CN117008134A

CN117008134A - Coherent laser radar system and detection method

Info

Publication number: CN117008134A
Application number: CN202310730465.1A
Authority: CN
Inventors: 王兴军
Original assignee: Peking University
Current assignee: Peking University
Priority date: 2023-06-19
Filing date: 2023-06-19
Publication date: 2023-11-07

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 laser radar system and detection method

Technical Field

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

Background

Under the background of the general AI technology and the hardware calculation improvement, the emerging application represented by automatic driving is widely focused by people, and the laser radar is an essential sensing device for high-safety-level automatic driving due to the high-precision detection capability of the laser radar. The development of high-performance miniaturized laser radar meeting the requirements of long-distance detection, quick response, anti-interference, high-precision imaging, eye safety and the like is urgent in the field of high-safety-level automatic driving.

Unlike traditional direct detection laser radar, coherent laser radar has the advantages of long detection distance, no interference from ambient light and integration, but the existing coherent laser radar has the problems of low detection rate and difficult parallelization.

Disclosure of Invention

The invention provides a coherent laser radar system and a detection method, which are used for solving the problems of low detection rate and high parallelization difficulty of a coherent laser radar in the prior art.

The invention provides a coherent laser radar system, which comprises a laser signal generation module, an optical phased array, a return light receiving module, a heterodyne detection receiver and a digital signal processing module, wherein the optical phased array is arranged on the laser signal generation 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 electric signal detection results; and 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.

According to the coherent laser radar system provided by the invention, a laser signal generation module comprises a pumping light source, a linear sweep frequency modulation unit, 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 signals; the optical beam splitter is used for carrying out power beam splitting on the amplified optical frequency comb signals to obtain a first optical frequency comb signal and a second optical frequency comb signal.

According to the coherent laser radar system provided by the invention, a laser signal generation module comprises a pumping light source, a linear sweep frequency modulation unit, a signal light frequency comb generator, a reference light frequency comb generator, a first light amplifier, a second light amplifier, a first light beam splitter and a second light 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 signals; the second optical amplifier is used for amplifying the reference optical frequency comb signal; the first optical beam splitter is used for carrying out 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 is used for carrying out 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 a 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.

According to the coherent laser radar system provided by the invention, a 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 mixing on a first optical frequency comb signal and a second optical frequency comb signal carrying detection target information, outputting an I path of optical signal and a Q path of optical signal which are 180 degrees different in phase, respectively converting the I path of optical signal and the Q path of 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.

The invention provides a coherent laser radar system, which also comprises a demultiplexer; the demultiplexer is arranged between the laser signal generating module and the return light receiving module, and is used for demultiplexing the second optical frequency comb signal and inputting the demultiplexed second optical frequency comb signal to the return light receiving module.

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

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

The invention also provides a detection method using the coherent lidar system according to any one of the above, the detection method comprising: the laser signal generating 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.

According to the detection method provided by the 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 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 signals; and the optical beam splitter performs power beam splitting on the amplified optical frequency comb signals to obtain a first optical frequency comb signal and a second optical frequency comb signal.

According to the detection method provided by the 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 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 a 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.

According to the coherent laser radar system and the detection method, a laser signal generating module generates multi-wavelength parallel optical frequency comb signals, power splitting is carried out to obtain a first optical frequency comb signal and a second optical frequency comb signal, an optical phased array is used for uniquely mapping comb tooth light of each serial number of the first optical frequency comb signal onto different azimuth angles of a detection space, the detection space contains a detection target, and a return light receiving module is used for receiving return light scattered by the detection target to obtain the first optical frequency comb signal carrying detection target information, so that multichannel parallel detection can be realized; the heterodyne detection receiver carries 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, the heterodyne detection result is processed into an electric signal detection result, the digital signal processing module receives the electric signal detection result, point cloud data of a detection target is generated based on the electric signal detection result, and high-speed detection can be achieved by adopting a multi-channel coherent laser radar system.

Drawings

In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a lidar system according to the present application;

FIG. 2 is a time-frequency plot of an optical frequency comb of the lidar system of the present application;

FIG. 3 is a schematic diagram of a lidar system according to the present application;

FIG. 4 is a third schematic diagram of a lidar system according to the present application;

FIG. 5 is a schematic diagram of a lidar system according to the present application;

fig. 6 is a schematic flow chart of a detection method provided by the application.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The terms "first," "second," and the like in this specification are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged, as appropriate, such that embodiments of the present application may be implemented in sequences other than those illustrated or described herein, and that the objects identified by "first," "second," etc. are generally of a type, and are not limited to the number of objects, such as the first object may be one or more.

It is to be understood that the terminology used in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. 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 indicates otherwise. The terms "comprises" and "comprising" indicate the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Based on the above, the coherent laser radar system and the detection method provided by the application generate multi-wavelength parallel optical frequency comb signals through the laser signal generating module, obtain a first optical frequency comb signal and a second optical frequency comb signal after power splitting, uniquely map the comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of a detection space by the optical phased array, the detection space contains a detection target, and then receive return light scattered by the detection target by the return light receiving module to obtain the first optical frequency comb signal carrying detection target information, so that parallel detection of multiple channels can be realized; the heterodyne detection receiver carries 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, the heterodyne detection result is processed into an electric signal detection result, the digital signal processing module receives the electric signal detection result, point cloud data of a detection target is generated based on the electric signal detection result, and high-speed detection can be achieved by adopting a multi-channel coherent laser radar system.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a lidar system according to the present invention.

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

The laser signal generating module 110 is configured to generate an optical frequency comb signal with multiple parallel wavelengths, and amplify the optical frequency comb signal; and carrying out power beam splitting on the amplified optical frequency comb signals to obtain a first optical frequency comb signal and a second optical frequency comb signal.

The optical phased array 120 is configured to uniquely map the comb light of each serial number of the first optical frequency comb signal onto different azimuth angles of a detection space, where the detection space includes a detection target.

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

The heterodyne detection receiver 140 is configured to mix and heterodyne detect the first optical frequency comb signal and the second optical frequency comb signal that carry the detection target information, and process the heterodyne detection result into an electrical signal detection result.

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

The laser radar is divided into coherent and incoherent types according to the system, and the laser radar system refers to the signal modulation mode and the working characteristics of the laser radar. For a laser radar of a coherent system, generally, the optical frequency of a transmitted signal is subjected to linear modulation to generate triangular waves, when target detection is performed, the optical signal needs to be divided into two paths, one path of optical signal is used as signal light for detecting a target, and the other path of optical signal is used as reference light (namely local oscillation light); after the signal light is subjected to target detection, return light carrying detection information can be generated, and after optical mixing is performed on the local oscillation light and the return light, the dynamic information of the detection target can be extracted through heterodyne detection.

An optical frequency comb (Optical Frequency Comb, OFC) refers to a multi-wavelength light source that is spectrally composed of a series of frequency components that are uniformly spaced and have a coherent stable phase relationship. The coherent optical frequency comb itself has multi-wavelength parallel output capability, and the basic principle is that a continuous laser beam is converted into a series of coherent light pulses, and the spectrum of the pulses consists of comb tooth channels with discrete frequency and equal interval distribution, so that the channel capacity and detection rate of the photoelectric sensing system can be greatly improved due to the characteristic of parallelization.

In this embodiment, the laser signal generating module 110 may be configured to generate an optical frequency comb signal with multiple parallel wavelengths, and amplify the optical frequency comb signal; the optical frequency comb signals can comprise a plurality of comb tooth lights with different sequence numbers, the comb tooth lights with different sequence numbers respectively represent optical signals with different wavelengths, and the optical signals with different wavelengths can be output in parallel so as to realize parallel detection of multiple channels.

Further, the laser signal generating module 110 may 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 is used as signal light, the second optical frequency comb signal is used as local oscillation 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.

The optical phased array (Optical Phased Arrays, OPA) can regulate and control the phases of light fields of different channels in the array under the action of specific voltage by applying the interference principle, and emit the light beams to the specific direction after beam focusing, and can sequentially generate high-intensity light beams in each set direction by sequentially changing the phase difference between adjacent channels, so that the effect of light beam scanning is realized.

When the laser radar detects a target, the beam deflection device is used for guiding the emitted beam to point to different directions to perform two-dimensional scanning on the detection space. The traditional beam deflection scheme changes the emitting direction of the optical signal through the mechanical rotation of inertial components such as a vibrating mirror, a rotating mirror and the like, and the device has poor stability, large volume and heavy weight; in addition, the inertial component also introduces additional Doppler frequency shift during rotation, which affects the accuracy of coherent detection.

Based on the above, the optical phased array adopted in the embodiment not only can be integrated, has small volume and light weight, but also does not contain an inertial component, solid-state scanning of a detection space can be realized through an electric control mode, and the grating waveguide antenna of the optical phased array has natural spectral dispersion response, so that optical frequency comb signal optical channels with different wavelengths can be mapped to different emission angles, and therefore, the optical phased array is adopted as a beam deflection device of a coherent laser radar system, so that the optical phased array is convenient to fuse with an optical frequency comb parallel signal source, and a multi-wavelength parallel laser radar transmitter is formed.

The coherent lidar system of the embodiment has the characteristics of high-speed detection and full solid-state because the transmitting, beam deflection and receiving parts in the multichannel lidar system can realize on-chip integration.

In this embodiment, the laser signal generating 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 map the comb tooth light of each serial number of the first optical frequency comb signal onto different azimuth angles of the detection space, so as to realize parallel detection of multiple channels.

The optical phased array 120 maps the comb light of each serial number of the first optical frequency comb signal onto different azimuth angles of a detection space, the detection space contains a detection target, and return light of different serial numbers carrying detection target information is formed after the comb light of each serial number is scattered on the surface of the detection target.

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

Compared with the second optical frequency comb signal, the space delay and Doppler frequency shift effects can be generated due to the fact that the comb tooth light of each serial number of the first optical frequency comb signal is scattered by the surface of the detection target.

The spatial time delay refers to the time required for the laser radar from transmitting the optical signal to receiving the return optical signal, and is determined by the distance between the laser radar and the detection target; the doppler shift effect refers to a phenomenon that when a detection target and a detection source are relatively moved, the frequency of light waves received by the detection source is different from the frequency of light waves emitted by the detection source. In the laser radar system, when laser irradiates a moving detection target, the frequency of return light changes due to scattering of the laser on the surface of the detection target, and the difference between the frequencies of the return light and the incident light is called doppler frequency difference or doppler frequency shift, and the doppler frequency difference can reflect information such as speed and vibration of the detection target.

In this embodiment, the heterodyne detection receiver 140 may perform simultaneous detection on multiple wavelength parallel channels, and may perform optical mixing on the first optical frequency comb signal and the second optical frequency comb signal that carry the detection target information, and perform heterodyne detection on intermediate frequencies corresponding to the first optical frequency comb signal and the second optical frequency comb signal, so that electrical signal detection results corresponding to the multiple wavelength parallel channels may be output simultaneously.

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

The point clouds refer to a data set of space points obtained by scanning and detecting by laser radar equipment, each point cloud comprises space coordinate information and speed information, wherein the coordinate information can be three-dimensional coordinate information, and the relative position relation between a detection target and a radar is reflected; the velocity information is related to the state of motion of the target, and the reflected information is more multidimensional.

The electric signal detection result can contain information such as the position, the speed, the depth and the vibration of the detection target and related information of the laser reflection signal, and the point cloud data of the detection target can be obtained by analyzing and calculating the electric signal detection result, so that the remote high-precision detection can be realized.

Alternatively, the lidar system may be an FMCW (Frequency-modulated continuous wave) -based radar system.

The FMCW-based lidar system has significant advantages in long-range detection, anti-interference, high-precision imaging, eye safety, and the like. Compared with the laser radars of other systems, the FMCW-based laser radar has high-precision multidimensional sensing capability, can simultaneously extract the distance information and the speed information of the target from a complete sweep frequency period, and is beneficial to the preliminary classification of the target in the detection space by the system; and secondly, the FMCW-based laser radar can resist environmental interference and reduce the transmitting power, so that the contradiction between the transmitting power and the measuring distance of the laser radar of other systems is effectively avoided, and the safety of human eyes is ensured. Because the coherent detection principle of the FMCW-based laser radar is very similar to that of the existing optical module system working in the optical communication C-band, the system can be solidified and miniaturized by means of a mature silicon-based integrated platform.

The embodiment provides a coherent laser radar system, which generates a multi-wavelength parallel optical frequency comb signal through a laser signal generating module, obtains a first optical frequency comb signal and a second optical frequency comb signal after power splitting, and uses an optical phased array to uniquely map comb tooth light of each serial number of the first optical frequency comb signal to different azimuth angles of a detection space, wherein the detection space contains a detection target, and then uses a return light receiving module to receive return light scattered by the detection target, so as to obtain the first optical frequency comb signal carrying detection target information, thereby realizing multi-channel parallel detection; the heterodyne detection receiver carries 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, the heterodyne detection result is processed into an electric signal detection result, the digital signal processing module receives the electric signal detection result, point cloud data of a detection target is generated based on the electric signal detection result, and high-speed detection can be achieved by adopting a multi-channel coherent laser radar system.

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

The pump light source is used for generating an optical carrier, and the linear sweep frequency modulation unit is used for carrying out frequency modulation on sidebands of the optical carrier.

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

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

Alternatively, the optical frequency comb signal may be generated by a kr optical frequency comb based on a micro-ring resonator, an electro-optical comb of a mach-zehnder modulator, a mode-locked laser, or the like, which is not limited in this embodiment.

Alternatively, the optical frequency comb generator may be implemented by adopting a soliton state of a kerr optical frequency comb based on a micro-ring resonant cavity, where the soliton state may be a turing comb, a bright soliton, a dark pulse, a soliton crystal, and the embodiment is not limited to this.

Alternatively, the optical frequency comb generator may be fabricated 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, and the like, as not limited by this embodiment.

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

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

The optical amplifier is an optical device capable of amplifying an optical signal, and the basic principle of the optical amplifier is that the energy of a light source is converted into the energy of the optical signal based on stimulated radiation of laser so as to amplify the optical signal and enhance the power and the signal quality of the optical signal. In the application process of the optical frequency comb, the output power and the signal quality of the optical signal need to be improved so as to meet the requirement of target detection, and the optical amplifier can amplify the optical signal of the optical frequency comb signal, so that the output power and the signal quality of the optical frequency comb signal are improved.

The optical beam splitter is used for carrying out power beam splitting on the amplified optical frequency comb signals to obtain a first optical frequency comb signal and a second optical frequency comb signal.

Alternatively, the pump light source may be integrated with the linear sweep modulation unit and the optical frequency comb generator, where the integration manner may be integrated by hybrid integration, heterogeneous integration, monolithic integration, and the like, which is not limited in this embodiment.

In some embodiments, the laser signal generation module includes a pump light source, a linear swept modulation unit, and a signal light frequency comb generator, a reference light 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 to generate an optical carrier.

The linear sweep frequency modulation unit is used for carrying out frequency modulation on sidebands of the optical carrier, carrying out power beam splitting on the modulated optical carrier to obtain signal light and reference light (namely local oscillator light), wherein the signal light and the reference light can be respectively used as pumps of the signal light frequency comb generator and the reference light frequency comb generator so as to excite and generate signal light frequency comb signals and reference light frequency comb signals (namely local oscillator light frequency comb signals) with different repetition frequencies.

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.

Specifically, the signal optical frequency comb signal and the reference optical frequency comb signal have the same mode locking state, but adjacent comb tooth channels are different in interval, so that different channels can have different direct current offset frequencies, and further parallelization coherent detection of a single coherent receiver can be realized under different intermediate frequency references.

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 carrying out 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 a 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.

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 intervals, the two optical frequency comb signal generators are aligned with each other except the center frequency of the pump, the absolute value of the center frequency difference of each corresponding serial number comb tooth channel around the optical frequency comb signal generator is increased in an equal difference array along the direction away from the pump, and the center frequency difference of the comb tooth channels at two sides of the pump is the opposite number; when all comb signals are subjected to optical mixing and heterodyne detection at the same time, a plurality of beat frequency results distributed in different frequency ranges are generated; at this time, the center frequency difference corresponding to different channels can be used as an intermediate frequency reference in coherent demodulation to identify the beat frequency result corresponding to each channel, so that all channels can be simultaneously demodulated in a coherent receiver.

In addition, because the interval between adjacent comb teeth channels and the difference between the repetition frequencies of the signal optical frequency comb signals and the reference optical frequency comb signals can influence the number of parallel channels and the frequency sweep bandwidth which are simultaneously recognized by a single coherent receiver, the whole parallelization scale and the measurement resolution of the laser radar system are further influenced, and therefore comprehensive consideration is needed.

Alternatively, the lidar system may be an FMCW-based lidar system, whose optical frequency modulated signal is a triangular wave, having two linear sweep intervals, an up sweep and a down sweep.

The laser radar system based on the double optical combs can greatly simplify the receiving end of the laser radar, can solve the problems of system complexity and cost increase caused by the need of a special demultiplexer and an arrayed receiving system of a parallel detection system, fully releases the performance advantage of the parallel system, and improves the overall stability, practicability and integration of the laser radar system. The multi-channel parallelization detection is realized, meanwhile, heterodyne detection of the multi-channel parallelization detection can be carried out by adopting only one coherent receiver at the receiving end, the performance gain of the FMCW-based laser radar can be obtained on the premise of not remarkably improving the complexity of the system, and the integration of the laser radar transmitting end and the receiving end is facilitated.

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, so as to obtain an accurate heterodyne detection result.

Alternatively, the pump light source may be integrated with the linear sweep modulation unit, the signal optical frequency comb generator, and the reference optical frequency comb generator, and the embodiment does not limit the integration manner.

The channel interval between the signal optical frequency comb and the reference optical frequency comb is different, and each comb tooth serial number channel has gradually increasing frequency difference after being excited by the same pump, so that the signal optical frequency comb can be used as an intermediate frequency reference for demodulation of each channel in coherent demodulation; thus, the parallel detection of multiple channels by a single coherent receiver can be realized without introducing a demultiplexing and arrayed receiving system.

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

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.

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

Alternatively, the coherent receiver may comprise a 90 ° optical mixer and 2 balanced detectors, together enabling parallel demodulation of the multichannel detection signal.

After carrying out optical mixing on a first optical frequency comb signal and a second optical frequency comb signal carrying detection target information, the 90-degree optical mixer outputs an I-path optical signal and a Q-path optical signal which are 180 degrees out of phase, wherein the two paths of optical signals correspond to left comb teeth and right comb teeth of pumping frequency respectively; the 2 balance detectors respectively convert the I-path optical signals and the Q-path optical signals into electric signals, the electric signals are input into the digital signal processing module after analog-to-digital conversion to extract time-frequency information, parallel coherent demodulation of multiple paths of signals is completed by combining intermediate frequency references of all channels, and finally, a point cloud pattern containing the depth and the speed of a detection target is generated according to a calculation result.

And 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.

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.

Specifically, the digital signal processing module can perform short-time fourier transform on the electric signal output by the external error detection receiver, and rapidly extract the frequency difference generated by each channel in the upper frequency sweep and the lower frequency sweep of the linear frequency modulation due to the space delay and the doppler frequency shift, so as to calculate the relative distance and the motion state of the detection target point corresponding to each comb channel.

Referring to fig. 2, fig. 2 is a time-frequency diagram of an optical frequency comb of the laser radar system of the present invention.

Fig. 2 (b) is a time-frequency curve of an optical frequency comb signal, where the optical frequency comb signal may include a plurality of comb teeth lights with different serial numbers, the comb teeth lights with different serial numbers respectively represent a plurality of optical signals with different wavelengths, and the plurality of optical signals with different wavelengths may be output in parallel.

FIG. 2 (b) shows a plurality of optical frequency comb signals of different frequencies, wherein the center frequencies of the comb teeth of different numbers are ω ₁ 、ω ₂ And so on, wherein the distances between adjacent comb teeth are the same, and the comb teeth have stable phase relation. It is understood that the wavelength and the frequency of the comb light have corresponding mathematical relationships, and the product of the wavelength and the frequency is the propagation speed of the comb light, which is understood by those skilled in the art and will not be described herein.

FIG. 2 (a) is a time-frequency curve of a single comb light with a swept bandwidth of a maximum frequency f _max With minimum frequency f _min Is a difference in (c).

FMCW-based lidars typically employ linear frequency modulation, wherein the common modulation signal may be a sine wave signal, a saw tooth wave signal, a triangular wave signal, or the like.

In some embodiments, the coherent lidar system further comprises a demultiplexer; the demultiplexer is arranged between the laser signal generating module and the return light receiving module, and is used for demultiplexing the second optical frequency comb signal and inputting the demultiplexed second optical frequency comb signal to the return light receiving module.

The demultiplexer is used to separate the multiple channels to achieve demultiplexing, i.e. to separate a plurality of optical signals of different wavelengths, so as to distribute the optical signals of different wavelengths to different receiving units. In order to realize parallelization detection of multiple channels, the optical phased array is required to uniquely map the comb tooth light with different serial numbers of the first optical frequency comb signal onto different azimuth angles of the detection target, the detection target can scatter and generate return light corresponding to the comb tooth light with different serial numbers, and before mixing and heterodyning detection are carried out on a plurality of return lights carrying detection target information and the second optical frequency comb signal, the comb tooth light separation channels with different serial numbers of the second optical frequency comb signal are required, so that the comb tooth light with different serial numbers of the second optical frequency comb signal can be coherent with the corresponding return light. Thus, channel separation can be performed by a demultiplexer to realize demultiplexing.

Alternatively, the demultiplexing function may be implemented using an arrayed waveguide grating, a cascaded mach-zehnder interferometer, a micro-ring resonator array, or the like, a device on a chip or a system with a wavelength demultiplexing function, which is not limited in this embodiment.

In some embodiments, the digital signal processing module is configured to perform fast fourier transform on the electrical signal detection result, extract a time-frequency characteristic curve, and calculate to obtain point cloud data of the detection target, where the point cloud data of the detection target includes depth information and speed information.

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

In order to realize parallel detection of multiple channels without increasing the number of laser emitting devices and corresponding laser receiving devices, an optical phased array or an avalanche photodiode array can be utilized to receive return light with multiple different wavelengths scattered by a detection target. The optical phased array and the Avalanche Photodiode (APD) array comprise a plurality of receiving units, can simultaneously receive a plurality of optical signals with different wavelengths, and are beneficial to realizing parallel detection of multiple channels.

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

Alternatively, the optical phased array can be implemented by using a separate diffraction grating and a deflection element or system with a single-axis rotation function, and the functional elements include a function of utilizing a spectrum dispersion principle to realize the spatial separation of parallel channels on a fast axis, and the slow-axis scanning is to change the angular orientation of an emitted light beam by controlling the phase difference between adjacent array waveguides of the optical phased array so as to realize the function of simultaneously operating a plurality of comb teeth with different wavelengths to perform two-dimensional scanning.

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

The invention also provides a specific example of a lidar system. Referring to fig. 3, fig. 3 is a schematic diagram of a laser radar system according to the second embodiment of the present invention.

In this embodiment, the lidar system includes: pump light source 300, linear sweep modulation unit 310, optical frequency comb generator 320, optical amplifier 330, optical splitter 340, optical phased array 350, 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 constitute a laser signal generating module.

Wherein the pump light source 300 is used for generating an optical carrier; the linear sweep frequency modulation unit 310 is configured to perform frequency modulation on sidebands of the optical carrier, and input the modulated optical carrier to the optical frequency comb signal generator 320; the optical frequency comb generator 320 is configured to generate multi-wavelength parallel optical frequency comb signals according to the modulated optical carrier; the optical amplifier 330 is used for amplifying the optical frequency comb signal; the optical splitter 340 is configured to 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.

Further, the first optical frequency comb signal is input to the optical phased array 350, and the optical phased array 350 is configured to uniquely map the comb light of each serial number of the first optical frequency comb signal onto different azimuth angles of a detection space, where the detection space includes a detection target.

Specifically, the comb-teeth light of each serial number of the first optical frequency comb signal (assuming that there are n serial numbers of comb-teeth light) is marked separately, for example, the comb-teeth light of serial number μ1 is marked as λ _μ1 Wherein lambda is _μ1 The frequency of the corresponding comb light is marked as omega ₁ Comb teeth with the number of mu 2 are optically marked as lambda _μ2 Wherein lambda is _μ2 The frequency of the corresponding comb light is marked as omega ₂ And so on. The optical phased array can uniquely map each serial number of comb tooth light to different azimuth angles of the detection space, wherein the comb tooth light is marked as lambda _μ1 The corresponding azimuth angle can be noted as θ _μ1 The comb teeth are optically marked as lambda _μ2 The corresponding azimuth angle can be noted as θ _μ2 Similarly, after the comb tooth light of each serial number is scattered on the surface of the detection target, return light with different serial numbers carrying the information of the detection target is formed.

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

The second optical frequency comb signal is input to the demultiplexer 360, and the demultiplexer 360 is configured to perform demultiplexing processing on the second optical frequency comb signal, and input the demultiplexed second optical frequency comb signal to the APD array 370.

In this embodiment, the APD array 370 may be further configured to perform mixing and heterodyne detection on the first optical frequency comb signal and the second optical frequency comb signal that carry the detection target information, and process the heterodyne detection result into an electrical signal detection result.

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

Specifically, the digital signal processing module 380 may be configured by a digital oscilloscope or a dedicated circuit chip, and is combined with a transimpedance amplifier and a subtracter, so as to perform fourier transform on the detection result of the electrical signal, extract a time-frequency characteristic curve, and calculate to obtain point cloud data of the detection target, where the point cloud data of the detection target may include depth information, velocity vector information and vibration information.

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

The invention also provides yet another specific example of a lidar system. Referring to fig. 4, fig. 4 is a schematic diagram of a third embodiment of the lidar system according to the present invention.

In this embodiment, the lidar system includes: the system comprises a pumping 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, a reference optical beam splitter 432, an optical beam splitter 440, a transmitting optical phased array 450, a receiving optical phased array 460, a heterodyne detection receiver 470, an intermediate frequency signal extraction unit 471, a coherent receiver 472, a digital signal processing module 480 and a display 490.

Specifically, the pump light source 400, the linear 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 splitter 422, and the reference optical splitter 432 may together form a laser signal generating module.

Wherein the pump light source 400 is used for generating an optical carrier; the linear sweep frequency modulation unit 410 is configured to perform frequency modulation on sidebands of the optical carrier, and perform power beam splitting on the modulated optical carrier to obtain signal light and reference light; wherein, the signal light is input to the signal light frequency comb generator 420, and the reference light is input to the reference light frequency comb generator 430; the signal optical frequency comb generator 420 is configured to generate a signal optical frequency comb signal with multiple wavelengths in parallel according to the signal light, and input the signal optical frequency comb signal to the signal optical amplifier 421; the reference optical frequency comb generator 430 is configured to generate a reference optical frequency comb signal parallel to multiple wavelengths according to the reference light, and input the reference optical frequency comb signal to the reference optical amplifier 431; the signal optical frequency comb signal and the reference optical frequency comb signal have the same mode locking state and have different comb channel frequency intervals.

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

The signal beam splitter 422 is configured to perform power splitting on the amplified signal optical frequency comb signal to obtain a first optical frequency comb signal and a third optical frequency comb signal.

The reference beam splitter 432 is configured to perform 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.

Specifically, the optical splitter 440 is configured 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 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, the detection space contains a detection target, and after the comb tooth light of each serial number is scattered by the surface of the detection target, return light with different serial numbers carrying information of the detection target is formed and received by the receiving optical phased array 460 serving as a return light receiving module.

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

The coherent receiver 472 is configured to perform optical mixing on a first optical frequency comb signal and a second optical frequency comb signal that carry detection target information, output an I-path optical signal and a Q-path optical signal that have phases different by 180 °, convert the I-path optical signal and the Q-path optical signal into electrical signals, and input the electrical signals to the digital signal processing module 480 after analog-to-digital conversion to extract time-frequency information.

The intermediate frequency signal extracting unit 471 is configured to beat the third optical frequency comb signal and the fourth optical frequency comb signal, convert the third optical frequency comb signal and the fourth optical frequency comb signal into an electrical signal, and input the electrical signal to the digital signal processing module 480 after analog-to-digital conversion to extract intermediate frequency information required for demodulating each channel.

In this embodiment, the coherent receiver 472 may include a mixer and a Photodiode (PD). Among them, a Photodiode (PD) is used for realizing photoelectric conversion.

Alternatively, the mixers may be spatially discrete components, or may be formed from integrated devices or systems on a chip, which is not limited in this embodiment.

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

Specifically, the digital signal processing module 480 may be configured by a digital oscilloscope or a dedicated circuit chip, and is combined with a transimpedance amplifier and a subtracter, so as to perform fast fourier transform on the detection result of the electrical signal, extract a time-frequency characteristic curve, and calculate to obtain point cloud data of the detection target.

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

The invention also provides yet another specific example of a lidar system. Referring to fig. 5, fig. 5 is a schematic structural diagram of a lidar system according to the present invention.

In this embodiment, the lidar system includes: the system comprises a pumping 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, a reference optical beam splitter 532, an optical beam splitter 540, an emitting optical phased array 550, an APD array 560, a heterodyne detection receiver 570, an intermediate frequency signal extraction unit 571, a coherent receiver 572, a digital signal processing module 580 and a display 590.

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

Wherein the pump light source 500 is used for generating an optical carrier; the linear sweep frequency modulation unit 510 is configured to perform frequency modulation on sidebands of an optical carrier, and perform power beam splitting on the modulated optical carrier to obtain signal light and reference light; wherein, the signal light is input to the signal light frequency comb generator 520, and the reference light is input to the reference light frequency comb generator 530; the signal optical frequency comb generator 520 is configured to generate a signal optical frequency comb signal with multiple wavelengths in parallel according to the signal light, and input the signal optical frequency comb signal to the signal optical amplifier 521; the reference optical frequency comb generator 530 is configured 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; the signal optical frequency comb signal and the reference optical frequency comb signal have the same mode locking state and have different comb channel frequency intervals.

The signal light amplifier 521 is configured to amplify the signal light frequency comb signal; the reference optical amplifier 531 is used for amplifying the reference optical frequency comb signal;

the signal light beam splitter 522 is configured to perform power splitting on the amplified signal optical frequency comb signal to obtain a first optical frequency comb signal and a third optical frequency comb signal;

the reference beam splitter 532 is configured to perform 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.

Specifically, the optical splitter 540 is configured 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, and the transmitting optical phased array 550 is configured to uniquely map the comb tooth light of each serial number of the first optical frequency comb signal onto different azimuth angles of a detection space, where the detection space includes a detection target, and after the comb tooth light of each serial number is scattered by a surface of the detection target, return light of different serial numbers carrying information of the detection target is formed and received by the APD array 560 as a return light receiving module.

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

The coherent receiver 572 is configured to perform optical mixing on a first optical frequency comb signal and a second optical frequency comb signal that carry detection target information, output an I-path optical signal and a Q-path optical signal that have phases different by 180 °, convert the I-path optical signal and the Q-path optical signal into electrical signals, and input the electrical signals to the digital signal processing module 580 after analog-to-digital conversion to extract time-frequency information.

The intermediate frequency signal extraction unit 571 is configured to beat the third optical frequency comb signal and the fourth optical frequency comb signal, convert the third optical frequency comb signal and the fourth optical frequency comb signal into an electrical signal, and input the electrical signal after analog-to-digital conversion to the digital signal processing module 580 to extract intermediate frequency information required for demodulating each channel.

In this embodiment, the coherent receiver 572 may include a mixer and a Photodiode (PD). Among them, a Photodiode (PD) is used for realizing photoelectric conversion.

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

Specifically, the digital signal processing module 580 may be configured by a digital oscilloscope or a dedicated circuit chip, and is combined with a transimpedance amplifier and a subtracter, so as to perform fast fourier transform on the detection result of the electrical signal, extract a time-frequency characteristic curve, and calculate to obtain point cloud data of the detection target.

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

Referring to fig. 6, fig. 6 is a flow chart of a detection method provided by the present invention.

The present invention also provides a detection method using the coherent lidar system according to any one of the above, in this embodiment, the detection method mainly includes steps 610 to 650, which specifically include the following steps:

step 610: the laser signal generating module generates a multi-wavelength parallel optical frequency comb signal, and amplifies the optical frequency comb signal; and carrying out power beam splitting on the amplified optical frequency comb signals to obtain a first optical frequency comb signal and a second optical frequency 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 a detection space, and the detection space contains a detection target.

Step 630: 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.

Step 640: 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.

Step 650: 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.

In some embodiments, 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 performs frequency modulation on 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 a first optical frequency comb signal and a second optical frequency comb signal.

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, 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.

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

And 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 apparatus embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.

From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on this understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the respective embodiments or some parts of the embodiments.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

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;

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;