Signal processing apparatus, detection apparatus, and terminal device

Abstract

A signal processing apparatus, a detection apparatus, and a terminal device, which relate to the technical field of detection and are used for reducing the cost and footprint of an optical delay line (1131). The signal processing apparatus comprises a frequency-modulated optoelectronic circuit (100), which comprises a light source (111), a first beam-splitting element (112), an optical delay element (113), a mixer (114), a photodetection element (115), a processing element (116), and a driving circuit (117). The optical delay element (113) comprises an optical delay line (1131) and a reflector (1132), wherein the optical delay line (1131) is configured to delay a first optical signal (S1) from the first beam-splitting element (112); a first optical signal (S1') after delaying is input to the reflector (1132); the reflector (1132) is configured to reflect back to the optical delay line (1131) the first optical signal (S1') after delaying, so that the optical delay line (1131) further delays the first optical signal (S1') after delaying that is reflected back; and a first optical signal (S1'') after further delaying is input to the mixer (114). In this way, a single optical delay line (1131) can be utilized to realize two delays for an optical signal. For the same delay duration, the length of the optical delay line is reduced by half, thereby decreasing the volume and footprint of the optical delay line and accordingly reducing hardware costs.

Description

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

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese Patent Application No. 202410994450.0, filed on July 23, 2024, and entitled “A signal processing device, a detection device and a terminal device”, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of detection, and in particular, to a signal processing device, a detection device and a terminal device. BACKGROUND

[0004] The frequency modulated continuous wave (FMCW) LiDAR in the direct modulation mode is currently a mainstream LiDAR, which uses a method of directly changing the frequency of the laser emitter to realize the detection of distance and speed. As shown in FIG. 1a, in an ideal case, the frequency of the modulation signal (L1) input into the FMCW LiDAR has a linear relationship with time, which is linearly reflected on the frequency of the laser emitter, so that the frequency change (L2) of the laser emitter also has a linear relationship with time.

[0005] However, in the frequency modulation process, due to the influence of the internal physical mechanism of the laser (such as imperfect manufacturing process, thermal effect and other factors), the input modulation signal L1 in the laser and the frequency of the laser emitter beam may have a non-linear relationship, which in turn causes the frequency change L2 of the laser emitter beam with time to also be non-linear, that is, the frequency modulation nonlinearity phenomenon occurs, as shown in FIG. 1b. The frequency modulation nonlinearity phenomenon will affect the measurement accuracy of the FMCW LiDAR. To solve this problem, the input modulation signal L1 in the laser needs to be calibrated. However, the current mainstream calibration scheme usually uses an asymmetric Mach-Zehnder interferometer (AMZI) structure based on an optical delay line, which requires a large number of optical delay lines, especially in the case of a large number of lasers, the number of optical delay lines is multiplied, so a large number of optical delay lines will occupy a very large space in the FMCW LiDAR, and the hardware cost will also be very high.

[0006] In summary, how to reduce the cost and space occupied by the optical delay line is a technical problem to be solved in the field of FMCW LiDAR. SUMMARY

[0007] The present application provides a signal processing device, a detection device and a terminal device to reduce the cost and space occupied by the optical delay line.

[0008] In a first aspect, the present application provides a signal processing device, comprising a frequency-modulated optoelectronic circuit, the frequency-modulated optoelectronic circuit comprising a light source, a first light splitting element, an optical delay element, a frequency mixer, a light detection element, a processing element, and a driving circuit, the light beam output by the light source enters the optical delay element after being processed by the first light splitting element, the light beam output by the light source enters the frequency mixer after being processed by the optical delay element, the light beam output by the light source is detected by the light detection element after being processed by the frequency mixer and is converted into an electrical signal, the electrical signal is processed by the processing element to obtain a feedback signal which is input into the driving circuit, and the feedback signal is used to calibrate the linearity between the modulation signal input into the driving circuit and the light beam output by the light source. The optical delay element comprises an optical delay line and a reflector, the optical delay line is used to delay a first light signal from the first light splitting element, and the delayed first light signal is input into the reflector; the reflector is used to reflect the delayed first light signal back to the optical delay line; and the optical delay line is further used to delay the reflected delayed first light signal again, and the delayed first light signal is input into the frequency mixer.

[0009] Based on the above structure, by arranging the reflector at one end of the optical delay line where the light signal is originally output, the reflected light signal can be reflected back to the optical delay line by the reflecting action of the reflector to be delayed again. In this way, the light signal can be delayed twice by using one optical delay line. For the same delay time, the length of the optical delay line can be reduced by half, the volume and space occupied by the optical delay line are reduced, and the hardware cost is also reduced accordingly. Therefore, when the above signal processing device is applied to a detection device (such as an FMCW LiDAR), the length and cost of the optical delay line required to be arranged in the FMCW LiDAR can be reduced, so that the system architecture of the FMCW LiDAR can be simplified and the system cost of the FMCW LiDAR can be reduced.

[0010] In a possible design, the reflector is a fiber loop mirror or a Bragg grating. In this way, the light beam can be reflected at a lower cost.

[0011] In a possible design, the optical delay line is a fiber delay line or an integrated waveguide delay line on a chip.

[0012] Based on the above design, the signal processing device can be applied to various optical delay lines, thereby having universality.

[0013] In a possible design, the optical delay element further includes an optical transmission element, the optical transmission element includes a first end, a second end and a third end, the first end is connected to the first light splitting element, the second end is connected to the optical delay line, and the third end is connected to the frequency mixer, and the first end to the second end and the second end to the third end are unidirectional transmission.

[0014] Based on the above design, the unidirectional transmission characteristics of the optical transmission element can be used to make the twice delayed optical signals enter the frequency mixer as much as possible.

[0015] In a further possible design, the optical transmission element is a circulator. The circulator has low cost and small size, and is easy to implement.

[0016] In a possible design, the signal processing device includes N frequency-modulated optoelectronic circuits, and the N frequency-modulated optoelectronic circuits share the same optical delay element, where N is an integer greater than or equal to 2.

[0017] Based on the above design, the number of optical delay lines required to be arranged in the signal processing device can be reduced, and an extremely simple architecture and extremely low cost can be achieved.

[0018] In a possible design, the signal processing device further includes a light combining element and a second light splitting element, the optical delay element is connected between an output end of the light combining element and an input end of the second light splitting element, N input ends of the light combining element are one-to-one connected to N first light splitting elements in the N frequency-modulated optoelectronic circuits, and N output ends of the second light splitting element are one-to-one connected to N frequency mixers in the N frequency-modulated optoelectronic circuits.

[0019] Based on the above design, the light combining element can be used to combine the N to-be-delayed signals corresponding to the N frequency-modulated optoelectronic circuits into a total to-be-delayed signal and input the total to-be-delayed signal to the optical delay element, so that the optical delay element delays the N to-be-delayed signals together, thereby realizing the scheme that the N frequency-modulated optoelectronic circuits share the same optical delay element. In addition, the second light splitting element can be used to split the total to-be-delayed signal after delay into N frequency mixers of the N frequency-modulated optoelectronic circuits, so as to realize separate frequency mixing of each frequency-modulated optoelectronic circuit.

[0020] In a possible design, the frequency-modulated optoelectronic circuit further includes a target measurement path, a first output end of the first light splitting element is connected to an input end of the optical delay element or the first light combining element, a second output end of the first light splitting element is connected to the frequency mixer, and a third output end of the first light splitting element is connected to the target measurement path; the first light splitting element is configured to split the light beam generated by the light source to obtain a detection signal, a local signal and a first optical signal, output the first optical signal through the first output end, output the local signal through the second output end, and output the detection signal through the third output end.

[0021] Based on the above design, the signal processing device can not only calibrate the modulation signal output by the driving circuit, but also perform target measurement. By calibrating the frequency modulation signal output by the driving circuit, the frequency of the emitted light beam of the light source can be made to change linearly with time, and further, the detection signal obtained based on the emitted light beam can meet the preset requirements, thereby improving the accuracy of the signal processing device in detecting the target.

[0022] In a further possible design, the first light splitting element includes a first beam splitter and a second beam splitter, the first output end of the first beam splitter is connected to the input end of the second beam splitter, the second output end of the first beam splitter is the third output end of the first light splitting element, the first output end of the second beam splitter is the first output end of the first light splitting element, and the second output end of the second beam splitter is the second output end of the first light splitting element. The first beam splitter is configured to split the light beam generated by the light source to obtain a detection signal and a second light signal, output the second light signal through the first output end, and output the detection signal through the second output end. The second beam splitter is configured to split the second light signal into a local signal and a first light signal, output the first light signal through the first output end, and output the local signal through the second output end.

[0023] Based on the above design, the functions of the first light splitting element can be realized by two beam splitters, which are low in cost and small in size, and are helpful to realize the small size and low cost of the signal processing device.

[0024] In a possible design, the signal processing device further includes a second light splitting element and a third light splitting element, the first light splitting element includes a beam splitter and a light processing element, and the N frequency modulation optoelectronic circuits share the same light delay element and the same light processing element. The N input ends of the light processing element are one-to-one connected to the first output ends of the N beam splitters in the N frequency modulation optoelectronic circuits, the second output ends of the N beam splitters are connected to the N target measurement paths in the N frequency modulation optoelectronic circuits, the light delay element is connected between the first output end of the light processing element and the input end of the second light splitting element, the N output ends of the second light splitting element are one-to-one connected to the first input ends of the N mixers in the N frequency modulation optoelectronic circuits, the second output end of the light processing element is connected to the input end of the third light splitting element, and the N output ends of the third light splitting element are one-to-one connected to the second input ends of the N mixers in the N frequency modulation optoelectronic circuits.

[0025] In a further design, the beam splitter is configured to split the light beam generated by the light source to obtain a detection signal and a second light signal, output the second light signal through the first output end, and output the detection signal through the second output end; the light processing element is configured to combine the N second light signals corresponding to the N frequency-modulated optoelectronic circuits, split the combined light signal into a first light signal and a third light signal, output the first light signal through the first output end, and output the third light signal through the second output end; and the second light splitting element is configured to split the first light signal after the time delay of the optical delay element into N first sub-light signals, and output the N first sub-light signals through the N output ends; and the third light splitting element is configured to split the third light signal into N local signals, and output the N local signals through the N output ends.

[0026] Based on the above design, the N to-be-delayed signals of the N frequency-modulated optoelectronic circuits can be combined into a total to-be-delayed signal by the light processing element, and input to the optical delay element, so that the optical delay element delays the to-be-delayed signals corresponding to the N frequency-modulated optoelectronic circuits together, thereby realizing the scheme that the N frequency-modulated optoelectronic circuits share the same optical delay element. In addition, the combined and delayed total to-be-delayed signal can be split into N mixers of the N frequency-modulated optoelectronic circuits by the second light splitting element, and the N local signals of the N frequency-modulated optoelectronic circuits can be combined into a total local signal by the light processing element, and then split into the mixers of the N frequency-modulated optoelectronic circuits by the third light splitting element, so as to realize the separate mixing of each frequency-modulated optoelectronic circuit.

[0027] In a possible design, the first light splitting element includes a beam splitter and a light processing element, and the N frequency-modulated optoelectronic circuits share the same optical delay element, the same light processing element, the same mixer, the same light detection element, and the same processing element. The N input ends of the light processing element are one-to-one connected to the first output ends of the N beam splitters in the N frequency-modulated optoelectronic circuits, the second output ends of the N beam splitters in the N frequency-modulated optoelectronic circuits are one-to-one connected to the target measurement circuits in the N frequency-modulated optoelectronic circuits, the optical delay element is connected between the first output end of the light processing element and the first input end of the mixer, the second output end of the light processing element is connected to the second input end of the mixer, and the N output ends of the processing element are one-to-one connected to the N drive circuits in the N frequency-modulated optoelectronic circuits.

[0028] In a further design, the beam splitter is configured to split the light beam generated by the light source to obtain a detection signal and a second light signal, output the second light signal through a first output end, and output the detection signal through a second output end; the light processing element is configured to combine the N second light signals corresponding to the N frequency-modulated optoelectronic circuits, and divide the combined light signal into a first light signal and a local signal, output the first light signal through a first output end, and output the local signal through a second output end; the frequency mixer is configured to mix the first light signal delayed by the optical delay element and the local signal to obtain an intermediate frequency signal; the light detection element is configured to receive the intermediate frequency signal; and the processing element is configured to determine the N feedback signals corresponding to the N frequency-modulated optoelectronic circuits according to the intermediate frequency signal, and output the N feedback signals through N output ends.

[0029] Based on the above design, the N to-be-delayed signals of the N frequency-modulated optoelectronic circuits can be combined into a total to-be-delayed signal by the light processing element, and input to the optical delay element, so that one optical delay element delays the to-be-delayed signals corresponding to the N frequency-modulated optoelectronic circuits together, realizing the scheme that the N frequency-modulated optoelectronic circuits share the same optical delay element. Moreover, the same frequency mixer, the same light detection element, and the same processing element can be used to uniformly mix, detect, and process the signals of the N frequency-modulated optoelectronic circuits, thereby greatly reducing the number of devices in the signal processing device, effectively reducing the size and cost of the signal processing device, and realizing the extremely simple architecture and extremely low cost of the signal processing device.

[0030] In a possible design, the processing element is configured to determine the feedback signal according to the intermediate frequency signal from the light detection element, and the feedback signal is input to the driving circuit. The driving circuit is configured to calibrate the linearity between the modulation signal input to the light source and the light beam output by the light source according to the feedback signal.

[0031] Based on the above design, the driving circuit can adjust the modulation signal output to the light source according to the feedback signal, so that the light source can output a light beam that conforms to the linear variation law under the action of the modulation signal.

[0032] In a possible design, the frequency-modulated optoelectronic circuit further includes an amplifier and an analog-to-digital converter, which are connected between the light detection element and the processing element. The amplifier is configured to amplify the intermediate frequency signal from the light detection element, and the analog-to-digital converter is configured to convert the amplified intermediate frequency signal into a digital signal.

[0033] Based on the above design, the power of the intermediate frequency signal is amplified by the amplifier, which can ensure that the intermediate frequency signal is successfully transmitted to the analog-to-digital conversion element. By sampling the intermediate frequency signal into a digital signal by the analog-to-digital conversion element, the subsequent software analysis of the processing element can be facilitated.

[0034] In a possible design of the signal processing apparatus, the signal processing apparatus further includes a target measurement path connected to the first light splitting element, where the target measurement path is configured to perform target measurement based on the probe signal from the first light splitting element.

[0035] Based on the above design, the target measurement can be performed based on the light beam after the modulation, so as to improve the detection accuracy of the target measurement path.

[0036] In a second aspect, the present application provides a detection apparatus, including the signal processing apparatus in the first aspect or any possible design of the first aspect.

[0037] In a third aspect, the present application provides a terminal device, including the detection apparatus in the second aspect or any possible design of the second aspect.

[0038] The technical effects achieved by the second aspect or the third aspect can refer to the beneficial effects described in the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0039] FIG. 1a shows an example of a linear relationship between a light beam and a modulation signal;

[0040] FIG. 1b shows an example of a nonlinear relationship between a light beam and a modulation signal;

[0041] FIG. 1c shows an example of a structure of a Sagnac loop reflector;

[0042] FIG. 2 shows an example of a possible application scenario to which the present application is applicable;

[0043] FIG. 3a shows an example of a structure of a direct modulation FMCW LiDAR;

[0044] FIG. 3b shows an example of a structure of a single-laser direct modulation FMCW LiDAR;

[0045] FIG. 3c shows an example of a structure of a multi-laser direct modulation FMCW LiDAR;

[0046] FIG. 4 shows an example of a structure of a signal processing apparatus provided by the present application;

[0047] FIG. 5 shows an example of a structure of another signal processing apparatus provided by the present application;

[0048] FIG. 6 shows an example of a structure of yet another signal processing apparatus provided by the present application;

[0049] FIG. 7 shows an example of a structure of still another signal processing apparatus provided by the present application;

[0050] Fig. 8a exemplarily shows a specific structural schematic diagram of a signal processing apparatus provided by the present application;

[0051] Fig. 8b exemplarily shows a specific structural schematic diagram of another signal processing apparatus provided by the present application;

[0052] Fig. 8c exemplarily shows a specific structural schematic diagram of still another signal processing apparatus provided by the present application;

[0053] Fig. 8d exemplarily shows a specific structural schematic diagram of yet another signal processing apparatus provided by the present application;

[0054] Fig. 8e exemplarily shows a specific structural schematic diagram of still another signal processing apparatus provided by the present application;

[0055] Fig. 8f exemplarily shows a specific structural schematic diagram of yet another signal processing apparatus provided by the present application;

[0056] Fig. 9 exemplarily shows a structural schematic diagram of a signal processing apparatus provided by embodiment one;

[0057] Fig. 10 exemplarily shows a structural schematic diagram of a signal processing apparatus provided by embodiment two;

[0058] Fig. 11 exemplarily shows a structural schematic diagram of a signal processing apparatus provided by embodiment three;

[0059] Fig. 12 exemplarily shows a structural schematic diagram of a signal processing apparatus provided by embodiment four;

[0060] Fig. 13a exemplarily shows a structural schematic diagram of a signal processing apparatus provided by the present application;

[0061] Fig. 13b exemplarily shows a structural schematic diagram of another signal processing apparatus provided by the present application;

[0062] Fig. 13c exemplarily shows a structural schematic diagram of still another signal processing apparatus provided by the present application;

[0063] Fig. 13d exemplarily shows a structural schematic diagram of yet another signal processing apparatus provided by the present application;

[0064] Fig. 14 exemplarily shows a structural schematic diagram of a detection apparatus provided by the present application;

[0065] Fig. 15 exemplarily shows a structural schematic diagram of a terminal device provided by the present application. DETAILED DESCRIPTION

[0066] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0067] The following explains some terms used in the present application. It should be noted that these explanations are provided for the convenience of those skilled in the art and do not constitute a limitation on the scope of protection sought by the present application.

[0068] I. Fiber loop mirror (FLM)

[0069] A fiber loop mirror is a structure that reflects a light beam by making a fiber into a loop shape. Some examples of fiber loop mirrors can include, but are not limited to, an optical loop mirror (OLM), a non-linear OLM (NOLM), a non-linear amplifying loop mirror (NALM), an 8-shaped fiber reflector, a Sagnac loop reflector (SLR), and the like.

[0070] Taking an SLR as an example, FIG. 1c shows a possible structural schematic diagram of an SLR. The SLR includes a fiber loop and a beam splitter, the beam splitter has one port on the left side and two ports on the right side, and the two ports on the right side are connected together by a fiber to form the above-mentioned fiber loop. If a light beam U is input on the left side port of the beam splitter, the light beam U will be split into two light beams U1 and U2 by the beam splitter, the two light beams U1 and U2 propagate in opposite directions in the fiber loop, and finally return to the beam splitter. At this time, the beam splitter becomes a beam combiner, and the two light beams U1 and U2 are combined to form a light beam S3, which is output from the left side port.

[0071] II. Bragg grating

[0072] A Bragg grating, also known as a distributed Bragg reflector (DBR), is designed according to the characteristic that the reflectivity of light at different medium interfaces is related to the size of the refractive index between the media. By periodically stacking thin films of different refractive indices together, when light passes through these thin films, the light reflected by each layer changes in phase angle and constructively interferes, thereby combining to produce strong reflected light. DBR is usually used in waveguides.

[0073] III. Mixing

[0074] Mixing, also known as coherent demodulation, refers to the difference in frequency and phase between two signals.

[0075] For example, in the FMCW LiDAR, the probe signal is usually a linear frequency modulation signal, also known as a Chirp signal. The Chirp signal is a signal whose frequency changes linearly with time, and is named after its frequency spectrum bandwidth falling within the audible range and sounding like a bird's chirp. After the Chirp signal interacts with the target object, the echo signal (i.e., the received signal) reflected back also has the same frequency change characteristic, that is, the echo signal is also a Chirp signal. However, according to the distance of the target, the echo signal will produce a certain phase difference and frequency difference relative to the probe signal. Therefore, after receiving the echo signal, the echo signal and the probe signal can be mixed, that is, the frequency and phase of the probe signal and the echo signal are subtracted, thereby obtaining a low-frequency beat signal, which is also called an intermediate frequency signal. The intermediate frequency signal contains the frequency difference information between the two signals, and the frequency difference is proportional to the target distance. At the same time, it also contains the Doppler effect information caused by the movement of the target, and the speed of the target can be calculated based on the Doppler effect information.

[0076] The foregoing introduces some terms involved in the present application, and the following introduces possible application scenarios of the present application.

[0077] In one possible implementation, the signal processing apparatus provided by the present application can be integrated into a detection apparatus, which can be installed on a vehicle, such as but not limited to a car, a ship, an airplane, a drone, a train, a subway, an automated guided vehicle (AGV), or a unmanned transport vehicle, etc. For example, please refer to FIG. 2, which shows a possible application scenario of the present application, in which the detection apparatus is installed on the front bumper of the vehicle. The detection apparatus can be used as an information collection source for path planning, to assist the driver to realize or automatically realize the safe driving of the vehicle. It can be understood that the detection apparatus can also be installed at other positions of the vehicle, such as around the vehicle lights, around the rearview mirror, near the vehicle door, at the rear bumper, behind the windshield, or on the roof, etc. at any position or multiple positions, to capture the environmental information around the vehicle. When the detection apparatus is installed behind the windshield, it has a lower requirement for the risk of stone collision, and will not affect the appearance of the vehicle. In addition, the front windshield itself has the functions of window heating, defogging, and windshield wiper cleaning.

[0078] It should be understood that the application scenarios described above are only examples, and the detection device provided by the present application can also be applied to other possible scenarios, and is not limited to the above-mentioned example scenarios. For example, the detection device can also be installed in a road side unit (RSU) as a roadside traffic detection device for realizing intelligent vehicle-road cooperative communication, etc. For another example, the detection device can also be applied to a terminal device or a component provided in a terminal device, such as a smart phone, a smart home device, a smart manufacturing device, a medical device, an industrial device, a robot, etc. Here, they will not be listed one by one. For another example, the detection device can also be applied to

[0079] It should be noted that the application scenarios described in the present application are for more clearly illustrating the technical solutions of the present application, and do not constitute a limitation on the technical solutions provided by the present application.

[0080] In addition, the above-mentioned application scenarios can be applied to the fields of unmanned driving, assisted driving, intelligent driving, automatic driving, networked vehicles, optical communication, security monitoring, biological medicine, surveying and mapping (such as three-dimensional mapping, remote sensing surveying and mapping), meteorological research, biomass and vegetation research, air quality monitoring, and aerospace applications, etc.

[0081] The above detection device may, for example, include but is not limited to a LiDAR, such as a direct modulation FMCW LiDAR. Before introducing the specific solutions provided by the present application, the related content of the direct modulation FMCW LiDAR will be introduced first.

[0082] As shown in FIG. 3a, a schematic diagram of the architecture of a currently mainstream direct modulation FMCW LiDAR is shown, which includes a light source, a light splitting element, a target measurement path, a reference calibration path, and a driving circuit. The reference calibration path is connected to one output end of the light splitting element, and the target measurement path is connected to the other output end of the light splitting element. Among them, the light source, the light splitting element, the reference calibration path, and the driving circuit constitute a loop, and therefore, the present application refers to this loop as a frequency modulation photoelectric loop (in some scenarios, it can also include the target measurement path). When the direct modulation FMCW LiDAR is working, the driving circuit can generate a modulation signal (L1) and input the modulation signal L1 to the light source. The modulation signal L1 can drive the light source to emit a light beam S with a frequency that changes linearly with time. The light splitting element splits the light beam S into a detection signal and a calibration signal, and outputs the detection signal to the target measurement path and the calibration signal to the reference calibration path. The target measurement path performs target measurement based on the detection signal to obtain the distance, speed, etc. of the target. 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, so that the frequency change of the light beam S emitted by the light source is linear with the input modulation signal L1 of the light source.

[0083] Exemplarily, taking the light source as a laser and the light splitting element as a beam splitter 1 as an example, please refer to FIG. 3b, a specific structural schematic diagram of a single-laser direct modulation FMCW LiDAR is shown. In this example, the reference calibration path can include a beam splitter 2, an optical delay line, a frequency mixer, an optical detection element and a processing element. The laser emits a light beam S according to the modulation signal L1 input by the driving circuit, the beam splitter 1 divides the light beam S into a detection signal and a calibration signal, the detection signal is input to the target measurement path for target measurement, and the calibration signal is input to the beam splitter 2. The beam splitter 2 divides the calibration signal into a signal light to be delayed and a calibration path local oscillator light, wherein the calibration path local oscillator light is directly input to the frequency mixer, and the signal light to be delayed is input to the frequency mixer after being delayed by the optical delay line. The frequency mixer mixes the calibration path local oscillator light and the delayed signal light to obtain an intermediate frequency signal. The optical detection element detects the intermediate frequency signal and inputs the detected intermediate frequency signal to the processing element. The processing element processes the intermediate frequency 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 according to the input feedback signal P.

[0084] Based on the single-laser direct modulation FMCW LiDAR architecture shown in FIG. 3b, it is extended to a multi-laser scenario, and the structure is shown in FIG. 3c. It can be known that in the multi-laser direct modulation FMCW LiDAR, a plurality of optical delay lines need to be set, and the number of the plurality of optical delay lines is one-to-one corresponding to the number of the plurality of lasers. Therefore, if it is extended to an N (N≥2) laser direct modulation FMCW LiDAR, the length of the optical delay line needs to be N times the length of the optical delay line in the single-laser direct modulation FMCW LiDAR. In the single-laser direct modulation FMCW LiDAR, the length of the optical delay line is related to the required delay time, which is generally on the order of meters. The length itself is already relatively long, and if it is extended to N lasers, the optical delay line on the order of meters multiplied by N times will have a very large size and hardware cost, occupying a large space in the FMCW LiDAR.

[0085] Therefore, the signal processing device is provided in the present application, which reflects the light beam output by the optical delay line back to the optical delay line through the reflector, so as to realize twice delay of the light beam by using one optical delay line, so as to shorten the length of the optical delay line by half. Optionally, when the signal processing device includes multiple lasers, the multiple lasers can also share the same optical delay line corresponding to multiple reference calibration paths, so as to reduce the number of optical delay lines. Based on this, the signal processing device is applied to the direct modulation FMCW LiDAR, whether it is a single-laser or a multi-laser direct modulation FMCW LiDAR, and the number of optical delay lines arranged can only be half of the length of the optical delay line in the existing single-laser direct modulation FMCW LiDAR, so that the size and hardware cost of the optical delay line can be effectively reduced, and the occupied space of the optical delay line in the direct modulation FMCW LiDAR can be reduced.

[0086] The signal processing device provided in the present application will be described in detail below in combination with FIGS. 4 to 13d.

[0087] It should be noted that in the drawings of the present application, two devices are connected through a "dashed line", which represents that the two devices are connected through an optical medium, such as an optical fiber, a waveguide or any medium that can transmit an optical signal. In general, the two devices connected by the "dashed line" can transmit an optical signal. Similarly, two devices are connected through a "solid line", which represents that the two devices are connected through an electrical medium (also referred to as electrical connection), such as a cable, a wire or any medium that can transmit an electrical signal. In general, the two devices connected by the "solid line" can transmit an electrical signal.

[0088] Referring to FIG. 4, a structural schematic diagram of a signal processing device provided in the present application is shown. The signal processing device includes a frequency modulation optoelectronic circuit 100, which includes a light source 111, a first light splitting element 112, an optical delay element 113, a frequency mixer 114, an optical detection element 115, a processing element 116 and a driving circuit 117. The optical delay element 113 includes an optical delay line 1131 and a reflector 1132. The optical delay line 1131 is used to delay a first optical signal (S1) from the first light splitting element 112, and the delayed first optical signal (S1') is input to the reflector 1132. The reflector 1132 is used to reflect the delayed first optical signal S1' back to the optical delay line, and the optical delay line 1131 delays the reflected delayed first optical signal S1' again. The re-delayed first optical signal (S1'') is input to the frequency mixer 114.

[0089] In the above, the frequency-modulated optoelectronic circuit 100 can be understood as a loop formed by the signal transmission between the various elements inside it. As shown in FIG. 4, the signal transmission flow of the loop can be: the light beam S output by the light source 111 enters the first light splitting element 112; the first light splitting element 112 splits the light beam S into the first light signal S1 and other light signals (not shown in the figure, and specific reference can be made to the content below); the first light signal S1 enters the optical delay element 113 for secondary delay, and then enters the frequency mixer 114 to perform frequency mixing with other signals (not shown in the figure, and specific reference can be made to the content below), to obtain the intermediate frequency signal Z; the intermediate frequency signal Z is detected by the optical detection element 115 and output to the processing element 116; the processing element 116 sends the feedback signal P to the driving circuit 117 according to the detected intermediate frequency signal Z; the driving circuit 117 adjusts the modulation signal L1 output to the light source 111 according to the feedback signal P, so as to calibrate the linearity between the modulation signal L1 and the light beam S output by the light source.

[0090] Based on the signal transmission flow in the above loop, the first light signal S1 entering the optical delay line 1131 and the first light signal S1” after secondary delay in the optical delay line 1131 will be transmitted on the same line, such as the line on the left side of the optical delay line 1131 in FIG. 4. To ensure that the first light signal S1” after secondary delay can smoothly enter the frequency mixer 114, in one example, as shown in FIG. 4, the line on the left side of the optical delay line 1131 can be divided into two branches, one branch connected to the first light splitting element 112 (referred to as the first branch), and the other branch connected to the frequency mixer 114 (referred to as the second branch). In this way, after the first light signal S1” after secondary delay in the optical delay line 1131 is output to the left from the left port of the optical delay line, at least a part of it will be transmitted from the second branch to the frequency mixer 114 to participate in the frequency mixing operation.

[0091] But the structure design in the above example will also cause a part of the second delayed first optical signal S1" to return to the first splitting element 112 from the first branch, thus causing signal waste. In order to avoid this problem, in another example, referring to FIG. 5, the optical delay element 113 can further include an optical transmission element 1133, which includes a first end a1, a second end a2 and a third end a3, the first end a1 is connected to the first splitting element 112, the second end a2 is connected to the optical delay line 1131, and the third end a3 is connected to the frequency mixer 114, the first end a1 to the second end a2 and the second end a2 to the third end a3 are unidirectional transmission. Based on this design, the first optical signal S1 emitted by the first splitting element 112 will enter the first end a1 of the optical transmission element 1133, and since the first end a1 to the second end a2 is unidirectional transmission, the first optical signal S1 will be output from the second end a2 of the optical transmission element 1133 to the optical delay line 1131, and then after being delayed twice by the optical delay line 1131 and the reflector 1132, it returns to the second end a2 of the optical transmission element 1133, and since the second end a2 to the third end a3 is unidirectional transmission, the second delayed first optical signal S1" will be output from the third end a3 of the optical transmission element 1133 to the frequency mixer 114.

[0092] Optionally, as shown in FIG. 5, the first splitting element 112 can have a first output end (b 11 ) and a second output end (b 12 ), and the frequency mixer 114 can have a first input end (c1) and a second input end (c2), the first output end b 11 of the first splitting element 112 is connected to the first end a1 of the optical transmission element 1133, the third end a3 of the optical transmission element 1133 is connected to the first input end c2 of the frequency mixer 114, and the second output end b 12 of the first splitting element 112 is connected to the second input end c2 of the frequency mixer 114. After the light source 111 outputs the light beam S, the first splitting element 112 can split the light beam S to obtain the first optical signal S1 and the calibration local oscillator signal, and output the first optical signal S1 through the first output end b 11 and output the calibration local oscillator signal through the second output end b 12 . The first optical signal S1 enters the first input end c1 of the frequency mixer 114 after being delayed twice by the optical delay element 113, and the calibration local oscillator signal directly enters the second input end c2 of the frequency mixer 114. The frequency mixer 114 receives the second delayed first optical signal S1" through the first input end c1 and receives the calibration local oscillator signal through the second input end c2, and performs frequency mixing processing on the second delayed first optical signal S1" and the calibration local oscillator signal, thereby obtaining the intermediate frequency signal Z.

[0093] In addition to the components shown in FIG. 5, the frequency-modulated optoelectronic circuit 100 can further include other components. For example, referring to FIG. 6, there is shown a schematic diagram of another frequency-modulated optoelectronic circuit provided by the present application, which can further include an amplifier 118 and / or an analog-to-digital conversion element 119. When the amplifier 118 is included, the amplifier 118 can be connected between the light detection element 115 and the processing element 116, for performing signal amplification on the intermediate frequency signal Z detected by the light detection element 115. When the analog-to-digital conversion element 119 is included, the analog-to-digital conversion element 119 can be connected between the light detection element 115 and the processing element 116, for performing analog-to-digital conversion on the intermediate frequency signal Z detected by the light detection element 115 to obtain a digital signal. When both the amplifier 118 and the analog-to-digital conversion element 119 are included, the amplifier 118 and the analog-to-digital conversion element 119 can be connected in series between the light detection element 115 and the processing element 116. The amplifier 118 can perform signal amplification on the intermediate frequency signal Z detected by the light detection element 115, and then input the amplified intermediate frequency signal Z to the analog-to-digital conversion element 119. The analog-to-digital conversion element 119 can perform analog-to-digital conversion on the amplified intermediate frequency signal Z to obtain a digital signal, and input the digital signal to the processing element 116.

[0094] Optionally, as shown in FIG. 6, the frequency-modulated optoelectronic circuit 100 can further include a target measurement path 120, and the first light splitting element 112 can further have a third output end (b 13 ) connected to the target measurement path 120. 13 The first light splitting element 112 can perform light splitting on the light beam S output by the light source 111 to obtain the first light signal S1, the calibration path local oscillator signal, and the detection signal, output the first light signal S1 through the first output end b 11 of the first light splitting element 112, output the calibration path local oscillator signal through the second output end b 12 of the first light splitting element 112, and output the detection signal through the third output end b 13 of the first light splitting element 112. Since the third output end b 13 is connected to the target measurement path 120, the detection signal can be received by the target measurement path 120, and the target measurement path 120 can perform target measurement based on the received detection signal.

[0095] As an example, as shown in FIG. 7, the target measurement path 120 can include a fourth light splitting element 121, a light transmission element 122, a frequency mixer 123, a light detection element 124, an amplifier 125, an analog-to-digital conversion element 126, and a processing element 127. The light transmission element 122 has a first end (d1), a second end (d2), and a third end (d3), and the first end d1 to the second end d2 and the second end d2 to the third end d3 are unidirectional transmission. The input end of the fourth light splitting element 121 is connected to the third output end b13 One output end of the fourth light splitting element 121 is connected to the first end d1 of the light transmission element 122, and the other output end is connected to one input end of the frequency mixer 123. The second end c2 of the light transmission element 122 is directed to the detection space, and the third end c3 of the light transmission element 122 is connected to the other input end of the frequency mixer 123. The frequency mixer 123, the light detection element 124, the amplifier 125, the analog-to-digital conversion element 126 and the processing element 127 are sequentially connected together.

[0096] Based on the above structure and connection relationship, as shown in FIG. 7, in the target measurement path 120, the fourth light splitting element 121 can receive the third output end b 13 The output detection signal, and perform light splitting processing on the detection signal to obtain a transmission signal and a target path local oscillator signal. The target path local oscillator signal is directly input to the frequency mixer 123. The transmission signal is input from the first end d1 of the light transmission element 122, output from the second end d2 of the light transmission element 122, and irradiated on the target in the detection space, and then reflected by the target back to the second end d2 of the light transmission element 122, and input from the third end d3 of the light transmission element 122 to the frequency mixer 123 (referred to as a reception signal or a return signal). The frequency mixer 123 performs frequency mixing processing on the target path local oscillator signal and the reception signal input thereto to obtain an intermediate frequency signal for target measurement. The light detection element 124 detects the intermediate frequency signal, and inputs the detected intermediate frequency signal to the amplifier 125. After the signal is amplified by the amplifier 125, it is input to the analog-to-digital conversion element 126. The analog-to-digital conversion element 126 performs analog-to-digital conversion on the input intermediate frequency signal to obtain a digital signal, and inputs the digital signal to the processing element 127. The processing element 127 processes the input digital signal to obtain related information of the target.

[0097] For example, the processing element 127 can perform fast Fourier transform (FFT) on the digital signal to extract distance information and motion state information of the target. The processing element 127 can also analyze the time variation trend of the frequency difference of the digital signal to obtain the change of the target position in different time intervals, and further calculate the speed of the target. In addition, the processing element 127 can output the distance, speed and other data of the target object, and further convert them into position information in three-dimensional space, which can be used for subsequent scene modeling, obstacle recognition or other application requirements.

[0098] The specific structure and function of each component in FIGS. 6 and 7 will be introduced below to give an exemplary implementation scheme.

[0099] 1. Light source

[0100] Optionally, the light source 111 can be any device capable of emitting light, such as a laser, including but not limited to: a vertical cavity surface emitting laser (VCSEL), an edge emitting laser (EEL), a diode pumped solid state laser (DPSS), or a fiber laser, etc.

[0101] In one example, the light source can emit a frequency-modulated continuous wave. In other words, the signal processing device can be a device in an FMCW LiDAR.

[0102] 2, light splitting element

[0103] Optionally, the light splitting element can be any device or combination of devices with light splitting function, such as a beam splitter, a beam combiner, a combination of a beam splitter and a beam splitter, or a combination of a beam splitter and a beam combiner, etc.

[0104] Here, the light splitting element refers to the first light splitting element 112 and / or the fourth light splitting element 121 described above.

[0105] For example, taking the first light splitting element 112 as an example, please refer to FIG. 8a, the first light splitting element 112 can specifically include a first beam splitter 1121 and a second beam splitter 1122. The input end of the first beam splitter 1121 is connected to the output end of the light source 111, the first output end (e 11 ) of the first beam splitter 1121 is connected to the input end of the second beam splitter 1122, the second output end (e 12 ) of the first beam splitter 1121 corresponds to the third output end b 13 of the first light splitting element 112, the first output end (e 21 ) of the second beam splitter 1122 corresponds to the first output end b 11 of the first light splitting element 112, and the second output end (e 22 ) of the second beam splitter 1122 corresponds to the second output end b 12 of the first light splitting element 112. Here, two ends correspond to each other means that the two ends are the same, or the two ends are connected through a line. For example, the second output end e 12 of the first beam splitter 1121 corresponds to the third output end b 13 of the first light splitting element 112 means that the second output end e 12 of the first beam splitter 1121 is the third output end b 13 of the first light splitting element 112, or the second output end e 12 of the first beam splitter 1121 is connected to the third output end b13 .

[0106] Based on the above structure and connection relationship, the light beam S output by the light source 111 enters the first beam splitter 1121, the first beam splitter 1121 performs light splitting processing on the light beam S to obtain a detection signal and a second light signal (S2). The first beam splitter 1121 outputs the detection signal through its second output end e 12 so that the detection signal enters the target measurement path 120 and participates in target measurement. The first beam splitter 1121 also outputs the second light signal S2 through its first output end e 11 so that the second light signal S2 enters the second beam splitter 1122. The second beam splitter 1122 performs light splitting processing on the second light signal S2 to obtain a calibration path local oscillator signal and a first light signal S1. The second beam splitter 1122 outputs the calibration path local oscillator signal through its second output end e 22 so that the calibration path local oscillator signal directly enters the frequency mixer 114. The second beam splitter 1122 also outputs the first light signal S1 through its first output end e 21 so that the first light signal S1 enters the optical delay element 113 and enters the frequency mixer 114 after twice delay of the optical delay element 113.

[0107] It should be noted that the above beam splitter can be any type of beam splitter, such as can include but not limited to: wavelength type beam splitter, power type beam splitter, polarization type beam splitter, and other types of beam splitter, etc.

[0108] 3, optical delay element

[0109] As described above, the optical delay element 113 can include an optical delay line 1131, a reflector 1132, and can also include an optical transmission element 1133.

[0110] Optionally, the optical delay line 1131 can be an element capable of delaying the transmission of an optical signal, such as can include but not limited to: a fiber delay line or an integrated waveguide delay line, etc.

[0111] Among them, the fiber delay line can realize the delay of the optical signal by using the transmission of the optical signal in the optical fiber, and generally has a relatively long length. The integrated waveguide delay line is a waveguide device made on a semiconductor chip, and its working principle is to realize signal delay by controlling the propagation path length of electromagnetic waves in a dielectric waveguide or silicon-based or other materials. The semiconductor material used by the integrated waveguide delay line can be silicon (Si), silicon nitride (SiN), etc., and the internal transmission is an optical signal. The integrated waveguide delay line has multiple advantages, including but not limited to: high integration, good programmability, high delay precision, easy integration with other circuits, smaller size, suitable for high-frequency applications, etc.

[0112] Optionally, the reflector 1132 can be an element capable of reflecting the optical signal, such as can include but is not limited to a mirror, a Sagnac loop reflector, or a Bragg grating, etc.

[0113] Taking the Sagnac loop reflector as an example, referring to FIG. 8a, the reflector 1132 can specifically include a third beam splitter 11321 and a loopback 11322, one end of the third beam splitter 11321 is connected to the optical delay line 1131, and the other two ends of the third beam splitter 11321 are connected together through an optical fiber, thereby constituting the above-mentioned loopback 11322. Based on this structure, the first optical signal S1' after the first time delay by the optical delay line 1131 will enter the third beam splitter 11321, and the third beam splitter 11321 performs light splitting processing on the first optical signal S1' to obtain two optical signals with equal optical intensity and equal phase. The two optical signals pass through the loopback 11322 in opposite directions and return to the third beam splitter 11321, at which time the optical intensity of the two optical signals is still equal and the phase is still equal, and the third beam splitter 11321 becomes a beam combiner to combine the two optical signals. The combined optical signal returns to the delay line 1131 along the original path and is subjected to the second time delay.

[0114] Optionally, the optical transmission element 1133 can be any device with at least three ports and unidirectional transmission between the ports, such as can be a circulator as shown in FIG. 8a, or can also be an isolator, or can also be a coupler. Although the coupler cannot completely transmit the second time delayed first optical signal S1" to the frequency mixer 114, by setting the interference parameters of each port of the coupler, the input and output signals of each port can be proportionally adjusted, thereby also ensuring that most of the second time delayed first optical signal S1" is transmitted to the frequency mixer 114. Of course, the optical transmission element 1133 can also be other devices, which are not specifically limited here.

[0115] 4. Frequency mixer

[0116] The frequency mixer can perform frequency mixing processing on the input signal to output an intermediate frequency signal. For example, as shown in FIG. 7, the frequency mixer 114 can perform frequency mixing processing on the input calibration path local oscillator signal and the second time delayed first optical signal S1" to obtain the intermediate frequency signal corresponding to the calibration path. The frequency mixer 123 can perform frequency mixing processing on the input target path local oscillator signal and the received signal to obtain the intermediate frequency signal corresponding to the target path.

[0117] It can be understood that the mixer can be any type of optical mixer. For example, taking the mixer 114 as an example, in one example, as shown in FIG. 8a, the mixer 114 can be a 180° optical mixer, the 180° optical mixer has two output ends, and the 180° optical mixer can coherently mix the calibration path local oscillator signal and the second delayed first optical signal S1” to make the relative phase difference of the two output ends 0° and 180°, respectively. For another example, as shown in FIG. 8b, the mixer 114 can be a 90° optical mixer, the 90° optical mixer has four output ends, and the 90° optical mixer can coherently mix the calibration path local oscillator signal and the second delayed first optical signal S1” to make the relative phase difference of the four output ends 0°, 90°, 180° and 270°, respectively. And so on, which will not be listed one by one here.

[0118] 5. Optical detection element

[0119] The optical detection element, also known as the optical receiver, is an electronic device for detecting an optical signal and converting the optical signal into an electrical signal. In the frequency-modulated optoelectronic circuit 100, the optical detection element is arranged behind the mixer, so it can detect the intermediate frequency signal output by the mixer and convert it into an electrical signal. Optionally, some examples of the optical detection element include but are not limited to: a phototube, a photomultiplier tube, a photodiode (PD), an avalanche photodiode (APD), a single photon avalanche diode (SPAD), etc.

[0120] For example, the PDs can include at least one PD, and the number of the at least one PD can be the same as the number of the output ends of the mixer arranged in front of the PDs. For example, the light detecting element 115 can include two PDs, i.e., PD1 and PD2, when the mixer 114 is a 180° optical mixer, as shown in FIGS. 7 and 8a. The input end of the PD1 and the input end of the PD2 are connected to the 180° optical mixer, and the output end of the PD1 and the output end of the PD2 are connected to the input end of the amplifier 118. The PD1 and the PD2 are used to detect the signals with a phase difference of 0° and 180° output by the 180° optical mixer, and convert the signals into electrical signals, which are then transmitted to the amplifier 118 in one line. For example, the light detecting element 115 can include four PDs, i.e., PD11, PD12, PD21 and PD22, when the mixer 114 is a 90° optical mixer, as shown in FIGS. 7 and 8b. The input ends of the four PDs are connected to the four output ends of the 90° optical mixer, and the output ends of each two PDs are connected to the input end of an amplifier. The four PDs are used to detect the signals with a phase difference of 0°, 90°, 180° and 270° output by the 90° optical mixer, and convert the signals into electrical signals, which are then transmitted to the subsequent amplifier in pairs.

[0121] 6. The amplifier

[0122] Optionally, the amplifier can be an element or a combination of elements with a signal amplification function. For example, a trans-impedance amplifier (TIA) can be included. The TIA can amplify the input signal with a certain strength and low noise, i.e., amplify the useful signal in the input signal while suppressing the amplification of the noise signal, so as to improve the optical signal noise ratio (OSNR).

[0123] For example, taking the TIA as an example, at least one TIA can be included in the amplifier, and the number of the at least one TIA can be related to the number of PDs included in the light detection element arranged in front of the at least one TIA, such as half the number of PDs. For example, taking the amplifier 118 as an example, in combination with FIGS. 7 and 8a, when the light detection element 115 includes two PDs, i.e., PD1 and PD2, the amplifier 118 can include one TIA, i.e., TIA 1180, and the output ends of PD1 and PD2 are connected to the input end of the TIA 1180 after being combined. Therefore, the two intermediate frequency signals detected by PD1 and PD2 are sent to the TIA 1180 after being combined into one, and the TIA 1180 can amplify the combined intermediate frequency signal with a certain strength. For another example, in combination with FIGS. 7 and 8b, when the light detection element 115 includes four PDs, i.e., PD11, PD12, PD21 and PD22, the amplifier 118 can include two TIAs, i.e., TIA 1181 and TIA 1182, and the output ends of PD11 and PD12 are connected to the input end of the TIA 1181 after being combined, and the output ends of PD21 and PD22 are connected to the input end of the TIA 1182 after being combined. Therefore, the two intermediate frequency signals detected by PD11 and PD12 are sent to the TIA 1181 (referred to as a first intermediate frequency signal Z1) after being combined into one, and the two intermediate frequency signals detected by PD21 and PD22 are sent to the TIA 1182 (referred to as a second intermediate frequency signal Z2) after being combined into one, and the TIA 1181 and the TIA 1182 respectively amplify the first intermediate frequency signal Z1 and the second intermediate frequency signal Z2 with a certain strength.

[0124] 7. Analog-to-digital conversion element

[0125] The analog-to-digital conversion element can sample the received time-continuous and amplitude-continuous analog signal and convert it into a time-discrete and amplitude-discrete digital signal to simplify the software processing operation of the subsequent processing element.

[0126] Optionally, the analog-to-digital conversion element can include at least one analog-to-digital converter (ADC), and the number of the at least one ADC can be the same as the number of the TIAs included in the amplifier arranged in front of the at least one ADC. For example, taking the analog-to-digital conversion element 119 as an example, in combination with FIG. 7 and FIG. 8a, when the amplifier 118 includes only one TIA, i.e., the TIA 1180, the analog-to-digital conversion element 119 can include only one ADC, i.e., the ADC 1190, and the input end of the ADC 1190 is connected to the output end of the TIA 1180, for performing analog-to-digital conversion on the amplified intermediate frequency signal Z output by the TIA 1180 to obtain a digital signal. For another example, in combination with FIG. 7 and FIG. 8b, when the amplifier 118 includes two TIAs, i.e., the TIA 1181 and the TIA 1182, the analog-to-digital conversion element 119 can also include two ADCs, i.e., the ADC 1191 and the ADC 1192, the input end of the ADC 1191 is connected to the output end of the TIA 1181, and the input end of the ADC 1192 is connected to the output end of the TIA 1182, and the output end of the ADC 1191 and the output end of the ADC 1192 are connected to the input end of the processing element 116 together. The ADC 1191 is configured to perform analog-to-digital conversion on the amplified first intermediate frequency signal Z1 output by the TIA 1181 to obtain a first digital signal, and the ADC 1192 is configured to perform analog-to-digital conversion on the amplified second intermediate frequency signal Z2 output by the TIA 1182 to obtain a second digital signal, and the first digital signal and the second digital signal are input to the processing element 116 together.

[0127] 8、processing element

[0128] The processing element refers to a component with a signal processing function, which can be a digital signal processor (DSP) for example. Taking the processing element 116 as an example, as shown in FIG. 8a or FIG. 8b, the processing element 116 can include a DSP 1160, which can process one or more digital signals output by the analog-to-digital conversion element 119 to obtain a feedback signal P, and input the feedback signal P to the driving circuit 117.

[0129] The feedback signal P can be used to calibrate the linearity between the modulation signal L1 output by the driving circuit 117 to the light source 111 and the light beam output by the light source 111, which is referred to as non-linear calibration in short. There can be multiple ways to achieve non-linear calibration, such as but not limited to frequency sweep monitoring and frequency modulation signal pre-distortion. Frequency sweep monitoring refers to calculating a frequency sweep curve by monitoring the change of the modulation signal L1, and determining whether the frequency sweep curve is linear. If not, it is calibrated to be linear. Frequency modulation signal pre-distortion refers to pre-compensating the modulation signal L1 that will produce non-linearity, so that the compensated modulation signal L1 is not distorted, that is, remains linear. Of course, there can be other ways of non-linear calibration, which are not limited here.

[0130] 9. Driving circuit

[0131] The driving circuit 117 can generate the modulation signal L1 according to the feedback signal P output by the processing element 116, and input the modulation signal L1 to the light source 111. The modulation signal L1 is used to drive the light source 111 to output a light beam S whose frequency changes linearly with time, such as a light beam S whose frequency changes linearly with time in the form of a triangular wave or a sawtooth wave.

[0132] In some cases, the driving circuit 117 also needs to be responsible for the timing control function, such as controlling the time window of the light source 111 to emit the light beam S, and synchronizing with the receiving end (i.e. the receiving operation of the target measurement path 120), so as to accurately demodulate the information in the echo signal (i.e. the received signal).

[0133] It should be noted that the above is an example of the elements on the calibration path (referring to the path where the first light splitting element 112, the optical delay element 113, the frequency mixer 114, the optical detection element 115, the amplifier 118, the analog-to-digital conversion element 119, and the processing element 116 are located) are described, and the related content of these elements also applies to the target measurement path 120. For example, in combination with the above FIG. 7 and FIG. 8a, when the fourth light splitting element 121 on the target measurement path 120 is a fourth beam splitter 1210, the frequency mixer 123 is a 180° optical frequency mixer, the optical detection element 124 includes PD3 and PD4, the amplifier 125 is a TIA 1250, the analog-to-digital conversion element 126 is an ADC 1260, and the processing element 127 is a DSP 1270, the structure of the frequency-modulated optoelectronic circuit 100 can be as shown in FIG. 8c. For another example, in combination with the above FIG. 7 and FIG. 8b, when the fourth light splitting element 121 on the target measurement path 120 is a fourth beam splitter 1210, the frequency mixer 123 is a 90° optical frequency mixer, the optical detection element 124 includes PD31, PD32, PD41, and PD42, the amplifier 125 includes a TIA 1251 and a TIA 1252, the analog-to-digital conversion element 126 includes an ADC 1261 and an ADC 1262, and the processing element 127 is a DSP 1270, the structure of the frequency-modulated optoelectronic circuit 100 is as shown in FIG. 8d. Of course, the frequency mixer 123 in the target measurement path 120 and the frequency mixer 114 in the calibration path can also be different types, such as the frequency mixer 123 in the target measurement path 120 is a 90° optical frequency mixer, and the frequency mixer 114 in the calibration path is a 180° optical frequency mixer, as shown in FIG. 8e, or vice versa, as shown in FIG. 8f. For related devices, refer to the above description, which will not be repeated here.

[0134] Based on the structure design of the above signal processing device, in one frequency-modulated optoelectronic circuit, by setting a reflector on the side where the optical delay line originally outputs the optical signal, the delayed optical signal can be reflected back to the optical delay line for further delay through the reflection of the reflector. In this way, the same optical signal can be delayed twice using one optical delay line. Compared with the prior art, the physical length of the optical delay line in one frequency-modulated optoelectronic circuit can be halved, while the delay time of the optical signal is not reduced. Therefore, the original delay effect can be maintained on the basis of reducing the size and cost of the optical delay line.

[0135] It can be understood that when the above signal processing device is applied to the FMCW LiDAR, the size of the optical delay line is halved through the reflector, which can reduce the occupied space of the optical delay line in the FMCW LiDAR, simplify the architecture design of the FMCW LiDAR, and reduce the cost of the FMCW LiDAR. Specifically, when the optical delay line is an optical fiber delay line, the occupied length of the optical fiber delay line in the FMCW LiDAR can be reduced, and the hardware cost of the FMCW LiDAR can be reduced. When the optical delay line is an integrated waveguide delay line, the occupied area of the integrated waveguide delay line in the corresponding chip of the FMCW LiDAR can be reduced, thereby the cost of the chip can be reduced, and the purpose of reducing the hardware cost of the FMCW LiDAR can be achieved.

[0136] The above describes the structure and function of one frequency-modulated optoelectronic circuit in the signal processing device in detail. In this application, the signal processing device can have only one frequency-modulated optoelectronic circuit, or can have multiple frequency-modulated optoelectronic circuits. When there are multiple frequency-modulated optoelectronic circuits, the structures of the multiple frequency-modulated optoelectronic circuits can be the same or different.

[0137] In the following, several possible structures of the signal processing device with multiple frequency-modulated optoelectronic circuits are exemplarily introduced through different embodiments.

[0138] It should be noted that each of the following embodiments is based on the structure of the frequency-modulated optoelectronic circuit 100 shown in FIG. 6. However, it should be understood that the same scheme can also be applied to any of the frequency-modulated optoelectronic circuits shown in FIGS. 4 to 8d, and the present application does not make specific limitations thereon.

[0139] In addition, for each of the embodiments introduced below, the terms and / or descriptions of different embodiments are consistent and can be mutually referred to if there is no special description and logical conflict, and the technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0140] Embodiment one

[0141] Please refer to FIG. 9, which shows a structural schematic diagram of a signal processing device provided by embodiment one. In this example, the signal processing device includes N frequency-modulated optoelectronic circuits, i.e., frequency-modulated optoelectronic circuit 100, frequency-modulated optoelectronic circuit 200, …, and frequency-modulated optoelectronic circuit N00, N is an integer greater than or equal to 2. The structures of the N frequency-modulated optoelectronic circuits are the same, and the structure of each frequency-modulated optoelectronic circuit can be referred to the above FIGS. 4 to 8f.

[0142] For example, in FIG. 9, the frequency-modulated optoelectronic circuit 100 includes the light source 111, the first light splitting element 112, the light transmission element 1133, the light delay line 1131, the reflector 1132, the frequency mixer 114, the light detection element 115, the amplifier 118, the analog-to-digital conversion element 119, the processing element 116, the driving circuit 117, and the target measurement path 120, as shown in the structure of FIG. 6. Similarly, the frequency-modulated optoelectronic circuit 200 includes the light source 211, the first light splitting element 212, the light transmission element 2133, the light delay line 2131, the reflector 2132, the frequency mixer 214, the light detection element 215, the amplifier 218, the analog-to-digital conversion element 219, the processing element 216, the driving circuit 217, and the target measurement path 220. Similarly, the frequency-modulated optoelectronic circuit N00 includes the light source N11, the first light splitting element N12, the light transmission element N133, the light delay line N131, the reflector N132, the frequency mixer N14, the light detection element N15, the amplifier N18, the analog-to-digital conversion element N19, the processing element N16, the driving circuit N17, and the target measurement path N20.

[0143] With the structure of the first embodiment, the structures of the N frequency-modulated optoelectronic circuits are the same, and the total length of the light delay lines in the N frequency-modulated optoelectronic circuits can be shortened by half, without reducing the time delay of the light signal by the N frequency-modulated optoelectronic circuits. Thus, the space occupied by the light delay lines in the N frequency-modulated optoelectronic circuits can be reduced, thereby simplifying the architecture of the N frequency-modulated optoelectronic circuits and reducing the cost.

[0144] The second embodiment

[0145] Referring to FIG. 10, a structure of a signal processing device according to the second embodiment is shown. In this example, the signal processing device includes N frequency-modulated optoelectronic circuits 100-N00, where N is an integer greater than or equal to 2. The N frequency-modulated optoelectronic circuits 100-N00 share the same light delay element 113, such as the same light transmission element 1133, the same light delay line 1131, and the same reflector 1132.

[0146] In the second embodiment, the other elements introduced above are separately provided in the N frequency-modulated optoelectronic circuits 100-1000 except that the optical delay element 113 is shared. For example, as shown in Fig. 10, the frequency-modulated optoelectronic circuit 100 includes the light source 111, the first light splitting element 112, the frequency mixer 114, the light detecting element 115, the amplifier 118, the analog-to-digital conversion element 119, the processing element 116, the driving circuit 117, and the target measurement path 120 introduced above. Similarly, the frequency-modulated optoelectronic circuit 200 includes the light source 211, the first light splitting element 212, the frequency mixer 214, the light detecting element 215, the amplifier 218, the analog-to-digital conversion element 219, the processing element 216, the driving circuit 217, and the target measurement path 220. The frequency-modulated optoelectronic circuit N00 includes the light source N11, the first light splitting element N12, the frequency mixer N14, the light detecting element N15, the amplifier N18, the analog-to-digital conversion element N19, the processing element N16, the driving circuit N17, and the target measurement path N20.

[0147] In addition to the above elements, as shown in Fig. 10, the signal processing device can further include the light combining element 130 having N input ends, i.e., f1, f2,..., fN, and the second light splitting element 140 having N output ends, i.e., g1, g2,..., gN. N N The N input ends f1-fN of the light combining element 130 are one-to-one connected to the first output ends b1-bN of the N first light splitting elements 112-N12 of the N frequency-modulated optoelectronic circuits 100-1000. N 11 The second output ends b1-bN of the N first light splitting elements 112-N12 of the N frequency-modulated optoelectronic circuits 100-1000 are respectively connected to one input end of the N frequency mixers 114-N14. N1 12 The third output ends b1-bN of the N first light splitting elements 112-N12 of the N frequency-modulated optoelectronic circuits 100-1000 are respectively connected to the other input end of the N frequency mixers 114-N14. N2 13 The N amplifiers 118-N18 of the N frequency-modulated optoelectronic circuits 100-1000 are respectively connected to the N light detecting elements 115-N15. N3 The N analog-to-digital conversion elements 119-N19 of the N frequency-modulated optoelectronic circuits 100-1000 are respectively connected to the N amplifiers 118-N18. N The N output ends g1-gN of the second light splitting element 140 are one-to-one connected to the other input end of the N frequency mixers 114-N14 of the N frequency-modulated optoelectronic circuits 100-1000. ​​​​

[0148] Based on the above structure and connection relationship, in each frequency-modulated optoelectronic circuit, the first beam splitting element splits the light beam generated by the light source to obtain a detection signal, a calibration local oscillator signal for the calibration path, and a first optical signal. The first beam splitting element inputs the detection signal to the target measurement path for target measurement through its third output end, inputs the calibration local oscillator signal for the calibration path to the mixer through its second output end, and inputs the first optical signal to the beam combining element 130 through its first output end. The beam combining element 130 receives N first optical signals S N output from the N first beam splitting elements 112 to N12 in the N frequency-modulated optoelectronic circuits 100 to N00 11 ~S 1N , combines the N first optical signals S 11 ~S 1N to obtain a signal to be delayed, and inputs the signal to be delayed to the optical delay element 113. The optical delay element 113 delays the signal to be delayed twice to obtain a doubly delayed signal, and inputs the doubly delayed signal to the second beam splitting element 140. The second beam splitting element 140 splits the doubly delayed signal to obtain N doubly delayed sub-optical signals S 11 ”~S 1N ”, and sends the N doubly delayed sub-optical signals S N ”~S 11 ” to the N mixers 114 to N14 in the N frequency-modulated optoelectronic circuits 100 to N00 through its N output ends g1 to g 1N respectively. In each frequency-modulated optoelectronic circuit, the mixer mixes the calibration local oscillator signal input by the first beam splitting element and the doubly delayed sub-optical signal input by the second beam splitting element 140 to obtain an intermediate frequency signal; the intermediate frequency signal is detected by the optical detection element and converted into an electrical signal, which is amplified by the amplifier and then output to the analog-to-digital conversion element. After being converted into a digital signal by the analog-to-digital conversion element, it is output to the processing element; the processing element obtains a feedback signal based on the digital signal, and inputs the feedback signal to the driving circuit; the driving circuit generates a modulation signal based on the feedback signal and inputs the modulation signal to the light source to calibrate the linearity between the modulation signal and the light beam output by the light source, so that the light source can output a light beam that conforms to the linear change law under the action of the modulation signal. After this light beam is split into the target measurement path (i.e., the detection signal), the detection accuracy of the target measurement path can be improved.

[0149] In the above, the light combining element 130 can be any device or combination of devices having a light combining function, such as a beam combiner, an optical coupler, or a combination of a beam combiner and a beam combiner, or a combination of a beam combiner and an optical coupler, etc., and the specific implementation is not limited. Taking a beam combiner as an example, the beam combiner can be any type of beam combiner, such as but not limited to a wavelength type beam combiner, a power type beam combiner, a polarization type beam combiner, or other types of beam combiners, etc. Similarly, the second light splitting element 140 can be any device or combination of devices having a light splitting function, such as a beam splitter, a beam splitter, or a combination of a beam splitter and a beam splitter, or a combination of a beam splitter and a beam splitter, etc., and the specific implementation is not limited. Taking a beam splitter as an example, the beam splitter can include but not limited to a wavelength type beam splitter, a power type beam splitter, a polarization type beam splitter, or other types of beam splitters, etc.

[0150] In addition, the structures and functions of other elements except the light combining element 130 and the second light splitting element 140 can be referred to the above description. For example, in combination with FIGS. 8a and 8b, for each frequency-modulated optoelectronic circuit, the first light splitting element can include two beam splitters, the frequency mixer can be a 180° optical frequency mixer or a 90° optical frequency mixer, the optical detection element 215 can include a plurality of PDs, the amplifier can include one or more TIAs, the analog-to-digital converter can include one or more ADCs, and the processing element can be a DSP, etc. The present application will not repeat the introduction of these contents one by one.

[0151] With the structure in the second embodiment, the N frequency-modulated optoelectronic circuits share the same optical delay line of the band reflector, and the presence of the reflector can shorten the physical length of the optical delay line by half. In addition, the N frequency-modulated optoelectronic circuits share the same optical delay line, which saves N-1 optical delay lines.

[0152] Therefore, the length of the optical delay line in the N frequency-modulated optoelectronic circuits can be only and also

[0153] The delay time of the optical signal of the N frequency-modulated optoelectronic circuits is reduced, so that the extremely simple architecture and extremely low cost of the FMCW LiDAR can be realized.

[0154] Embodiment three

[0155] Referring to FIG. 11, a structural schematic diagram of a signal processing device provided by the third embodiment is shown. In this example, the signal processing device includes N frequency-modulated optoelectronic circuits 100-N00, where N is an integer greater than or equal to 2. The N frequency-modulated optoelectronic circuits 100-N00 share the same optical delay element 113, such as the same optical transmission element 1133, the same optical delay line 1131, and the same reflector 1132. Also, in each frequency-modulated optoelectronic circuit, the first light splitting element includes a beam splitter and an optical processing element 230, such as the first light splitting element 112 in the frequency-modulated optoelectronic circuit 100 includes a beam splitter 1121 and an optical processing element 230, the first light splitting element 212 in the frequency-modulated optoelectronic circuit 200 includes a beam splitter 2121 and an optical processing element 230, and so on, the first light splitting element N12 in the frequency-modulated optoelectronic circuit N00 includes a beam splitter N121 and an optical processing element 230. That is, the N frequency-modulated optoelectronic circuits 100-N00 also share the same optical processing element 230.

[0156] In the third embodiment, except that the optical delay element 113 and the optical processing element 230 are shared, the other elements introduced above are separately provided in the N frequency-modulated optoelectronic circuits 100-N00. For example, as shown in FIG. 11, the frequency-modulated optoelectronic circuit 100 includes the light source 111, the beam splitter 1121, the frequency mixer 114, the optical detection element 115, the amplifier 118, the analog-to-digital conversion element 119, the processing element 116, the driving circuit 117, and the target measurement path 120 introduced above. Similarly, the frequency-modulated optoelectronic circuit 200 includes the light source 211, the beam splitter 2121, the frequency mixer 214, the optical detection element 215, the amplifier 218, the analog-to-digital conversion element 219, the processing element 216, the driving circuit 217, and the target measurement path 220. The frequency-modulated optoelectronic circuit N00 includes the light source N11, the beam splitter N121, the frequency mixer N14, the optical detection element N15, the amplifier N18, the analog-to-digital conversion element N19, the processing element N16, the driving circuit N17, and the target measurement path N20.

[0157] In addition to the above elements, as shown in FIG. 11, the signal processing device can further include a second light splitting element 240 and a third light splitting element 250. The second light splitting element 240 has N outputs, i1, i2, …, i N , and the third light splitting element 250 has N outputs, j1, j2, …, j N . The optical processing element 230 has N inputs, h1, h2, …, h N , and two outputs, a first output h N+1 and a second output h N+2 . The N inputs h1-h NOne output end of each of the N beam splitters 1121 to N121 that respectively connect the N frequency modulation optoelectronic circuits 100 to N00 in a one-to-one correspondence is connected to one input end of each of the N mixers 114 to N14 of the N frequency modulation optoelectronic circuits 100 to N00. The other output end of each of the N beam splitters 1121 to N121 is connected to one of the N target measurement paths 120 to N20 of the N frequency modulation optoelectronic circuits 100 to N00 in a one-to-one correspondence. The optical delay element 113 is connected to the first output end h of the optical processing element 230 N+1 Between the input end of the second beam splitting element 240, for example, the first end a1 of the optical transmission element 1133 in the optical delay element 1133 is connected to the first output end h of the optical processing element 230 N+1 The third end a3 of the optical transmission element 1133 is connected to the input end of the second beam splitting element 240, and the N output ends i1 to i of the second beam splitting element 240 N Are respectively connected to one input end of each of the N mixers 114 to N14 of the N frequency modulation optoelectronic circuits 100 to N00 in a one-to-one correspondence. The second output end h of the optical processing element 230 N+2 Is connected to the input end of the third beam splitting element 250, and the N output ends j1 to j of the third beam splitting element 250 N Are respectively connected to the other input end of each of the N mixers 114 to N14 of the N frequency modulation optoelectronic circuits 100 to N00 in a one-to-one correspondence.

[0158] Based on the above structure and connection relationship, in each frequency modulation optoelectronic circuit, the beam splitter splits the light beam generated by the light source to obtain a detection signal and a second optical signal, inputs the detection signal to the target measurement path for target measurement, and inputs the second optical signal to the optical processing element 230. The optical processing element 230 receives the N second optical signals S N Output by the N beam splitters 1121 to N121 in the N frequency modulation optoelectronic circuits 100 to N00 through its N input ends h1 to h 21 ~S 2N , combines the N second optical signals S 21 ~S 2N , then performs beam splitting processing to obtain a signal to be delayed and a third optical signal S3, inputs the signal to be delayed to the optical delay element 113 through its first output end h N+1 , and inputs the third optical signal S3 to the third beam splitting element 250 through its second output end h N+2 . The optical delay element 113 performs two delays on the signal to be delayed to obtain a doubly delayed signal, and inputs the doubly delayed signal to the second beam splitting element 240. The second beam splitting element 240 performs beam splitting processing on the doubly delayed signal to obtain N doubly delayed sub-optical signals S 11 ”~S 1N ” and outputs the N doubly delayed sub-optical signals S N ”~S 11 ” through its N output ends i1 to i1N The N calibration local oscillator signals are respectively sent to the N mixers 114-N14 in the N frequency-modulated optoelectronic circuits 100-N00. The third light splitting element 250 performs light splitting processing on the third light signal S3 to obtain N calibration local oscillator signals, and sends the N calibration local oscillator signals to the N outputs j1-jN of the third light splitting element 250. N The N calibration local oscillator signals are respectively sent to the N mixers 114-N14 in the N frequency-modulated optoelectronic circuits 100-N00. In each frequency-modulated optoelectronic circuit, the mixer performs mixing processing on the twice-delayed sub-light signal input from the second light splitting element 240 and the calibration local oscillator signal input from the third light splitting element 250 to obtain an intermediate frequency signal; the intermediate frequency signal is detected by the light detection element and converted into an electrical signal, the electrical signal is amplified by the amplifier and input to the analog-to-digital conversion element, and after being converted into a digital signal by the analog-to-digital conversion element, the digital signal is input to the processing element; the processing element obtains a feedback signal according to the digital signal, and inputs the feedback signal to the driving circuit; the driving circuit generates a modulation signal according to the feedback signal, and inputs the modulation signal to the light source, so as to calibrate the linearity between the modulation signal and the light beam output by the light source.

[0159] In the above, the light processing element 230 can be a device or a combination of devices having the function of first combining light and then splitting light, such as a beam combiner, or a combination of a beam combiner and a beam splitter, etc. The second light splitting element 240 or the third light splitting element 250 can be a device or a combination of devices having the function of splitting light, such as a beam splitter, a beam combiner, or a combination of a beam splitter and a beam splitter, or a combination of a beam splitter and a beam combiner, etc. Taking a beam splitter as an example, the beam splitter can include but is not limited to a wavelength-type beam splitter, a power-type beam splitter, a polarization-type beam splitter, or other types of beam splitters, etc.

[0160] In addition, the structures and functions of other elements except the light processing element 230, the second light splitting element 240, and the third light splitting element 250 can be referred to the above description. For example, in combination with FIGS. 8a and 8b, for each frequency-modulated optoelectronic circuit, the mixer can be a 180° optical mixer or a 90° optical mixer, the light detection element 215 can include multiple PDs, the amplifier can include one or more TIAs, the analog-to-digital converter can include one or more ADCs, and the processing element can be a DSP, etc. The present application does not repeat the introduction of these contents one by one.

[0161] Adopting the structure in Embodiment 3, in addition to sharing the same optical delay line with a reflector, the N frequency-modulated optoelectronic circuits can also share the same optical processing element, that is, share some elements in the first beam splitting element. Thus, in addition to achieving the effects in Embodiment 2 above, the number of other devices (such as beam splitters in the first beam splitting element) in the N frequency-modulated optoelectronic circuits can be saved, thereby further reducing the volume and cost of the signal processing device, and making it easier to achieve the minimalist architecture and extremely low cost of the signal processing device.

[0162] Embodiment 4

[0163] Please refer to FIG. 12, which shows a schematic structural diagram of a signal processing device provided in Embodiment 4. In this example, the signal processing device includes N frequency-modulated optoelectronic circuits 100 to N00, where N is an integer greater than or equal to 2. Among them, the N frequency-modulated optoelectronic circuits 100 to N00 share the same optical delay element 113. For example, they share the same optical transmission element 1133, the same optical delay line 1131, and the same reflector 1132. In addition, the N frequency-modulated optoelectronic circuits 100 to N00 also share the same mixer 114, the same optical detection element 115, the same amplifier 118, the same analog-to-digital conversion element 119, and the same processing element 116. And in each frequency-modulated optoelectronic circuit, the first beam splitting element includes a beam splitter and an optical processing element 230, and the N frequency-modulated optoelectronic circuits 100 to N00 also share the same optical processing element 230.

[0164] In Embodiment 4, except that the optical delay element 113, the optical processing element 230, the mixer 114, the optical detection element 115, the amplifier 118, the analog-to-digital conversion element 119, and the processing element 116 are shared, the other elements introduced above are separately provided in the N frequency-modulated optoelectronic circuits 100 to N00. For example, as shown in FIG. 12, the frequency-modulated optoelectronic circuit 100 includes the light source 111, the beam splitter 1121, the drive circuit 117, and the target measurement path 120 introduced above. Similarly, the frequency-modulated optoelectronic circuit 200 includes the light source 211, the beam splitter 2121, the drive circuit 217, and the target measurement path 220.... The frequency-modulated optoelectronic circuit N00 includes the light source N11, the beam splitter N121, the drive circuit N17, and the target measurement path N20.

[0165] As shown in FIG. 12, similar to Embodiment 3 above, the optical processing element 230 has N input terminals h1 to h N , and two output terminals h N+1 and h N+2 , and the processing element 116 has N output terminals, namely k1, k2,..., k N . The N input terminals h1 to h of the optical processing element 230 NOne output end of each of the N beam splitters 1121 to N121 that are connected in one-to-one correspondence to the N frequency-modulated optoelectronic circuits 100 to N00 is connected, and the other output end of each of the N beam splitters 1121 to N121 is connected in one-to-one correspondence to the N target measurement paths 120 to N20 of the N frequency-modulated optoelectronic circuits 100 to N00. The optical delay element 113 is connected to the first output end h of the optical processing element 230 N+1 Between one input end of the mixer, for example, the first end a1 of the optical transmission element 1133 in the optical delay element 113 is connected to the first output end h of the optical processing element 230 N+1 The third end a3 of the optical transmission element 1133 is connected to one input end of the mixer 114, and the second output end h of the optical processing element 230 N+2 is connected to the other input end of the mixer 114

[0166] Based on the above structure and connection relationship, in each frequency-modulated optoelectronic circuit, the beam splitter splits the light beam generated by the light source to obtain a detection signal and a second optical signal, inputs the detection signal to the target measurement path for target measurement, and inputs the second optical signal to the optical processing element 230. The optical processing element 230 receives the N second optical signals S N output by the N beam splitters 1121 to N121 in the N frequency-modulated optoelectronic circuits 100 to N00 through its N input ends h1 to h 21 ~S 2N , combines the N second optical signals S 21 ~S 2N , then performs beam splitting processing to obtain a signal to be delayed and a local oscillator signal of the calibration path, inputs the signal to be delayed to the optical delay element 113 through its first output end h N+1 , and inputs the local oscillator signal of the calibration path to the mixer 114 through its second output end d N+2 The optical delay element 113 delays the signal to be delayed twice to obtain a doubly delayed signal, and inputs the doubly delayed signal to the mixer 114. The mixer 114 mixes the local oscillator signal of the calibration path input by the optical processing element 230 and the doubly delayed signal input by the optical delay element 113 to obtain an intermediate frequency signal. The intermediate frequency signal is detected by the optical detection element 115 and converted into an electrical signal. The electrical signal is amplified by the amplifier 118 and then input to the analog-to-digital conversion element 119. After being converted into a digital signal by the analog-to-digital conversion element 119, it is input to the processing element 116. The processing element 116 obtains N feedback signals according to the digital signal, and through its N output ends k1 to k NThe N feedback signals are input to N drive circuits 117-N17 in the N frequency-modulated optoelectronic circuits 100-N00, respectively. In each frequency-modulated optoelectronic circuit, the drive circuit generates a modulation signal according to the feedback signal and inputs the modulation signal to the light source to calibrate the linearity between the modulation signal and the light beam output by the light source.

[0167] In the above, the structure and function of each element can be seen from the above description. For example, in combination with Embodiment Three, Figs. 8a and 8b, the light processing element 230 can be a beam splitter, the frequency mixer 114 can be a 180° optical frequency mixer or a 90° optical frequency mixer, the light detection element 115 can include a plurality of PDs, the amplifier 118 can include one or more TIAs, the analog-to-digital converter 119 can include one or more ADCs, and the processing element 116 can be a DSP, etc. The present application does not repeat the introduction of these contents one by one.

[0168] With the structure in Embodiment Four, the N frequency-modulated optoelectronic circuits can share the same light processing element, the same frequency mixer, the same light detection element, the same amplifier, the same analog-to-digital conversion element, and the same processing element in addition to sharing the same optical delay line of the same strip reflector. Therefore, in addition to the effects in Embodiment Two above, the number of other devices in the N frequency-modulated optoelectronic circuits can be greatly saved, thereby effectively reducing the size and cost of the signal processing device and realizing an extremely simple architecture and extremely low cost of the signal processing device.

[0169] It should be noted that the above is only an exemplary introduction of several possible structures of the signal processing device including multiple frequency-modulated optoelectronic circuits, and in actual signal processing devices, the above structures can be simply deformed to obtain other structures, for example:

[0170] In one example, in combination with the above, the amplifier and the analog-to-digital conversion element in each frequency-modulated optoelectronic circuit are optional, and therefore the amplifiers and the analog-to-digital conversion elements in Figs. 9-12 above can also be absent. For example, taking the signal processing device shown in Fig. 12 as an example, the amplifier 118 and the analog-to-digital conversion element 119 therein can be absent, and the corresponding structure is shown in Fig. 13a. In this structure, the N frequency-modulated optoelectronic circuits can share the same optical delay line 1131 of the same strip reflector 1132, the same light processing element 230, the same frequency mixer 114, the same light detection element 115, and the same processing element 116.

[0171] In another example, in combination with FIG. 11 and FIG. 12, the N frequency-modulated optoelectronic circuits can share one or more of the same frequency mixer 114, the same photodetector 115, the same amplifier 118, the same analog-to-digital conversion element 119, and the same processing element 116 in addition to sharing the same optical delay line 1131 and the same optical processing element 230 of the same band reflector 1132. For example:

[0172] Referring to FIG. 13b, a signal processing device is shown that shares the same frequency mixer 114 but does not share the photodetector, the amplifier, the analog-to-digital conversion element, and the processing element. In this example, the signal processing device can further include a fifth light splitting element 260, which can be a wavelength-type, power-type, polarization-type, or other type of light splitting element without limitation. The fifth light splitting element 260 has N outputs, i.e., m1, m2, …, m N The input of the fifth light splitting element 260 is connected to the output of the frequency mixer 114, and the N outputs m1-m N of the fifth light splitting element 260 are respectively connected to the inputs of the N photodetectors 115-N15 of the N frequency-modulated optoelectronic circuits 100-1000. Based on this structure and connection relationship, the frequency mixer 114 mixes the twice-delayed signal output by the optical delay element 113 and the calibration local oscillator signal output by the optical processing element 230 to obtain an intermediate frequency signal, and inputs the intermediate frequency signal to the fifth light splitting element 260; the fifth light splitting element 260 splits the intermediate frequency signal to obtain N sub-intermediate frequency signals, and outputs the N sub-intermediate frequency signals through the N outputs m1-m N of the fifth light splitting element 260 to the N photodetectors 115-N15 of the N frequency-modulated optoelectronic circuits 100-1000, respectively. The subsequent processing operations of each frequency-modulated optoelectronic circuit are described above and will not be repeated here;

[0173] Referring to FIG. 13c, a signal processing device is shown that shares the same frequency mixer 114 and the photodetector 115 but does not share the processing element. In this example, the signal processing device can further include a multi-port element 270, which has one input and N outputs (i.e., n1, n2, …, n N The input of the multi-port element 270 is connected to the output of the photodetector 115, and the N outputs n1-n NThe input ends of the N processing elements 116-N16 of the N frequency-modulated optoelectronic circuits 100-N00 are connected one by one. Based on the structure and the connection relationship, the light detection element 115 detects the intermediate frequency signals output by the mixers 114 and converts the intermediate frequency signals into electrical signals, which are then input to the multi-port element 270; the multi-port element 270 splits the electrical signals to obtain N sub-electrical signals and transmits the N sub-electrical signals through its N output ends m1-m N The N sub-electrical signals are respectively output to the N processing elements 116-N16 of the N frequency-modulated optoelectronic circuits 100-N00. The subsequent processing operations of each frequency-modulated optoelectronic circuit are described above and will not be repeated here.

[0174] Please refer to FIG. 13d, which shows a signal processing device sharing the same light detection element 115 and processing element 116 but not sharing the mixers. In this example, the signal processing device can also include a second light splitting element 240, a third light splitting element 250, and a light combining element 280. The contents of the second light splitting element 240 and the third light splitting element 250 are described above in Embodiment Three. The light combining element 280 has N input ends, i.e., r1, r2, …, r N The N input ends r1-r N The output ends of the N mixers 114-N14 in the N frequency-modulated optoelectronic circuits 100-N00 are connected one by one, and the output end of the light combining element 280 is connected to the input end of the light detection element 115. Based on the structure and the connection relationship, the light combining element 280 can receive the N intermediate frequency signals transmitted by the N mixers 114-N14 in the N frequency-modulated optoelectronic circuits 100-N00 through its N input ends r1-r N The N intermediate frequency signals transmitted by the N mixers 114-N14 in the N frequency-modulated optoelectronic circuits 100-N00 are received, and the N intermediate frequency signals are combined into one signal, which is detected by the light detection element 115 and converted into an electrical signal, which is then transmitted to the processing element 116. The processing element 116 generates N feedback signals according to the electrical signal and transmits the N feedback signals through its N output ends K1-K N The N feedback signals are respectively transmitted to the drive circuits 117-N17 in the N frequency-modulated optoelectronic circuits 100-N00.

[0175] It should be understood that there are many possible structures of signal processing devices, which will not be listed one by one here.

[0176] It should be noted that when the signal processing device comprises N frequency-modulated optoelectronic circuits, the target measurement paths in the N frequency-modulated optoelectronic circuits can be separate or shared. For example, the above Figs. 9-13d show a scheme in which the N frequency-modulated optoelectronic circuits have different target measurement paths, but in other schemes, the N frequency-modulated optoelectronic circuits can share a common target measurement path, or some of the frequency-modulated optoelectronic circuits share a common target measurement path, while the other frequency-modulated optoelectronic circuits have their own independent target measurement paths. Among them, the first light splitting element in the frequency-modulated optoelectronic circuits sharing the same target measurement path can input the detection signals obtained by light splitting into the same target measurement path, and the multiple detection signals are combined into one path in the same target measurement path, and then split into a transmission signal and a target path local oscillator signal. The transmission signal is emitted into the detection space to detect the target, while the target path local oscillator signal is input into the mixer to wait for mixing with the returned echo signal. In this way, by sharing one target measurement path, the detection signals obtained by light splitting of the light beams modulated by multiple frequency-modulated optoelectronic circuits can be combined into one signal to measure the target together, which not only saves the number of target measurement paths to be set, saves the cost of components and occupies space, but also improves the power of the detection signal of the measured target.

[0177] In addition, when the signal processing device comprises N frequency-modulated optoelectronic circuits, the N to-be-delayed signals corresponding to the N frequency-modulated optoelectronic circuits need to be combined into one path and then split into multiple paths, therefore, in order to realize the accuracy of beam splitting, the N to-be-delayed signals need to have differences in wavelength. For example, the N light beams output by the N light sources in the N frequency-modulated optoelectronic circuits can be light beams of different wavelengths. After these light beams of different wavelengths are split by the N first light splitting elements into to-be-delayed signals of different wavelengths, they are combined into a multi-wavelength light beam. After the multi-wavelength light beam is processed by the optical delay element, it is split into N delayed light beams, and the N delayed light beams enter the respective mixers to mix with the calibration path local oscillator signals of the corresponding wavelengths.

[0178] Among them, the light splitting can be based on wavelength splitting, power splitting, or resonance splitting, and the specific implementation is not limited. For example, when the light splitting is based on wavelength splitting, pure delayed light beams of different wavelengths can be split, and these delayed light beams of different wavelengths are output to the respective mixers for mixing with the calibration path local oscillator signals of the same wavelength. When the light splitting is based on power splitting or resonance splitting, although each path may have multiple wavelengths of delayed light beams (for example, each path of the delayed light beam is a mixed light beam of each wavelength), when mixing in the mixer, the wavelength of the calibration path local oscillator signal is used for mixing with the wavelength of the delayed light beam, and other wavelengths are not used. Therefore, based on power splitting or resonance splitting, the subsequent mixing and processing functions can also be realized.

[0179] Based on the structure and functional principle of the signal processing apparatus described above, the present application can also provide a detection apparatus, please refer to FIG. 14. The detection apparatus 1400 comprises a signal processing apparatus 1410, which can be any of the signal processing apparatuses described above, such as the signal processing apparatuses shown in FIGS. 4-7, 8a-8f, 9-12, 13a-13d described above.

[0180] Optionally, the detection apparatus 1400 can be a laser radar, such as a FMCW LiDAR.

[0181] Optionally, as shown in FIG. 14 described above, the detection apparatus 1400 can further comprise a window 1420 for protecting the internal signal processing apparatus 1410 and can transmit the light beams emitted by the signal processing apparatus 1410.

[0182] It should be noted that the detection apparatus architecture shown in FIG. 14 is only an example, and in other examples, the detection apparatus can comprise more, less or different structures, and each structure can comprise more, less or different components, which are not specifically limited by the present application.

[0183] In addition, any existing or future detection apparatus with an optical delay line can adopt the structure design of the above signal processing apparatus. In addition, as the detection technology develops, the detection apparatus structure provided by the present application is also applicable to the same technical problem, which is not specifically limited by the present application.

[0184] Based on the structure and functional principle of the detection apparatus described above, the present application can also provide a terminal device, please refer to FIG. 15. The terminal device 1500 comprises a detection apparatus 1510, which can be any of the detection apparatuses described above, such as the detection apparatus 1400 in FIG. 14 described above.

[0185] Optionally, as shown in FIG. 15 described above, the terminal device 1500 can further comprise a processor 1520 for calling programs or instructions to control the operation of the above-mentioned detection apparatus 1510. Further, the processor 1520 can also receive the associated information of the target from the detection apparatus 1510. When the terminal device 1500 is a vehicle, the processor 1520 can also perform path planning, braking or starting of the vehicle according to the information obtained. For example, the latitude and longitude can be used to determine the position of the vehicle, or the speed and direction can be used to determine the driving direction and destination of the vehicle in the future period of time, or the distance of the surrounding objects can be used to determine the number and density of obstacles around the vehicle.

[0186] Further, the terminal device 1500 can further include a memory 1530 configured to store programs or instructions. Of course, the terminal device 1500 can further include other devices, such as a wireless communication device, etc.

[0187] The processor 1520 can include one or more processing units. For example, the processor 1520 can include an application processor (AP), an image signal processor (ISP), a controller, a DSP, or other programmable logic device, transistor logic device, hardware component, or any combination thereof, etc. Different processing units can be independent devices or integrated in one or more processors.

[0188] The memory 1530 includes, but is not limited to, a random access memory (RAM), a flash memory, a read-only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically EPROM (EEPROM), a register, a hard disk, a mobile hard disk, a CD-ROM, or any other form of storage medium well known in the art. The memory medium is coupled to the processor such that the processor can read information from, and write information to, the memory medium. Of course, the memory medium can be a component of the processor. The processor and the memory medium can be located in an ASIC.

[0189] For example, the terminal device 1500 described above can be a vehicle (e.g., a self-driving car, a smart car, an electric car, or a digital car, etc.), a robot, a surveying device, a drone, a smart home device (e.g., a television, a sweeping robot, a smart table lamp, a sound system, a smart lighting system, an electrical control system, a home background music, a home theater system, an intercom system, or a video monitoring, etc.), a smart manufacturing device (e.g., an industrial device), a smart transportation device (e.g., an AGV, a self-driving vehicle, or a truck, etc.), or a smart terminal (a mobile phone, a computer, a tablet computer, a palmtop computer, a desktop computer, a headset, a sound system, a wearable device, a vehicle-mounted device, a virtual reality device, an augmented reality device, etc.), etc.

[0190] In the present application, "at least one" means one or more, "multiple" means two or more. The "and / or" describes the relationship between the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent: the existence of A alone, the existence of A and B together, and the existence of B alone, where A and B can be singular or plural. In the textual description of the present application, the character " / ", generally indicates that the associated objects before and after are in an "or" relationship.

[0191] In addition, in the present application, the words "optionally" or "exemplary" are used to mean as an example, illustration, or description. Any embodiment or design solution described in the present application as "optional" or "exemplary" should not be interpreted as more preferred or advantageous than other embodiments or design solutions. Alternatively, it can be understood that the use of the words "example" or "optional" is intended to present the concept in a specific way, and does not constitute a limitation on the present application.

[0192] It can be understood that various numerical numbers involved in the present application are only for the convenience of differentiation, and are not used to limit the scope of the embodiments of the present application. The size of the serial number of the above processes does not mean the order of execution, and the execution order of the processes should be determined according to its function and inherent logic. The terms "first", "second", "third" and the like similar expressions are used to distinguish similar objects, and do not necessarily be used to describe a specific order or sequence. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, including a series of steps or units. The method, system, product or device does not necessarily limit to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

Claims

1. A signal processing device, characterized by, The application relates to a frequency modulation photoelectric circuit, which comprises a light source, a first light splitting element, a light delay element, a frequency mixer, a light detecting element, a processing element and a driving circuit; the light beam output by the light source enters the light delay element after being processed by the first light splitting element, enters the frequency mixer after being delayed by the light delay element, is detected by the light detecting element after being mixed by the frequency mixer, and is converted into an electric signal; the electric signal is processed by the processing element to obtain a feedback signal which is input into the driving circuit; the feedback signal is used for calibrating the linearity between the modulation signal input into the light source by the driving circuit and the light beam output by the light source. The light delay element comprises a light delay line and a reflector. The light delay line is used for delaying a first light signal from the first light splitting element, and the delayed first light signal is input into the reflector; the reflector reflects the delayed first light signal back, and the reflected first light signal is delayed again, and the again-delayed first light signal is input into the frequency mixer. The reflector is a fiber loop reflector or a Bragg grating.

2. The apparatus of claim 1, wherein, The light delay line is a fiber delay line or an integrated waveguide delay line on a chip.

3. The apparatus of claim 1 or 2, wherein, The light delay element further comprises a light transmission element, the light transmission element comprises a first end, a second end and a third end, and the first end to the second end and the second end to the third end are unidirectional transmission; 4. The device of any one of claims 1 to 3, wherein, The first end is connected with the first light splitting element, the second end is connected with the light delay line, and the third end is connected with the frequency mixer. The light transmission element is a circulator.

5. The apparatus of claim 4, wherein, The signal processing device comprises N frequency modulation photoelectric circuits, the N frequency modulation photoelectric circuits share one light delay element, and N is an integer greater than or equal to 2.

6. The device of any one of claims 1 to 5, wherein, The signal processing device further comprises a light combining element and a second light splitting element; 7. The apparatus of claim 6, wherein, The light delay element is connected between the output end of the light combining element and the input end of the second light splitting element, N first light splitting elements in the N frequency modulation photoelectric circuits are connected with N input ends of the light combining element one by one, and N frequency mixers in the N frequency modulation photoelectric circuits are connected with N output ends of the second light splitting element one by one. The frequency modulation photoelectric circuit further comprises a target measurement path, a first output end of the first light splitting element is connected with the input end of the light delay element or a first light combining element, a second output end of the first light splitting element is connected with the frequency mixer, and a third output end of the first light splitting element is connected with the target measurement path.

8. The device of any one of claims 1 to 7, wherein, The first light splitting element is used for performing light splitting processing on the light beam generated by the light source to obtain a detection signal, a local signal and the first light signal, outputs the first light signal through the first output end, outputs the local signal through the second output end, and outputs the detection signal through the third output end. ​ 9. The apparatus of claim 8, wherein, The first light splitting element comprises a first beam splitter and a second beam splitter, a first output end of the first beam splitter is connected to an input end of the second beam splitter, a second output end of the first beam splitter is a third output end of the first light splitting element; a first output end of the second beam splitter is a first output end of the first light splitting element, a second output end of the second beam splitter is a second output end of the first light splitting element; The first beam splitter is configured to perform light splitting on a light beam generated by the light source to obtain the detection signal and a second light signal, and output the second light signal through the first output end and output the detection signal through the second output end; The second beam splitter is configured to split the second light signal into the local signal and the first light signal, and output the first light signal through the first output end and output the local signal through the second output end.

10. The apparatus of claim 6, wherein, The signal processing device further comprises a second light splitting element and a third light splitting element, the first light splitting element comprises a beam splitter and a light processing element, and the N frequency-modulated optoelectronic circuits share the same light processing element, the same frequency mixer, the same light detection element and the same processing element; N input ends of the light processing element are connected to first output ends of N beam splitters in the N frequency-modulated optoelectronic circuits in a one-to-one correspondence, and second output ends of the N beam splitters are connected to N target measurement paths in the N frequency-modulated optoelectronic circuits; The optical delay element is connected between a first output end of the light processing element and an input end of the second light splitting element, and N output ends of the second light splitting element are connected to first input ends of N frequency mixers in the N frequency-modulated optoelectronic circuits in a one-to-one correspondence; A second output end of the light processing element is connected to an input end of the third light splitting element, and N output ends of the third light splitting element are connected to second input ends of N frequency mixers in the N frequency-modulated optoelectronic circuits in a one-to-one correspondence.

11. The apparatus of claim 10, wherein The beam splitter is configured to perform light splitting on a light beam generated by the light source to obtain a detection signal and a second light signal, and output the second light signal through the first output end and output the detection signal through the second output end; The light processing element is configured to combine N second light signals corresponding to the N frequency-modulated optoelectronic circuits, split the combined light signal into the first light signal and a third light signal, and output the first light signal through the first output end and output the third light signal through the second output end; The second light splitting element is configured to split the first light signal after time delay by the optical delay element into N first sub-light signals, and output the N first sub-light signals through the N output ends; The third light splitting element is configured to split the third light signal into N local signals, and output the N local signals through the N output ends.

12. The apparatus of claim 6, wherein, The first light splitting element comprises a beam splitter and a light processing element, and the N frequency-modulated optoelectronic circuits share the same light processing element, the same frequency mixer, the same light detection element and the same processing element; The N input ends of the light processing element are one-to-one connected to the first output ends of the N beam splitters in the N frequency-modulated optoelectronic circuits, and the second output ends of the N beam splitters in the N frequency-modulated optoelectronic circuits are one-to-one connected to the target measurement paths in the N frequency-modulated optoelectronic circuits; The light delay element is connected between the first output end of the light processing element and the first input end of the frequency mixer, and the second output end of the light processing element is connected to the second input end of the frequency mixer; The N output ends of the processing element are one-to-one connected to the N drive circuits in the N frequency-modulated optoelectronic circuits.

13. The apparatus of claim 12, wherein The beam splitter is configured to split the light beam generated by the light source to obtain a detection signal and a second light signal, and output the second light signal through the first output end and output the detection signal through the second output end; The light processing element is configured to combine the N second light signals corresponding to the N frequency-modulated optoelectronic circuits, and divide the combined light signal into the first light signal and a local signal, and output the first light signal through the first output end and output the local signal through the second output end; The frequency mixer is configured to mix the first light signal delayed by the light delay element and the local signal to obtain an intermediate frequency signal; The light detection element is configured to receive the intermediate frequency signal; The processing element is configured to determine N feedback signals corresponding to the N frequency-modulated optoelectronic circuits according to the intermediate frequency signal, and output the N feedback signals through the N output ends.

14. The apparatus of any one of claims 1 to 13, wherein The processing element is configured to determine a feedback signal according to the intermediate frequency signal from the light detection element, and the feedback signal is input to the drive circuit; The drive circuit is configured to calibrate the linearity between the modulation signal input to the light source by the drive circuit and the light beam output by the light source according to the feedback signal.

15. The device of any one of claims 1 to 14, wherein, The frequency-modulated optoelectronic circuit further comprises an amplifier and an analog-to-digital converter, and the amplifier and the analog-to-digital converter are connected between the light detection element and the processing element; The amplifier is configured to amplify the intermediate frequency signal from the light detection element; The analog-to-digital converter is configured to perform analog-to-digital conversion on the amplified intermediate frequency signal to obtain a digital signal.

16. The apparatus of any one of claims 1-15, wherein, The target measurement path is connected to the first light splitting element; The target measurement path is configured to perform target measurement based on the detection signal from the first light splitting element.

17. A detection device, characterized by The signal processing apparatus comprises any one of claims 1 to 16.

18. A terminal device, comprising: The detection apparatus comprises claim 17.

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