing. The time-delayed TM light enters the first polarization element 310, which maintains the polarization direction of the time-delayed TM light and outputs it to the third beam splitter 540. The third beam splitter 540 splits the time-delayed TM light into M second frequency-modulated optoelectronic circuits 210 to 2M0, each corresponding to a time-delayed TM light, which is then transmitted to its respective mixer.

[0226] Using the structure shown in Figure 15b above, the optical signals of the second linear polarization state in multiple second frequency-modulated optoelectronic circuits and the optical signals of the first linear polarization state in a first frequency-modulated optoelectronic circuit are transmitted in opposite directions on the same optical delay line. Therefore, multiple second frequency-modulated optoelectronic circuits and a first frequency-modulated optoelectronic circuit can share the same optical delay line for delay processing based on polarization multiplexing. This can save the number of optical delay lines that need to be set in the signal processing device, and does not reduce the delay time of the optical signals by multiple second frequency-modulated optoelectronic circuits and a first frequency-modulated optoelectronic circuit. Thus, a very simple architecture and extremely low cost of signal processing device can be achieved.

[0227] Scenario 3: The signal processing device has multiple first frequency modulation optoelectronic circuits and multiple second frequency modulation optoelectronic circuits.

[0228] In scenario three, referring to Figure 15c, the signal processing device may include N first frequency-modulated photoelectric circuits 110 to 1N0 as described in scenario one, and M second frequency-modulated photoelectric circuits 210 to 2M0 as described in scenario two. Here, N and M are both integers greater than or equal to 2. The values ​​of N and M can be the same or different, and there is no specific limitation.

[0229] To achieve the reuse of the same optical delay line 400, as shown in Figure 15c, the signal processing device may further include the first beam combiner 510 and the second beam splitter 520 described in scenario one above, as well as the second beam combiner 530 and the third beam splitter 540 described in scenario two above. The first beam combiner 510 and the second beam splitter 520 can enable N first frequency-modulated optoelectronic circuits 110 to 1N0 to share the same optical delay line 400, and the second beam combiner 530 and the third beam splitter 540 can enable M second frequency-modulated optoelectronic circuits 210 to 2M0 to share the same optical delay line 400. Therefore, using the structure shown in Figure 15c, multiple first frequency-modulated optoelectronic circuits and multiple second frequency-modulated optoelectronic circuits can reuse the same optical delay line, which can further reduce the number of optical delay lines required in the signal processing device, achieving a minimalist architecture and extremely low cost for the signal processing device.

[0230] It should be noted that the relevant content of scenarios one to three in Implementation Scheme 1 also applies to scenarios one to three in Implementation Scheme 2. For example, in scenarios one to three of Implementation Scheme 2, N first frequency-modulated photoelectric circuits and one second frequency-modulated photoelectric circuit, M second frequency-modulated photoelectric circuits and one first frequency-modulated photoelectric circuit, or N first frequency-modulated photoelectric circuits and M second frequency-modulated photoelectric circuits can share the same target measurement path, or some frequency-modulated photoelectric circuits can share the same target measurement path, while other frequency-modulated photoelectric circuits have their own separate target measurement paths, etc. As another example, in scenarios one to three of Implementation Scheme 2, the wavelength of the first linearly polarized optical signal in any first frequency-modulated photoelectric circuit is different from the wavelength of the first linearly polarized optical signal in other first frequency-modulated photoelectric circuits, and the wavelength of the second linearly polarized optical signal in any second frequency-modulated photoelectric circuit is different from the wavelength of the second linearly polarized optical signal in other second frequency-modulated photoelectric circuits.

[0231] Furthermore, in Implementation Scheme 2, based on the interference characteristics and independence of light, the wavelength of the first linearly polarized light signal in any first frequency-modulated photoelectric circuit and the wavelength of the first linearly polarized light signal in any second frequency-modulated photoelectric circuit can be the same or different. For example, in conjunction with Scenario 3 above, the N light sources of the N first frequency-modulated photoelectric circuits can emit N first linearly polarized light signals with different wavelengths, and the M light sources of the M second frequency-modulated photoelectric circuits can emit M second linearly polarized light signals with different wavelengths. The N first linearly polarized light signals and the M second linearly polarized light signals can have the same wavelength, or they can have completely different wavelengths, or they can have one or more wavelengths that are the same and the others that are different, without limitation.

[0232] Furthermore, the above two implementation schemes are merely illustrative examples of two possible ways to achieve the transmission of two or more optical signals in the same optical delay line in the same direction or in opposite directions 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 two or more linearly polarized optical signals in the same direction or in opposite directions is within the scope of protection of this application, and this application does not make any specific limitations on it.

[0233] In this application, the signal processing apparatus may further include a target measurement path, which is a path used for detecting a target. The target measurement path can send a detection signal into the detection space and receive the signal reflected back from the target in the detected space, and then detect relevant information about the target based on the signal.

[0234] For example, taking the target measurement path 113 in Figure 6 as an example, as shown in Figure 16a, the target measurement path 113 may include a fourth 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 b 53 It is unidirectional transmission. The input terminal of the fourth beam splitter 1131 is connected to the third output terminal c of the first beam splitter 112. 13 One output terminal of the fourth 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.

[0235] Based on the above structure and connection relationship, as shown in Figure 16a, in the target measurement path 113, the fourth beam splitter 1131 can receive the third output terminal c of the first beam splitter 112. 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 53The 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.

[0236] 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.

[0237] Understandably, the optical transmission element 1132 described above can be any device with at least three ports and unidirectional transmission between ports. For example, it can be a circulator as shown in Figure 16a, 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 1132 may also be other devices, which are not specifically limited here.

[0238] Furthermore, the target measurement paths in different frequency-modulated optoelectronic circuits can be separate or shared. For example, Figure 16a shows a scheme where two frequency-modulated optoelectronic circuits have different target measurement paths. Please refer to Figure 16b, which shows a scheme where two frequency-modulated optoelectronic circuits share the same target measurement path 113. In the shared case, the fourth beam splitter 1131 in the target measurement path 113 shown in Figure 16a can be replaced by an optical processing 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 optical processing element 1138 has two input terminals and two output terminals, one of which is connected to the third output terminal c of the first beam splitter 112 in the first frequency-modulated optoelectronic circuit 110. 13The other input terminal is connected to the third output terminal i of the first beam splitter 212 in the second frequency modulation photoelectric circuit 210. 13 One output terminal 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.

[0239] Based on the structure and connection relationship shown in Figure 16b, the optical processing element 1138 can receive the detection signal split by the first beam splitter 112 in the first frequency-modulated photoelectric circuit 110 and the detection signal split by the first beam splitter 212 in the second frequency-modulated photoelectric circuit 210 through its two input terminals. The optical processing element 1138 combines these two detection signals into one signal, and then splits them into a transmission signal and a 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 one signal and used to measure the target together. 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.

[0240] The specific structure and function of each component shown in the above figures will be described below to provide an exemplary implementation scheme.

[0241] 1. Light source

[0242] 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.

[0243] 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 an FMCW LiDAR.

[0244] 2. Spectrometer

[0245] 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.

[0246] For example, taking the first beam splitter 112 in Figure 12 as an example (see Figure 17a), the first 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 corresponds to the input terminal of the first beam splitter 112, that is, it is connected to the output terminal of the light source 111. The first output terminal (t) of the first beam splitter 1121... 11 ) Connect the input terminal of the second beam splitter 1122, and the second output terminal (t) of the first beam splitter 1121 12 The third output terminal c corresponding to the first beam splitter 112 13 The first output terminal (t) of the second beam splitter 1122 21 The first output terminal c of the first beam splitter 112 11 The second output terminal (t) of the second beam splitter 1122 22 The second output terminal c corresponding to the first beam splitter 112 12 Here, "two ends corresponding" means that the two ends are the same end, or the two ends are connected by a line. For example, the second output terminal t of the first beam splitter 1121 12 The third output terminal c corresponding to the first beam splitter 112 13 This refers to the second output terminal t of the first beam splitter 1121. 12 That is, the third output terminal c of the first beam splitter 112 13 Or the second output terminal t of the first beam splitter 1121 12 The third output terminal c of the first beam splitter 112 is connected via optical fiber. 13 .

[0247] Based on the above structure and connection, the optical signal S output by the light source 111 enters the first beam splitter 1121. The first beam splitter 1121 performs beam splitting on the optical signal S to obtain a detection signal and a first optical signal (S1). The first beam splitter 1121 then outputs the signal through its second output terminal t. 12 The output detection signal is sent to the target measurement path 113 to participate in the target measurement. The first beam splitter 1121 also outputs a detection signal through its first output terminal t. 11 The first optical signal S1 is output, causing it to enter the second beam splitter 1122. The second beam splitter 1122 performs beam splitting on the first optical signal S1, obtaining the calibration path local oscillator signal and the first linearly polarized optical signal S. 11 The second beam splitter 1122 outputs through its second output terminal t 22 The output calibration path local oscillator signal is directly fed into mixer 114. The second beam splitter 1122 also outputs the signal through its first output terminal t. 21 Output the first linearly polarized optical signal S 11 This makes the light signal S in the first linearly polarized state... 11After passing through the first polarization element 310, the optical delay element 400, and the second polarization element 320 in sequence, the signal enters the mixer 114.

[0248] 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, resonant beam splitters, and other types of beam splitters, etc., without specific limitations here.

[0249] 3. Polarization control element

[0250] Here, the polarization control element can include the aforementioned first polarization element and second polarization element. The first polarization element and the second polarization element can be PSRs, as shown in Figure 7 or Figure 13 above, or they can be PBSs, as shown in Figure 9 or Figure 14 above. In some scenarios, it can also be a combination of PSBs and PSRs. For example, the PBS 312 in Figure 9 above can also 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, thereby realizing the function of the PBS. There are many other possible implementation methods, which will not be repeated here.

[0251] 4. Optical Delay Line

[0252] 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.

[0253] 5. Mixer

[0254] In a frequency modulation optoelectronic circuit, the mixer can perform frequency mixing on the input signal and output an intermediate frequency signal.

[0255] 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 12 above as an example, as shown in Figure 17a, mixer 114 can be a 180° optical mixer, which can process the local oscillator signal of the calibration path and the delayed optical signal S in the first frequency modulation optoelectronic circuit 110. 11Coherent 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 17b, mixer 114 can be a 90° optical mixer with four outputs, which can process the local oscillator signal of the calibration path and the delayed optical signal S 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.

[0256] 6. Optical detection element

[0257] 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).

[0258] 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 placed in front of it. For example, taking the photodetector element 115 in Figure 12 as an example, and referring to Figures 12 and 17a, 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 12 and 17b, when mixer 114 is a 90° optical mixer, the optical detection element 115 may specifically include four photodetectors (PDs): 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.

[0259] 7. Amplifier

[0260] 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).

[0261] 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 12 as an example, combined with Figures 12 and 17a, 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 amplify the combined intermediate frequency signal with a certain intensity of low noise. For example, referring to Figures 12 and 17b, 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 Z1), and 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 Z2). TIA 1181 and TIA 1182 respectively amplify the first intermediate frequency signal Z1 and the second intermediate frequency signal Z2 with a certain intensity of low noise.

[0262] 8. Analog-to-digital converter

[0263] 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.

[0264] 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 12 as an example, in conjunction with Figures 12 and 17a, 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 Z output by TIA 1180 to obtain a digital signal. For example, referring to Figures 12 and 17b, when amplifier 118 includes two TIAs, namely TIA 1181 and TIA 1182, analog-to-digital conversion 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 perform analog-to-digital conversion on the amplified first intermediate frequency signal Z1 output from TIA 1181 to obtain a first digital signal. ADC 1192 is used to perform analog-to-digital conversion on the amplified second intermediate frequency signal Z2 output from TIA 1182 to obtain a second digital signal. The first and second digital signals are input together to processing element 116.

[0265] 9. Processing Components

[0266] 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 12 as an example, as shown in Figure 17a or Figure 17b, 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 P, and input the feedback signal P into the drive circuit 117.

[0267] 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.

[0268] 10. Drive circuit

[0269] 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).

[0270] It should be noted that Figures 17a and 17b above are only examples of the components in the calibration path of the first frequency modulation photoelectric circuit 110 (referring to the path containing the first beam splitter 112, the first polarization element 310, the optical delay line 400, the second polarization element 320, 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 photoelectric circuit 110 (referring to the fourth beam splitter 1131, the optical transmission element 1132, the mixer 1133, the photodetector 1134, the amplifier 1135, the analog-to-digital converter 1136, and the processing element 116 shown in Figure 16a). The path where 37 is located, or the path where the optical processing element 1138, optical transmission element 1132, mixer 1133, optical detection element 1134, amplifier 1135, analog-to-digital conversion element 1136 and processing element 1137 are located as shown in Figure 16b), the calibration path in the second frequency-modulated optoelectronic circuit 210 (referring to the path where the first beam splitter 212, first polarization element 310, optical delay line 400, second polarization element 320, mixer 214, optical detection element 215, amplifier 218, analog-to-digital conversion element 219 and processing element 216 are located), the target measurement path 213 in the second frequency-modulated optoelectronic circuit 210, and other calibration paths and target measurement paths in the first frequency-modulated optoelectronic circuit or the second frequency-modulated optoelectronic circuit.

[0271] Furthermore, within the same first frequency-modulated photoelectric circuit or the same second 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, the mixer in the calibration path can be of the same type or different types, and the mixer in the target measurement path can also be of the same type or different types. For example, the following examples illustrate this:

[0272] Referring to Figures 16a, 17a, and 17b above, when the optical signals in the first frequency-modulated optoelectronic circuit 110 and the second frequency-modulated optoelectronic circuit 210 are transmitted in opposite directions along the same optical delay line 400, the first beam splitter 112 in the first frequency-modulated optoelectronic circuit 110 includes a first beam splitter 1121 and a second beam splitter 1122, the mixer 114 is a 180° optical mixer, the photodetector 115 includes PD11 and PD12, the amplifier 118 is a TIA 1180, the analog-to-digital converter 119 is an ADC 1190, and the processing element 116 is a DSP 1160. The fourth beam splitter 1131 on the target measurement path 113 is a third beam splitter 11310, the mixer 1133 is a 180° optical mixer, the photodetector 1134 includes PD13 and PD14, the amplifier 1135 is a TIA 11350, and the analog-to-digital converter 1136 is an ADC. 11360, processing element 1137 is DSP 11370, the first beam splitter 212 in the second frequency modulation optoelectronic circuit 210 includes a first beam splitter 2121 and a second beam splitter 2122, mixer 214 is a 90° optical mixer, photodetector 215 includes PD21a, PD21b, PD22a and PD22b, amplifier 218 includes TIA 2181 and TIA 2182, analog-to-digital converter 219 includes ADC 2191 and ADC 2192, processing element 216 is DSP 2160, the fourth beam splitter on the target measurement path 213 is a fourth beam splitter 21310, mixer is a 180° optical mixer, photodetector includes PD23 and PD24, amplifier is TIA 21350, analog-to-digital converter is ADC 21360, and processing element is DSP. At 21370, the specific structure of the signal processing device can be shown in Figure 18a;

[0273] Referring to Figures 16a, 17a, and 17b above, when the optical signals in the first frequency-modulated optoelectronic circuit 110 and the second frequency-modulated optoelectronic circuit 210 are transmitted in opposite directions along the same optical delay line 400, the first beam splitter 112 in the first frequency-modulated optoelectronic circuit 110 includes a first beam splitter 1121 and a second beam splitter 1122, the mixer 114 is a 180° optical mixer, the photodetector 115 includes PD11 and PD12, the amplifier 118 is a TIA 1180, the analog-to-digital converter 119 is an ADC 1190, and the processing element 116 is a DSP 1160. The fourth beam splitter 1131 on the target measurement path 113 is a third beam splitter 11310, the mixer 1133 is a 90° optical mixer, the photodetector 1134 includes PD13a, PD13b, PD14a, and PD14b, and the amplifier 1135 includes TIA 11351 and TIA 11352. 11352, Analog-to-digital converter 1136 includes ADC 11361 and ADC 11362, and processing element 1137 is DSP 11370. The first beam splitter 212 in the second frequency modulation optoelectronic circuit 210 includes a first beam splitter 2121 and a second beam splitter 2122. The mixer 214 is a 180° optical mixer. The photodetector 215 includes PD21 and PD22. The amplifier 218 is a TIA 2180. The analog-to-digital converter 219 is an ADC 2190. The processing element 216 is a DSP 2160. The fourth beam splitter on the target measurement path 213 is a fourth beam splitter 21310. The mixer is a 180° optical mixer. The photodetector includes PD23 and PD24. The amplifier is a TIA 21350. The analog-to-digital converter is an ADC 21360. The processing element is a DSP. At 21370, the specific structure of the signal processing device can be shown in Figure 18b;

[0274] Referring to Figures 6, 16b, 17a, and 17b above, when the first frequency-modulated photoelectric circuit 110 and the second frequency-modulated photoelectric circuit 210 share the same target measurement path 113, the first beam splitting element 112 in the first frequency-modulated photoelectric circuit 110 includes a first beam splitter 1121 and a second beam splitter 1122, the mixer 114 is a 90° optical mixer, the photodetector element 115 includes PD11a, PD11b, PD12a, and PD12b, the amplifier 118 includes TIA 1181 and TIA 1182, the analog-to-digital converter element 119 includes ADC 1191 and ADC 1192, and the processing element 116 is a DSP. 1160, in the second frequency modulation optoelectronic circuit 210, the first beam splitter 212 includes a first beam splitter 2121 and a second beam splitter 2122; the mixer 214 is a 90° optical mixer; the photodetector 215 includes PD21a, PD21b, PD22a and PD22b; the amplifier 218 includes TIA 2181 and TIA 2182; the analog-to-digital converter 219 includes ADC 2191 and ADC 2192; and the processing element 216 is a DSP 2160. On the target measurement path 113, the beam combining and splitting element 1138 is a beam combiner / splitter 11380; the mixer 1133 is a 90° optical mixer; the photodetector 1134 includes PD13a, PD13b, PD14a and PD14b; the amplifier 1135 includes TIA 11351 and TIA 11352; and the analog-to-digital converter 1136 includes an ADC. When 11361, ADC 11362, and processing element 1137 are DSP 11370, the specific structure of the signal processing device can be shown in Figure 18c.

[0275] Referring to Figures 6, 16b, 17a, and 17b above, when the first frequency-modulated photoelectric circuit 110 and the second frequency-modulated photoelectric circuit 210 share the same target measurement path 113, the first beam splitting element 112 in the first frequency-modulated photoelectric circuit 110 includes a first beam splitter 1121 and a second beam splitter 1122, the mixer 114 is a 90° optical mixer, the photodetector element 115 includes PD11a, PD11b, PD12a, and PD12b, the amplifier 118 includes TIA 1181 and TIA 1182, the analog-to-digital converter element 119 includes ADC 1191 and ADC 1192, and the processing element 116 is a DSP. 1160. In the second frequency modulation optoelectronic circuit 210, the first beam splitter 212 includes a first beam splitter 2121 and a second beam splitter 2122, the mixer 214 is a 180° optical mixer, the photodetector 215 includes PD21 and PD22, the amplifier 218 is a TIA 2180, the analog-to-digital converter 219 is an ADC 2190, and the processing element 216 is a DSP 2160. In the target measurement path 113, the beam combining and splitting element 1138 is a beam combiner and splitter 11380, the mixer 1133 is a 180° optical mixer, the photodetector 1134 includes PD13 and PD14, the amplifier 1135 is a TIA 11350, the analog-to-digital converter 1136 is an ADC 11360, and the processing element 1137 is a DSP 11370. The specific structure of the signal processing device can be shown in Figure 18d.

[0276] Understandably, other similar related structures can be deduced from the above content, and will not be listed one by one here.

[0277] Based on the structure and functional principle of the signal processing device described above, this application can also provide a detection device, as shown in FIG19. The detection device 1900 includes a signal processing device 1910, 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 FIG18d.

[0278] Alternatively, the detection device 1900 can be a lidar, such as an FMCW LiDAR.

[0279] Optionally, as shown in Figure 19 above, the detection device 1900 may further include a window 1920, which is used to protect the internal signal processing device 1910 and can transmit the light signal emitted by the signal processing device 1910.

[0280] It should be noted that the detection device architecture shown in Figure 19 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.

[0281] 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 20. The terminal device 2000 may include the signal processing device described above, or it may include a detection device 2010, which may be a detection device from any of the above embodiments, such as the detection device 1900 in Figure 19.

[0282] Optionally, as shown in Figure 20 above, the terminal device 2000 may further include a processor 2020, which is used to call programs or instructions to control the operation of the detection device 2010. Furthermore, the processor 2020 may also receive target-related information from the detection device 2010. When the terminal device 2000 is a vehicle, the processor 2020 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.

[0283] Furthermore, optionally, the terminal device 2000 may also include a memory 2030 for storing programs or instructions. Of course, the terminal device 2000 may also include other devices, such as wireless communication devices.

[0284] Processor 2020 may include one or more processing units. For example, processor 2020 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.

[0285] The memory 2030 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.

[0286] For example, the terminal device 2000 mentioned above 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.).

[0287] 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.

[0288] 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.

[0289] 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.

[0290] 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.

[0291] 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

A signal processing device, characterized in that, include: A first frequency-modulated (FM) optoelectronic circuit and a second FM optoelectronic circuit, each of which includes a light source, a first beam splitter, a polarization control element, an optical delay line, a mixer, a photodetector, a processing element, and a driving circuit; the first and second FM optoelectronic circuits share the polarization control element and the optical delay line; the polarization control element is used to receive a first linearly polarized optical signal split by the first beam splitter in the first FM optoelectronic circuit and a second linearly polarized optical signal split by the first beam splitter in the second FM optoelectronic circuit, so that the first and second linearly polarized optical signals are output to the optical delay line with orthogonal polarization directions, and outputs the delayed optical signal in the first FM optoelectronic circuit in the form of a first linearly polarized state to the mixer in the first FM optoelectronic circuit, and outputs the delayed optical signal in the second FM optoelectronic circuit in the form of a second linearly polarized state to the mixer in the second FM optoelectronic circuit. The apparatus as claimed in claim 1, characterized in that, The first linear polarization state is the same as the second linear polarization state, or the first linear polarization state is orthogonal to the second linear polarization state. The apparatus as described in claim 1 or 2, 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 beam splitter in the first frequency-modulated optoelectronic circuit, the first beam splitter in the second frequency-modulated optoelectronic circuit, and the first end of the optical delay line. The second polarization element is connected between the mixer in the first frequency-modulated optoelectronic circuit, the mixer in the second frequency-modulated optoelectronic circuit, and the second end of the optical delay line. The first polarization element is used to receive the first linearly polarized optical signal after being split by the first beam splitter in the first frequency-modulated optoelectronic circuit and the second linearly polarized optical signal after being split by the first beam splitter in the second frequency-modulated optoelectronic circuit. The optical signals are in two linearly polarized states, so that the first linearly polarized optical signal and the second linearly polarized optical signal are output to the optical delay line with orthogonal polarization directions; the second polarization element is used to receive the delayed optical signal in the first frequency-modulated photoelectric circuit and the delayed optical signal in the second frequency-modulated photoelectric circuit, output the delayed optical signal in the first frequency-modulated photoelectric circuit in the form of a first linear polarization state to the mixer in the first frequency-modulated photoelectric circuit, and output the delayed optical signal in the second frequency-modulated photoelectric circuit in the form of a second linear polarization state to the mixer in the second frequency-modulated photoelectric circuit. The apparatus as described in claim 3, characterized in that, The first linear polarization state is the same as the second linear polarization state. Both the first polarization element and the second polarization element have a first end, a second end, and a third end. The third end transmits signals with the first end in the original polarization direction, and the third end transmits signals with the second end in the polarization direction after a 90° rotation. The first end of the first polarization element is connected to the first beam splitter in the first frequency-modulated optoelectronic circuit, the second end of the first polarization element is connected to the first beam splitter in the second 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 first end of the second polarization element is connected to the mixer in the first frequency-modulated optoelectronic circuit, the second end of the second polarization element is connected to the mixer in the second 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 apparatus as claimed in claim 4, characterized in that, Both the first polarization element and the second polarization element are polarization rotating beam splitters (PSRs). The first polarization element is used to maintain the polarization direction of the first linearly polarized optical signal unchanged and rotate the polarization direction of the second linearly polarized optical signal by 90° to obtain a third linearly polarized optical signal. After combining the third linearly polarized optical signal and the first linearly polarized optical signal, the result is output to the optical delay line. The second polarization element is used to split the delayed optical signal to obtain a delayed first linearly polarized optical signal and a delayed third linearly polarized optical signal. The polarization direction of the delayed first linearly polarized optical signal remains unchanged, and it is output to the mixer in the first frequency-modulated optoelectronic circuit. The polarization direction of the delayed third linearly polarized optical signal is rotated by 90° to obtain a delayed second linearly polarized optical signal, which is then output to the mixer in the second frequency-modulated optoelectronic circuit. The apparatus as described in claim 3, characterized in that, The first linear polarization state is orthogonal to the second linear polarization state. Both the first polarization element and the second polarization element have a first end, a second end, and a third end. The third end transmits signals with the first end in the original polarization direction, and the third end transmits signals with the second end in the original polarization direction. The first end of the first polarization element is connected to the first beam splitter in the first frequency-modulated optoelectronic circuit, the second end of the first polarization element is connected to the first beam splitter in the second 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 first end of the second polarization element is connected to the mixer in the first frequency-modulated optoelectronic circuit, the second end of the second polarization element is connected to the mixer in the second 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 apparatus as claimed in claim 6, characterized in that, Both the first polarization element and the second polarization element are polarized beam splitters (PBS). The first polarization element is used to combine the first linearly polarized optical signal and the second linearly polarized optical signal and output them to the optical delay line. The second polarization element is used to split the delayed optical signal to obtain the delayed first linearly polarized optical signal and the delayed second linearly polarized optical signal. The delayed first linearly polarized optical signal is output to the mixer in the first frequency-modulated optoelectronic circuit, and the delayed second linearly polarized optical signal is output to the mixer in the second frequency-modulated optoelectronic circuit. The apparatus as described in any one of claims 4 to 7, characterized in that, The first frequency-modulated optoelectronic circuit has N components, where N is an integer greater than or equal to 2. The signal processing device further includes a first beam combiner and a second beam splitter. The N input terminals of the first beam combiner are connected one-to-one to the N first beam splitters in the N first frequency-modulated optoelectronic circuits, and the output terminal of the first beam combiner is connected to the first terminal of the first polarization element. The input terminal of the second beam splitter is connected to the first terminal of the second polarization element, and the N output terminals of the second beam splitter are connected one-to-one to the N mixers in the N first frequency-modulated optoelectronic circuits. The apparatus as described in any one of claims 4 to 8, characterized in that, The second frequency-modulated photoelectric circuit has M components, where M is an integer greater than or equal to 2. The signal processing device further includes a second beam combiner and a third beam splitter. The M input terminals of the second beam combiner are connected one-to-one to the M first beam splitters in the M second frequency-modulated photoelectric circuits, and the output terminal of the second beam combiner is connected to the second terminal of the first polarization element. The input terminal of the third beam splitter is connected to the second terminal of the second polarization element, and the M output terminals of the third beam splitter are connected one-to-one to the M mixers in the M second frequency-modulated photoelectric circuits. The apparatus as described in claim 1 or 2, 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 beam splitter in the first frequency-modulated optoelectronic circuit, the mixer in the second frequency-modulated optoelectronic circuit, and the first end of the optical delay line. The second polarization 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 second end of the optical delay line. The first polarization element is used to receive the first linearly polarized optical signal after being split by the first beam splitter in the first frequency-modulated optoelectronic circuit and the delayed optical signal in the second frequency-modulated optoelectronic circuit, and outputs the first linearly polarized optical signal... The optical signal is output to the optical delay line, and the delayed optical signal in the second frequency-modulated optoelectronic circuit is output to the mixer in the second frequency-modulated optoelectronic circuit in the form of a second linear polarization state; the second polarization element is used to receive the second linear polarization state optical signal after being split by the first beam splitting element in the second frequency-modulated optoelectronic circuit and the delayed optical signal in the first frequency-modulated optoelectronic circuit, output the second linear polarization state optical signal to the optical delay line in a polarization direction perpendicular to the first linear polarization state optical signal, and output the delayed optical signal in the first frequency-modulated optoelectronic circuit to the mixer in the first frequency-modulated optoelectronic circuit in the form of a first linear polarization state. The apparatus as claimed in claim 10, characterized in that, The first linear polarization state is the same as the second linear polarization state. Both the first polarization element and the second polarization element have a first end, a second end, and a third end. The third end transmits signals with the first end in the original polarization direction, and the third end transmits signals with the second end in the polarization direction after a 90° rotation. The first end of the first polarization element is connected to the first beam splitter in the first frequency-modulated optoelectronic circuit, the second end of the first polarization element is connected to the mixer in the second 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 first end of the second polarization element is connected to the mixer in the first frequency-modulated optoelectronic circuit, the second end of the second polarization element is connected to the first beam splitter in the second 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 apparatus as claimed in claim 11, characterized in that, Both the first polarization element and the second polarization element are polarization rotating beam splitters (PSRs). The first polarization element is used to maintain the polarization direction of the first linearly polarized optical signal unchanged, output it to the optical delay line, and rotate the polarization direction of the third linearly polarized optical signal after delay processing by the optical delay line by 90° to obtain the second linearly polarized optical signal after delay processing. The second linearly polarized optical signal after delay processing is then output to the mixer of the second frequency-modulated optoelectronic circuit. The second polarization element is used to rotate the polarization direction of the second linearly polarized optical signal by 90° to obtain the third linearly polarized optical signal and output it to the optical delay line, and to maintain the polarization direction of the first linearly polarized optical signal after delay processing unchanged and output it to the mixer of the first frequency-modulated optoelectronic circuit. The apparatus as claimed in claim 10, characterized in that, The first linear polarization state is orthogonal to the second linear polarization state. Both the first polarization element and the second polarization element have a first end, a second end, and a third end. The third end transmits signals with the first end in the original polarization direction, and the third end transmits signals with the second end in the original polarization direction. The first end of the first polarization element is connected to the first beam splitter in the first frequency-modulated optoelectronic circuit, the second end of the first polarization element is connected to the mixer in the second 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 first end of the second polarization element is connected to the mixer in the first frequency-modulated optoelectronic circuit, the second end of the second polarization element is connected to the first beam splitter in the second 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 apparatus as claimed in claim 10, characterized in that, Both the first polarization element and the second polarization element are polarized beam splitters (PBS). The first polarization element is used to maintain the polarization direction of the first linearly polarized optical signal unchanged and output it to the optical delay line, and to maintain the polarization direction of the delayed second linearly polarized optical signal unchanged and output it to the mixer of the second frequency-modulated optoelectronic circuit. The second polarization element is used to maintain the polarization direction of the second linearly polarized optical signal unchanged and output it to the optical delay line, and to maintain the polarization direction of the delayed first linearly polarized optical signal unchanged and output it to the mixer of the first frequency-modulated optoelectronic circuit. The apparatus as described in any one of claims 10 to 14, characterized in that, The first frequency-modulated optoelectronic circuit has N components, where N is an integer greater than or equal to 2. The signal processing device further includes a first beam combiner and a second beam splitter. The N input terminals of the first beam combiner are connected one-to-one to the N first beam splitters in the N first frequency-modulated optoelectronic circuits, and the output terminal of the first beam combiner is connected to the first terminal of the first polarization element. The input terminal of the second beam splitter is connected to the first terminal of the second polarization element, and the N output terminals of the second beam splitter are connected one-to-one to the N mixers in the N first frequency-modulated optoelectronic circuits. The apparatus as described in any one of claims 10 to 15, characterized in that, The second frequency-modulated photoelectric circuit has M components, where M is an integer greater than or equal to 2. The signal processing device further includes a second beam combiner and a third beam splitter. The M input terminals of the second beam combiner are connected one-to-one to the M first beam splitters in the M second frequency-modulated photoelectric circuits, and the output terminal of the second beam combiner is connected to the second terminal of the second polarization element. The input terminal of the third beam splitter is connected to the second terminal of the first polarization element, and the M output terminals of the third beam splitter are connected one-to-one to the M mixers in the M second frequency-modulated photoelectric circuits. The apparatus as described in any one of claims 3 to 16, characterized in that, The signal processing device satisfies any one of the following: when both the first polarization element and the second polarization element are PSR, the optical signals input to the first polarization element are TE light and TE light, and the optical signals output from the first polarization element are TE light and TM light; the optical signals input to the second polarization element are TE light and TM light, and the optical signals output from the second polarization element are TE light and TE light; when both the first polarization element and the second polarization element are PBS, the optical signals input to the first polarization element are TE light and TM light, and the optical signals output from the first polarization element are TE light and TM light; the optical signals input to the second polarization element are TE light and TM light, and the optical signals output from the second polarization element are TE light and TM light. The output optical signals are TE and TM light; when both the first polarization element and the second polarization element are PSR, the optical signals input to the first polarization element are P and P light, the optical signals output from the first polarization element are P and S light, the optical signals input to the second polarization element are P and S light, and the optical signals output from the second polarization element are P and P light; or, when both the first polarization element and the second polarization element are PBS, the optical signals input to the first polarization element are P and S light, the optical signals output from the first polarization element are P and S light, the optical signals input to the second polarization element are P and S light, and the optical signals output from the second polarization element are P and S light. The apparatus as described in any one of claims 1 to 17, characterized in that, The optical delay line is either an optical fiber delay line or an on-chip integrated waveguide delay line. The apparatus as described in any one of claims 1 to 18, characterized in that, Each frequency-modulated optoelectronic circuit further includes a target measurement path; the polarization control element and the optical delay line are connected between the first output terminal of the first beam splitter and the first input terminal of the mixer; the second output terminal of the first beam splitter is connected to the second input terminal of the mixer; and the third output terminal of the first beam splitter is connected to the target measurement path. The first beam splitter is used to split the optical signal generated by the light source to obtain a local oscillator signal, a signal to be delayed, and a detection signal. It outputs the signal to be delayed through its first output terminal, the local oscillator signal through its second output terminal, and the detection signal through its third 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 detection signal. The apparatus according to claim 17 is characterized in that, In each frequency-modulated optoelectronic circuit: the first beam splitter 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 light signal to obtain the local oscillator signal and the signal to be delayed, output the signal to be delayed through its first output terminal, and output the local oscillator signal through its second output terminal. The apparatus as described in any one of claims 1 to 20, characterized in that, Each frequency-modulated photoelectric circuit further includes an amplifier and an analog-to-digital converter, the amplifier and the analog-to-digital converter being connected between the photodetector and the processing element; the amplifier is used to amplify the intermediate frequency signal from the photodetector. The analog-to-digital converter is used to perform analog-to-digital conversion on the amplified intermediate frequency signal to obtain a digital signal. A detection device, characterized in that, Includes the signal processing apparatus as described in any one of claims 1 to 21. 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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