Lidar system, smart device, and lidar detection method

Abstract

The embodiment of the present application relates to the technical field of laser radar, and discloses a kind of laser radar systems, the laser radar system includes: laser, for emitting continuous wave laser;Kerr optical frequency comb module, for generating kerr optical frequency comb according to the continuous wave laser;Signal generator, for producing first linear frequency modulation electrical signal;Modulation module, for loading the first linear frequency modulation electrical signal to the envelope of each wavelength laser in the kerr optical frequency comb, form the amplitude modulation light wave for the detection of the laser radar system.By the above mode, the embodiment of the present application improves the accuracy of laser radar system detection.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, specifically to a lidar system, intelligent device, and lidar detection method. Background Technology

[0002] With the development of science and technology, lidar is widely used in intelligent equipment such as autonomous driving, intelligent robot navigation, and drones. LiDAR is a radar system that uses laser beams to detect the position, velocity, and other characteristics of a target object. Its working principle is to first emit a detection laser beam towards the target object, then compare the received reflected signal from the target object with the emitted signal, process it, and obtain relevant information about the target object.

[0003] In the process of implementing the embodiments of the present invention, the inventors of this application discovered that when existing lidar systems use linear frequency modulated continuous waves to detect the distance and velocity of targets, the way in which the laser output light frequency is changed by altering the injection current of the laser has obvious nonlinearity, thereby reducing the accuracy of laser detection. Summary of the Invention

[0004] In view of the above problems, embodiments of the present invention provide a lidar system, a smart device, and a lidar detection method to solve the technical problem of low detection accuracy of lidar systems in the prior art.

[0005] According to one aspect of the present invention, a lidar system is provided, the method comprising:

[0006] A laser used to emit continuous wave laser light;

[0007] Kerr optical frequency comb module, used to generate Kerr optical frequency comb based on the continuous wave laser;

[0008] A signal generator is used to generate a first linear frequency modulated electrical signal;

[0009] The modulation module is used to load the first linear frequency modulated electrical signal onto the envelope of each wavelength of laser in the Kerr optical frequency comb to form an amplitude-modulated light wave for detection by the lidar system.

[0010] In one alternative embodiment, the Kerr optical frequency comb module includes a Kerr resonant cavity that converts continuous-wave laser at a resonant frequency into a Kerr optical frequency comb, the Kerr optical frequency comb comprising multiple multi-wavelength lasers with equally spaced frequencies.

[0011] In one alternative embodiment, the Kerr optical frequency comb module is a microring or microdisk fabricated on a chip in an aluminum nitride thin film, and the modulator is integrated in the aluminum nitride thin film.

[0012] In one alternative embodiment, both the Kerr optical frequency comb module and the modulator are disposed on the chip.

[0013] In one optional embodiment, the signal generator is used to generate a linear frequency modulated (LFM) electrical signal and split it into a first LFM electrical signal and a local oscillator (LO) electrical signal; the lidar system further includes: an optical component for emitting the amplitude-modulated (AM) light wave into space and receiving the reflected light; a detection module for receiving the reflected light and extracting the reflected electrical signal of the reflected light; and a processing module for receiving the LO electrical signal sent by the signal generator and calculating the distance and / or radial velocity of each target in space based on the LO electrical signal and the reflected electrical signal.

[0014] In one alternative embodiment, the optical component includes a scanner and a dispersive element; the scanner is used to change the emission direction of the amplitude-modulated light wave; the dispersive element is used to receive the amplitude-modulated light wave after its emission direction has been changed by the scanner, and to simultaneously emit the amplitude-modulated light wave in different directions in space.

[0015] In one alternative embodiment, an adjustable filter is further provided between the Kerr optical frequency comb module and the modulator, or an adjustable filter is further provided between the modulation module and the optical component; the optical component is a collimator and a dispersive element; the adjustable filter is used to adjust the frequency of the laser at each wavelength in the Kerr optical frequency comb; the dispersive element is used to scatter the amplitude-modulated light wave into space for spatial scanning.

[0016] In one alternative embodiment, the lidar system further includes a circulator; a first port of the circulator is used to receive an amplitude-modulated light wave transmitted by the modulator; a second port of the circulator is used to transmit the amplitude-modulated light wave to the optical component and to receive reflected light returned by the optical component; and a third port of the circulator is used to transmit the reflected light to the detection module.

[0017] In one optional embodiment, the detection module includes multiple detectors, and the processing module includes multiple electric mixers, filters, and a calculation module; each detector is connected to a corresponding electric mixer, and each electric mixer is connected to a corresponding filter; each detector is used to receive reflected light of a corresponding wavelength and extract the corresponding reflected electrical signal; each electric mixer is used to generate a difference frequency electrical signal and a sum frequency electrical signal based on the received reflected electrical signal sent by the corresponding detector and the local oscillator electrical signal; the filter is used to receive the difference frequency electrical signal and the sum frequency electrical signal sent by the corresponding electric mixer and filter out the sum frequency electrical signal to obtain the difference frequency electrical signal; the calculation module is used to determine the distance and / or radial velocity of each target in the computational space based on the difference frequency electrical signal.

[0018] According to another aspect of the present invention, a smart device is provided, the smart device including the aforementioned lidar system.

[0019] According to another aspect of the present invention, a detection method for lidar is provided.

[0020] The method, applied in a lidar system, includes:

[0021] Emitting continuous wave laser;

[0022] A Kerr optical frequency comb is generated based on the continuous wave laser;

[0023] Generate the first linear frequency modulated electrical signal;

[0024] The first linear frequency modulated electrical signal is applied to the envelope of each wavelength of laser light in the Kerr optical frequency comb to form an amplitude modulated light wave for detection by the lidar system.

[0025] In one alternative approach, generating the first linear frequency modulated (LFM) electrical signal includes: generating the LFM electrical signal and splitting it into the first LFM electrical signal and a local oscillator signal; the method further includes: emitting the amplitude-modulated light wave into space and receiving the reflected light; extracting the reflected electrical signal of the reflected light; and calculating the distance and / or radial velocity of each target in space based on the local oscillator signal and the reflected electrical signal.

[0026] The lidar system of this invention emits a continuous-wave laser from a laser, and a Kerr optical frequency comb module generates a Kerr optical frequency comb based on the continuous-wave laser. A signal generator generates a first linear frequency-modulated electrical signal. The modulation module loads the first linear frequency-modulated electrical signal onto the envelope of each wavelength of the laser in the Kerr optical frequency comb to form an amplitude-modulated light wave for detection by the lidar system. This effectively overcomes the problem of low detection accuracy caused by frequency modulation nonlinearity resulting from changing the laser current to generate the laser, and improves the detection accuracy.

[0027] Furthermore, by combining Kerr optical frequency combs with dispersive elements, tunable filters, or scanners, wavelength division multiplexing can be effectively utilized to achieve efficient and rapid detection.

[0028] Furthermore, by designing the Kerr optical frequency comb module as a microring or microdisk of aluminum nitride thin film on the chip, and integrating the modulator in the aluminum nitride thin film, the size and complexity of the lidar are effectively reduced.

[0029] The above description is merely an overview of the technical solutions of the embodiments of the present invention. In order to better understand the technical means of the embodiments of the present invention and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0030] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0031] Figure 1 A schematic diagram of the structure of the lidar system provided in an embodiment of the present invention is shown;

[0032] Figure 2 A schematic diagram of the structure of the lidar system provided in an embodiment of the present invention is shown;

[0033] Figure 3 A schematic diagram of a lidar system provided in another embodiment of the present invention is shown;

[0034] Figure 4 This invention provides a schematic diagram of the structure of the Kerr optical frequency comb module and modulator in a lidar system according to an embodiment of the present invention.

[0035] Figure 5 A schematic diagram of the structure of a lidar system provided in another embodiment of the present invention is shown;

[0036] Figure 6 A schematic diagram of a lidar system provided in another embodiment of the present invention is shown;

[0037] Figure 7 A schematic flowchart of the detection method of lidar provided in an embodiment of the present invention is shown. Detailed Implementation

[0038] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0039] The basic principle of FMCW (Frequency Modulated Continuous Wave) lidar is as follows: A triangular-wave linearly frequency-modulated continuous wave is used, divided into a local oscillator and a transmitted light. The transmitted light propagates through space to the target surface and is reflected. A portion of the reflected light is received by the lidar. Since the frequencies of the local oscillator and the received light are different, the frequency of the difference signal obtained by mixing them is the frequency difference between the two. Because it is linearly frequency-modulated, the frequency difference is proportional to the round-trip propagation time of the transmitted / received light. Therefore, the target distance can be calculated by measuring the frequency of the difference signal. Furthermore, if the target has a radial velocity, the difference signals obtained from the upper and lower frequency sweeps will have different frequencies. The radial velocity of the target can be calculated by determining the difference between the two.

[0040] However, the inventors of this application discovered during implementation that existing FMCW lidar primarily uses semiconductor lasers such as DFB and DBR lasers for direct frequency modulation. The specific principle is: by changing the injection current of the laser, the refractive index of the medium in the resonant cavity is altered, thereby changing the wavelength of the mode in the laser resonant cavity, and thus achieving the effect of changing the laser output frequency. However, theoretically, the injection current and the wavelength of the mode in the laser cavity are linearly related, but wavelength and frequency are inversely proportional, i.e., a significant nonlinear relationship, which reduces the detection accuracy of the lidar. Therefore, in practice, changing the laser output frequency by altering the injection current of the laser has significant nonlinearity. To calibrate this nonlinearity, complex open-loop and closed-loop architectures and algorithms are required, increasing the system complexity. All of these factors increase the complexity and cost of this type of FMCW lidar system.

[0041] On the other hand, existing solutions also include FMCW lidar systems that use CW (Continuous Wave) lasers for external modulation. In these solutions, the laser outputs a CW continuous wave, and an external radio frequency linear frequency modulated (RFLM) signal generator produces a linear frequency modulated (LFM) electrical signal. This LFM signal is first split into a local oscillator signal, and the remaining LFM signal is modulated onto the laser envelope to form an amplitude-modulated (AM) light wave. However, existing solutions only allow one laser to operate on a single wavelength, failing to utilize the advantages of wavelength division multiplexing (WDM). If multiple wavelengths are required, multiple lasers are needed, significantly increasing the size, cost, and complexity of the FMCW system.

[0042] Based on this, this application provides a lidar system that can effectively reduce the size, cost and complexity of the lidar system while improving the detection accuracy of the lidar system.

[0043] Example 1:

[0044] like Figure 1 As shown, an embodiment of the present invention provides a lidar system, the system comprising:

[0045] Laser 10 is used to emit continuous wave laser.

[0046] Kerr optical frequency comb module 20 is used to generate a Kerr optical frequency comb based on the continuous wave laser.

[0047] Signal generator 30 is used to generate a first linear frequency modulated electrical signal.

[0048] The modulation module 40 is used to load the first linear frequency modulated electrical signal onto the envelope of each wavelength of laser in the Kerr optical frequency comb to form an amplitude modulated light wave for detection by the lidar system.

[0049] Specifically, laser 10 is a CW laser, and the Kerr frequency comb module 20 includes a Kerr resonant cavity. After the continuous wave laser emitted by laser 10 is received by the Kerr frequency comb module 20, when the continuous wave laser at the resonant frequency couples into the Kerr resonant cavity, it will continuously accumulate in it, causing the optical power in the Kerr resonant cavity to continuously increase. When the optical power reaches a certain level, the four-wave mixing effect appears, and part of the original frequency laser is converted into laser at other resonant frequencies of the Kerr resonant cavity, forming an optical frequency comb. This optical frequency comb is a series of multi-wavelength lasers evenly distributed in frequency and sent to the modulation module 40. Since the Kerr resonant cavity is a device that realizes optical frequency combing through four-wave mixing, it has a periodic resonant frequency (i.e., FSR) in the frequency domain. Only lasers at the resonant frequency can couple into the Kerr resonant cavity. Therefore, the required frequency of multi-wavelength laser can be obtained by presetting the wavelength of laser 10 and the structural parameters of the Kerr resonant cavity according to the design requirements. The Kerr resonant cavity can be a microsphere, a microcylinder, or a microring or microdisk on a chip, etc. In this embodiment of the invention, the signal generator 30 is an FMCW radio frequency signal generator, which emits a linear frequency modulated (LFM) electrical signal. This LFM electrical signal is split into a first LFM electrical signal and a local oscillator (LO) electrical signal, and the first LFM electrical signal is sent to the modulation module 40. The modulation module 40 loads the first LFM electrical signal onto the envelope of lasers of various wavelengths in the optical frequency comb, thereby obtaining an amplitude-modulated (AM) light wave. This AM light wave is used for detection by a lidar system. Specifically, the lidar system emits the AM light wave into space and receives the reflected light. The reflected electrical signal is extracted from the reflected light and compared with the LO electrical signal to achieve target detection. This AM light wave is emitted into space through a collimator, and spatial scanning is achieved through a scanner. The reflected light portion after hitting the target is received by the optical system as received light. Then, the received light is used by a detector to extract the envelope LFM electrical signal as the received electrical signal. The received electrical signal and the LO electrical signal are then mixed by an electrical mixer and low-pass filtered to obtain a difference frequency electrical signal. The advantage of external modulation is that the linear frequency modulated signal is generated by a signal generator, and its linearity is better than that of linear frequency modulation generated by semiconductor lasers by changing the current, without the need for additional nonlinear calibration.

[0050] Among them, such as Figure 2 As shown, the lidar system further includes: an optical component 50 for emitting the amplitude-modulated light wave into space and receiving the reflected light; a detection module 60 for receiving the reflected light and extracting the reflected electrical signal; and a processing module 70 for receiving the local oscillator signal sent by the signal generator and calculating the distance and / or radial velocity of each target in space based on the local oscillator signal and the reflected electrical signal.

[0051] The lidar system of this invention emits a continuous-wave laser from a laser, and a Kerr optical frequency comb module generates a Kerr optical frequency comb based on the continuous-wave laser. A signal generator generates a first linear frequency modulated electrical signal. The modulation module loads the first linear frequency modulated electrical signal onto the envelope of each wavelength of the laser in the Kerr optical frequency comb to form an amplitude-modulated light wave for detection by the lidar system. This effectively overcomes the problem of low detection accuracy caused by the nonlinearity of frequency modulation resulting from changing the laser current to generate the laser, ensuring the linearity of the linear frequency modulation and thus improving the detection accuracy.

[0052] Example 2:

[0053] like Figure 3 As shown in the figure, an embodiment of the present invention provides a lidar system, which includes: a CW laser, a Kerr resonant cavity, a modulator, an FMCW radio frequency signal generator, optical components, a detection module, and a processing module. In this embodiment, the lidar system further includes a circulator. A first port of the circulator is used to receive an amplitude-modulated light wave transmitted by the modulator. A second port of the circulator is used to transmit the amplitude-modulated light wave to the optical components and receive reflected light returned by the optical components. A third port of the circulator is used to transmit the reflected light to the detection module. The optical components include a collimator, a scanner, and a dispersive element. Specifically, the scanner is used to change the emission direction of the amplitude-modulated light wave; the dispersive element is used to receive the amplitude-modulated light wave after its emission direction has been changed by the scanner, and to simultaneously emit the amplitude-modulated light wave in different directions in space. The detection module includes multiple detectors, and the processing module includes multiple electric mixers, filters, and a calculation module. Each detector is connected to a corresponding electric mixer, and each electric mixer is connected to a corresponding filter. Specifically, the detector is used to receive reflected light of a corresponding wavelength and extract the corresponding reflected electrical signal; the electric mixer is used to generate a difference frequency electrical signal and a sum frequency electrical signal based on the received reflected electrical signal sent by the corresponding detector and the local oscillator electrical signal; the filter is used to receive the difference frequency electrical signal and the sum frequency electrical signal sent by the corresponding electric mixer, and filter out the sum frequency electrical signal to obtain the difference frequency electrical signal; the calculation module is used to determine the distance and / or radial velocity of each target in the computational space based on the difference frequency electrical signal.

[0054] The specific working process of this lidar system is as follows: The CW laser emits continuous wave laser light. After receiving the continuous wave laser light, the Kerr resonant cavity generates a Kerr optical frequency comb based on the continuous wave laser light and sends the laser light of each wavelength in the Kerr optical frequency comb to the modulator. The FMCW radio frequency signal generator generates a linear frequency modulated electrical signal and splits it into a first linear frequency modulated electrical signal and a local oscillator electrical signal. The first linear frequency modulated electrical signal is sent to the modulator, and the local oscillator electrical signal is sent to each electrical mixer. The modulator modulates a first linear frequency modulated (LFM) electrical signal with lasers of various wavelengths in the optical frequency comb, loading the LFM electrical signal onto the envelopes of each wavelength of laser to form amplitude-modulated (AM) light waves. These AM light waves are sent to the first port of a circulator, which then transmits them to a collimator via its second port. The collimator then transmits the AM light waves into space. A scanner changes the emission direction of the AM light waves to achieve spatial scanning. A dispersive element receives the AM light waves after the scanner has changed their emission direction, separating the AM light waves in different directions in space to form multiple beams of light rotating simultaneously. In one specific implementation of this invention, the scanner and the dispersive element can cooperate in the same dimension. For example, the scanner scans in vertical space, while the dispersive element also separates the AM light waves in vertical space. That is, the fields of view of the AM light waves from the scanner and the dispersive element are superimposed in parallel directions (vertical or horizontal), increasing the scanning range in vertical space. In another specific implementation of the present invention, the scanner and the dispersive element cooperate in the vertical direction. For example, the scanner can scan in the vertical space, and the dispersive element can split the amplitude-modulated light wave in the horizontal direction, so that the lidar system can scan both the horizontal and vertical spaces at the same time.

[0055] After amplitude-modulated light waves of different wavelengths scan the space, the reflected light from each beam hits its respective target. The lidar system combines these beams into multi-wavelength reflected light using optical components. After being received at the second port of the circulator, the reflected light is input through the third port of the circulator and separated into different wavelengths using beam-splitting optical components (such as an AWG arrayed waveguide grating, like a Demux wavelength division multiplexer). Each wavelength of reflected light enters and exits its corresponding detector, which extracts the linear frequency-modulated electrical signal on the envelope of the corresponding reflected light as the reflected electrical signal. Each electrical mixer receives its corresponding reflected electrical signal and inputs it to a low-pass filter to obtain a difference frequency electrical signal. The calculation module analyzes and calculates based on these difference frequency signals to obtain the distance and / or radial velocity of each target in space.

[0056] In embodiments of the present invention, such as Figure 4As shown, the Kerr resonant cavity and modulator are located on the same chip. The Kerr resonant cavity is a microring or microdisk fabricated in an aluminum nitride thin film on the chip, and the modulator is integrated into the aluminum nitride thin film. This arrangement significantly reduces the size and complexity of the lidar. Figure 4 Figure a shows the structural arrangement of a modulator with only one electrode, an aluminum nitride waveguide, and a Kerr resonator. The Kerr resonator is a circular ring structure, the aluminum nitride waveguide is a linear structure, and the modulator includes one electrode. Figure 4 Figure b shows the structural arrangement of a modulator with two electrodes, an aluminum nitride waveguide, and a Kerr resonator. The Kerr resonator is a circular ring structure, the aluminum nitride waveguide is a linear structure, and the modulator includes two electrodes. Figure 4 As can be seen, the embodiments of the present invention integrate the Kerr resonator and the modulator onto a single chip, specifically integrated into an aluminum nitride thin film, which greatly reduces the size of the radar laser system and simplifies its structure.

[0057] The lidar system of this invention emits continuous-wave laser light from a laser. A Kerr optical frequency comb module generates a Kerr optical frequency comb based on the continuous-wave laser light, and a signal generator generates a first linear frequency-modulated electrical signal. A modulation module loads the first linear frequency-modulated electrical signal onto the envelope of each wavelength of laser light in the Kerr optical frequency comb, forming an amplitude-modulated light wave for detection by the lidar system. This effectively overcomes the frequency modulation nonlinearity problem caused by generating laser light by changing the laser current. The linearity is better than that of linear frequency modulation generated by changing the current in semiconductor lasers, and no additional nonlinear calibration is required, thereby improving detection accuracy. Furthermore, by combining the Kerr optical frequency comb with a dispersive element and a scanner, wavelength division multiplexing can be effectively utilized. While improving the detection accuracy of the lidar system, the size, cost, and complexity of the lidar system can be effectively reduced, and the detection dimension and detection range can be increased, further improving detection efficiency. Furthermore, by setting the scanner and dispersive element to cooperate in the same dimension (parallel to each other), the scanning range in vertical space is increased; by setting the scanner and dispersive element to cooperate in different dimensions (perpendicular to each other), the lidar system can simultaneously scan horizontal and vertical spaces.

[0058] Example 3:

[0059] like Figure 5As shown in the figure, an embodiment of the present invention provides a lidar system, which includes: a CW laser, a Kerr resonant cavity, a modulator, a tunable filter, an FMCW radio frequency signal generator, optical components, a detection module, and a processing module. In this embodiment, the lidar system further includes a circulator. A first port of the circulator is used to receive amplitude-modulated light waves transmitted by the modulator. A second port of the circulator is used to transmit the amplitude-modulated light waves to the optical components and receive reflected light returned by the optical components. A third port of the circulator is used to transmit the reflected light to the detector. The tunable filter is used to adjust the frequency of each wavelength of laser light in the Kerr frequency comb. The optical components of the lidar system in this embodiment include a collimator and a dispersive element, which scatters the amplitude-modulated light waves in different directions in space for spatial scanning. The detection module includes multiple detectors, and the processing module includes multiple electric mixers, filters, and a computing module. Each detector is connected to a corresponding electric mixer, and each electric mixer is connected to a corresponding filter. Specifically, the detector is used to receive reflected light of a corresponding wavelength and extract the corresponding reflected electrical signal; the electrical mixer is used to generate a difference frequency electrical signal and a frequency electrical signal based on the received reflected electrical signal sent by the corresponding detector and the local oscillator electrical signal; the filter is used to receive the difference frequency electrical signal and the frequency electrical signal sent by the corresponding electrical mixer, and filter out the sum frequency electrical signal to obtain the difference frequency electrical signal; the calculation module is used to determine the distance and / or radial velocity of each target in the computational space based on the difference frequency electrical signal. Figure 6 As shown, in another embodiment of the present invention, the tunable filter can also be disposed between the modulation module and the optical component. Specifically, the output terminal of the modulation module is connected to the input terminal of the tunable filter, which adjusts the frequency of each wavelength of laser light in the Kerr optical frequency comb, outputs laser light of different frequencies, and outputs the laser light to the optical component through a circulator.

[0060] The specific working process of this lidar system is as follows: A CW laser emits continuous-wave laser light. After receiving the continuous-wave laser light, the Kerr resonant cavity generates a Kerr optical frequency comb based on the continuous-wave laser light. The laser light of each wavelength in the Kerr optical frequency comb is then sent to an adjustable filter. The adjustable filter filters the laser light in the optical frequency comb and sends the filtered optical frequency comb to the modulator. During the operation of the lidar system, the parameters of the adjustable filter can be dynamically adjusted each time, thus resulting in different wavelengths of the filtered optical frequency comb. An FMCW radio frequency signal generator generates a linear frequency modulated electrical signal and splits it into a first linear frequency modulated electrical signal and a local oscillator signal. The first linear frequency modulated electrical signal is sent to the modulator, and the local oscillator signal is sent to each electrical mixer. The modulator modulates a first linear frequency modulated (LFM) electrical signal with laser beams of various wavelengths in the filtered optical frequency comb. The LFM signal is then loaded onto the envelopes of each wavelength of laser light, forming amplitude-modulated (AM) light waves. These AM light waves are sent to the first port of a circulator, which then transmits them through its second port to a collimator. The collimator then transmits the AM light waves into space. A dispersive element receives the AM light waves after their emission direction has been altered by the scanner, separating the AM light waves in different directions in space to form multiple beams. In this embodiment, an adjustable filter selects each frequency in the optical frequency comb, and the beams are then emitted in the same manner. Because the dispersive element causes different wavelengths to be emitted in different spatial directions, by changing the frequency band of the adjustable filter to select different frequencies in the optical frequency comb, different directions of emission into space can be achieved through the dispersive element, thus enabling spatial scanning. This method allows for multi-directional spatial scanning without any rotating parts.

[0061] After amplitude-modulated light waves of different wavelengths scan the space, the reflected light from each beam hits its respective target. The lidar system combines these beams into multi-wavelength reflected light using optical components. After being received at the second port of the circulator, the reflected light is input through the third port of the circulator and separated into different wavelengths using beam-splitting optical components (such as an AWG arrayed waveguide grating, like a Demux wavelength division multiplexer). Each wavelength of reflected light then enters and exits its corresponding detector. Each electrical mixer receives its corresponding reflected electrical signal and inputs it to a low-pass filter to obtain a difference frequency electrical signal. The calculation module analyzes and calculates based on these difference frequency signals to obtain the distance and / or radial velocity of each target in space.

[0062] In this embodiment of the invention, the Kerr resonant cavity and the modulator are disposed on the same chip. The Kerr resonant cavity is a micro-ring or micro-disk of aluminum nitride thin film on the chip, and the modulator is integrated into the aluminum nitride thin film. This arrangement greatly reduces the size and complexity of the lidar. In this embodiment of the invention, combined with... Figure 3 and Figure 4An adjustable filter is positioned between the Kerr resonant cavity and the modulator. Combined with... Figure 3 and Figure 5 The tunable filter can also be placed after the modulator, with the Kerr resonant cavity connected to the modulator and the modulator connected to the tunable filter.

[0063] The lidar system of this invention emits a continuous-wave laser from a laser. A Kerr optical frequency comb module generates a Kerr optical frequency comb based on the continuous-wave laser, and a signal generator generates a first linear frequency-modulated electrical signal. A modulation module loads the first linear frequency-modulated electrical signal onto the envelope of each wavelength of the laser in the Kerr optical frequency comb to form an amplitude-modulated light wave for detection by the lidar system. This effectively overcomes the problem of frequency modulation nonlinearity caused by generating laser by changing the laser current. The linearity of the lidar system of this invention is better than that of linear frequency modulation generated by changing the current of a semiconductor laser. It does not require additional nonlinear calibration, ensuring the linearity of frequency modulation and improving detection accuracy.

[0064] Furthermore, by combining a Kerr optical frequency comb, a tunable filter, and a dispersive element, each frequency in the optical frequency comb can be selected by the tunable filter and then emitted in the same way. Since the dispersive element causes different wavelengths to be emitted in different spatial directions, by changing the frequency band of the tunable filter to select different frequencies in the optical frequency comb, it is possible to achieve spatial scanning by emitting in different directions in space through the dispersive element. In this way, multi-directional spatial scanning can be achieved without any rotating parts.

[0065] Example 4:

[0066] This invention provides an intelligent device that includes the lidar system described in any of the above embodiments. The intelligent device may be an autonomous driving device, an intelligent robot navigation device, an intelligent transportation facility, or a drone, etc., and this invention does not impose specific limitations. The specific structure of the lidar system in this intelligent device is largely consistent with the structure of the lidar system embodiments described above, and will not be repeated here.

[0067] Example 5:

[0068] like Figure 7 As shown in the figure, this embodiment of the invention provides a detection method for lidar, which is applied to a lidar system. The method includes:

[0069] Step 110: Emit a continuous wave laser.

[0070] Step 120: Generate a Kerr frequency comb based on the continuous wave laser.

[0071] Step 130: Generate a first linear frequency modulated electrical signal; wherein, firstly, a linear frequency modulated electrical signal is generated, and then split into the first linear frequency modulated electrical signal and the local oscillator signal.

[0072] Step 140: The first linear frequency modulated electrical signal is loaded onto the envelope of each wavelength of laser in the Kerr optical frequency comb to form an amplitude modulated light wave for detection by the lidar system.

[0073] The detection method of the lidar in this embodiment of the invention further includes the following steps:

[0074] Step 150: The amplitude-modulated light wave is emitted into space and the reflected light is received.

[0075] Step 160: Extract the reflected electrical signal of the reflected light.

[0076] Step 170: Calculate the distance and / or radial velocity of each target in space based on the local oscillator signal and the reflected signal.

[0077] The detection method of the lidar in this embodiment of the invention is based on the lidar system of any of the above embodiments. The specific implementation steps of the method are generally consistent with the specific working process of the lidar system in the above embodiments, and will not be repeated here.

[0078] The detection method of the lidar in this embodiment of the invention emits a continuous wave laser, generates a Kerr optical frequency comb based on the continuous wave laser, and produces a first linear frequency modulated electrical signal; the first linear frequency modulated electrical signal is loaded onto the envelope of each wavelength of the laser in the Kerr optical frequency comb to form an amplitude modulated light wave for detection by the lidar system. This method can effectively overcome the problem of frequency modulation nonlinearity caused by changing the laser current to generate laser, and the linearity is better than that of linear frequency modulation generated by changing the current of semiconductor lasers. It does not require additional nonlinear calibration, thereby improving the detection accuracy of the lidar system.

[0079] The algorithms or displays provided herein are not inherently related to any particular computer, virtual system, or other device. Various general-purpose systems can also be used in conjunction with the teachings herein. The required structure for constructing such systems is apparent from the above description. Furthermore, the embodiments of the present invention are not directed to any particular programming language. It should be understood that the content of the invention described herein can be implemented using various programming languages, and the above description of specific languages ​​is for the purpose of disclosing the best mode of implementation of the invention.

[0080] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0081] Similarly, it should be understood that, in order to streamline the invention and aid in understanding one or more of the various aspects of the invention, features of the embodiments of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the invention. However, this disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim.

[0082] Those skilled in the art will understand that modules in the device of the embodiments can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and can be divided into multiple sub-modules, sub-units, or sub-components. Except where at least some of such features and / or processes or units are mutually exclusive, any combination can be used to combine all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or device so disclosed. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0083] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be construed as limiting the order of execution.

Claims

1. A lidar system, characterized in that, The lidar system includes: A laser used to emit continuous wave laser light; Kerr optical frequency comb module, used to generate Kerr optical frequency comb based on the continuous wave laser; A signal generator is used to generate a first linear frequency modulated electrical signal; the signal generator is an FMCW radio frequency signal generator, the signal generator emits a linear frequency modulated electrical signal, and splits the linear frequency modulated electrical signal into a first linear frequency modulated electrical signal and a local oscillator signal, and sends the first linear frequency modulated electrical signal to the modulation module; A modulation module is used to load the first linear frequency modulated electrical signal onto the envelope of each wavelength of laser light in the Kerr optical frequency comb to form an amplitude modulated light wave for detection by the lidar system; the lidar system emits the amplitude modulated light wave into space and receives the reflected light; the reflected electrical signal is extracted from the reflected light and compared with the local oscillator signal for target detection; The Kerr optical frequency comb module is a microring or microdisk fabricated on the chip in an aluminum nitride thin film; the Kerr optical frequency comb module and the modulation module are disposed on the chip, and the modulation module is integrated in the aluminum nitride thin film; The lidar system also includes: Optical components for emitting the amplitude-modulated light wave into space and receiving the reflected light that returns; A detection module is used to receive the reflected light and extract the reflected electrical signal of the reflected light; The processing module is used to receive the local oscillator electrical signal sent by the signal generator, and calculate the distance and / or radial velocity of each target in space based on the local oscillator electrical signal and the reflected electrical signal; The detection module includes multiple detectors, and the processing module includes multiple electric mixers, filters, and a computing module; each detector is connected to a corresponding electric mixer, and each electric mixer is connected to a corresponding filter. The detector is used to receive reflected light of a corresponding wavelength and extract the corresponding reflected electrical signal; The electric mixer is used to receive the reflected electrical signal sent by the corresponding detector and the local oscillator signal; The filter is used to receive the reflected electrical signal and the local oscillator signal sent by the corresponding electric mixer to obtain the difference frequency electrical signal; The calculation module is used to determine the distance and / or radial velocity of each target in the computational space based on the difference frequency electrical signal.

2. The lidar system according to claim 1, characterized in that, The Kerr optical frequency comb module includes a Kerr resonant cavity, which converts continuous wave laser at the resonant frequency into a Kerr optical frequency comb. The Kerr optical frequency comb includes multiple wavelength lasers with equally spaced frequencies.

3. The lidar system according to claim 1, characterized in that, The optical components include a scanner and a dispersive element; The scanner is used to change the emission direction of the amplitude-modulated light wave; The dispersive element is used to receive the amplitude-modulated light wave after its emission direction has been changed by the scanner, and to simultaneously emit the amplitude-modulated light wave in different directions in space.

4. The lidar system according to claim 1, characterized in that, An adjustable filter is further provided between the Kerr optical frequency comb module and the modulation module, or an adjustable filter is further provided between the modulation module and the optical component; the optical component is a collimator and a dispersive element; The adjustable filter is used to adjust the frequency of the laser at each wavelength in the Kerr optical frequency comb; The dispersive element is used to scatter the amplitude-modulated light wave into space for spatial scanning.

5. The lidar system according to claim 1, characterized in that, The lidar system also includes a circulator; The first port of the circulator is used to receive the amplitude-modulated light wave sent by the modulation module; The second port of the circulator is used to send the amplitude-modulated light wave to the optical component and to receive the reflected light returned by the optical component; The third port of the circulator is used to send the reflected light to the detection module.

6. A smart device, characterized in that, The intelligent device includes the lidar system according to any one of claims 1-5.

7. A detection method for lidar, characterized in that, Applied to the lidar system as described in claims 1-5, the method includes: Emitting continuous wave laser; A Kerr optical frequency comb is generated based on the continuous wave laser; A linear frequency modulated (LFM) electrical signal is generated; the LFM electrical signal is split into a first LFM electrical signal and a local oscillator signal. The first linear frequency modulated electrical signal is loaded onto the envelope of each wavelength of laser in the Kerr optical frequency comb to form an amplitude modulated light wave for detection by the lidar system; wherein, the amplitude modulated light wave is emitted into space and the reflected light is received; the reflected electrical signal is extracted from the reflected light and compared with the local oscillator signal for target detection.

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