Transceiving coaxial phased array lidar chip and control method therefor

Abstract

The present invention provides a transceiving coaxial phased array LiDAR chip and a control method therefor. The transceiving coaxial phased array LiDAR chip comprises: a laser emitting unit, a general beam splitter, a transceiving phased array, a balanced detector array and a signal processing and control unit; a phase modulator of a phased array unit in the transceiving phased array is separately connected to light-exit paths of the general beam splitter, and performs phase modulation on light output by the general beam splitter; after that, the light is divided into reference light and signal light, the signal light passing through a first port and a second port of a circulator and then being radiated by grating radiation antennas into a free space, and the reference light passing through a frequency shifter and then being input into a 90-degree optical mixer together with an echo optical signal returned by a third port of the circulator; then, balanced detectors receive output signals, convert same into electric signals and transmit same to the signal processing and control unit, so as to calculate three-dimensional depth and / or speed information of a target region. By means of a transceiving coaxial phased array LiDAR and a coherent detection means, the present invention achieves chip integration of a transmitting end and a detection end of the LiDAR, and has higher signal-to-noise ratio and integration degree compared with traditional LiDAR systems.

Description

A transceiver coaxial phased array laser radar chip and its control method Technical Field

[0001] The present invention relates to the technical field of electrical components, and in particular to a transceiver coaxial phased array laser radar chip and a control method thereof. Background Art

[0002] Three-dimensional imaging lidar systems usually require a larger field of view to meet actual application needs. Their field of view angle is related to the scanning range of the transmitted laser beam. Similarly, the receiving system also needs a field of view with a corresponding angle range to achieve matching of the transmitting and receiving fields of view. However, the larger the receiving field of view, the more ambient background light and stray light there is, and the lower the signal-to-noise ratio of the lidar system.

[0003] The existing laser radar system has a large blind spot, large stray light, and low signal-to-noise ratio, and cannot meet the requirements of a three-dimensional imaging laser radar system.

[0004] Therefore, a technical lidar system with small blind area, less stray light and high signal-to-noise ratio is needed.

[0005] Summary of the Invention

[0006] The present invention aims to solve the problems of large blind spots, large stray light, and low signal-to-noise ratio in existing laser radar systems. It provides a transceiver coaxial phased array laser radar chip and its control method, which realizes the transmission and reception of laser signals simultaneously through the phased array. Since the transmitting optical axis and the receiving optical axis coincide, it is beneficial to reduce the blind spot of the laser radar system; and the use of the phased array for radar reception is equivalent to using a receiving optical system with a flexibly steerable field of view, avoiding the problems of large stray light and low signal-to-noise ratio caused by using a static large field of view reception to achieve transceiver field of view matching. At the same time, a 90° optical mixer is used in combination with a balanced detector to achieve coherent detection and improve the signal-to-noise ratio. The transceiver coaxial phased array laser radar chip adopts easy-to-integrate means such as semiconductor devices and printed circuit boards, which can give full play to the advantages of the optoelectronic integration process platform to achieve a high signal-to-noise ratio, high integration, and low-cost monolithic laser radar system.

[0007] The present invention provides a transceiver coaxial phased array laser radar chip, a laser emitting unit, a total beam splitter, a transceiver phased array optically connected in sequence, a balanced detector array optically connected to the transceiver phased array receiving output port, and a signal processing and control unit electrically connected to the laser emitting unit, the transceiver phased array, and the balanced detector array;

[0008] The laser emitting unit generates an optical signal under the control of the signal processing and control unit and outputs it to the main beam splitter. The main beam splitter divides the optical signal into N optical signals and outputs them to the transceiver phased array respectively. The transceiver phased array, under the control of the signal processing and control unit, phase-modulates the N optical signals and outputs them as N phase-modulated signal lights and N phase-modulated reference lights respectively. The N phase-modulated signal lights are projected to the detection area by the transceiver phased array for scanning. The scanning deflection angle is (θ x0 ,θ y0 ), N is greater than 2, the transceiver phased array receives the echo signal light reflected by the target in the detection area and performs coherent mixing with the frequency-shifted N-way phase-modulated reference light to generate a beat frequency signal output to the balanced detector array. The receiving field of view center direction of the transceiver phased array is (θ x0 ,θ y0 ), the balanced detector array converts the beat frequency signal carrying the echo signal information into an electrical signal and outputs it to the signal processing and control unit, which processes the electrical signal and calculates the three-dimensional depth and / or velocity information of the target in the detection area based on the time difference between the light signal output by the laser emitting unit and the echo signal.

[0009] The transceiver coaxial phased array laser radar chip described in the present invention, as a preferred embodiment, comprises N phased array elements, all of which are optically connected to the output end of the total beam splitter;

[0010] The phased array element includes an optically connected phase modulator, a 1×2 beam splitter, a circulator, a grating radiation antenna, a frequency shifter connected to another output of the 1×2 beam splitter, and a 90° optical mixer connected to the third port of the circulator. The output of the frequency shifter is also connected to the input of the 90° optical mixer. The 90° optical mixer is optically connected to the input of the balanced detector array.

[0011] The circulator includes a first port optically connected to the output end of the 1×2 beam splitter, a second port optically connected to the grating radiation antenna end, and a third port connected to the input end of the 90° optical mixer. N-channel phase-modulated signal light is output to the grating radiation antenna through the first port and the second port in sequence, and the echo signal enters the 90° optical mixer through the grating radiation antenna, the second port, and the third port in sequence.

[0012] The present invention discloses a transceiver coaxial phased array laser radar chip. As a preferred embodiment, the phase modulator is electrically connected to the signal processing and control unit. Under the control of the signal processing and control unit, the phase modulator makes the optical signal have a phase Δφ0, and projects the output signal light to the detection area for scanning through N grating radiation antennas. The scanning deflection angle is (θ x0 ,θ y0 ), the phase Δφ0 makes N grating radiation antennas (θ x0 ,θ y0 ) direction has a maximum value.

[0013] The transceiver coaxial phased array laser radar chip described in the present invention preferably has a 1×2 beam splitter with a splitting ratio of 1:1 to 1:99, a frequency shift of 1 to 100 MHz, a 90° optical mixer with a multimode interference coupler or a directional coupler and a phase shifter, and grating radiation antennas with a one-dimensional or two-dimensional periodic arrangement or a sparse arrangement. The number of grating radiation antennas in the x and y directions is n1 and n2, respectively, and n1×n2=N.

[0014] The grating radiation antenna has a period of T i When arranged, the scanning angle range θ in the x and y directions i (i=x, y) is:

[0015] Where λ is the wavelength of the signal transmitted by the lidar system.

[0016] The transceiver coaxial phased array laser radar chip described in the present invention is preferably configured such that the laser emitting unit is a semiconductor laser chip or a fiber laser, the output wavelength of the laser emitting unit is between the visible light and far infrared bands, and the laser signal emitted by the laser emitting unit is a pulsed laser signal or a frequency modulated continuous wave laser signal that can be used for time-of-flight ranging method or frequency modulated continuous wave ranging method, respectively.

[0017] The total beam splitter and the laser emission unit are connected through an on-chip waveguide. The total beam splitter is a 1×N beam splitter. The number of array elements in the balanced detector array is N.

[0018] The signal processing and control unit includes amplifiers, filters and processors.

[0019] The present invention provides a control method for a transceiver coaxial phased array laser radar chip, comprising the following steps:

[0020] S1: The transceiver coaxial phased array lidar chip starts working, laser emission enters step S2, and echo signal reception and processing enters step S3;

[0021] S2, the optical signal output by the laser emitting unit is divided into N optical signals by the total beam splitter and transmitted to the transceiver phased array. The transceiver phased array performs phase control on the N optical signals according to the control signal of the signal processing and control unit, and then splits the N optical signals to obtain N phase-modulated reference lights and N phase-modulated signal lights. The N phase-modulated reference lights are frequency-shifted to obtain N frequency-shifted reference lights, and then enter step S3. The N phase-modulated signal lights are radiated into free space by the transceiver phased array, and the emission direction is (θ x0 ,θ y0 ), and generate an echo signal to enter step S3;

[0022] S3, the transceiver phased array receives the echo signal and performs coherent mixing with N-way frequency-shifted reference light to obtain a beat frequency signal which is output to the balanced detector array. The receiving field of view center of the transceiver phased array is (θ x0 ,θ y0 ), the balanced detector array converts the beat frequency signal with echo signal information into an electrical signal and outputs it to the signal processing and control unit. The signal processing and control unit analyzes and obtains the three-dimensional information of the target area, and the control method of the transceiver coaxial phased array lidar chip is completed.

[0023] The control method of a transceiver coaxial phased array lidar chip described in the present invention is, as a preferred embodiment, in step S2, the transceiver phased array includes N phased array elements, and the phased array elements include an optically connected phase modulator, a beam splitter, a circulator, a grating radiation antenna, a frequency shifter connected to another outlet of the beam splitter, and a 90° optical mixer connected to the third port of the circulator. The outlet of the frequency shifter is also connected to the inlet of the 90° optical mixer. The inlet of the phase modulator is optically connected to the N outlets of the total beam splitter, and the 90° optical mixer is optically connected to the inlet of the balanced detector array.

[0024] In the (m, n)th phased array element, the optical signal is first phase-modulated by the phase modulator, and the phase Δφ0(m, n) is set to obtain the phase-modulated signal light. The phase Δφ0(m, n) compensates the phase of the (m, n)th grating radiation antenna so that the N phase-modulated signal lights emitted by the N grating radiation antennas are at (θ x0 ,θ y0 ) direction, θ x0 ,θ y0 are the azimuth angles of the outgoing light in the x and y directions respectively; in step S2, the phase modulator makes the (m, n)-th reference light have a phase Δφ0(m, n); in step S3, the echo signal is superimposed on the superimposed output signal of the phase-modulated reference light and is superimposed on (θ x0 ,θ y0 ) direction has a maximum value.

[0025] The control method of a transceiver coaxial phased array laser radar chip described in the present invention is preferably implemented in step S2.

[0026] Where Δφ1(m,n) is the value of the (m,n)th grating radiation antenna at (θ x1 ,θ y1 ) direction, T x is the arrangement period of N grating radiation antennas in the x direction, T y is the arrangement period of N grating radiation antennas in the y direction, θ x1 ,θ y1 are the azimuths in the x and y directions respectively;

[0027] When the (m, n)th grating radiation antenna is at (θ x1 ,θ y1 ) direction when the optical path phase delay and phase difference Δφ0(m,n) are compensated: x1 =θ x0 ,θ y1 =θ y0 .

[0028] The control method of a transceiver coaxial phased array laser radar chip described in the present invention is preferably such that in step S3, the signal received by the (m, n)th grating radiation antenna is:

[0029] Among them, E i (θ x2 ,θ y2 ) is the optical field of the echo signal at (θ x2 ,θ y2 ) direction, G(θ x2 ,θ y2 ) is the unit pattern of a single grating radiation antenna, which means (θ x2 ,θ y2 ) direction of the plane wave vector and the electric field coupling strength of the grating radiation antenna, Δφ2(m,n) is (θ x2 ,θ y2 ) direction to the (m, n)th grating radiation antenna:

[0030] The phase modulator controls the phase of N phased array elements. The reference light phase modulation value of the phased array element where the (m, n)th grating radiation antenna is located is Δφ0(m, n). The sum of the received signals of the N phased array elements is:

[0031] When Δφ2=Δφ0, that is, θ x2 =θ x0 ,θ y2 =θ y0 When , the superimposed signal has a maximum value.

[0032] The control method of a transceiver coaxial phased array lidar chip described in the present invention is, as a preferred embodiment, in step S2, the phase difference between the N-channel frequency-shifted reference light and the N-channel phase-modulated signal light is Δf, and in step S3, the signal frequency of the beat signal is Δf.

[0033] The present invention provides a transceiver coaxial phased array laser radar chip, comprising:

[0034] A laser emitting unit, used for generating a laser signal;

[0035] A total beam splitter, connected to the laser emitting unit, for dividing the laser signal generated by the laser emitting unit into multiple paths;

[0036] A transceiver phased array is used to split the single-channel laser signal into signal light and reference light, project the signal light into a detection area for scanning, and simultaneously receive the echo light signal reflected by the target in the detection area and perform coherent mixing with the frequency-shifted reference light to generate a beat frequency signal;

[0037] A balanced detector array is connected to the transceiver phased array and is used to convert the beat frequency signal into an electrical signal.

[0038] A signal processing and control unit, configured to process the electrical signal and calculate the position and / or velocity information of the target in the detection area, and also to control the laser emission and phase modulation of the laser emission unit and the transceiver phased array;

[0039] The transceiver phased array also includes multiple identical phased array units, which include a phase modulator, a 1×2 beam splitter, a circulator, a grating radiation antenna, a frequency shifter and a 90° optical mixer. The phase modulator is used to control the phase of the laser signal in the phased array unit according to the control signal of the signal processing and control unit. The 1×2 beam splitter is used to divide the laser signal into reference light and signal light. The circulator allows the signal light to enter from port 1 and exit from port 2 of the circulator, and then be coupled into free space by the grating radiation antenna, while allowing the echo signal light to enter from port 2 and exit from port 3. The frequency shifter shifts the frequency of the reference light. The 90° optical mixer performs coherent mixing on the echo signal light and the reference light output from port 3 of the circulator to generate a beat frequency signal.

[0040] The laser emitting unit is a semiconductor laser chip or fiber laser, and its wavelength is between visible light and far infrared band.

[0041] The laser signal emitted by the laser emitting unit is a pulsed laser signal or a frequency modulated continuous wave laser signal, which can be used for a time-of-flight ranging method or a frequency modulated continuous wave ranging method respectively.

[0042] The total beam splitter, the transceiver phased array and the balanced detector array are semiconductor devices.

[0043] The transceiver phased array has N phased array units, where N is greater than 2.

[0044] The beam splitting ratio of the total beam splitter is 1×N, where N is the number of elements in the phased array unit.

[0045] The number of array elements of the balanced detector array is N, which is used to receive the coherent mixing signal of the reference light and the echo signal light and convert it into an electrical signal. Each balanced detector includes two balanced photodiodes, including two inputs and one output.

[0046] The 1×2 beam splitter is used to split the laser signal into signal light and reference light, with the splitting ratio of reference light to signal light ranging from 1:1 to 1:99.

[0047] The frequency shifter has a frequency shift range of 1 to 100 MHz and is used to frequency modulate the reference light to facilitate subsequent coherent mixing detection with the echo signal light.

[0048] The 90° optical mixer is a multimode interference coupler or is composed of a directional coupler and a phase shifter, and is used to mix the echo signal light and the reference light to generate a beat frequency signal.

[0049] The grating radiating antennas in the phased array are arranged in a one-dimensional or two-dimensional periodic or sparse manner, and are used to achieve one-dimensional or two-dimensional beam scanning in the far field. The number of grating radiating antennas in the x and y directions is n1 and n2 respectively, and n1×n2=N. When the antennas are arranged periodically, the scanning angle range θ in the x and y directions is i (i=x, y) and the grating radiation antenna period T i The relationship is:

[0050] Where λ is the wavelength of the signal transmitted by the lidar system.

[0051] The signal processing and control unit is a printed circuit board or other integrated system, which includes an amplifier, a filter, a processor, etc., and is used to send control information to the laser emitting unit and the phase modulator, and to calculate the distance information and / or speed information of the target relative to the laser radar chip based on the feedback electrical signal.

[0052] The technical solution includes: a laser emitting unit, a total beam splitter, a transceiver phased array, a balanced detector array, and a signal processing and control unit. The transceiver phased array includes multiple repeating units, each of which includes a phase modulator, a 1×2 beam splitter, a circulator, a grating radiation antenna, a frequency shifter, and a 90° optical mixer. The phase modulator is connected to each optical path of the total beam splitter. After phase modulation, the light output by the total beam splitter is divided into reference light and signal light after passing through the 1×2 beam splitter. The signal light passes through port 1 of the circulator and port 2, and is then coupled into free space by the grating radiation antenna. After passing through the frequency shifter, the reference light and the echo signal light returned from port 3 of the circulator are input into a 90° optical mixer, which is then received by the balanced detector and converted into an electrical signal and transmitted to the signal processing and control unit to calculate the three-dimensional depth and / or velocity information of the target area. The present disclosure realizes chip integration of the laser radar transmitter and detector through a transceiver coaxial phased array laser radar and coherent detection means. Compared with traditional laser radar systems, the signal-to-noise ratio and integration are higher.

[0053] The present invention has the following advantages:

[0054] The present invention provides a coaxial phased array laser radar chip for transmission and reception, which realizes the transmission and reception of laser signals simultaneously through the phased array. Since the transmitting optical axis and the receiving optical axis coincide with each other, it is beneficial to reduce the blind spot of the laser radar system; and the use of the phased array for radar reception is equivalent to using a receiving optical system with a flexibly steerable field of view, avoiding the problem of large stray light and low signal-to-noise ratio caused by using a static large field of view reception to achieve transmission and reception field matching. At the same time, a 90° optical mixer is used in combination with a balanced detector to realize coherent detection and improve the signal-to-noise ratio. The present invention adopts easy-to-integrate means such as semiconductor devices and printed circuit boards, which can give full play to the advantages of the optoelectronic integration process platform to realize a high signal-to-noise ratio, high integration, and low-cost monolithic laser radar system. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is a schematic diagram of the architecture of a transceiver coaxial phased array lidar chip;

[0056] FIG2 is a schematic diagram of a single phased array element structure of a transceiver coaxial phased array laser radar chip;

[0057] FIG3 is a schematic diagram of the arrangement of grating radiation antennas for a transceiver coaxial phased array lidar core;

[0058] FIG4 is a flow chart of a control method for a transceiver coaxial phased array lidar chip;

[0059] FIG5 is a flow chart of a control method for transmitting and receiving a coaxial phased array laser radar chip in Example 3.

[0060] Figure numerals: 1. Laser emitting unit; 2. Total beam splitter; 3. Transceiver phased array; 31. Phase modulator; 32. 1×2 beam splitter; 33. Circulator; 331. First port; 332. Second port; 333. Third port; 34. Grating radiation antenna; 35. Frequency shifter; 36. 90° optical mixer; 4. Balanced detector array; 5. Signal processing and control unit. DETAILED DESCRIPTION

[0061] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0062] Example 1

[0063] As shown in Figures 1 and 2, a transceiver coaxial phased array laser radar chip comprises a laser emitting unit 1, a total beam splitter 2, a transceiver phased array 3 optically connected in sequence, a balanced detector array 4 optically connected to the receiving output port of the transceiver phased array 3, and a signal processing and control unit 5 electrically connected to the laser emitting unit 1, the transceiver phased array 3, and the balanced detector array 4.

[0064] The laser emitting unit 1 generates an optical signal under the control of the signal processing and control unit 5 and outputs it to the total beam splitter 2. The total beam splitter 2 splits the optical signal into N optical signals and outputs them to the transceiver phased array 3. The transceiver phased array 3, under the control of the signal processing and control unit 5, phase-modulates the N optical signals and outputs them as N phase-modulated signal lights and N phase-modulated reference lights. The N phase-modulated signal lights are projected to the detection area by the transceiver phased array 3 for scanning. The scanning deflection angle is (θ x0 ,θ y0 ), N is greater than 2, the transceiver phased array 3 receives the echo signal light reflected by the target in the detection area and performs coherent mixing with the frequency-shifted N-way phase-modulated reference light to generate a beat frequency signal which is output to the balanced detector array 4. The receiving field of view center direction of the transceiver phased array 3 is (θ x0 ,θ y0 ), the balanced detector array 4 converts the beat signal and the echo signal into electrical signals and outputs them to the signal processing and control unit 5, which processes the electrical signals and calculates the three-dimensional depth and / or velocity information of the target in the detection area based on the time difference between the light signal output by the laser emitting unit 1 and the echo signal;

[0065] The transceiver phased array 3 includes N phased array elements that are optically connected to the output end of the main beam splitter 2;

[0066] As shown in FIG2 , the phased array element includes an optically connected phase modulator 31, a 1×2 beam splitter 32, a circulator 33, a grating radiation antenna 34, a frequency shifter 35 connected to another outlet of the 1×2 beam splitter 32, and a 90° optical mixer 36 connected to the third port of the circulator 33. The outlet of the frequency shifter 35 is also connected to the inlet of the 90° optical mixer 36. The 90° optical mixer 36 is optically connected to the inlet of the balanced detector array 4.

[0067] The circulator 33 includes a first port 331 optically connected to the output end of the 1×2 beam splitter 32, a second port 332 optically connected to the end of the grating radiation antenna 34, and a third port 333 connected to the input end of the 90° optical mixer 36. The N-channel phase-modulated signal light is sequentially output to the grating radiation antenna 34 via the first port 331 and the second port 332. The echo signal enters the 90° optical mixer 36 via the grating radiation antenna 34, the second port 332, and the third port 333.

[0068] The phase modulator 31 is electrically connected to the signal processing and control unit 5. Under the control of the signal processing and control unit 5, the phase modulator 31 makes the signal light have a phase Δφ0, and the output signal light is scanned to the detection area through the N grating radiation antennas 34. The scanning deflection angle is (θ x0 ,θ y0), the phase Δφ0 makes the N grating radiation antennas 34 at (θ x0 ,θ y0 ) The echo signal superposition received in the direction has a maximum value;

[0069] The 1×2 beam splitter 32 has a splitting ratio of 1:1 to 1:99, the frequency shifter 35 has a frequency shift of 1 to 100 MHz, the 90° optical mixer 36 is a multimode interference coupler or includes a directional coupler and a phase shifter, the grating radiation antennas 34 are arranged in a one-dimensional or two-dimensional periodic pattern, or the grating radiation antennas 34 are arranged in a specific sparse pattern, and the number of grating radiation antennas in the x and y directions is n1 and n2, respectively, where n1×n2=N;

[0070] As shown in FIG3 , the grating radiation antenna 34 has a period T i When arranged, the scanning angle range θ in the x and y directions i (i=x, y) is:

[0071] Where λ is the wavelength of the signal transmitted by the lidar system;

[0072] The laser emitting unit 1 is a semiconductor laser chip or a fiber laser. The output wavelength of the laser emitting unit 1 is between the visible light and far infrared bands. The laser signal emitted by the laser emitting unit 1 is a pulsed laser signal or a frequency modulated continuous wave laser signal that can be used for time-of-flight ranging method or frequency modulated continuous wave ranging method respectively.

[0073] The total beam splitter 2 and the laser emitting unit 1 are connected via an on-chip waveguide. The total beam splitter 2 is a 1×N beam splitter. The number of array elements of the balanced detector array 4 is N.

[0074] The signal processing and control unit 5 includes an amplifier, a filter and a processor.

[0075] Example 2

[0076] As shown in FIG4 , a control method for transmitting and receiving a coaxial phased array lidar chip includes the following steps:

[0077] S1: The transceiver coaxial phased array lidar chip starts working, laser emission enters step S2, and echo signal reception and processing enters step S3;

[0078] S2. The optical signal output by the laser emitting unit 1 is split into N optical signals by the total beam splitter 2 and transmitted to the transceiver phased array 3. The transceiver phased array 3 performs phase control on the N optical signals according to the control signal of the signal processing and control unit 5, and then splits the N optical signals into N phase-modulated reference lights and N phase-modulated signal lights. The N phase-modulated reference lights are frequency-shifted to obtain N frequency-shifted reference lights, and the process proceeds to step S3. The N phase-modulated signal lights are radiated into free space by the transceiver phased array 3, and the emission direction is (θx0 ,θ y0 ), and generate an echo signal to enter step S3;

[0079] The transceiver phased array 3 includes N phased array elements, each of which includes an optically connected phase modulator 31, a beam splitter 32, a circulator 33, a grating radiation antenna 34, a frequency shifter 35 connected to another outlet of the beam splitter 32, and a 90° optical mixer 36 connected to the third port of the circulator 33. The outlet of the frequency shifter 35 is also connected to the inlet of the 90° optical mixer 36. The inlet of the phase modulator 31 is optically connected to each of the N outlets of the total beam splitter 2, and the 90° optical mixer 36 is optically connected to the inlet of the balanced detector array 4.

[0080] The phase modulator 31 makes the (m, n)th reference light have a phase Δφ0(m, n);

[0081] In the (m, n)th phased array element, the optical signal is first phase-modulated by the phase modulator 31, and the phase Δφ0(m, n) is set to obtain the phase-modulated signal light. The phase Δφ0(m, n) compensates the phase of the (m, n)th grating radiation antenna 34 so that the N phase-modulated signal lights emitted by the N grating radiation antennas 34 are at (θ x0 ,θ y0 ) direction, θ x0 ,θ y0 are the azimuth angles of the outgoing light in the x and y directions respectively;

[0082] Wherein, Δφ1(m,n) is the (m,n)th grating radiation antenna 34 at (θ x1 ,θ y1 ) direction, T x is the arrangement period of N grating radiation antennas in the x direction, T y is the arrangement period of N grating radiation antennas in the y direction, θ x1 ,θ y1 are the azimuths in the x and y directions respectively;

[0083] When the (m, n)th grating radiation antenna 34 is at (θ x1 ,θ y1 ) direction when the optical path phase delay and phase difference Δφ0(m,n) are compensated: x1 =θ x0 ,θ y1 =θ y0 ;

[0084] The phase difference between the N frequency-shifted reference beams and the N phase-modulated signal beams is Δf.

[0085] S3, the transceiver phased array 3 receives the echo signal and performs coherent mixing with N-way frequency-shifted reference light to obtain a beat frequency signal which is output to the balanced detector array 4. The receiving field of view center of the transceiver phased array 3 is (θ x0 ,θ y0 ), the balanced detector array 4 converts the beat frequency signal with the echo signal information into an electrical signal and outputs it to the signal processing and control unit 5, which analyzes the signal and obtains the three-dimensional information of the target area;

[0086] The superposition output signal of the echo signal and the phase-modulated reference light is (θ x0 ,θ y0 ) direction has a maximum value;

[0087] The signal received by the (m, n)th grating radiation antenna 34 is:

[0088] Among them, E i (θ x2 ,θ y2 ) is the optical field of the echo signal at (θ x2 ,θ y2 ) direction, G(θ ，2 ,θ y2 ) is the unit pattern of a single grating radiation antenna, which means (θ ，2 ,θ y2 ) direction of the plane wave vector and the electric field coupling strength of the grating radiation antenna, Δφ2(m,n) is (θ ，2 ,θ y2 ) direction reaches the optical path phase difference of the (m, n)th grating radiation antenna 34:

[0089] The phase modulator 31 performs phase control on the N phased array elements. The reference light phase modulation value of the phased array element where the (m, n) grating radiation antenna is located is Δφ0(m, n). The N phased array elements receive signals superimposed and E R (θ x0 ,θ y0 )for:

[0090] When Δφ2=Δφ0, that is, θ ，2 =θ ，0 ,θ y2 =θ y0 When , the superimposed signal has a maximum value;

[0091] The signal frequency of the beat signal is Δf;

[0092] The control method for transmitting and receiving coaxial phased array lidar chips is completed.

[0093] Example 3

[0094] As shown in Figures 1 to 4, a transceiver coaxial phased array laser radar chip and its control method,

[0095] Figure 1 shows a schematic diagram of a transceiver coaxial phased array LiDAR chip in an embodiment of the present disclosure. Referring to Figure 1 , the transceiver coaxial phased array LiDAR chip includes: a laser emitting unit 1, a total beam splitter 2, a transceiver phased array 3, a balanced detector array 4, and a data processing and control unit 5.

[0096] Among them, the laser emitting unit 1 is used to emit a laser signal. Optionally, the laser emitting unit is a semiconductor laser, and its laser signal is a pulse signal. The total beam splitter 2 and the laser emitting unit 1 are connected by an on-chip waveguide, which is used to split the light output by the laser emitting unit 1 into N paths and transmit them to the transceiver phased array 3. The transceiver phased array 3 has N phased array elements, wherein each element is respectively connected to each output light path of the total beam splitter 2. Each element changes the direction of the system's output laser signal through phase modulation to complete the scanning of the target area. The target reflected echo laser signal is received by the transceiver phased array 3 and converted into an electrical signal by the balanced detector array 4. The signal processing and control unit 5 calculates the distance to the target through the time difference between the transmitted pulse and the received echo pulse, and at the same time forms three-dimensional information of the target by combining the scanning of the transmitted light beam by the transceiver phased array.

[0097] Figure 2 shows a schematic diagram of a single element of a transceiver phased array according to an embodiment of the present disclosure. The transceiver phased array 3 comprises nine identical phased array units. Each element includes a phase modulator 31, a 1×2 beam splitter 32, a circulator 33, a grating radiating antenna 34, a frequency shifter 35, and a 90° optical mixer 36.

[0098] The phase modulator 31 controls the phase of the laser signal in the phased array unit according to the control signal from the signal processing and control unit 5, adjusting the direction of the transmitting and receiving fields of view. A 1×2 beam splitter 32 splits the laser signal into reference light and signal light, with a power ratio of 4:1 between the signal light and the reference light. The signal light enters port 1 and exits port 2 of the circulator 33, and is then coupled into free space by the grating radiation antenna 34. The reference light is frequency-shifted by the frequency shifter 35, resulting in a frequency difference of Δf = 3 MHz with the signal light. The echo signal light reflected from the target is received by the grating radiation antenna 34, enters port 2 and exits port 3 of the circulator 33, and enters a 90° optical mixer 36 for coherent mixing with the frequency-shifted reference light, generating a beat signal with a signal frequency of Δf. The circulator is a multi-port device that ensures the isolation of the echo laser signal from the transmitted laser signal.

[0099] FIG3 shows a schematic diagram of the arrangement of grating radiation antennas of multiple elements of the phased array for transmitting and receiving the present invention. 34 is a grating radiation antenna of a single element. The grating radiation antennas of the 9 elements are evenly arranged, and the arrangement periods in the x and y directions are T x and T y .

[0100] When the phased array is used for transmission, the phase of each element of the phased array is controlled by the phase modulator 31 so that the phase adjustment value of the phased array element where the (m, n) grating radiation antenna is located is:

[0101] Then when the (m, n)th grating radiation antenna is at (θ x1 ,θ y1 ) direction:

[0102] When the phase difference Δφ0(m,n) produced by phase modulation is compensated, that is, θ x1 =θ x0 ,θ y1 =θ y0 When all the grating radiation antennas emit light at (θ c0 ,θ y0 ) direction, the light from the N grating radiating antennas is coherent and constructive, resulting in a very strong beam in that direction. At the same time, in other directions, because the "all in phase" is not satisfied, the beam intensity is very small, that is, the phased array outgoing light in (θ x0 ,θ y0 By controlling the phase modulator 31 of each element of the transceiver phased array 3, the phased array output light can be scanned in the target area.

[0103] When the phased array is used for reception, the signal received by the (m, n)th grating radiation antenna can be expressed as the following integral form:

[0104] Among them, E i (θ x2 ,θ y2 ) is the optical field of the echo signal at (θ x2 ,θ y2 ) direction, G(θ x2 ,θ y2 ) is the unit pattern of a single grating radiation antenna, which means (θ x2 ,θ y2 ) direction of the plane wave vector and the electric field coupling strength of the grating radiation antenna, Δφ2(m,n) is (θ x2 ,θ y2 ) direction to the (m, n)th grating radiation antenna:

[0105] At the same time, since the phase modulator 31 controls the phase of each element of the phased array, the reference light phase modulation value of the phased array element where the (m, n) grating radiation antenna is located is Δφ0(m, n)

[0106] The sum of the received signals of all phased array elements and E R (θ x0 ,θ y0 )for:

[0107] From the above formula, we can see that when Δφ2=Δφ0, that is, θ x2 =θ x0 ,θ y2 =θ y0 When , the superimposed signal has a maximum value.

[0108] Therefore, the phased array can be regarded as a lensless optical system that rotates according to the phase difference. When the phase modulator 31 adjusts the phase value of the phased array element where the (m, n) grating radiation antenna is located to Δφ0(m, n), the transmission angle of the transmitting and receiving phased array is (θ x0 ,θ y0 ), the receiving field of view center is also (θ x0 ,θ y0 ).

[0109] FIG5 shows a flowchart of the phased array laser radar, and FIG4 is combined with the flowchart of the transceiver phased array laser radar system of this embodiment to illustrate the workflow:

[0110] (1) The laser emitting unit 1 provides a light source input to the total beam splitter 2, which is evenly divided into N parts and sent to the transceiver phased array 3 with N phased array units;

[0111] (2) In the (m, n)th phased array unit, the optical signal is first phase-modulated by the phase modulator 31 to set the phase:

[0112] Then it is divided into reference light and signal light to be output by the beam splitter 32;

[0113] (3) The signal light is input to port 1 of the circulator 33, output from port 2, and diffracted into free space by the grating antenna 34. Since the (m, n)th phased array unit has a set phase difference Δφ0(m, n), in (θ x0 ,θ y0 ) direction to form an equiphase surface, the output light will be in (θ x0 ,θ y0 ) direction;

[0114] (4) The echo signal light in all directions is received by the grating radiation antenna 34, input by port 2 of the circulator 33, and output by port 3;

[0115] (5) The reference light passes through the frequency shifter 35, making it have a frequency difference of Δf with the signal light, and then inputs into the 90° optical mixer 36. Since the (m, n)th reference light has a phase of Δφ0(m, n), the final received superimposed output signal is at (θ x0 ,θ y0 ) direction has a maximum value.

[0116] (6) The coherent mixing signal is converted into an electrical signal by the balanced detector 4, and then processed by the data processing and control unit 5 to obtain the three-dimensional information of the target area.

[0117] In existing technologies, the laser emission axis of the off-axis laser radar system and the receiving axis of the telescope do not coincide. Since the field of view of the receiving optical path is limited, the echo signal in the off-axis light-receiving optical path needs to reach a certain distance before entering the receiving field of view. This also leads to a large blind spot in the field of view of the off-axis laser radar. The farther the distance between the transmitting axis and the receiving axis, the larger the blind spot, which is usually around 4m.

[0118] This embodiment can realize coaxial detection of transmission and reception, and can share the same transmitting and receiving lens. The transmitting and receiving fields of view overlap, and there is no need to align the transmitting and receiving fields of view. There is no blind spot problem caused by the incomplete overlap of the transmitting field of view and the receiving field of view of the off-axis transmitting and receiving radar system. In theory, there is only a blind spot caused by the dead time of the detector inside the system, which is about 0.1m-2m.

[0119] Compared with direct detection, this embodiment uses a balanced detector coherent detection system, which provides P ref / O r Additional gain, O ref is the reference optical power, O r The weaker the received signal, the more pronounced the advantage of balanced detector coherent detection. The effectiveness of balanced detector coherent detection is related to the splitting ratio. When the splitting ratio is 1:1, the signal-to-noise ratio is typically more than 20dB higher than that of single detector detection.

[0120] This LiDAR system uses a coaxial phased array for transmission and reception, which controls the transmission and reception fields of view through the phased array. The system's reception field of view flexibly rotates with the transmission field of view, resulting in a small static field of view and a large dynamic field of view. This helps reduce stray light and improve the signal-to-noise ratio. It also solves the problem of large blind spots and difficult alignment caused by traditional optical phased arrays that are only used for transmission and not for reception, and the different axes of the transmission and reception paths. The system also uses a coherent detection system, which helps improve the signal-to-noise ratio. At the same time, because all key components of the LiDAR are based on semiconductor materials, it is easy to integrate optical components and printed circuit boards, which improves the integration of the LiDAR system. This LiDAR has the advantages of flexible field of view, high signal-to-noise ratio, easy integration, and low cost.

[0121] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A transceiver coaxial phased array laser radar chip, characterized by: A laser emitting unit (1), a total beam splitter (2), and a transceiver phased array (3) optically connected in sequence, a balanced detector array (4) optically connected to a receiving output port of the transceiver phased array (3), and a signal processing and control unit (5) electrically connected to the laser emitting unit (1), the transceiver phased array (3), and the balanced detector array (4); The laser emitting unit (1) generates an optical signal under the control of the signal processing and control unit (5) and outputs the optical signal to the total beam splitter (2). The total beam splitter (2) splits the optical signal into N optical signals and outputs the signals to the transceiver phased array (3). The transceiver phased array (3) performs phase modulation on the N optical signals under the control of the signal processing and control unit (5) and outputs the signals as N phase-modulated signal lights and N phase-modulated reference lights. The N phase-modulated signal lights are projected to the detection area for scanning via the transceiver phased array (3). The scanning deflection angle is (θ x0 ,θ y0 ), N is greater than 2, the transceiver phased array (3) receives the echo signal light reflected by the target in the detection area and performs coherent mixing with the frequency-shifted N-channel phase-modulated reference light to generate a beat frequency signal which is output to the balanced detector array (4), and the receiving field of view center direction of the transceiver phased array (3) is (θ x0 ,θ y0 ), the balanced detector array (4) converts the beat signal with echo signal information into an electrical signal and outputs it to the signal processing and control unit (5), the signal processing and control unit (5) processes the electrical signal and calculates the three-dimensional depth and / or speed information of the target in the detection area based on the time difference between the light signal output by the laser emitting unit (1) and the echo signal.

2. The transceiver coaxial phased array laser radar chip according to claim 1, characterized in that: The transceiver phased array (3) comprises N phased array elements, all of which are optically connected to the output end of the total beam splitter (2); The phased array element comprises an optically connected phase modulator (31), a 1×2 beam splitter (32), a circulator (33), a grating radiation antenna (34), a frequency shifter (35) connected to another outlet of the 1×2 beam splitter (32), and a 90° optical mixer (36) connected to a third port of the circulator (33), the outlet of the frequency shifter (35) is also connected to the inlet of the 90° optical mixer (36), and the 90° optical mixer (36) is optically connected to the inlet of the balanced detector array (4); The circulator (33) comprises a first port (331) optically connected to the output end of the 1×2 beam splitter (32), a second port optically connected to the end of the grating radiation antenna (34), (332) and a third port (333) connected to the input end of the 90° optical mixer (36), the N-channel phase-modulated signal light is output to the grating radiation antenna (34) via the first port (331) and the second port (332) in sequence, and the echo signal enters the 90° optical mixer (36) via the grating radiation antenna (34), the second port (332) and the third port (333) in sequence.

3. The transceiver coaxial phased array laser radar chip according to claim 2, characterized in that: The phase modulator (31) is electrically connected to the signal processing and control unit (5). Under the control of the signal processing and control unit (5), the phase modulator (31) causes the optical signal to have a phase Δφ0, and projects the output signal light to the detection area for scanning via the N grating radiation antennas (34). The scanning deflection angle is (θ x0 ,θ y0 ), the phase Δφ0 makes the N grating radiation antennas (34) at (θ x0 ,θ y0 ) direction has a maximum value.

4. The transceiver coaxial phased array laser radar chip according to claim 2, characterized in that: The 1×2 beam splitter (32) has a beam splitting ratio of 1:1 to 1:99, the frequency shift of the frequency shifter (35) is 1 to 100 MHz, the 90° optical mixer (36) is a multimode interference coupler or includes a directional coupler and a phase shifter, the grating radiation antennas (34) are arranged in a one-dimensional or two-dimensional periodic manner, or the grating radiation antennas (34) are sparsely arranged, and the numbers of the grating radiation antennas (34) in the x and y directions are n1 and n2 respectively, and n1×n2=N; The grating radiation antenna (34) has a period T i When arranging, the scanning angle range of x and y directions is θ i (i=x, y) is: Where λ is the wavelength of the signal emitted by the lidar system.

5. The transceiver coaxial phased array laser radar chip according to claim 1, characterized in that: The laser emitting unit (1) is a semiconductor laser chip or a fiber laser, the output wavelength of the laser emitting unit (1) is between the visible light and far infrared bands, and the laser signal emitted by the laser emitting unit (1) is a pulse laser signal or a frequency modulated continuous wave laser signal that can be used for a time-of-flight ranging method or a frequency modulated continuous wave ranging method respectively; The total beam splitter (2) and the laser emitting unit (1) are connected via an on-chip waveguide, and the total beam splitter (2) is a 1×N beam splitter; the array of the balanced detector array (4) is The number of elements is N; The signal processing and control unit (5) comprises an amplifier, a filter and a processor.

6. A control method for transmitting and receiving a coaxial phased array laser radar chip, characterized in that: The following steps are involved: S1, the transceiver coaxial phased array laser radar chip starts working, the laser emission enters step S2, and the echo signal reception and processing enters step S3; S2, the optical signal output by the laser emitting unit (1) is divided into N optical signals by the total beam splitter (2) and transmitted to the transceiver phased array (3), the transceiver phased array (3) performs phase control on the N optical signals according to the control signal of the signal processing and control unit (5) and then splits them to obtain N phase-modulated reference lights and N phase-modulated signal lights, the N phase-modulated reference lights are frequency-shifted to obtain N frequency-shifted reference lights and enter step S3, the N phase-modulated signal lights are radiated to free space by the transceiver phased array (3), and the emission direction is (θ x0 ,θ y0 ), and generate an echo signal to enter step S3; S3, the transceiver phased array (3) receives the echo signal and performs coherent mixing with the N frequency-shifted reference lights to obtain a beat frequency signal which is output to a balanced detector array (4), and the receiving field of view center of the transceiver phased array (3) is (θ x0 ,θ y0 ), the balanced detector array (4) converts the beat frequency signal with echo signal information into an electrical signal and outputs it to the signal processing and control unit (5), the signal processing and control unit (5) performs analysis to obtain three-dimensional information of the target area, and the control method for transmitting and receiving the coaxial phased array laser radar chip is completed.

7. The control method for a transceiver coaxial phased array laser radar chip according to claim 1, characterized in that: In step S2, the transceiver phased array (3) includes N phased array elements, and the phased array elements include an optically connected phase modulator (31), a beam splitter (32), a circulator (33), a grating radiation antenna (34), a frequency shifter (35) connected to another outlet of the beam splitter (32), a 90° optical mixer (36) connected to the third port of the circulator (33), the outlet of the frequency shifter (35) is also connected to the inlet of the 90° optical mixer (36), the inlet of the phase modulator (31) is optically connected to the N outlets of the total beam splitter (2), and the 90° optical mixer (36) is optically connected to the inlet of the balanced detector array (4); In the (m, n)th phased array element, the optical signal is first phase-modulated by the phase modulator (31), and the phase Δφ0(m, n) is set to obtain phase-modulated signal light. The phase Δφ0(m, n) compensates the phase of the (m, n)th grating radiation antenna (34) so ​​that the N phase-modulated signal lights emitted by the N grating radiation antennas (34) are at (θ x0 ,θ y0 ) direction, θ x0 ,θ y0 are the azimuth angles of the outgoing light in the x and y directions respectively; In step S2, the phase modulator (31) makes the (m, n)th reference light have the phase Δφ0(m, n); In step S3, the superposition output signal of the echo signal and the phase-modulated reference light is (θ x0 ,θ y0 ) direction has a maximum value.

8. The control method for a transceiver coaxial phased array laser radar chip according to claim 7, characterized in that: In step S2, Wherein, Δφ1(m, n) is the value of the (m, n)th grating radiation antenna (34) at (θ x1 ,θ y1 ) direction, T x is the arrangement period of the N grating radiation antennas in the x direction, T y is the arrangement period of the N grating radiation antennas in the y direction, θ x1 ,θ y1 are the azimuths in the x and y directions respectively; When the (m, n)th grating radiation antenna (34) is at (θ x1 ,θ y1 ) direction when the optical path phase delay and phase difference Δφ0(m,n) are compensated: i x1 =θ x0 、the y1 =θ y0 。 9. The control method for a transceiver coaxial phased array laser radar chip according to claim 7, characterized in that: In step S3, the signal received by the (m, n)th grating radiation antenna (34) is: Among them, E i (θ x2 ,θ y2 ) is the optical field of the echo signal at (θ x2 ,θ y2 ) direction, G(θ x2 ,θ y2 ) is the unit radiation pattern of a single grating radiation antenna, indicating that (θ x2 ,θ y2 ) direction of the plane wave vector and the electric field coupling intensity of the grating radiation antenna, Δφ2(m, n) is (θ x2 ,θ y2 ) direction to the (m, n)th grating radiation antenna (34): The phase modulator (31) performs phase control on the N phased array elements, the reference light phase modulation value of the phased array element where the (m, n)th grating radiation antenna is located is Δφ0(m, n), and the superposition sum of the received signals of the N phased array elements is: When Δφ2=Δφ0, that is, θ x2 =θ x0 ,θ y2 =θ y0 When , the superimposed signal has a maximum value.

10. The control method for a transceiver coaxial phased array laser radar chip according to claim 6, characterized in that: In step S2, the phase difference between the N channels of frequency-shifted reference light and the N channels of phase-modulated signal light is Δf. In step S3, the signal frequency of the beat signal is Δf.

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