All-solid-state laser radar device based on wavelength-swept laser

Abstract

The application discloses a kind of full solid-state laser radar devices based on wavelength scanning laser. Including wavelength scanning laser, light beam splitter, PD probe, light circulator, APD probe, collimator, optical dispersion device and broadband optical filter.Wavelength scanning laser in the application is in wavelength limited fourier domain mode-locked working state, pulse laser is emitted at a certain angle after passing through optical dispersion device, when laser wavelength changes, laser emission angle also changes, so that the distance detection information in the emission angle range is completed.The application uses wavelength scanning laser as laser light source, uses optical filter as wavelength scanning device, uses wavelength limited fourier domain mode-locked as core working principle, converts wavelength scanning into beam space scanning by optical dispersion device, and realizes full solid-state laser radar function.

Description

Technical Field

[0001] This invention belongs to the field of lidar technology and relates to an all-solid-state lidar device based on a wavelength scanning laser. Background Technology

[0002] LiDAR (Light Detection and Ranging) is a device that uses laser light (beams) as its working medium to detect spatial distance or the speed of moving objects. It typically consists of a laser transmitter, an optical receiver, and an information processing system. With the development of intelligent vehicles, especially the emergence of autonomous vehicles, LiDAR, capable of spatial detection, has become one of the most promising core components for achieving autonomous driving.

[0003] Currently, there are three main technological approaches to LiDAR: 1. Mechanical LiDAR, which uses an electric motor to achieve overall mechanical rotation. This technology is mature and high-performance, but its manufacturing process is difficult, costly, and has low reliability, making it difficult to meet automotive standards. 2. Hybrid solid-state LiDAR, including rotating mirror, gyratory mirror, and MEMS galvanometer technologies. This technology is low-cost and simple in structure, but has poor vibration resistance and limited lifespan, making it risky to meet automotive standards. 3. All-solid-state LiDAR, currently researched using OPA and Flash technologies. This technology achieves a purely solid-state solution with a compact structure and high reliability, but its maturity is low, ranging performance is low, and it is greatly affected by the environment, currently failing to meet the needs of autonomous driving applications. Therefore, inventing a high-performance, novel all-solid-state LiDAR is of great significance. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by proposing an all-solid-state lidar device based on a wavelength scanning laser and its ranging method.

[0005] One aspect of the present invention provides an all-solid-state lidar device based on a wavelength scanning laser; comprising a wavelength scanning laser, an optical beam splitter, a PD probe, an optical circulator, an APD probe, a collimator, an optical dispersion device, and a broadband optical filter.

[0006] The output of the wavelength scanning laser is connected to the input fiber of the optical beam splitter; the main output of the optical beam splitter is connected to the first port fiber of the optical circulator; the secondary output of the optical beam splitter is connected to the input fiber of the PD probe; the second port of the optical circulator is connected to the input fiber of the collimator; the third port of the optical circulator is connected to the input fiber of the APD probe; the laser output from the collimator is injected into the optical dispersive device; the laser output from the optical dispersive device passes through a broadband optical filter and is emitted into the surrounding environment.

[0007] The wavelength scanning laser includes a semiconductor optical amplifier, a section of optical fiber, a fast scanning optical filter, a slow scanning optical filter, an optical coupler, and an optical isolator. The input end of the semiconductor optical amplifier is connected to one end of the section of optical fiber. The output end of the semiconductor optical amplifier is connected to the input end of the fast scanning optical filter. The output end of the fast scanning optical filter is connected to the input end of the slow scanning optical filter. The output end of the slow scanning optical filter is connected to the input end of the optical coupler. One output end of the optical coupler is connected to the input end of the optical isolator. The output end of the optical isolator is connected to the other end of the section of optical fiber. The other output end of the optical coupler serves as the output end of the wavelength scanning laser. The semiconductor optical amplifier, the section of optical fiber, the fast scanning optical filter, the slow scanning optical filter, the optical coupler, and the optical isolator constitute a ring-shaped resonant cavity.

[0008] Another aspect of the present invention provides a ranging method for the above-described all-solid-state lidar device:

[0009] The wavelength scanning laser is adjusted to be in a wavelength-limited Fourier domain mode-locked state, and the wavelength of the output pulsed laser is determined by the center wavelength of the slow scanning filter and changes periodically at a frequency of kHz or lower.

[0010] After passing through an optical dispersive device, the pulsed laser is emitted at a certain angle. When the laser wavelength changes from λ1 to λ... N When the laser emission angle changes, β changes, which is the maximum horizontal scanning angle of the lidar.

[0011] When the laser output wavelength is λ i When the emitted laser hits an obstacle, part of the light is reflected back to the lidar along its original path, and then injected into the optical circulator to reach the APD probe. The distance D between the obstacle and the lidar is determined by multiplying the time delay Δt between the laser pulse at the PD probe and the reflected laser at the APD probe by the speed of light c. i =Δt×c. When the center wavelength of the slow-scan filter completes the change from λ1 to λ N With one cycle of scanning, the lidar obtains distance detection information within the emission angle range β.

[0012] The present invention also provides an application of an all-solid-state lidar device based on a wavelength scanning laser in an autonomous vehicle.

[0013] The beneficial effects of this invention are as follows: This invention uses a wavelength scanning laser as the laser source, a mature optical filter as the wavelength scanning device, and wavelength-limited Fourier domain mode-locking as the core working principle. Through optical dispersive devices, wavelength scanning is converted into beam spatial scanning, realizing the function of an all-solid-state lidar. This invention is applicable to lidar distance detection and 3D space information detection technologies, and has broad application prospects in fields such as autonomous vehicles, aerospace, and industrial manufacturing. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention.

[0015] Figure 2 This is a schematic diagram of the driving electrical signal applied to the fast scanning optical filter in this invention.

[0016] Figure 3 This is a schematic diagram of wavelength scanning and division of the wavelength scanning laser in this invention. Detailed Implementation

[0017] like Figure 1 As shown, this embodiment includes a semiconductor optical amplifier 1, a section of optical fiber 2, a fast scanning optical filter 3, a slow scanning optical filter 4, an optical coupler 5, an optical isolator 6, an optical beam splitter 7, a PD probe 8, an optical circulator 9, an APD probe 10, a collimator 11, an optical dispersion device 12, a broadband optical filter 13, an optical filter driver 14, and a data processing module 15.

[0018] The semiconductor optical amplifier 1 has an output power greater than 10mW and an operating bandwidth covering 1450-1650nm.

[0019] The aforementioned fiber 2 is a 1950-meter-long ordinary single-mode fiber, used as a delay fiber within the cavity of a wavelength scanning laser.

[0020] The fast scanning optical filter 3 is an electrically driven, all-solid-state optical filter with a response frequency of 5MHz, a wavelength scanning range covering 1450-1650nm, and a transmission bandwidth of F1=0.1nm.

[0021] The slow-scanning optical filter 4 is an electrically driven, all-solid-state optical filter with a response frequency of 10kHz, a wavelength scanning range covering 1450-1650nm, and a transmission bandwidth of F2 = 0.1nm.

[0022] The optical dispersion device 12 described above can achieve spatial spectral dispersion in the range of 1450-1650nm, and can be a holographic grating, a dispersive prism and an emitting mirror, or a combination thereof.

[0023] The operating wavelength range is 1450-1650nm, ensuring that the lidar scanning range reaches 100 degrees.

[0024] The input end of semiconductor optical amplifier 1 is connected to one end of a section of optical fiber 2; the output end of semiconductor optical amplifier 1 is connected to the input end of fast scanning optical filter 3; the output end of fast scanning optical filter 3 is connected to the input end of slow scanning optical filter 4; the output end of slow scanning optical filter 4 is connected to the input end of optical coupler 5; one output end of optical coupler 5 is connected to the input end of optical isolator 6; the output end of optical isolator 6 is connected to the other end of a section of optical fiber 2; the above semiconductor optical amplifier 1, section of optical fiber 2, fast scanning optical filter 3, slow scanning optical filter 4, optical coupler 5, and optical isolator 6 are connected to form the resonant cavity of a ring-structured wavelength scanning laser; the other output end (a% port) of optical coupler 5 in the wavelength scanning laser is used as the output end of the wavelength scanning laser.

[0025] Connect the two output terminals of the optical filter driver 14 to the control ports of the fast scanning optical filter 3 and the slow scanning optical filter 4 respectively; connect the input terminal of the optical filter driver 14 to the data processing module 15.

[0026] The wavelength scanning laser in this embodiment has three operating modes, and its operating principle is as follows:

[0027] The first mode: In the wavelength scanning laser with a ring cavity structure, the semiconductor optical amplifier 1 provides a gain for the working band of 1450-1650nm. When the center wavelengths of the fast scanning optical filter 3 and the slow scanning optical filter 4 coincide and remain unchanged, the laser corresponding to the center wavelength forms a stable continuous laser output in the resonant cavity due to the balance between gain and loss. In this case, the wavelength scanning laser is in a fixed laser wavelength working state, and the output laser wavelength is the center wavelength of the fast scanning optical filter and the slow scanning optical filter.

[0028] The second mode: When the fast scanning optical filter 3 and the slow scanning optical filter 4 are connected to the periodic electrical signal (e.g., period T) of the optical filter driver 14. f Driven by a triangular wave signal of 5 microseconds, and with the wavelength scanning laser's resonant cavity requiring light to travel one revolution in time T... L = 10 microseconds (i.e., the reciprocal of the laser's fundamental frequency) is twice the period of the optical filter driver, i.e., T L =2T f When the wavelength scanning laser is in the Fourier domain mode-locked state, the output wavelength range is the continuous laser within the scanning range of the fast scanning optical filter 3 and the slow scanning optical filter 4, and the output laser wavelength changes periodically.

[0029] The third mode: When the fast scanning optical filter 3 is subjected to a periodic electrical signal (e.g., with a period of T) from the optical filter driver 14. f Driven by a triangular wave signal of 5 microseconds, and with the wavelength scanning laser's resonant cavity requiring light to travel one revolution in time T... L =10 microseconds is twice the period of the optical filter driver, that is, T L =2T f If the center wavelength of the slow scanning optical filter 4 remains unchanged or is in a slowly changing state, then the wavelength scanning laser is in a wavelength-limited Fourier domain mode-locked working state, and the output wavelength range is a periodic pulse laser with the center wavelength of the slow scanning optical filter. The output laser pulse width is determined by the center wavelength bandwidth of the fast scanning optical filter 3 and the slow scanning optical filter 4 and the scanning wavelength range of the fast scanning optical filter, which is 2.5 nanoseconds.

[0030] The other output of optical coupler 5 is connected to the optical fiber at the input of optical beam splitter 7; the main output of optical beam splitter 7 is connected to the optical fiber at the first port of optical circulator 9; the secondary output of optical beam splitter 7 is connected to the optical fiber at the input of PD probe 8; the second port of optical circulator 9 is connected to the optical fiber at the input of collimator 11; the third port of optical circulator 9 is connected to the optical fiber at the input of APD probe 10; the laser output from collimator 11 is injected into optical dispersion device 12; the laser output from optical dispersion device 12 passes through broadband optical filter 13 and is emitted into the surrounding environment; broadband optical filter 13 allows the laser output from the scanning laser to transmit with low loss and prevents external ambient light from being injected into the lidar system.

[0031] After the radar device described above is constructed, it begins the ranging process based on the following working principle: the wavelength scanning laser is in a wavelength-limited Fourier domain mode-locked state, and the wavelength of the output pulsed laser is determined by the center wavelength of the slow-scan filter and changes periodically at a frequency of kHz or lower. The data processing module controls the optical filter driver to load a driving electrical signal with a frequency of 1kHz onto the slow-scan optical filter 4. The data processing module 15 controls the amplitude of the driving electrical signal loaded by the optical filter driver 14 onto the slow-scan optical filter so that the center wavelength scanning range of the slow-scan optical filter covers 1450-1650nm. The data processing module 15 uses the periodic signal of the optical filter driver 14 as the data processing period time, and divides the output laser wavelength within the wavelength scanning range into 2000 equal parts according to half a period time and marks them as changing from λ1 to λ2. 2000 The other half-cycle serves as redundant information.

[0032] In one embodiment: the wavelength of the output pulsed laser is determined by the center wavelength of the slow-scan filter 4 and varies periodically from 1450-1650nm at a frequency of 1kHz. The wavelength from 1450nm to 1650nm is divided into 2000 wavelengths with a transmission bandwidth of 0.1nm, and the wavelength variation is denoted as λ. i (i is a natural number from 1 to 2000), see Figure 3 .

[0033] Pulsed laser light has a specific exit angle after passing through an optical dispersive device, when the laser wavelength changes from λ1 to λ 2000 When the laser emission angle changes by β (100 degrees), it becomes the maximum horizontal scanning angle of the lidar.

[0034] When the laser output wavelength is λ i When the emitted laser hits an obstacle, part of the light is reflected back to the lidar along its original path, and then injected into the optical circulator to reach the APD probe. Based on the product of the time delay Δt between the laser pulse at the PD probe and the reflected laser at the APD probe, and the speed of light c, the distance D between the obstacle and the lidar can be determined. i =Δt×c. When the center wavelength of the slow-scan filter completes the change from λ1 to λ 2000 In one cycle of scanning, the lidar obtains distance detection information within the emission angle range β (100 degrees), realizing the single-line lidar ranging function.

[0035] In one embodiment, the wavelength scanning laser is configured to operate in a wavelength-limited Fourier domain mode-locked state as follows:

[0036] Based on the preliminary calculation of the optical path length of the resonant cavity of the wavelength-scanning laser, the period T corresponding to the fundamental frequency of the resonant cavity is calculated. L =10 microseconds, the data processing module 15 controls the optical filter driver 14 to load the period T of the drive electrical signal to the fast scanning optical filter 3. f =5 microseconds to achieve fast scanning optical filter T L =2T f The driving electrical signal frequency is 200kHz; the data processing module 15 controls the amplitude of the driving electrical signal applied to the fast scanning optical filter 3 by the optical filter driver 14, so that the center wavelength scanning range of the fast scanning optical filter covers 1450-1650nm, see Figure 2 Turn on semiconductor optical amplifier 1 to ensure that the wavelength scanning laser is in wavelength-limited Fourier domain mode-locked operation.

[0037] In one embodiment, multi-line lidar ranging can be achieved by using a single wavelength scanning laser and adding laser beam splitting and detection in another dimension, or by integrating multiple wavelength scanning lasers and detection devices.

[0038] In summary, this invention is applicable to fields such as autonomous vehicles, aerospace, and industrial manufacturing, and realizes lidar distance detection technology with advantages such as all-solid-state structure, high reliability, and strong anti-interference capability.

Claims

1. A solid-state lidar device based on a wavelength scanning laser, comprising a wavelength scanning laser, an optical beam splitter, a PD probe, an optical circulator, an APD probe, a collimator, an optical dispersive device, and a broadband optical filter, characterized in that: The output of the wavelength scanning laser is connected to the input fiber of the optical beamsplitter; the main output of the optical beamsplitter is connected to the first port fiber of the optical circulator; the secondary output of the optical beamsplitter is connected to the input fiber of the PD probe; the second port of the optical circulator is connected to the input fiber of the collimator; the third port of the optical circulator is connected to the input fiber of the APD probe; the laser output from the collimator is injected into the optical dispersive device; the laser output from the optical dispersive device passes through a broadband optical filter and is emitted into the surrounding environment. The wavelength scanning laser includes a semiconductor optical amplifier, a section of optical fiber, a fast scanning optical filter, a slow scanning optical filter, an optical coupler, and an optical isolator. The input end of the semiconductor optical amplifier is connected to one end of the section of optical fiber. The output end of the semiconductor optical amplifier is connected to the input end of the fast scanning optical filter. The output end of the fast scanning optical filter is connected to the input end of the slow scanning optical filter. The output end of the slow scanning optical filter is connected to the input end of the optical coupler. One output end of the optical coupler is connected to the input end of the optical isolator. The output end of the optical isolator is connected to the other end of the section of optical fiber. The other output end of the optical coupler serves as the output end of the wavelength scanning laser. The semiconductor optical amplifier, the section of optical fiber, the fast scanning optical filter, the slow scanning optical filter, the optical coupler, and the optical isolator constitute a ring-shaped resonant cavity.

2. The all-solid-state lidar device based on a wavelength scanning laser according to claim 1, characterized in that: It also includes an optical filter driver and a data processing module; the two outputs of the optical filter driver are respectively connected to the control port signals of the fast scanning optical filter and the slow scanning optical filter; the input of the optical filter driver is connected to the data processing module; the PD probe and the APD probe are also connected to the data processing module.

3. The all-solid-state lidar device based on a wavelength scanning laser according to claim 1, characterized in that: The semiconductor optical amplifier has an output power greater than 10mW and an operating bandwidth covering 1450-1650nm.

4. The all-solid-state lidar device based on a wavelength scanning laser according to claim 3, characterized in that: The fast scanning optical filter is an electrically driven, all-solid-state optical filter with a response frequency in the MHz range, a wavelength scanning range covering 1450-1650nm, and a transmission bandwidth of F1. The slow-scanning optical filter is an electrically driven, all-solid-state optical filter with a response frequency in the kHz range, a wavelength scanning range covering 1450-1650nm, and a transmission bandwidth of F2.

5. The all-solid-state lidar device based on a wavelength scanning laser according to claim 3, characterized in that: The optical dispersive device is used to achieve spatial spectral dispersion in the range of 1450-1650nm.

6. A ranging method, employing the all-solid-state lidar device based on a wavelength scanning laser as described in any one of claims 1 to 5, characterized in that: The wavelength scanning laser is adjusted to be in a wavelength-limited Fourier domain mode-locked state, and the wavelength of the output pulsed laser is determined by the center wavelength of the slow scanning filter and changes periodically at a frequency of kHz or lower. After passing through an optical dispersive device, the pulsed laser is emitted at a certain angle. When the laser wavelength changes from λ1 to λ... N When the laser emission angle changes, β changes, which is the maximum horizontal scanning angle of the lidar. When the laser output wavelength is λ i When the emitted laser hits an obstacle, part of the light is reflected back to the lidar along its original path, and then injected into the optical circulator to reach the APD probe. The distance D between the obstacle and the lidar is determined by multiplying the time delay Δt between the laser pulse at the PD probe and the reflected laser at the APD probe by the speed of light c. i =Δt×c; When the center wavelength of the slow-scan filter completes the change from λ1 to λ N With one cycle of scanning, the lidar obtains distance detection information within the emission angle range β.

7. The ranging method according to claim 6, characterized in that: Adjusting the wavelength scanning laser to put it into a wavelength-limited Fourier domain mode-locked operating state specifically involves: When the fast scanning optical filter is driven by the periodic electrical signal of the optical filter driver, and the time required for the light to travel one revolution in the resonant cavity of the wavelength scanning laser is equal to or an integer multiple of the period of the optical filter driver, and the center wavelength of the slow scanning optical filter remains unchanged or is in a slowly changing state, then the wavelength scanning laser is in the wavelength-limited Fourier domain mode-locked operating state.

8. The ranging method according to claim 6 or 7, characterized in that: Multi-line lidar ranging can be achieved by using a single wavelength scanning laser and adding laser beam splitting and detection in another dimension, or by integrating multiple wavelength scanning lasers and detection devices.

9. The application of an all-solid-state lidar device based on a wavelength scanning laser, as described in any one of claims 1 to 5, in an autonomous vehicle.

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