CN117008134A - Coherent laser radar system and detection method - Google Patents

Abstract

The invention provides a coherent laser radar system and a detection method, which relate to the technical field of laser detection. The invention generates a first optical frequency comb signal and a second optical frequency comb signal which are parallel with multiple wavelengths through the laser signal generating module, the optical phased array is used for uniquely mapping comb tooth light of each serial number of the first optical frequency comb signal to detection targets in different azimuth angles of a detection space, and then a return light receiving module is used for receiving return light, so that parallel detection of multiple channels can be realized; the heterodyne detection receiver is used for mixing and heterodyne detection, heterodyne detection results are processed into electric signal detection results, the digital signal processing module receives the electric signal detection results, point cloud data of a detection target are generated based on the electric signal detection results, and high-speed detection can be achieved by adopting a multichannel coherent laser radar system.

Description

Coherent lidar system and detection method

Technical field

The invention relates to the field of laser detection technology, and in particular to a coherent laser radar system and a detection method.

Background technique

Against the background of improvements in general AI technology and hardware computing power, emerging applications represented by autonomous driving have received widespread attention. Lidar is an indispensable sensing device for high-safety autonomous driving due to its high-precision detection capabilities. There is an urgent need to develop high-performance, miniaturized lidar that meets the needs of long-range detection, fast response, anti-interference, high-precision imaging, and human eye safety in the field of high-safety autonomous driving.

Different from traditional direct detection lidar, coherent lidar has the advantages of long detection range, no interference from ambient light, and can be integrated. However, existing coherent lidar has the problems of slow detection rate and difficulty in parallelization.

Contents of the invention

The present invention provides a coherent lidar system and a detection method to solve the problems of slow detection rate and high parallelization difficulty of coherent lidar in the prior art.

The invention provides a coherent lidar system, which includes a laser signal generating module, an optical phased array, a return light receiving module, a heterodyne detection receiver and a digital signal processing module; the laser signal generating module is used to generate multi-wavelength parallel light The frequency comb signal is used to amplify the optical frequency comb signal; the amplified optical frequency comb signal is power splitted to obtain the first optical frequency comb signal and the second optical frequency comb signal; the optical phased array is used to combine the first optical frequency comb signal and the second optical frequency comb signal. The comb tooth light of each serial number of the optical frequency comb signal is uniquely mapped to different azimuth angles of the detection space. The detection space contains the detection target; the return light receiving module is used to receive the return light scattered by each detection target to obtain the detection target. The first optical frequency comb signal of the target information; a heterodyne detection receiver, used for mixing and heterodyne detection of the first optical frequency comb signal and the second optical frequency comb signal carrying the detection target information, and heterodyne detection The detection results are processed into electrical signal detection results; the digital signal processing module is used to receive the electrical signal detection results and generate point cloud data of the detection target based on the electrical signal detection results.

According to a coherent lidar system provided by the present invention, the laser signal generation module includes a pump light source, a linear sweep modulation unit and an optical frequency comb generator, an optical amplifier and an optical beam splitter; the pump light source is used to generate an optical carrier wave; the linear sweep The frequency modulation unit is used to frequency modulate the sidebands of the optical carrier; the optical frequency comb generator is used to generate multi-wavelength parallel optical frequency comb signals based on the modulated optical carrier; the optical amplifier is used to amplify the optical frequency comb signal; The beam splitter is used to power split the amplified optical frequency comb signal to obtain a first optical frequency comb signal and a second optical frequency comb signal.

According to a coherent lidar system provided by the present invention, the laser signal generation module includes a pump light source, a linear frequency sweep modulation unit, a signal optical frequency comb generator, a reference optical frequency comb generator, a first optical amplifier, and a second optical amplifier. , the first optical beam splitter and the second optical beam splitter; the pump light source is used to generate an optical carrier wave; the linear sweep modulation unit is used to frequency modulate the sidebands of the optical carrier wave, and power the modulated optical carrier wave After splitting, the signal light and reference light are obtained; the signal optical frequency comb generator is used to generate a multi-wavelength parallel signal optical frequency comb signal based on the signal light, and input the signal optical frequency comb signal to the first optical amplifier; the reference optical frequency comb generator The device is used to generate a multi-wavelength parallel reference optical frequency comb signal based on the reference light, and input the reference optical frequency comb signal to the second optical amplifier; wherein the signal optical frequency comb signal and the reference optical frequency comb signal have the same mode locking state; It has different comb tooth channel frequency intervals; the first optical amplifier is used to amplify the signal optical frequency comb signal; the second optical amplifier is used to amplify the reference optical frequency comb signal; the first optical beam splitter is used to amplify the amplified optical frequency comb signal. The signal optical frequency comb signal is power splitted to obtain the first optical frequency comb signal and the third optical frequency comb signal; the second optical beam splitter is used to power split the amplified reference optical frequency comb signal to obtain the second optical frequency comb signal. Frequency comb signal and fourth optical frequency comb signal; wherein, the first optical frequency comb signal is used for target detection, the second optical frequency comb signal is used for local oscillator reference, the second optical frequency comb signal and the return light after detection are optically After mixing, a mixed signal is obtained, from which the depth information and speed information of the detection target can be extracted; the third optical frequency comb signal and the fourth optical frequency comb signal are used to generate an intermediate frequency signal, and the intermediate frequency signal serves as a multi-channel coherent solution Tuned frequency reference.

According to a coherent lidar system provided by the present invention, the heterodyne detection receiver includes a coherent receiver and an intermediate frequency signal extraction unit; the intermediate frequency signal extraction unit is used to beat the third optical frequency comb signal and the fourth optical frequency comb signal. Afterwards, it is converted into an electrical signal, and after analog-to-digital conversion, it is input into the digital signal processing module to extract the intermediate frequency information required for demodulation of each channel; the coherent receiver is used to analyze the first optical frequency comb signal carrying detection target information and the second optical signal. After the frequency comb signal is optically mixed, the I optical signal and Q optical signal with a phase difference of 180° are output. The I optical signal and Q optical signal are converted into electrical signals respectively. After analog-to-digital conversion, they are input to digital signal processing. module to extract time-frequency information; the digital signal processing module completes parallel coherent demodulation of multi-channel signals based on time-frequency information and combined with the intermediate frequency information of each channel.

According to a coherent laser radar system provided by the present invention, it also includes a demultiplexer; the demultiplexer is arranged between the laser signal generating module and the return light receiving module, and is used to demultiplex the second optical frequency comb signal. Process, and input the demultiplexed second optical frequency comb signal to the return optical receiving module.

According to a coherent laser radar system provided by the present invention, the digital signal processing module is used to perform fast Fourier transform on the electrical signal detection results, extract the time-frequency characteristic curve and calculate and generate point cloud data of the detection target, wherein the detection target The point cloud data includes depth information and velocity information.

According to a coherent lidar system provided by the present invention, the return light receiving module is an optical phased array or an avalanche photodiode array.

The present invention also provides a detection method using the coherent lidar system as described in any one of the above. The detection method includes: a laser signal generation module generates a multi-wavelength parallel optical frequency comb signal, and amplifies the optical frequency comb signal; The final optical frequency comb signal is power splitted to obtain the first optical frequency comb signal and the second optical frequency comb signal; the optical phased array uniquely maps the comb tooth light of each serial number of the first optical frequency comb signal to the detection space At different azimuth angles, the detection space contains detection targets; the return light receiving module receives the return light scattered by each detection target, and obtains the first optical frequency comb signal carrying detection target information; the heterodyne detection receiver carries detection targets The first optical frequency comb signal and the second optical frequency comb signal of the information are mixed and heterodyne detected, and the heterodyne detection result is processed into an electrical signal detection result; the digital signal processing module receives the electrical signal detection result, and performs heterodyne detection based on the electrical signal. The detection results generate point cloud data of the detection target.

According to a detection method provided by the present invention, the laser signal generation module generates a multi-wavelength parallel optical frequency comb signal, and amplifies the optical frequency comb signal; the amplified optical frequency comb signal is power splitted to obtain the first optical frequency comb signal. The comb signal and the second optical frequency comb signal include: the pump light source generates an optical carrier; the linear frequency sweep modulation unit frequency modulates the sidebands of the optical carrier; the optical frequency comb generator generates multi-wavelength parallel signals based on the modulated optical carrier. Optical frequency comb signal; the optical amplifier amplifies the optical frequency comb signal; the optical beam splitter performs power splitting on the amplified optical frequency comb signal to obtain the first optical frequency comb signal and the second optical frequency comb signal.

According to a detection method provided by the present invention, the laser signal generation module generates a multi-wavelength parallel optical frequency comb signal, and amplifies the optical frequency comb signal; the amplified optical frequency comb signal is power splitted to obtain the first optical frequency comb signal. The comb signal and the second optical frequency comb signal include: the pump light source generates an optical carrier; the linear frequency sweep modulation unit performs frequency modulation on the sidebands of the optical carrier, and performs power splitting on the modulated optical carrier to obtain the signal light sum Reference light; the signal optical frequency comb generator generates a multi-wavelength parallel signal optical frequency comb signal based on the signal light, and inputs the signal optical frequency comb signal to the first optical amplifier; the reference optical frequency comb generator generates a multi-wavelength parallel signal based on the reference light a reference optical frequency comb signal, and input the reference optical frequency comb signal to the second optical amplifier; wherein the signal optical frequency comb signal and the reference optical frequency comb signal have the same mode-locking state and different comb channel frequency intervals; The first optical amplifier amplifies the signal optical frequency comb signal; the second optical amplifier is used to amplify the reference optical frequency comb signal; the first optical beam splitter performs power splitting on the amplified signal optical frequency comb signal to obtain the third optical frequency comb signal. An optical frequency comb signal and a third optical frequency comb signal; the second optical beam splitter performs power splitting on the amplified reference optical frequency comb signal to obtain a second optical frequency comb signal and a fourth optical frequency comb signal; wherein, The first optical frequency comb signal is used for target detection, the second optical frequency comb signal is used for the local oscillator reference, and the second optical frequency comb signal is optically mixed with the returned light after detection to obtain a mixed signal. From the mixed signal Depth information and speed information of the detection target can be extracted; the third optical frequency comb signal and the fourth optical frequency comb signal are used to generate an intermediate frequency signal, and the intermediate frequency signal is used as a frequency reference for multi-channel coherent demodulation.

The invention provides a coherent lidar system and detection method that generates multi-wavelength parallel optical frequency comb signals through a laser signal generation module, and performs power splitting to obtain a first optical frequency comb signal and a second optical frequency comb signal. The optical phased array uniquely maps the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of the detection space. The detection space contains the detection target, and then the return light receiving module receives the return light scattered by the detection target. , the first optical frequency comb signal carrying detection target information is obtained, which can realize multi-channel parallel detection; the heterodyne detection receiver mixes the first optical frequency comb signal carrying detection target information and the second optical frequency comb signal. frequency and heterodyne detection, and process the heterodyne detection results into electrical signal detection results. The digital signal processing module receives the electrical signal detection results, and generates point cloud data of the detection target based on the electrical signal detection results, using multi-channel coherent lidar. The system can achieve high-speed detection.

Description of the drawings

In order to explain the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are of the present invention. For some embodiments of the invention, those of ordinary skill in the art can also obtain other drawings based on these drawings without exerting creative efforts.

Figure 1 is one of the structural schematic diagrams of the laser radar system provided by the present invention;

Figure 2 is a time-frequency curve diagram of the optical frequency comb of the lidar system of the present invention;

Figure 3 is the second structural schematic diagram of the laser radar system provided by the present invention;

Figure 4 is the third structural schematic diagram of the laser radar system provided by the present invention;

Figure 5 is the fourth structural schematic diagram of the laser radar system provided by the present invention;

Figure 6 is a schematic flow chart of the detection method provided by the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention. , not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

The terms "first", "second", etc. in this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It is to be understood that the figures so used are interchangeable under appropriate circumstances so that the embodiments of the present application can be practiced in orders other than those illustrated or described herein, and that "first," "second," etc. are distinguished Objects are usually of one type, and the number of objects is not limited. For example, the first object can be one or multiple.

It should be understood that the terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The terms "comprises" and "comprising" indicate the presence of described features, integers, steps, operations, elements and/or components but do not exclude the presence of one or more other features, integers, steps, operations, elements, components and/or The existence or addition to its collection.

Different from traditional direct detection lidar, coherent lidar has the advantages of long detection range, no interference from ambient light, and can be integrated. However, existing coherent lidar has the problems of slow detection rate and difficulty in parallelization.

Based on this, the invention provides a coherent lidar system and detection method that generates multi-wavelength parallel optical frequency comb signals through a laser signal generation module, and performs power splitting to obtain a first optical frequency comb signal and a second optical frequency comb signal. Comb signal, the optical phased array uniquely maps the comb light of each serial number of the first optical frequency comb signal to different azimuth angles of the detection space. The detection space contains the detection target, and then the return light receiving module receives the detection target scattering The returned light is used to obtain the first optical frequency comb signal carrying detection target information, which can realize multi-channel parallel detection; the heterodyne detection receiver detects the first optical frequency comb signal and the second optical frequency comb signal carrying detection target information. The signal is mixed and heterodyne detected, and the heterodyne detection results are processed into electrical signal detection results. The digital signal processing module receives the electrical signal detection results and generates point cloud data of the detection target based on the electrical signal detection results. It uses multi-channel Coherent lidar systems enable high-speed detection.

Please refer to Figure 1, which is one of the structural schematic diagrams of the laser radar system provided by the present invention.

The lidar system includes a laser signal generation module 110, an optical phased array 120, a return light receiving module 130, a heterodyne detection receiver 140 and a digital signal processing module 150.

The laser signal generation module 110 is used to generate a multi-wavelength parallel optical frequency comb signal and amplify the optical frequency comb signal; perform power splitting on the amplified optical frequency comb signal to obtain the first optical frequency comb signal and the second optical frequency comb signal. frequency comb signal.

The optical phased array 120 is used to uniquely map the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of the detection space, and the detection space contains the detection target.

The return light receiving module 130 is used to receive the return light scattered by each detection target and obtain a first optical frequency comb signal carrying detection target information.

The heterodyne detection receiver 140 is used to perform frequency mixing and heterodyne detection on the first optical frequency comb signal and the second optical frequency comb signal carrying detection target information, and process the heterodyne detection results into electrical signal detection results.

The digital signal processing module 150 is used to receive the electrical signal detection results and generate point cloud data of the detection target based on the electrical signal detection results.

Lidar can be divided into coherent and non-coherent categories according to its system. Lidar system refers to the signal modulation method and working characteristics of lidar. For coherent system lidar, the optical frequency of the emitted signal is usually linearly modulated to generate a triangular wave. When detecting a target, the optical signal needs to be divided into two channels, one of which is used as the signal light for detecting the target, and the other The optical signal is used as the reference light (i.e., local oscillator light); after the signal light is detected for the target, a return light carrying detection information will be generated. After the local oscillator light and the return light are optically mixed, the detection target can be extracted through heterodyne detection. Dynamic Information.

Optical Frequency Comb (OFC) refers to a multi-wavelength light source composed of a series of uniformly spaced frequency components with coherent and stable phase relationships on the spectrum. Among them, the coherent state optical frequency comb itself has the ability to output multiple wavelengths in parallel. Its basic principle is to convert a continuous laser beam into a series of coherent light pulses. The spectra of these pulses are composed of comb channels with discrete frequencies and equally spaced distribution. , due to its parallel characteristics, it can greatly improve the channel capacity and detection rate of the photoelectric sensing system.

In this embodiment, the laser signal generation module 110 can be used to generate a multi-wavelength parallel optical frequency comb signal and amplify the optical frequency comb signal; wherein the optical frequency comb signal can include multiple comb teeth with different serial numbers. Different serial numbers The comb teeth respectively represent optical signals of different wavelengths, and multiple optical signals of different wavelengths can be output in parallel to achieve multi-channel parallel detection.

Further, the laser signal generation module 110 can perform power splitting on the amplified optical frequency comb signal to obtain a first optical frequency comb signal and a second optical frequency comb signal, where the first optical frequency comb signal serves as the signal light, and the second optical frequency comb signal serves as the signal light. The optical frequency comb signal serves as local oscillator light. The first optical frequency comb signal is input to the optical phased array 120 , and the second optical frequency comb signal is input to the heterodyne detection receiver 140 .

Optical Phased Arrays (OPA) use the principle of interference to regulate the phase of the light field of different channels in the array under the action of a specific voltage, focus the beam and launch it in a specific direction, by sequentially changing the distance between adjacent channels. The phase difference can produce high-intensity beams in each set direction in sequence, thereby achieving the beam scanning effect.

When lidar detects a target, it is necessary to use a beam deflection device to guide the emitted beam to point in different directions to perform a two-dimensional scan of the detection space. The traditional beam deflection scheme changes the emission direction of the optical signal through the mechanical rotation of inertial components such as galvanometers and rotating mirrors. Such devices have poor stability, are large and bulky; in addition, the inertial components will also introduce additional components when rotating. The Doppler frequency shift affects the accuracy of coherent detection.

Based on this, the optical phased array used in this embodiment is not only integrated, small in size, light in weight, and does not contain inertial components, but can realize solid-state scanning of the detection space through electronic control. The grating of the optical phased array The waveguide antenna has a natural spectral dispersion response, so that the optical frequency comb signal optical channels of different wavelengths will be mapped to different emission angles. Therefore, an optical phased array is used as the beam deflection device of the coherent lidar system to facilitate the integration with the optical frequency comb. Parallel signal sources are fused to form a multi-wavelength parallel lidar transmitter.

Since the transmitting, beam deflection and receiving parts of the multi-channel lidar system can be integrated on-chip, the coherent lidar system of this embodiment has the characteristics of high-speed detection and full solid-state.

In this embodiment, the laser signal generation module 110 inputs the first optical frequency comb signal to the optical phased array, and the optical phased array 120 uses spectral dispersion to uniquely combine the comb teeth of each serial number of the first optical frequency comb signal. Map to different azimuth angles of the detection space to achieve multi-channel parallel detection.

The optical phased array 120 uniquely maps the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of the detection space. The detection space contains the detection target, and the comb tooth light of each serial number is scattered by the surface of the detection target. Finally, return light with different serial numbers carrying detection target information is formed.

The return light receiving module 130 is used to receive the return light scattered by each detection target, obtain a first optical frequency comb signal carrying detection target information, and input the first optical frequency comb signal carrying detection target information to the heterodyne detection Receiver 140.

Compared with the second optical frequency comb signal, since the comb tooth light of each sequence number of the first optical frequency comb signal is scattered by the detection target surface, spatial delay and Doppler frequency shift effects will occur.

It should be noted that the spatial delay refers to the time required for the lidar to transmit the light signal and receive the return light signal, which is determined by the distance between the lidar and the detection target; the Doppler frequency shift effect refers to the time required when detecting When the target and the detection source move relative to each other, the frequency of the light wave received by the detection source is different from the frequency of the light wave emitted by the detection source. In the lidar system, when the laser irradiates a moving detection target, the laser is scattered by the surface of the detection target, causing the frequency of the returned light to change. The difference in frequency between the returned light and the incident light is called the Doppler frequency difference. Or Doppler frequency shift, Doppler frequency difference can reflect information such as the speed and vibration of the detected target.

In this embodiment, the heterodyne detection receiver 140 can simultaneously detect multi-wavelength parallel channels by optically mixing the first optical frequency comb signal and the second optical frequency comb signal carrying detection target information, and then Both perform heterodyne detection on their corresponding intermediate frequencies, and can simultaneously output electrical signal detection results corresponding to multi-wavelength parallel channels.

Further, the signal processing module 150 is configured to receive the electrical signal detection results, and generate point cloud data of the detection target based on the electrical signal detection results.

It should be noted that point cloud refers to a data set of spatial points scanned and detected by lidar equipment. Each point cloud contains spatial coordinate information and velocity information. The coordinate information can be three-dimensional coordinate information, reflecting the detection The relative positional relationship between the target and the radar; the speed information is related to the target's motion state, and the reflected information is more dimensional.

The electrical signal detection results can include the position, speed, depth, vibration and other information of the detection target and the relevant information of the laser reflection signal. By analyzing and calculating the electrical signal detection results, the point cloud data of the detection target can be obtained, which can achieve high-speed detection over long distances. Precision detection.

Alternatively, the lidar system may be a radar system based on FMCW (Frequency-Modulated ContinuousWave).

FMCW-based lidar systems have significant advantages in long-range detection, anti-interference, high-precision imaging, and human eye safety. By analogy with other systems of lidar, FMCW-based lidar has high-precision multi-dimensional sensing capabilities and can simultaneously extract the distance information and speed information of the target within a complete frequency sweep cycle, which is conducive to the system's preliminary classification of targets in the detection space. ; Secondly, FMCW-based lidar can resist environmental interference, reduce transmission power, effectively avoid the contradiction between the transmission power and measurement distance of other systems of lidar, and ensure the safety of human eyes. Since the coherent detection principle of FMCW-based lidar is very similar to the existing optical module system working in the C-band of optical communications, it can rely on mature silicon-based integration platforms to achieve solid-state and miniaturization of the system.

This embodiment provides a coherent lidar system that generates multi-wavelength parallel optical frequency comb signals through a laser signal generation module, and performs power splitting to obtain a first optical frequency comb signal and a second optical frequency comb signal. The controlled array uniquely maps the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of the detection space. The detection space contains the detection target, and then the return light receiving module receives the return light scattered by the detection target to obtain the carried The first optical frequency comb signal carrying detection target information can realize multi-channel parallel detection; the heterodyne detection receiver mixes and externalizes the first optical frequency comb signal and the second optical frequency comb signal carrying detection target information. Differential detection, and processes the heterodyne detection results into electrical signal detection results. The digital signal processing module receives the electrical signal detection results and generates point cloud data of the detection target based on the electrical signal detection results. This can be achieved by using a multi-channel coherent lidar system. High speed detection.

In some embodiments, the laser signal generation module includes a pump light source, a linear sweep modulation unit and an optical frequency comb generator, an optical amplifier and an optical beam splitter.

The pump light source is used to generate an optical carrier wave, and the linear frequency sweep modulation unit is used to frequency modulate the sidebands of the optical carrier wave.

Alternatively, the pump light source may be a narrow linewidth laser, a hybrid integrated external cavity laser, or an on-chip integrated tunable semiconductor laser that can provide laser output, which is not limited in this embodiment.

The optical frequency comb generator is used to generate multi-wavelength parallel optical frequency comb signals based on the modulated optical carrier.

Alternatively, the optical frequency comb signal can be generated by a Kerr optical frequency comb based on a microring resonator, an electro-optical comb of a Mach-Zehnder modulator, a mode-locked laser, etc., which is not limited in this embodiment.

Optionally, the optical frequency comb generator can be implemented using the soliton state of a Kerr optical frequency comb based on a microring resonator, where the soliton state can be a Turing comb, a bright soliton, a dark pulse, a soliton crystal, etc. This embodiment is suitable for This is not a limitation.

Alternatively, the optical frequency comb generator can be prepared based on different dielectric material platforms, including but not limited to silicon nitride, gallium phosphide, aluminum gallium arsenide, lithium niobate, aluminum nitride, gallium nitride, silicon on insulator, etc. , this embodiment does not limit this.

Alternatively, the detection signals of different wavelengths may be composed of comb teeth generated by a single optical frequency comb, or may be composed of comb teeth generated by multiple optical frequency combs, which is not limited in this embodiment.

The optical amplifier receives the multi-wavelength parallel optical frequency comb signal generated by the optical frequency comb generator, and amplifies the optical frequency comb signal.

An optical amplifier is an optical device that can amplify optical signals. Its basic principle is based on the stimulated radiation of laser, which converts the energy of the light source into the energy of the optical signal to amplify the optical signal and enhance the efficiency of the optical signal. power and signal quality. In the application process of optical frequency comb, the output power and signal quality of the optical signal need to be improved to meet the needs of target detection. The optical amplifier can amplify the optical signal of the optical frequency comb signal, so that the output power of the optical frequency comb signal and Signal quality is improved.

The optical beam splitter is used to power split the amplified optical frequency comb signal to obtain a first optical frequency comb signal and a second optical frequency comb signal.

Optionally, the pump light source can be integrated with a linear sweep modulation unit and an optical frequency comb generator, and the integration method can adopt integration processes such as hybrid integration, heterogeneous integration, and monolithic integration, which are not limited in this embodiment.

In some embodiments, the laser signal generation module includes a pump light source, a linear sweep modulation unit, a signal optical frequency comb generator, a reference optical frequency comb generator, a first optical amplifier, a second optical amplifier, and a first optical beam splitter. detector and a second beam splitter.

The pump light source is used to generate optical carrier waves.

The linear frequency sweep modulation unit is used to frequency modulate the sidebands of the optical carrier, and perform power splitting on the modulated optical carrier to obtain signal light and reference light (i.e., local oscillator light). The signal light and reference light can be used as The signal optical frequency comb generator and the reference optical frequency comb generator are pumped to excite and generate the signal optical frequency comb signal and the reference optical frequency comb signal (ie, the local oscillator optical frequency comb signal) with different repetition frequencies.

The signal optical frequency comb generator is used to generate a multi-wavelength parallel signal optical frequency comb signal based on the signal light, and input the signal optical frequency comb signal to the first optical amplifier.

The reference optical frequency comb generator is used to generate a multi-wavelength parallel reference optical frequency comb signal based on the reference light, and input the reference optical frequency comb signal to the second optical amplifier; wherein the signal optical frequency comb signal and the reference optical frequency comb signal have the same Mode-locked status and with different comb channel frequency intervals.

Specifically, the signal optical frequency comb signal and the reference optical frequency comb signal have the same mode-locked state, but the spacing between adjacent comb tooth channels is different, so that different channels can have different DC bias frequencies, and thus can be used in different intermediate frequency reference Under this method, parallelized coherent detection of a single coherent receiver is achieved.

The first optical amplifier is used to amplify the signal optical frequency comb signal.

The second optical amplifier is used to amplify the reference optical frequency comb signal.

The first optical beam splitter is used to power split the amplified optical frequency comb signal to obtain a first optical frequency comb signal and a third optical frequency comb signal.

The second optical beam splitter is used to power split the amplified reference optical frequency comb signal to obtain a second optical frequency comb signal and a fourth optical frequency comb signal.

Among them, the first optical frequency comb signal is used for target detection, the second optical frequency comb signal is used for the local oscillator reference, and the second optical frequency comb signal is optically mixed with the returned light after detection to obtain a mixed signal. The depth information and speed information of the detection target can be extracted from the signal; the third optical frequency comb signal and the fourth optical frequency comb signal are used to generate an intermediate frequency signal, and the intermediate frequency signal is used as a frequency reference for multi-channel coherent demodulation.

It should be noted that the signal optical frequency comb signal and the local oscillator optical frequency comb signal are generated by two optical frequency comb signal generators with different adjacent comb tooth channel spacing. In addition to the pump center frequency being aligned, the surrounding The absolute value of the center frequency difference of each corresponding serial number comb channel increases in an arithmetic sequence in the direction away from the pump, and the center frequency difference of the comb channels on both sides of the pump is an inverse number; when all comb signals are processed simultaneously During optical mixing and heterodyne detection, many beat frequency results distributed in different frequency ranges will be generated; at this time, the center frequency difference corresponding to different channels can be used as the intermediate frequency reference during coherent demodulation to identify the beat frequency corresponding to each channel. frequency results so that all channels can be demodulated simultaneously in a coherent receiver.

In addition, due to the spacing between adjacent comb channels and the difference in repetition frequency between the signal optical frequency comb signal and the reference optical frequency comb signal, it will affect the number of parallel channels and frequency sweep bandwidth recognized by a single coherent receiver at the same time, thereby affecting the overall lidar system. The parallelization scale and measurement resolution need to be considered comprehensively.

Optionally, the lidar system may be a lidar system based on FMCW, whose optical frequency modulation signal is a triangular wave and has two linear frequency sweep intervals: an upper frequency sweep and a lower frequency sweep.

It should be noted that the lidar system based on dual optical combs can greatly simplify the receiving end of the lidar and can solve the problem of increased system complexity and cost caused by the need for dedicated demultiplexers and arrayed receiving systems in parallel detection systems. problem, fully unleash the performance advantages of parallel systems, and improve the overall stability, practicality and integration of the lidar system. While realizing multi-channel parallel detection, only one coherent receiver can be used at the receiving end to perform heterodyne detection of multi-channel parallel detection, and FMCW-based lidar can be obtained without significantly increasing the complexity of the system. performance gain, and is conducive to the integration of the laser radar transmitter and receiver.

In this embodiment, the third optical frequency comb signal and the fourth optical frequency comb signal need to be input to the heterodyne detection receiver, and the difference between the signal laser and the reference laser is extracted to obtain accurate heterodyne detection results.

Optionally, the pump light source can be integrated with the linear frequency sweep modulation unit, the signal optical frequency comb generator, and the reference optical frequency comb generator. This embodiment does not limit the integration method.

The channel spacing between the signal optical frequency comb and the reference optical frequency comb in this embodiment is different. After being excited by the same pump, each comb tooth serial number channel has a gradually increasing frequency difference, so it can be used as the intermediate frequency for demodulation of each channel during coherent demodulation. Reference; In this way, it is possible to use a single coherent receiver to complete parallel detection of multiple channels without introducing demultiplexing and array receiving systems.

In some embodiments, the heterodyne detection receiver includes a coherent receiver and an intermediate frequency signal extraction unit.

The coherent receiver is used to optically mix the first optical frequency comb signal and the second optical frequency comb signal that carry the detection target information, and then output the I optical signal and the Q optical signal with a phase difference of 180°, and combine the I optical signal and the Q optical signal respectively. The path optical signal and Q path optical signal are converted into electrical signals, and after analog-to-digital conversion, they are input into the digital signal processing module to extract time-frequency information.

Specifically, the I-channel mixed optical signal and the Q-channel mixed optical signal with a phase difference of 180° can respectively correspond to the comb channels on both sides of the pump center frequency.

Optionally, the coherent receiver can include a 90° optical mixer and 2 balanced detectors to achieve parallel demodulation of multi-channel detection signals.

Among them, the 90° optical mixer optically mixes the first optical frequency comb signal and the second optical frequency comb signal that carry the detection target information, and then outputs the I optical signal and the Q optical signal with a phase difference of 180°. , the two optical signals respectively correspond to the left comb teeth and the right comb teeth of the pump frequency; the two balanced detectors respectively convert the I optical signal and the Q optical signal into electrical signals, which are input to digital signal processing after analog-to-digital conversion. The module extracts time-frequency information and combines it with the intermediate frequency reference of each channel to complete parallel coherent demodulation of multi-channel signals. Finally, based on the calculation results, a point cloud pattern containing the depth and speed of the detection target is generated.

Further, the intermediate frequency signal extraction unit is used to beat the third optical frequency comb signal and the fourth optical frequency comb signal and convert them into electrical signals. After analog-to-digital conversion, they are input to the digital signal processing module to extract and demodulate each channel. required IF information.

The digital signal processing module completes parallel coherent demodulation of multi-channel signals based on time-frequency information and combined with the intermediate frequency information of each channel.

Specifically, the digital signal processing module can perform short-time Fourier transform on the electrical signal output by the heterodyne detection receiver, and quickly extract the upsweep and downsweep of linear frequency modulation due to spatial delay and Doppler frequency shift of each channel. The frequency difference generated within the frequency range is used to calculate the relative distance and motion state of the detection target points corresponding to each comb channel.

Please refer to Figure 2. Figure 2 is a time-frequency curve diagram of the optical frequency comb of the lidar system of the present invention.

Among them, Figure 2(b) shows the time-frequency curve of the optical frequency comb signal. The optical frequency comb signal can include multiple comb tooth lights with different serial numbers. The comb tooth lights with different serial numbers respectively represent multiple optical signals of different wavelengths. Multiple comb tooth lights. Optical signals of different wavelengths can be output in parallel.

Figure 2(b) contains multiple optical frequency comb signals of different frequencies. The center frequencies of the comb teeth with different numbers are ω ₁ and ω ₂ respectively, and so on. The spacing between adjacent comb teeth is the same. , with a stable phase relationship. It can be understood that the wavelength and frequency of the comb-tooth light have corresponding mathematical relationships. The product of the wavelength and the frequency is the propagation speed of the comb-tooth light. Those skilled in the art can understand and will not elaborate here.

Figure 2(a) shows the time-frequency curve of a single comb light. Its sweep bandwidth is the difference between the maximum frequency f _max and the minimum frequency f _min .

FMCW-based lidar usually uses linear frequency modulation, and commonly used modulation signals can be sine wave signals, sawtooth wave signals, triangle wave signals, etc.

In some embodiments, the coherent lidar system further includes a demultiplexer; the demultiplexer is provided between the laser signal generating module and the return light receiving module, and is used to demultiplex the second optical frequency comb signal, And the demultiplexed second optical frequency comb signal is input to the return optical receiving module.

The demultiplexer is used to separate multiple channels to achieve demultiplexing, that is, to separate multiple optical signals of different wavelengths to distribute the optical signals of different wavelengths to different receiving units. In order to achieve multi-channel parallel detection, the optical phased array needs to be used to uniquely map the comb teeth of different numbers of the first optical frequency comb signal to different azimuth angles of the detection target. The detection target will scatter to generate comb teeth of different numbers. For the return light corresponding to the light, before performing mixing and heterodyne detection on the multiple return lights carrying detection target information and the second optical frequency comb signal, it is necessary to separate the comb tooth light channels with different numbers of the second optical frequency comb signal. , so that the comb tooth light of different numbers in the second optical frequency comb signal can be coherent with the corresponding return light. Therefore, a demultiplexer can be used to separate channels and achieve demultiplexing.

Optionally, the demultiplexing function can be implemented using arrayed waveguide gratings, cascaded Mach-Zehnder interferometers, micro-ring resonator arrays and other on-chip devices or systems with wavelength demultiplexing functions, which are not limited in this embodiment. .

In some embodiments, the digital signal processing module is used to perform fast Fourier transform on the electrical signal detection results, extract the time-frequency characteristic curve and calculate the point cloud data of the detection target, wherein the point cloud data of the detection target includes depth information and velocity information.

In some embodiments, the return light receiving module is an optical phased array or an avalanche photodiode array.

In order to achieve multi-channel parallel detection without increasing the number of laser transmitting equipment and corresponding laser receiving equipment, optical phased arrays or avalanche photodiode arrays can be used to receive return light of multiple different wavelengths scattered by the detection target. Optical phased arrays and avalanche photodiode (APD) arrays contain multiple receiving units, which can receive multiple optical signals of different wavelengths at the same time, which is conducive to realizing multi-channel parallel detection.

Alternatively, the optical phased array, APD array and heterodyne detection receiver can be implemented using integrated optical circuit devices.

Alternatively, the optical phased array can be implemented using a discrete diffraction grating and a deflection element or system with a single-axis rotation function. The functional elements include using the principle of spectral dispersion to achieve spatial separation of parallel channels on the fast axis and the slow axis. Scanning is to change the angular direction of the emitted beam by controlling the phase difference between adjacent array waveguides of the optical phased array to achieve the function of simultaneously manipulating multiple comb teeth of different wavelengths for two-dimensional scanning.

Alternatively, the optical phased array can use an on-chip integrated emission system to emit the detection light, for example, using an on-chip integrated emission system such as an optical phased array system or a focal plane array. The light emission mode of the on-chip integrated emission system includes both the end face emission of the waveguide array at the edge of the optical chip and the emission of the waveguide antenna array in a direction perpendicular to the surface of the optical chip, which is not limited in this embodiment.

The present invention also provides a specific example of a lidar system. Please refer to Figure 3. Figure 3 is a second structural schematic diagram of the laser radar system provided by the present invention.

In this embodiment, the lidar system includes: a pump light source 300, a linear sweep modulation unit 310, an optical frequency comb generator 320, an optical amplifier 330, an optical beam splitter 340, an optical phased array 350, and a demultiplexer 360, APD array 370, digital signal processing module 380 and display 390.

Specifically, the pump light source 300, the linear sweep modulation unit 310, the optical frequency comb generator 320, the optical amplifier 330, and the optical beam splitter 340 may together form a laser signal generation module.

Among them, the pump light source 300 is used to generate an optical carrier; the linear sweep modulation unit 310 is used to frequency modulate the sidebands of the optical carrier, and input the modulated optical carrier to the optical frequency comb signal generator 320; the optical frequency comb The generator 320 is used to generate a multi-wavelength parallel optical frequency comb signal according to the modulated optical carrier; the optical amplifier 330 is used to amplify the optical frequency comb signal; the optical beam splitter 340 is used to amplify the amplified optical frequency comb signal. After power splitting, a first optical frequency comb signal and a second optical frequency comb signal are obtained.

Further, the first optical frequency comb signal is input to the optical phased array 350, and the optical phased array 350 is used to uniquely map the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of the detection space, The detection space contains detection targets.

Specifically, each serial number of the comb tooth light of the first optical frequency comb signal (assuming that there are n serial numbers of comb tooth lights) is marked separately. For example, the comb tooth light with the serial number μ1 is marked as λ _μ1 , where λ _μ1 corresponds to The frequency of the comb light is marked as ω ₁ , the comb light with serial number μ2 is marked as λ _μ2 , and the frequency of the comb light corresponding to λ _μ2 is marked as ω ₂ , and so on. The optical phased array can uniquely map the comb light of each serial number to different azimuth angles in the detection space. The comb light is recorded as λ _μ1 , and the corresponding azimuth angle can be recorded as θ _μ1 , and the comb light is recorded as λ _μ2 . The azimuth angle of can be recorded as θ _μ2 , and by analogy, after the comb light of each serial number is scattered by the detection target surface, a different serial number of return light carrying the detection target information is formed.

Further, the APD array 370 serves as a return light receiving module, and is used to receive return light of different numbers scattered by the detection target, and obtain a first optical frequency comb signal carrying detection target information.

The second optical frequency comb signal is input to the demultiplexer 360. The demultiplexer 360 is used to demultiplex the second optical frequency comb signal and input the demultiplexed second optical frequency comb signal to APD Array 370.

In this embodiment, the APD array 370 can also be used to perform frequency mixing and heterodyne detection on the first optical frequency comb signal and the second optical frequency comb signal carrying detection target information, and process the heterodyne detection results into electrical signals. Signal detection results.

Further, the digital signal processing module 380 serves as a signal processing module for receiving the electrical signal detection results and generating point cloud data of the detection target based on the electrical signal detection results.

Specifically, the digital signal processing module 380 can be composed of a digital oscilloscope or a dedicated circuit chip, combined with a transimpedance amplifier and a subtractor, to perform Fourier transformation on the electrical signal detection results, extract the time-frequency characteristic curve and calculate the detection target The point cloud data of the detected target can include depth information, velocity vector information and vibration information.

Further, the display 390 may be used to display the point cloud data of the detection target calculated by the digital signal processing module 380 . The point cloud data may be a point cloud pattern containing the depth and speed of the detected target.

The present invention also provides another specific example of the lidar system. Please refer to Figure 4. Figure 4 is a third structural schematic diagram of the laser radar system provided by the present invention.

In this embodiment, the lidar system includes: a pump light source 400, a linear sweep modulation unit 410, a signal optical frequency comb generator 420, a reference optical frequency comb generator 430, a signal optical amplifier 421, a reference optical amplifier 431, a signal Optical beam splitter 422, reference optical beam splitter 432, optical beam splitter 440, transmitting optical phased array 450, receiving optical phased array 460, heterodyne detection receiver 470, intermediate frequency signal extraction unit 471, coherent receiver 472 , digital signal processing module 480 and display 490.

Specifically, the pump light source 400, the linear frequency sweep modulation unit 410, the signal optical frequency comb generator 420, the reference optical frequency comb generator 430, the signal optical amplifier 421, the reference optical amplifier 431, the signal optical beam splitter 422, the reference optical The beam splitters 432 may together form a laser signal generating module.

Among them, the pump light source 400 is used to generate an optical carrier; the linear sweep modulation unit 410 is used to frequency modulate the sidebands of the optical carrier, and perform power splitting on the modulated optical carrier to obtain signal light and reference light; where , the signal light is input to the signal optical frequency comb generator 420, and the reference light is input to the reference optical frequency comb generator 430; the signal optical frequency comb generator 420 is used to generate a multi-wavelength parallel signal optical frequency comb signal based on the signal light, and The signal optical frequency comb signal is input to the signal optical amplifier 421; the reference optical frequency comb generator 430 is used to generate a multi-wavelength parallel reference optical frequency comb signal according to the reference light, and input the reference optical frequency comb signal to the reference optical amplifier 431; signal The optical frequency comb signal and the reference optical frequency comb signal have the same mode-locking state and different comb tooth channel frequency intervals.

The signal optical amplifier 421 is used to amplify the signal optical frequency comb signal; the reference optical amplifier 431 is used to amplify the reference optical frequency comb signal.

The signal light beam splitter 422 is used to power split the amplified signal light frequency comb signal to obtain a first optical frequency comb signal and a third optical frequency comb signal.

The reference optical beam splitter 432 is used to power split the amplified reference optical frequency comb signal to obtain a second optical frequency comb signal and a fourth optical frequency comb signal.

Specifically, the optical beam splitter 440 is used to combine the third optical frequency comb signal and the fourth optical frequency comb signal, and input the third optical frequency comb signal and the fourth optical frequency comb signal to the heterodyne detection receiver 470 .

Further, the first optical frequency comb signal is input to the transmitting optical phased array 450. The transmitting optical phased array 450 is used to uniquely map the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of the detection space. On the top, the detection space contains the detection target. After being scattered by the detection target surface, the comb light of each serial number forms return light of different serial numbers carrying the detection target information, and is received by the receiving optical phased array 460 as the return light receiving module. .

The heterodyne detection receiver 470 includes a coherent receiver 472 and an intermediate frequency signal extraction unit 471.

Among them, the coherent receiver 472 is used to optically mix the first optical frequency comb signal and the second optical frequency comb signal carrying the detection target information, and then output the I optical signal and the Q optical signal with a phase difference of 180°. The I optical signal and the Q optical signal are respectively converted into electrical signals, and then input into the digital signal processing module 480 after analog-to-digital conversion to extract time-frequency information.

The intermediate frequency signal extraction unit 471 is used to beat the third optical frequency comb signal and the fourth optical frequency comb signal and convert them into electrical signals. After analog-to-digital conversion, they are input to the digital signal processing module 480 to extract the required demodulation for each channel. intermediate frequency information.

In this embodiment, coherent receiver 472 may include a mixer and a photodiode (PD). Among them, photodiodes (PD) are used to achieve photoelectric conversion.

Alternatively, the mixer may be a spatially discrete component or may be composed of an on-chip integrated device or system, which is not limited in this embodiment.

Further, the digital signal processing module 480 is used to receive the electrical signal detection results, and obtain point cloud data of the detection target based on the electrical signal detection results.

Specifically, the digital signal processing module 480 can be composed of a digital oscilloscope or a dedicated circuit chip, combined with a transimpedance amplifier and a subtractor, to perform fast Fourier transform on the electrical signal detection results, extract the time-frequency characteristic curve and calculate the detection Point cloud data of the target.

Further, the display 490 may be used to display the point cloud data of the detected target calculated by the digital signal processing module 480 . The point cloud data may be a point cloud pattern containing depth and velocity information of the detected target.

The present invention also provides another specific example of the lidar system. Please refer to FIG. 5 , which is the fourth structural schematic diagram of the lidar system provided by the present invention.

In this embodiment, the lidar system includes: a pump light source 500, a linear sweep modulation unit 510, a signal optical frequency comb generator 520, a reference optical frequency comb generator 530, a signal optical amplifier 521, a reference optical amplifier 531, a signal Optical beam splitter 522, reference optical beam splitter 532, optical beam splitter 540, transmitting optical phased array 550, APD array 560, heterodyne detection receiver 570, intermediate frequency signal extraction unit 571, coherent receiver 572, digital signal Processing module 580 and display 590.

Specifically, the pump light source 500, the linear frequency sweep modulation unit 510, the signal optical frequency comb generator 520, the reference optical frequency comb generator 530, the signal optical amplifier 521, the reference optical amplifier 531, the signal optical beam splitter 522, the reference optical The beam splitters 532 may together form a laser signal generating module.

Among them, the pump light source 500 is used to generate an optical carrier; the linear sweep modulation unit 510 is used to frequency modulate the sidebands of the optical carrier, and perform power splitting on the modulated optical carrier to obtain signal light and reference light; where , the signal light is input to the signal optical frequency comb generator 520, and the reference light is input to the reference optical frequency comb generator 530; the signal optical frequency comb generator 520 is used to generate a multi-wavelength parallel signal optical frequency comb signal based on the signal light, and The signal optical frequency comb signal is input to the signal optical amplifier 521; the reference optical frequency comb generator 530 is used to generate a multi-wavelength parallel reference optical frequency comb signal according to the reference light, and input the reference optical frequency comb signal to the reference optical amplifier 531; signal The optical frequency comb signal and the reference optical frequency comb signal have the same mode-locking state and different comb tooth channel frequency intervals.

The signal optical amplifier 521 is used to amplify the signal optical frequency comb signal; the reference optical amplifier 531 is used to amplify the reference optical frequency comb signal;

The signal light beam splitter 522 is used to power split the amplified signal light frequency comb signal to obtain the first optical frequency comb signal and the third optical frequency comb signal;

The reference optical beam splitter 532 is used to power split the amplified reference optical frequency comb signal to obtain a second optical frequency comb signal and a fourth optical frequency comb signal.

Specifically, the optical beam splitter 540 is used to combine the third optical frequency comb signal and the fourth optical frequency comb signal, and input the third optical frequency comb signal and the fourth optical frequency comb signal to the heterodyne detection receiver 570 .

Further, the first optical frequency comb signal is input to the transmitting optical phased array 550. The transmitting optical phased array 550 is used to uniquely map the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of the detection space. On the detection space, the detection space contains the detection target. After being scattered by the surface of the detection target, the comb light of each serial number forms return light of different serial numbers carrying the detection target information, and is received by the APD array 560 as the return light receiving module.

The heterodyne detection receiver 570 includes a coherent receiver 572 and an intermediate frequency signal extraction unit 571.

Among them, the coherent receiver 572 is used to optically mix the first optical frequency comb signal and the second optical frequency comb signal carrying the detection target information, and then output the I optical signal and the Q optical signal with a phase difference of 180°. The I optical signal and the Q optical signal are respectively converted into electrical signals, and then input into the digital signal processing module 580 after analog-to-digital conversion to extract time-frequency information.

The intermediate frequency signal extraction unit 571 is used to beat the third optical frequency comb signal and the fourth optical frequency comb signal and convert them into electrical signals. After analog-to-digital conversion, they are input to the digital signal processing module 580 to extract the required demodulation for each channel. intermediate frequency information.

In this embodiment, coherent receiver 572 may include a mixer and a photodiode (PD). Among them, photodiodes (PD) are used to achieve photoelectric conversion.

Alternatively, the mixer may be a spatially discrete component or may be composed of an on-chip integrated device or system, which is not limited in this embodiment.

Further, the digital signal processing module 580 serves as a signal processing module for receiving the electrical signal detection results and obtaining point cloud data of the detection target based on the electrical signal detection results.

Specifically, the digital signal processing module 580 can be composed of a digital oscilloscope or a dedicated circuit chip, combined with a transimpedance amplifier and a subtractor, to perform fast Fourier transformation on the electrical signal detection results, extract the time-frequency characteristic curve and calculate the detection Point cloud data of the target.

Further, the display 590 may be used to display the point cloud data of the detected target calculated by the digital signal processing module 580 . The point cloud data may be a point cloud pattern containing the depth and speed of the detected target.

Please refer to Figure 6, which is a schematic flow chart of the detection method provided by the present invention.

The present invention also provides a detection method using the coherent lidar system as described in any of the above. In this embodiment, the detection method mainly includes steps 610 to 650. The specific steps are as follows:

Step 610: The laser signal generation module generates a multi-wavelength parallel optical frequency comb signal, and amplifies the optical frequency comb signal; the amplified optical frequency comb signal is power splitted to obtain the first optical frequency comb signal and the second optical frequency comb signal. comb signal.

Step 620: The optical phased array uniquely maps the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of the detection space, and the detection space contains the detection target.

Step 630: The return light receiving module receives the return light scattered by each detection target, and obtains a first optical frequency comb signal carrying detection target information.

Step 640: The heterodyne detection receiver performs frequency mixing and heterodyne detection on the first optical frequency comb signal and the second optical frequency comb signal carrying detection target information, and processes the heterodyne detection results into electrical signal detection results.

Step 650: The digital signal processing module receives the electrical signal detection results and generates point cloud data of the detection target based on the electrical signal detection results.

In some embodiments, the laser signal generation module generates multi-wavelength parallel optical frequency comb signals and amplifies the optical frequency comb signals; the amplified optical frequency comb signals are power splitted to obtain the first optical frequency comb signal and the third optical frequency comb signal. Two optical frequency comb signals, including:

The pump light source generates an optical carrier wave; the linear frequency sweep modulation unit frequency modulates the sidebands of the optical carrier wave.

The optical frequency comb generator generates multi-wavelength parallel optical frequency comb signals based on the modulated optical carrier; the optical amplifier amplifies the optical frequency comb signals.

The optical beam splitter performs power splitting on the amplified optical frequency comb signal to obtain a first optical frequency comb signal and a second optical frequency comb signal.

In some embodiments, the laser signal generation module generates multi-wavelength parallel optical frequency comb signals and amplifies the optical frequency comb signals; the amplified optical frequency comb signals are power splitted to obtain the first optical frequency comb signal and the third optical frequency comb signal. Two optical frequency comb signals, including:

The pump light source generates an optical carrier; the linear frequency sweep modulation unit performs frequency modulation on the sidebands of the optical carrier, and performs power splitting on the modulated optical carrier to obtain signal light and reference light.

The signal optical frequency comb generator generates a multi-wavelength parallel signal optical frequency comb signal based on the signal light, and inputs the signal optical frequency comb signal to the first optical amplifier.

The reference optical frequency comb generator generates a multi-wavelength parallel reference optical frequency comb signal based on the reference light, and inputs the reference optical frequency comb signal to the second optical amplifier.

Among them, the signal optical frequency comb signal and the reference optical frequency comb signal have the same mode locking state and different comb tooth channel frequency intervals.

The first optical amplifier amplifies the signal optical frequency comb signal; the second optical amplifier is used to amplify the reference optical frequency comb signal.

The first optical beam splitter performs power splitting on the amplified optical frequency comb signal to obtain a first optical frequency comb signal and a third optical frequency comb signal.

The second optical beam splitter performs power splitting on the amplified reference optical frequency comb signal to obtain a second optical frequency comb signal and a fourth optical frequency comb signal.

Among them, the first optical frequency comb signal is used for target detection, the second optical frequency comb signal is used for the local oscillator reference, and the second optical frequency comb signal is optically mixed with the returned light after detection to obtain a mixed signal. The depth information and speed information of the detection target can be extracted from the signal; the third optical frequency comb signal and the fourth optical frequency comb signal are used to generate an intermediate frequency signal, and the intermediate frequency signal is used as a frequency reference for multi-channel coherent demodulation.

The device embodiments described above are only illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in One location, or it can be distributed across multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Persons of ordinary skill in the art can understand and implement the method without any creative effort.

Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the part of the above technical solution that essentially contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., including a number of instructions to cause a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments or certain parts of the embodiments.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be used Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent substitutions are made to some of the technical features; however, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. The coherent laser radar system is characterized by comprising a laser signal generation module, an optical phased array, a return light receiving module, a heterodyne detection receiver and a digital signal processing module;

the laser signal generation module is used for generating multi-wavelength parallel optical frequency comb signals and amplifying the optical frequency comb signals; carrying out power beam splitting on the amplified optical frequency comb signals to obtain first optical frequency comb signals and second optical frequency comb signals;

the optical phased array is used for uniquely mapping the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of a detection space, and the detection space comprises a detection target;

The return light receiving module is used for receiving the return light scattered by each path of detection target to obtain a first optical frequency comb signal carrying detection target information;

the heterodyne detection receiver is used for carrying out frequency mixing and heterodyne detection on the first optical frequency comb signal and the second optical frequency comb signal which carry detection target information, and processing heterodyne detection results into electrical signal detection results;

the digital signal processing module is used for receiving the electric signal detection result and generating point cloud data of the detection target based on the electric signal detection result.

2. A coherent lidar system according to claim 1, wherein the laser signal generation module comprises a pump light source, a linear swept modulation unit and an optical frequency comb generator, an optical amplifier and an optical beam splitter;

the pump light source is used for generating an optical carrier wave;

the linear sweep frequency modulation unit is used for carrying out frequency modulation on sidebands of the optical carrier;

the optical frequency comb generator is used for generating multi-wavelength parallel optical frequency comb signals according to the modulated optical carrier waves;

the optical amplifier is used for amplifying the optical frequency comb signal;

the optical beam splitter is used for performing power beam splitting on the amplified optical frequency comb signals to obtain the first optical frequency comb signals and the second optical frequency comb signals.

3. A coherent lidar system according to claim 1, wherein the laser signal generation module comprises a pump light source, a linear swept modulation unit and a signal optical frequency comb generator, a reference optical frequency comb generator, a first optical amplifier, a second optical amplifier, a first optical beam splitter and a second optical beam splitter;

the pump light source is used for generating an optical carrier wave;

the linear sweep frequency modulation unit is used for modulating the frequency of the sidebands of the optical carrier, and carrying out power beam splitting on the modulated optical carrier to obtain signal light and reference light;

the signal light frequency comb generator is used for generating a signal light frequency comb signal with multiple wavelengths in parallel according to the signal light and inputting the signal light frequency comb signal to the first optical amplifier;

the reference optical frequency comb generator is used for generating a multi-wavelength parallel reference optical frequency comb signal according to the reference light and inputting the reference optical frequency comb signal to the second optical amplifier; the signal optical frequency comb signal and the reference optical frequency comb signal have the same mode locking state and have different comb tooth channel frequency intervals;

the first optical amplifier is used for amplifying the signal optical frequency comb signal; the second optical amplifier is used for amplifying the reference optical frequency comb signal;

The first optical beam splitter is used for performing power beam splitting on the amplified signal optical frequency comb signals to obtain first optical frequency comb signals and third optical frequency comb signals;

the second optical beam splitter is used for performing power beam splitting on the amplified reference optical frequency comb signal to obtain a second optical frequency comb signal and a fourth optical frequency comb signal;

the first optical frequency comb signal is used for target detection, the second optical frequency comb signal is used for local oscillation reference, the second optical frequency comb signal and the detected return light are subjected to optical mixing to obtain a mixed signal, and depth information and speed information of the detection target can be extracted from the mixed signal; the third optical frequency comb signal and the fourth optical frequency comb signal are used for generating an intermediate frequency signal, and the intermediate frequency signal is used as a frequency reference for multi-channel coherent demodulation.

4. A coherent lidar system according to claim 3, characterized in that the heterodyne detection receiver comprises a coherent receiver and an intermediate frequency signal extraction unit;

the intermediate frequency signal extraction unit is used for performing beat frequency on the third optical frequency comb signal and the fourth optical frequency comb signal, converting the third optical frequency comb signal and the fourth optical frequency comb signal into electric signals, and inputting the electric signals into the digital signal processing module after analog-to-digital conversion so as to extract intermediate frequency information required by demodulating each channel;

The coherent receiver is used for carrying out optical frequency mixing on a first optical frequency comb signal and a second optical frequency comb signal carrying detection target information, outputting an I-path optical signal and a Q-path optical signal which are 180 degrees different in phase, respectively converting the I-path optical signal and the Q-path optical signal into electric signals, and inputting the electric signals into the digital signal processing module after analog-to-digital conversion so as to extract time-frequency information;

and the digital signal processing module completes parallel coherent demodulation of multiple paths of signals according to the time-frequency information and by combining intermediate frequency information of each channel.

5. A coherent lidar system according to claim 2, further comprising a demultiplexer;

the demultiplexer is arranged between the laser signal generating module and the return light receiving module, and is used for performing demultiplexing processing on the second optical frequency comb signal and inputting the demultiplexed second optical frequency comb signal to the return light receiving module.

6. A coherent lidar system according to claim 1, wherein the coherent lidar system is a laser radar system,

the digital signal processing module is used for carrying out fast Fourier transform on the electric signal detection result, extracting a time-frequency characteristic curve, and then calculating to generate point cloud data of the detection target, wherein the point cloud data of the detection target comprises depth information and speed information.

7. A coherent lidar system according to any of claims 1 to 6, wherein the return light receiving module is an optical phased array or an avalanche photodiode array.

8. A detection method using the coherent lidar system according to any of claims 1 to 6, the detection method comprising:

the laser signal generation module generates a multi-wavelength parallel optical frequency comb signal and amplifies the optical frequency comb signal; carrying out power beam splitting on the amplified optical frequency comb signals to obtain first optical frequency comb signals and second optical frequency comb signals;

the optical phased array uniquely maps the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of a detection space, and the detection space comprises a detection target;

the return light receiving module receives the return light scattered by each path of detection target to obtain a first optical frequency comb signal carrying detection target information;

the heterodyne detection receiver mixes and heterodynes the first optical frequency comb signal and the second optical frequency comb signal carrying detection target information, and processes the heterodyne detection result into an electric signal detection result;

The digital signal processing module receives the electric signal detection result and generates point cloud data of the detection target based on the electric signal detection result.

9. The detection method according to claim 8, wherein the laser signal generating module generates a multi-wavelength parallel optical frequency comb signal, and amplifies the optical frequency comb signal; the amplified optical frequency comb signal is subjected to power beam splitting to obtain a first optical frequency comb signal and a second optical frequency comb signal, and the method comprises the following steps:

generating an optical carrier by a pumping light source;

the linear sweep frequency modulation unit is used for modulating the frequency of the sidebands of the optical carrier;

the optical frequency comb generator generates multi-wavelength parallel optical frequency comb signals according to the modulated optical carrier waves;

the optical amplifier amplifies the optical frequency comb signal;

and the optical beam splitter performs power beam splitting on the amplified optical frequency comb signals to obtain the first optical frequency comb signals and the second optical frequency comb signals.

10. The detection method according to claim 8, wherein the laser signal generating module generates a multi-wavelength parallel optical frequency comb signal, and amplifies the optical frequency comb signal; the amplified optical frequency comb signal is subjected to power beam splitting to obtain a first optical frequency comb signal and a second optical frequency comb signal, and the method comprises the following steps:

Generating an optical carrier by a pumping light source;

the linear sweep frequency modulation unit is used for carrying out frequency modulation on sidebands of the optical carrier, and carrying out power beam splitting on the modulated optical carrier to obtain signal light and reference light;

the signal light frequency comb generator generates a signal light frequency comb signal with multiple wavelengths in parallel according to the signal light, and inputs the signal light frequency comb signal to the first optical amplifier;

the reference optical frequency comb generator generates a multi-wavelength parallel reference optical frequency comb signal according to the reference light, and inputs the reference optical frequency comb signal to the second optical amplifier; the signal optical frequency comb signal and the reference optical frequency comb signal have the same mode locking state and have different comb tooth channel frequency intervals;

the first optical amplifier amplifies the signal optical frequency comb signal; the second optical amplifier is used for amplifying the reference optical frequency comb signal;

the first optical beam splitter performs power splitting on the amplified signal optical frequency comb signals to obtain first optical frequency comb signals and third optical frequency comb signals;

the second optical beam splitter performs power beam splitting on the amplified reference optical frequency comb signal to obtain a second optical frequency comb signal and a fourth optical frequency comb signal;

The first optical frequency comb signal is used for target detection, the second optical frequency comb signal is used for local oscillation reference, the second optical frequency comb signal and the detected return light are subjected to optical mixing to obtain a mixed signal, and depth information and speed information of the detection target can be extracted from the mixed signal; the third optical frequency comb signal and the fourth optical frequency comb signal are used for generating an intermediate frequency signal, and the intermediate frequency signal is used as a frequency reference for multi-channel coherent demodulation.