Continuous wave frequency modulation phased array laser radar chip, scanning method and laser radar

Abstract

The present application provides a continuous wave frequency modulated phased array laser radar chip, scanning method, and laser radar. The chip includes an input coupler for coupling input light to the chip; a first coupler for transmitting the light for transmission coupled to the chip to a beam splitter; a beam splitter for splitting the light for transmission and outputting multiple transmission light waves; a phase modulator for phase-modulating the transmission light waves; an optical antenna for transmitting the phase-modulated transmission light waves into space and receiving the reflected light waves reflected by the measured object in space, and transmitting the reflected light waves to a receiving light processing layer via the phase modulator, the beam splitter, and the first coupler; a first coupler for receiving the received light received by the optical antenna on the chip and transmitting the received light to the receiving light processing layer; and a receiving light processing layer for performing signal processing on the received light and outputting an electrical signal. This ensures consistent performance with traditional phased array systems with separate transmitters and receivers while reducing the complexity of the entire system.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of radar technology, and in particular to a continuous wave frequency modulated phased array laser radar chip, a scanning method, and a laser radar. Background Art

[0002] The concept of continuous-wave frequency-modulated phased array lidar has long been proposed, and various design solutions are under development. The basic modules in current continuous-wave frequency-modulated phased array lidars are also mature, such as the light source module, beam splitter module, phase modulation module, balanced detection module, and optical antenna on the lidar chip. To achieve light transmission and reception, continuous-wave frequency-modulated phased array lidar chips typically use two independent phased array systems (which can include beam splitters, phase modulation modules, optical antennas, etc.) to achieve transmission and reception.

[0003] For example, one phased array system uses a phase modulation module to adjust the phase to transmit light at different angles, while another phased array system follows the transmission angle of the transmitting system on the lidar chip to detect light reflected back to the chip along the same path. However, this doubles the number of components on the chip, making it more complex. Similarly, the driver circuit in the lidar system, which drives the chip to operate normally, also requires twice the control volume, which is detrimental to the entire lidar system.

[0004] There is no solution in the prior art that can reduce the complexity of the entire system while ensuring the same performance as a traditional phased array system with separate transmitters and receivers. Summary of the Invention

[0005] The embodiments of the present application provide a continuous wave frequency modulated phased array lidar chip, a scanning method, and a lidar, which can ensure the same performance as a traditional phased array system with separate transmitters and receivers while reducing the complexity of the entire system.

[0006] In a first aspect, an embodiment of the present application provides a continuous wave frequency modulated phased array laser radar chip, comprising: an input coupler, a first coupler, a beam splitter, a phase modulator, an optical antenna, and a received light processing layer;

[0007] The input coupler and the receiving light processing layer are respectively connected to the first coupler through waveguides, and the first coupler, beam splitter, phase modulator and optical antenna are sequentially connected through waveguides;

[0008] The input coupler is used to couple input light to the chip;

[0009] The first coupler is used to transmit the light for emission coupled to the chip to the beam splitter;

[0010] The beam splitter is used to split the light for emission and output multiple emission light waves;

[0011] The phase modulator is used to phase modulate the transmitted light wave;

[0012] The optical antenna is configured to transmit the phase-modulated transmitted light wave into space, receive the reflected light wave reflected by the measured object in the space, and transmit the reflected light wave to the receiving light processing layer via the phase modulator, the beam splitter, and the first coupler;

[0013] The first coupler is further configured to receive received light on the chip via the optical antenna and transmit the received light to the received light processing layer;

[0014] The received light processing layer is used to perform signal processing on the received light and output an electrical signal.

[0015] In one possible design, the continuous wave frequency modulated phased array lidar chip as described above further includes: a power divider;

[0016] The input end of the power divider is connected to the input coupler via a waveguide, and the output end of the power divider is connected to the first coupler and the receiving light processing layer;

[0017] The power divider is used to distribute energy of the light coupled to the chip to obtain emission light and local light. The emission light is transmitted to the first coupler, and the local light is transmitted to the receiving light processing layer.

[0018] In one possible design, in the continuous wave frequency modulated phased array lidar chip described above, the receiving light processing layer includes: a balanced detector and a second coupler;

[0019] The input end of the second coupler is connected to the output end of the power divider and the first coupler through a waveguide, and the output end of the second coupler is connected to the balanced detector through a waveguide;

[0020] The second coupler is configured to beat the local light and the reflected light wave, and transmit the beat light wave to the balanced detector;

[0021] The balanced detector is used to detect the beat light wave and output an electrical signal of the detected light wave.

[0022] In one possible design, the continuous wave frequency modulated phased array lidar chip described above further includes: an SOI substrate;

[0023] The input coupler, the first coupler, the beam splitter, the phase modulator, the optical antenna, and the receiving light processing layer are located on the top silicon layer of the SOI substrate.

[0024] In a possible design, the waveguide in the chip is a TE mode single-mode waveguide, and the shape of the TE mode single-mode waveguide is a ridge waveguide or a strip waveguide.

[0025] In one possible design, in the continuous wave frequency modulated phased array lidar chip as described above, the power divider is an optical switch type power divider.

[0026] In one possible design, in the continuous wave frequency modulated phased array lidar chip described above, the balanced detectors are two waveguide silicon germanium detectors.

[0027] In one possible design, in the continuous wave frequency modulated phased array lidar chip as described above, the structure of the first coupler is a 2*1 multimode interference coupler or a 2*2 multimode interference coupler, and the structure of the second coupler is a 50:50 directional coupler or a 2*2 multimode interference coupler.

[0028] In a second aspect, an embodiment of the present application provides a phased array lidar, comprising a continuous wave frequency modulated phased array lidar chip as described in any one of the first aspects above.

[0029] In a third aspect, an embodiment of the present application provides a scanning method applied to a phased array laser radar of the above-mentioned continuous wave frequency modulation phased array laser radar chip, the method comprising:

[0030] When the light source is turned on, the power divider is adjusted to adjust the light used for emission and the local light used for balanced detection to a preset ratio, wherein the light source is a laser with a periodic linear frequency change, and the light of the light source is coupled to the chip through an input coupler;

[0031] adjusting the phase modulator so that the light emitted from the optical antenna is emitted from a preset first direction;

[0032] Adjusting the voltage or current of the phase modulator to remain constant so that, while the optical antenna is transmitting, the received light reflected by the object to be measured passes through the phase modulator and the beam splitter in sequence, is reversely transmitted through the first coupler output end of the first coupler to the fourth input end of the first coupler, and is then transmitted through the fourth input end to the second input end of the second coupler, wherein the received light beats with the local light in the second coupler, and the resulting light wave is transmitted to the balanced detector, which outputs a detected electrical signal;

[0033] Continue to adjust the phase modulator so that the light emitted from the optical antenna is emitted from a preset second direction, and continue to adjust the voltage or current of the phase modulator unchanged so that the balanced detector outputs the detected electrical signal, until the phase modulator is adjusted so that the object to be measured is scanned at least once by the phased array lidar.

[0034] The embodiment of the present application provides a continuous wave frequency modulation phased array laser radar chip, a scanning method and a laser radar, wherein the continuous wave frequency modulation phased array laser radar chip includes: an input coupler, a first coupler, a beam splitter, a phase modulator, an optical antenna and a receiving light processing layer; the input coupler and the receiving light processing layer are respectively connected to the first coupler through a waveguide, and the first coupler, the beam splitter, the phase modulator and the optical antenna are connected in sequence through a waveguide; the input coupler is used to couple input light to the chip; the first coupler is used to transmit the light for transmission coupled to the chip to the beam splitter; the beam splitter , for splitting the transmitted light and outputting multiple transmitted light waves; the phase modulator is used to phase-modulate the transmitted light waves; the optical antenna is used to transmit the phase-modulated transmitted light waves into space, and receive the reflected light waves reflected by the measured object in the space, and transmit the reflected light waves to the receiving light processing layer via the phase modulator, the beam splitter, and the first coupler; the first coupler is also used to receive the received light received on the chip by the optical antenna and transmit the received light to the receiving light processing layer; the receiving light processing layer is used to perform signal processing on the received light and output an electrical signal. Because the continuous wave frequency modulation phased array lidar chip separates the transmitted signal light and the received signal light on the chip through the first coupler, and the beam splitter, phase modulator, and optical antenna work together to achieve the transmission and reception of light at different angles in space, achieving integrated transmission and reception. In addition, the continuous wave frequency modulation phased array lidar chip uses the same phased array system for transmission and reception, which has a compact structure and greatly simplifies the complexity of the entire system.

[0035] It should be understood that the contents described in the above summary of the invention are not intended to limit the key or important features of the embodiments of the present application, nor are they intended to limit the scope of the present application. Other features of the present application will become easier to understand through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0037] Figure 1 A schematic diagram of the structure of a continuous wave frequency modulated phased array lidar chip provided in an embodiment of the present application;

[0038] Figure 2 A schematic structural diagram of a continuous wave frequency modulated phased array lidar chip provided in yet another embodiment of the present application;

[0039] Figure 3 A schematic diagram of the structure of a continuous wave frequency modulated phased array lidar chip provided in yet another embodiment of the present application;

[0040] Figure 4 A schematic structural diagram of a continuous wave frequency modulated phased array lidar chip provided in another embodiment of the present application;

[0041] Figure 5 A schematic diagram of the structure of an SOI substrate including a protective layer in a continuous wave frequency modulated phased array laser radar provided in yet another embodiment of the present application;

[0042] Figure 6 A schematic diagram of a scanning method according to an embodiment of the present invention;

[0043] Figure 7 A schematic diagram of the transmission process in a scanning method provided in yet another embodiment of the present application;

[0044] Figure 8 A schematic diagram of the receiving process in the scanning method provided in another embodiment of the present application.

[0045] Reference numerals:

[0046] 10-input coupler 20-first coupler 30-beam splitter 40-phase modulator 50-optical antenna 60-receiving light processing layer 70-power divider 601-second coupler 602-balanced detector 11-substrate silicon layer 12-buried oxide layer 13-top silicon layer 14-protective layer DETAILED DESCRIPTION

[0047] The following describes embodiments of the present application in more detail with reference to the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be construed as limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are for illustrative purposes only and are not intended to limit the scope of protection of the present application.

[0048] The terms "first," "second," "third," "fourth," and the like (if any) in the description and claims of the embodiments of the present application and in the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein, for example, can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusions.

[0049] Figure 1 This is a schematic diagram of the structure of the continuous wave frequency modulated phased array laser radar chip provided in the embodiment of this application. Figure 1 As shown, the continuous wave frequency modulated phased array laser radar chip provided in this embodiment includes: an input coupler 10, a first coupler 20, a beam splitter 30, a phase modulator 40, an optical antenna 50 and a receiving light processing layer 60.

[0050] The input coupler 10 and the receiving light processing layer 60 are respectively connected to the first coupler 20 via waveguides, and the first coupler 20, the beam splitter 30, the phase modulator 40 and the optical antenna 50 are sequentially connected via waveguides.

[0051] Specifically, the input coupler 10 is used to couple the input light to the chip. The first coupler 20 is used to transmit the light for emission coupled to the chip to the beam splitter. The beam splitter 30 is used to split the light for emission and output multiple emission light waves; the phase modulator 40 is used to phase-modulate the emission light waves; the optical antenna 50 is used to transmit the phase-modulated emission light waves into space, and receive the reflected light waves reflected back by the measured object in the space, and transmit the reflected light waves to the receiving light processing layer 60 through the phase modulator 40, the beam splitter 30 and the first coupler 20; the first coupler 20 is also used to receive the received light received on the chip through the optical antenna 50, and transmit the received light to the receiving light processing layer 60; the receiving light processing layer 60 is used to perform signal processing on the received light and output an electrical signal. The chip further includes an SOI substrate; the input coupler 10, the first coupler 20, the beam splitter 30, the phase modulator 40, the optical antenna 50, and the received light processing layer 60 are located on the top silicon layer 13 of the SOI substrate. The reflected light wave is the light wave reflected back after the transmitted light wave reaches the object being measured in the space.

[0052] In practical applications, a continuous-wave frequency-modulated phased array lidar chip can be integrated on a standard substrate compatible with CMOS technology, namely an SOI substrate, and the various devices on the chip can be connected via waveguides. The SOI substrate comprises, from bottom to top, a substrate silicon layer 11, a buried oxide layer 12, and a top silicon layer 13. The input coupler 10, the first coupler 20, the beam splitter 30, the phase modulator 40, the optical antenna 50, and the received light processing layer 60 are formed on the top silicon layer 13 of the SOI substrate. In this embodiment, there is no restriction on the material and thickness of each layer of the SOI substrate. The material and thickness of each layer can be customized according to different requirements, or a conventional standard CMOS process SOI substrate product can be used. For example, the substrate silicon layer 11 is made of silicon with a thickness of 400 to 800 μm; the buried oxide layer 12 is made of silicon dioxide with a thickness of 2 μm; and the top silicon layer 13 is made of silicon with a thickness of 220 nm.

[0053] The input coupler 10 is used to couple laser light emitted by an off-chip laser to the chip. The off-chip laser light here can serve as input light, and its frequency is linearly modulated. The laser is a laser with a periodic, linearly varying frequency. Current continuous-wave frequency-modulated phased array LiDAR chips typically use two independent phased array systems to transmit and receive light. This doubles the number of devices on the chip, making it more complex. Similarly, the driver circuit in the LiDAR system, which drives the chip to operate normally, also requires twice the control capability, which is detrimental to the entire LiDAR system.

[0054] To solve the above problems, the present embodiment adopts the coordinated work of the first coupler 20, the beam splitter 30, the phase modulator 40, and the optical antenna 50 to realize the transmission and reception of light at different angles in space, so that the transmission and reception of the continuous wave frequency modulated phased array lidar chip use the same phased array system, realizing the integration of transmission and reception. At the same time, due to the compact structure on the chip, the complexity of the entire system is reduced.

[0055] Specifically, the beam splitter 30, the phase modulator 40 and the optical antenna 50 are the phased array module of the phased array laser radar. The beam splitter 30 can split a beam of light into several beams, the specific number of which is not limited in this application.

[0056] For example, the first coupler 20 uses the input coupler 10 to couple the input light to the light for transmission on the chip and transmit it to the beam splitter 30. The beam splitter 30 splits the light into 8 beams, and then each beam is phase-modulated by the phase modulator 40 and transmitted through the optical antenna 50. Similarly, when the optical antenna 50 receives a signal, the beam splitter 30, phase modulator 40, and optical antenna 50 also work in the same manner, but in the opposite order. That is, the light for transmission is emitted from the optical antenna 50 from free space and reflected by the object to be measured before being received into the waveguide on the chip. After being phase-modulated by the phase modulator 40, it is merged into a waveguide through the beam splitter and transmitted to the first coupler. Through the coordinated operation of various components, the transmission and reception of light at different angles are achieved, and the transmission and reception share a set of the above-mentioned components, that is, the same module for transmission and reception.

[0057] Among them, the input coupler 10 is used to couple light waves to the chip. It can couple high-power input light into the chip, and then transmit the light for emission from the light coupled to the chip to the beam splitter 30 through the first coupler 20. The beam splitter 30 splits the light for emission, so the light for emission from the light coupled into the input coupler 10 is divided into several light waves after passing through the beam splitter 30. The phase of each beam or each light wave after splitting is then adjusted by the phase modulator 40, that is, the phase of the light wave in the waveguide is changed. After the phase of the light wave in the waveguide is adjusted by the phase modulator 40, it is transmitted through the waveguide to the optical antenna 50 and emitted into space. The emitted light is reflected back by the object to be measured and received on the chip through the optical antenna 50. It is transmitted through the phase modulator 40 and the beam splitter 30 to the output port of the second coupler 601, which is the port connected to the beam splitter 30, and then transmitted in reverse to an input port of the second coupler 601, which is the port connected to the receiving light processing layer 60, and transmitted to the receiving light processing layer 60, so that the receiving light processing layer 60 processes the received light and outputs an electrical signal.

[0058] The continuous wave frequency modulated phased array laser radar chip provided in this embodiment includes: an input coupler 10, a first coupler 20, a beam splitter 30, a phase modulator 40, an optical antenna 50, and a receiving light processing layer 60; the input coupler 10 and the receiving light processing layer 60 are respectively connected to the first coupler 20 through a waveguide, and the first coupler 20, the beam splitter 30, the phase modulator 40 and the optical antenna 50 are connected in sequence through a waveguide; the input coupler 10 is used to couple the input light to the chip; the first coupler 20 is used to transmit the light for transmission coupled to the chip to the beam splitter 30; the beam splitter 30 is used to transmit the light for transmission coupled to the chip to the optical antenna 50; The transmitted light is split to output multiple transmitted light waves; the phase modulator 40 is used to modulate the phase of the transmitted light waves; the optical antenna 50 is used to transmit the phase-modulated transmitted light waves into space, and receive the reflected light waves reflected back by the object under test in the space, and transmit the reflected light waves to the receiving light processing layer 60 through the phase modulator 40, the beam splitter 30 and the first coupler 20; the first coupler 20 is also used to receive the received light on the chip received by the optical antenna 50, and transmit the received light to the receiving light processing layer 60; the receiving light processing layer 60 is used to perform signal processing on the received light and output an electrical signal. Since the continuous wave frequency modulation phased array laser radar chip separates the signal light for transmission and the signal light for reception on the chip through the first coupler 20, and the beam splitter 30, phase modulator 40 and optical antenna 50 work together, the transmission and reception of light at different angles in space are realized, and the integration of transmission and reception is realized. In addition, the transmission and reception of the continuous wave frequency modulation phased array laser radar chip use the same phased array system, which has a compact structure and greatly simplifies the complexity of the entire system.

[0059] In order to achieve accurate adjustment of the energy of the emitted light and the local light in scenarios with different light source intensities, the emitted light or the light for emission is sequentially transmitted to the first coupler 20, the beam splitter 30, the phase modulator 40 and the optical antenna 50 and emitted into space, see Figure 2 , Figure 2 This is a schematic diagram of the structure of a continuous wave frequency modulated phased array lidar chip provided in another embodiment of the present application. Building on the previous embodiment, this embodiment provides a detailed description of the continuous wave frequency modulated phased array lidar chip. The continuous wave frequency modulated phased array lidar chip also includes a power divider 70.

[0060] The input end of the power divider 70 is connected to the input coupler 10 via a waveguide, and the output end of the power divider 70 is connected to the first coupler 20 and the receiving light processing layer 60. Specifically, the power divider 70 is used to distribute the energy of the light coupled to the chip to obtain emitted light and local light. The emitted light is transmitted to the first coupler 20, and the local light is transmitted to the receiving light processing layer 60.

[0061] In this embodiment, the front end of the power divider 70 is connected to the input coupler 10 via a waveguide, and the rear end of the power divider 70 is connected to the front end of the first coupler 20 (i.e., an input end of the first coupler 20) and the front end of the receiving light processing layer 60 (an input end of the receiving light processing layer 60) via waveguides. The power divider 70 may be an optical switch-type power divider that can precisely adjust the ratio of the energy of the transmitted light to the energy of the local light processed by the receiving light processing layer 60, and transmit the adjusted transmitted light (or transmitted light) to the beam splitter 30, and transmit the adjusted local light to the receiving light processing layer 60. Generally, the power divider 70 can be replaced by a directional coupler of a specific structure. However, once the structure of the directional coupler is determined, the energy ratio between the transmitted light and the local light is fixed, so the energy ratio cannot be adjusted. This, to a certain extent, affects the flexibility of the continuous wave frequency modulated phased array laser radar for integrated transmission and reception. Therefore, an adjustable power divider 70 can be used to finely distribute the power of the transmitted light and the local light.

[0062] In order to process the received light signal and output the detected electrical signal, see Figure 3 , Figure 3 This is a structural diagram of a continuous wave frequency modulated phased array laser radar chip provided in another embodiment of the present application. This embodiment is based on the above embodiment, for example, Figure 2 Based on the above embodiment, a detailed description of the continuous wave frequency modulated phased array lidar chip is provided. The receiving light processing layer 60 includes: a balanced detector 602 and a second coupler 601; the input end of the second coupler 601 is connected to the output end of the power divider 70 and the first coupler 20 via a waveguide, and the output end of the second coupler 601 is connected to the balanced detector 602 via a waveguide; the second coupler 601 is used to beat the local light and the reflected light wave, and transmit the beat light wave to the balanced detector 602; the balanced detector 602 is used to detect the beat light wave and output an electrical signal of the detected light wave.

[0063] In this embodiment, the second coupler 601 has two input ends and one output end. The second coupler 601 can be a 50:50 directional coupler or a 2*2 multimode interference coupler. Different types of second couplers 601 can be selected according to different scenarios. One input end of the second coupler 601, namely the first input end, is connected to the rear end of the power divider 70. Another input end of the second coupler 601, namely the second input end, is connected to the first coupler 20. The output end of the second coupler 601, namely the second coupler output end, is connected to the balanced detector 602.

[0064] In a possible design, the output end of the second coupler includes two first output ports; and the balanced detector 602 is two waveguide silicon germanium detectors.

[0065] There may be two input waveguide ports, and the two input waveguide ports in the balanced detector 602 are respectively connected to the two first output ports of the output end of the second coupler through waveguides.

[0066] Specifically, the first input port is used to input the local light for balanced detection distributed by the power divider 70, and the second input port is used to input the received light transmitted from the output port of the first coupler 20 to the input port of the first coupler 20. The two light beams have different frequencies, beat each other in the second coupler 601, and the beat signal is transmitted to the balanced detector 602 through the two first output ports of the second coupler 601, so that the balanced detector 602 detects the beat light wave (signal) and outputs the electrical signal of the detected light wave.

[0067] In one possible design, the first coupler 20 is provided with a third input end, a fourth input end and a first coupler output end. The structure of the first coupler 20 can be a 2*1 multimode interference coupler or a 2*2 multimode interference coupler. Different types of second couplers 601 can be selected according to different scenarios.

[0068] The third input end is a port connected to the power distributor 70 , the fourth input end is a port connected to the receiving light processing layer 60 , and the first coupler output end is a port connected to the beam splitter 30 .

[0069] Specifically, the first coupler 20 is specifically used to: transmit the light for emission adjusted by the power divider 70 to the beam splitter 30 through the third input end, receive the received light received by the optical antenna 50 on the chip and then transmitted through the phase modulator 40 and the beam splitter 30 in sequence through the first coupler output end, and transmit it in reverse to the fourth input end, and transmit the received light to the second input end through the fourth input end.

[0070] In this embodiment, the first coupler 20 has two input ports and one output port. One input port of the first coupler 20, namely the third input port, is connected to the rear end of the power divider 70, another input port of the first coupler 20, namely the fourth input port, is connected to the second input port of the second coupler 601, and the output port of the first coupler 20, namely the first coupler output port, is connected to the beam splitter 30.

[0071] Specifically, the first coupler 20 is used to separate the light for transmission and the received light on the chip, wherein the third input end of the first coupler 20 is used to transmit the light for transmission allocated by the power divider 70 connected to it to the beam splitter 30 connected to the first coupler output end of the first coupler 20, and the light for transmission is transmitted into space through the phase modulator 40 and the optical antenna 50; the transmitted light is reflected back by the object to be measured and received on the chip through the optical antenna 50, and is transmitted to the first coupler output end through the phase modulator 40 and the beam splitter 30, and is transmitted in reverse to another input port of the first coupler 20, namely the fourth input end, through the first coupler output end, and is transmitted to the second coupler 601 through the fourth input end.

[0072] It should be noted that the output end of the first coupler may include one output port or two output ports. If the first coupler 20 is a 2*1 multimode interference coupler, the output end of the first coupler includes one output port, see Figure 1-Figure 3 As shown in any figure, the position and connection relationship of the first coupler 20 on the chip are the same as those described in the above embodiment, and will not be repeated here. If the first coupler is a 2*2 multimode interference coupler, the output end of the first coupler includes two output ports. In addition to the above Figure 1-Figure 3 In addition to the functions of the above-described embodiment, it also has the function of a first-stage beam splitter.

[0073] Specifically, see Figure 4 , Figure 4 This is a schematic diagram of the structure of a continuous-wave frequency-modulated phased array lidar chip provided in another embodiment of the present application. The two output ports are respectively connected to a beam splitter 30. In addition to the functions described in the above embodiment, the first coupler 20 also functions as a one-to-two beam splitter. That is, the two output waveguides outputted from the two output ports of the first coupler 20 are directly split in the beam splitter 30 at the next level. This is different from the beam splitter 30 in the above embodiment, which needs to split from a single waveguide. This improves the overall operating efficiency of the lidar system.

[0074] In one possible design, to achieve optical connectivity between various devices, based on the above-described embodiment, the waveguide in the continuous-wave frequency-modulated phased array lidar chip provided in this embodiment is a single-mode TE-mode waveguide, shaped as a ridge waveguide or a strip waveguide. The use of a single-mode TE-mode waveguide enables directionally guiding the light waves within the waveguide. Each device is disposed on the top silicon layer 13 of the SOI substrate.

[0075] In one possible design, this embodiment, based on the above embodiments, provides detailed descriptions of the various components on the continuous-wave frequency-modulated phased array lidar chip. The input coupler 10 is an end-face coupler or a grating coupler; the beam splitter 30 is a directional coupler or a multimode interference coupler (or a cascaded 1*2 multimode interference coupler); and the optical antenna 50 is a grating-type optical antenna. The grating is a second-order diffraction grating.

[0076] Specifically, in this embodiment, after the light waves in each waveguide are phase-adjusted by the phase modulator 40, they are transmitted from the waveguide to the optical antenna 50 and emitted into space. In this embodiment, the optical antenna 50 can be a second-order diffraction grating etched on a silicon array waveguide, i.e., a grating-type optical antenna. The specific parameters of the grating, such as the grating period, duty cycle, and etching depth, are all related to the operating wavelength. When etching the grating on the waveguide, the grating period must be calculated based on the etching depth. To achieve a small far-field divergence angle along the waveguide direction and high longitudinal radar scanning resolution, the second-order diffraction grating of the optical antenna 50 is designed to have a shallow etching depth of 20 to 100 nm. Since the optical wavelength range is 1.5 to 1.6 μm, the effective refractive index of the waveguide array for this wavelength range is approximately 2.38. According to the second-order diffraction grating formula, the second-order diffraction grating period is 600 to 680 nm. This means that the grating is uniformly etched on the silicon waveguide at the distance of each grating period. The width of the grating is determined by the duty cycle, which is the ratio of the grating width to the grating period. Calculations show that in the wavelength range of 1.5 to 1.6 μm, the outward radiation efficiency is highest when the duty cycle of the second-order diffraction grating is 0.4 to 0.6.

[0077] In this embodiment, the input coupler 10 can be selected as an end face coupler or a grating coupler. Then, after the end face coupler or grating coupler couples the light wave to the chip, the light wave is transmitted through the single-mode waveguide of the TE mode to the waveguide corresponding to the multimode interference coupler, star coupler or directional coupler, any beam splitter 30. The light wave is divided into a sufficient number of parts, and each beam of light wave is phase-modulated by the phase modulator 40 and then transmitted to the optical antenna 50, so that the optical antenna 50 transmits the light wave with the phase changed by the phase modulator 40 into space, realizing the transmission and reception of light at different angles, ensuring the same performance as the traditional phased array system with separate transmission and reception, while simplifying the structure of the entire lidar system.

[0078] In one possible design, this embodiment, based on the above embodiment, provides a detailed description of the phase modulator 40. For example, the phase modulator 40 in the above-mentioned continuous wave frequency modulated phased array lidar chip can be a thermo-optical phase modulator or an electro-optical phase modulator.

[0079] Among them, the thermo-optical phase modulator is used to heat the waveguide and change the phase of the light wave in the waveguide by changing the refractive index of the waveguide through the thermo-optical effect; the electro-optical phase modulator is used to inject current into the waveguide and change the phase of the light wave in the waveguide by changing the refractive index of the waveguide through the electro-optical effect.

[0080] Specifically, the thermo-optical phase modulator can be a top-heating type or a double-sided heating type, that is, the heating electrodes are placed on the top or both sides of the waveguide. By applying current or voltage bias, the heat generated by the heating electrodes is transferred to the waveguide (which can be a silicon waveguide). Since silicon is a material with a very high thermo-optical coefficient, it is easy to change the refractive index in the waveguide, thereby changing the phase of the light waves in each waveguide. It should be noted that to avoid the heating electrodes being too close to the waveguide, which will absorb the light in the waveguide and cause large losses, the heating electrodes need to be a certain distance away from the waveguide, generally greater than 2μm. In this embodiment, there is no limitation on the materials of the heating electrodes and metal leads, but generally the resistivity of the heating electrodes is approximately an order of magnitude greater than that of the metal leads. The electro-optical phase modulator injects current into the waveguide. When the current passes through, the refractive index of the silicon can be adjusted, thereby changing the phase of the light waves in each waveguide.

[0081] In one possible design, this embodiment, based on any of the above embodiments, provides a detailed description of a continuous-wave frequency-modulated phased array LiDAR chip. The above-described continuous-wave frequency-modulated phased array LiDAR chip further includes a protective layer 14. This protective layer 14 is located above and completely covers the top silicon layer 13. The material of the protective layer 14 is compatible with CMOS processes, and the refractive index of the protective layer 14 is lower than that of silicon.

[0082] In this embodiment, a protective layer 14 covers the entire continuous-wave frequency-modulated phased array lidar chip. This protective layer 14 is a low-refractive-index protective layer. The material of this low-refractive-index protective layer can be silicon dioxide, and its thickness can be 2 to 5 μm. The thickness of this protective layer 14 is matched to the operating wavelength.

[0083] Specifically, see Figure 3 or Figure 4 , and combined with Figure 5 As shown, Figure 5A schematic diagram of the SOI substrate structure containing a protective layer in a continuous wave frequency modulated phased array laser radar provided in another embodiment of the present application. The phased array laser radar may include: the phased array laser radar includes: an input coupler 10, a balanced detector 602, a power divider 70, two couplers (i.e., a first coupler 20 and a second coupler 601), a beam splitter 30, a phase modulator 40 and an optical antenna 50; all of the above devices are arranged on an SOI substrate, which includes: a substrate silicon layer 11, a buried oxide layer 12 and a top silicon layer 13; the input coupler 10 is used to couple the laser emitted by the laser outside the chip to the chip; the balanced detector 602 is used to detect the received signal, and its structure can be a waveguide type silicon germanium detector with two waveguide interfaces at the input; the power divider 70 is used to adjust the ratio of the energy of the emitted light to the energy of the local light for balanced detection; and then the distribution The two good light waves are respectively transmitted to the first coupler 20 and the second coupler 601. The second coupler 601 is used to beat the received light and the local light on the chip and output it to the balanced detector 602. The balanced detector 602 outputs the detected electrical signal. The first coupler 20 is used to separate the light for transmission and the light for reception on the chip. The light for transmission is sequentially transmitted into space through the beam splitter 30, the phase modulator 40 and the optical antenna 50. The transmitted light is reflected by the object to be measured and is received on the chip by the optical antenna 50. It is then transmitted to the second coupler output end of the second coupler 601 through the phase modulator 40 and the beam splitter 30, and then transmitted back to the fourth input end of the second coupler 601 and transmitted to the first coupler 20. Through the coordinated operation of the beam splitter 30, the phase modulator 40 and the optical antenna 50, the transmission and reception of light at different angles in space are achieved. Since the continuous wave frequency modulated phased array laser radar chip used for transmission and reception uses the same phased array system for transmission and reception, the structure is compact, which greatly simplifies the complexity of the entire phased array laser system. Especially for large array phased array laser radars, the improvement effect is more significant.

[0084] An embodiment of the present application provides a phased array laser radar, which includes the continuous wave frequency modulation phased array laser radar chip described in any of the above embodiments.

[0085] In this embodiment, the phased array laser radar includes a continuous wave frequency modulated phased array laser radar chip, which includes: an input coupler 10, a first coupler 20, a beam splitter 30, a phase modulator 40, an optical antenna 50, and a receiving light processing layer 60; the input coupler 10 and the receiving light processing layer 60 are respectively connected to the first coupler 20 through a waveguide, and the first coupler 20, the beam splitter 30, the phase modulator 40 and the optical antenna 50 are connected in turn through a waveguide; the input coupler 10 is used to couple the input light to the chip; the first coupler 20 is used to couple the input light to the chip; The light for transmission combined onto the chip is transmitted to the beam splitter 30; the beam splitter 30 is used to split the light for transmission; the phase modulator 40 is used to adjust the phase of each split light wave; the optical antenna 50 is used to transmit the light wave with the phase changed by the phase modulator 40 into space, and receive the light wave reflected by the object being measured back onto the chip; the first coupler 20 is also used to receive the received light received onto the chip by the optical antenna 50 and transmit the received light to the received light processing layer 60. Because the continuous wave frequency modulation phased array lidar chip separates the signal light for transmission and the signal light for reception on the chip through the first coupler 20, and the beam splitter 30, phase modulator 40, and optical antenna 50 work together to achieve transmission and reception of light at different angles in space, achieving integrated transmission and reception. Moreover, the continuous wave frequency modulation phased array lidar chip uses the same phased array system for transmission and reception, resulting in a compact structure and greatly simplifying the complexity of the entire phased array lidar system.

[0086] To facilitate understanding of the structure of the continuous-wave frequency-modulated phased array lidar chip and how it works, thereby ensuring performance consistent with traditional phased array systems with separate transmitters and receivers while reducing the complexity of the entire system, the following explanation can be used. It should be noted that the following method does not limit the applicable scenarios and implementation methods of the continuous-wave frequency-modulated phased array lidar chip.

[0087] See also Figure 6 As shown, Figure 6 A schematic diagram of the scanning method provided in the embodiment of the present application. Figure 3 and Figure 4 This embodiment provides a detailed description of the scanning method. The method includes:

[0088] Step S101: When the light source is turned on, the power divider 70 is adjusted to adjust the light used for emission and the local light used for balanced detection to a preset ratio, wherein the light source is a laser with a periodic linear frequency change, and the light of the light source is coupled to the chip through an input coupler.

[0089] In this embodiment, the method is applied to a phased array lidar such as the above-mentioned continuous wave frequency modulated phased array lidar chip. First, turn on the light source, which is a laser with a periodic linear frequency change, that is, first turn on the linear frequency modulated laser, and couple the light source to the phased array lidar chip through the input coupler. Then adjust the power divider 70 to distribute the transmitted light power and the local light power through the power divider 70. Specifically, adjust the power divider 70 to adjust the light used for transmission and the local light used for balanced detection to a suitable ratio, for example, the intensity of the light used for transmission is 10 times the intensity of the local light used for balanced detection.

[0090] Step S102: Adjust the phase modulator so that the light emitted from the optical antenna is emitted from a preset first direction.

[0091] In this embodiment, the voltage or current of the phase modulator 40 is adjusted, and the emission spot is optimized by the optimization algorithm, so that the emission light is emitted in a specific direction, that is, a preset first direction. At this time, the direction of the emission light (the preset first direction) is recorded as direction 1. The schematic diagram of the emission process is shown in FIG. Figure 7 As shown, Figure 7 This is a schematic diagram of the transmission process in the scanning method provided in another embodiment of the present application. Figure 7 The device type is not specifically limited. For example, the first coupler 20 can be a 2*1 multimode interference coupler or a 2*2 multimode interference coupler. Specifically, the light for emission distributed by the power divider 70 passes through the first coupler 20, beam splitter 30, phase modulator 40, and optical antenna 50 on the chip in sequence and is finally emitted into space. The optimization algorithm can be an exhaustive method, gradient descent method, stochastic gradient descent method, or other optimization algorithm, as long as a converged optimal result can be obtained. This embodiment does not limit the algorithm for optimizing the light spot.

[0092] Step S103: Adjust the voltage or current of the phase modulator to remain unchanged so that when the optical antenna transmits, the received light reflected by the object to be measured passes through the phase modulator and the beam splitter in sequence, is reversely transmitted to the fourth input end of the first coupler through the first coupler output end of the first coupler, and is transmitted to the second input end of the second coupler 601 through the fourth input end, wherein the received light beats with the local light in the second coupler 601, and the light wave after the beat is transmitted to the balanced detector 602, and the detected electrical signal is output by the balanced detector 602.

[0093] In this embodiment, the voltage or current of the phase modulator 40 is maintained constant, and the phased array lidar synchronously receives the light spot reflected by the object being measured. Specifically, because the optical path is reversible, if the light emitted in step S102 needs to return to the chip along the same path and be combined into the first coupler at maximum power, the voltage or current of the phase modulator 40 must be maintained consistent with the voltage or current in step S102. The optical antenna 50 is used for both transmission and reception. When the phase modulator 40 is a thermo-optical phase modulator, it is voltage-driven; when the phase modulator 40 is an electro-optical phase modulator, it is current-driven.

[0094] The received light (i.e., the received signal or received signal light) then passes through the on-chip phase modulator 40, beam splitter 30, first coupler, and other components, where it beats with the local light in the second coupler 601. The resulting beat optical signal (i.e., the beat light wave) is transmitted to the balanced detector 602 for detection, which then outputs the detected electrical signal.

[0095] Specifically, see Figure 8 As shown, Figure 8 This is a schematic diagram of the receiving process in the scanning method provided in another embodiment of the present application. The beat frequency optical signal is transmitted to the two input waveguides of the balanced detector 602. The balanced detector 602 can eliminate part of the noise signal and finally output the detected electrical signal. Figure 8 There is no specific limitation on the device type, for example, the first coupler 20 can be a 2*1 multimode interference coupler or a 2*2 multimode interference coupler.

[0096] S104, continue adjusting the phase modulator so that the light emitted from the optical antenna is emitted from a preset second direction, and continue adjusting the voltage or current of the phase modulator to remain unchanged so that the balanced detector outputs the detected electrical signal, until the phase modulator is adjusted so that the object to be measured is scanned at least once in its entirety by the phased array lidar.

[0097] In this embodiment, the next position of the object to be measured is detected until all positions of the object to be measured are scanned at least once by the phased array laser radar, thereby obtaining contour information of multiple objects to be measured.

[0098] Specifically, after the first position of the object to be measured is measured, the voltage or current of the phase modulator 40 is adjusted so that the light emitted from the optical antenna is emitted from a new direction (the preset second direction), which is recorded as direction 2, and the operations from step S102 to step S103 are continuously repeated to detect new detection signals, and so on, until the object to be measured is scanned at least once by the laser radar and sufficient contour information of the object to be measured is obtained.

[0099] In this embodiment, the coordinated operation of the beam splitter 30, phase modulator 40, and optical antenna 50 enables the transmission and reception of light at different angles in space. Because the continuous-wave frequency-modulated phased array LiDAR chip for both transmission and reception utilizes the same phased array system, the compact structure significantly simplifies the complexity of the entire phased array laser system. This improvement is particularly significant for large-array phased array LiDARs.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A continuous wave frequency modulated phased array laser radar chip, characterized in that: include: An input coupler, a first coupler, a beam splitter, a phase modulator, an optical antenna, and a receiving light processing layer; The input coupler and the receiving light processing layer are respectively connected to the first coupler through waveguides, and the first coupler, beam splitter, phase modulator and optical antenna are sequentially connected through waveguides; The input coupler is used to couple input light to the chip; The first coupler is used to transmit the light for emission coupled to the chip to the beam splitter; The beam splitter is used to split the light used for emission and output multiple emission light waves; The phase modulator is used to modulate the phase of the transmitted light wave and keep the voltage / current unchanged when receiving the reflected light; The optical antenna is configured to transmit the phase-modulated transmitted light wave into space, receive the reflected light wave reflected by the measured object in the space, and transmit the reflected light wave to the receiving light processing layer via the phase modulator, the beam splitter, and the first coupler. The optical antenna is a second-order diffraction grating. The first coupler is further configured to receive the received light on the chip via the optical antenna and transmit the received light to the received light processing layer. The structure of the first coupler is: Multimode interference coupler or A multimode interference coupler, wherein the first coupler is further used to separate the transmitted light and the received light on the chip; The received light processing layer is used to perform signal processing on the received light and output an electrical signal.

2. The continuous wave frequency modulated phased array laser radar chip according to claim 1, characterized in that: The chip further includes: a power distributor; The input end of the power divider is connected to the input coupler via a waveguide, and the output end of the power divider is connected to the first coupler and the receiving light processing layer; The power divider is used to distribute energy of the light coupled to the chip to obtain emission light and local light. The emission light is transmitted to the first coupler, and the local light is transmitted to the receiving light processing layer.

3. The continuous wave frequency modulated phased array laser radar chip according to claim 2, characterized in that: The receiving light processing layer includes: a balanced detector and a second coupler; The input end of the second coupler is connected to the output end of the power divider and the first coupler through a waveguide, and the output end of the second coupler is connected to the balanced detector through a waveguide; The second coupler is configured to beat the local light and the reflected light wave, and transmit the beat light wave to the balanced detector; The balanced detector is used to detect the beat light wave and output an electrical signal of the detected light wave.

4. The continuous wave frequency modulated phased array laser radar chip according to claim 1, characterized in that: The chip further includes: an SOI substrate; The input coupler, the first coupler, the beam splitter, the phase modulator, the optical antenna, and the receiving light processing layer are located on the top silicon layer of the SOI substrate.

5. The continuous wave frequency modulated phased array laser radar chip according to claim 1, characterized in that: The waveguide in the chip is a TE mode single-mode waveguide, and the shape of the TE mode single-mode waveguide is a ridge waveguide or a strip waveguide.

6. The continuous wave frequency modulated phased array laser radar chip according to claim 2 or 3, characterized in that: The power distributor is an optical switch type power distributor.

7. The continuous wave frequency modulated phased array laser radar chip according to claim 3, characterized in that: The balanced detector is two waveguide silicon germanium detectors.

8. The continuous wave frequency modulated phased array laser radar chip according to claim 3, characterized in that: The second coupler is a 50:50 directional coupler or Multimode interference coupler.

9. A phased array laser radar, characterized in that: Comprising the continuous wave frequency modulated phased array lidar chip according to any one of claims 1 to 8.

10. A scanning method, characterized in that: The phased array laser radar applied to the continuous wave frequency modulated phased array laser radar chip according to claim 3, the method comprising: When the light source is turned on, the power divider is adjusted to adjust the light used for emission and the local light used for balanced detection to a preset ratio, wherein the light source is a laser with a periodic linear frequency change, and the light of the light source is coupled to the chip through an input coupler; adjusting the phase modulator so that light emitted from the optical antenna is emitted from a preset first direction, wherein the optical antenna is a secondary diffraction grating; The voltage or current of the phase modulator is adjusted to remain unchanged so that when the optical antenna transmits, the received light reflected by the object to be measured passes through the phase modulator and the beam splitter in sequence, is transmitted in reverse through the first coupler output end of the first coupler to the fourth input end of the first coupler, and is transmitted to the second input end of the second coupler through the fourth input end, wherein the received light beats with the local light in the second coupler, and the light wave after the beat is transmitted to the balanced detector, and the detected electrical signal is output by the balanced detector. The structure of the first coupler is as follows: Multimode interference coupler or A multimode interference coupler, wherein the first coupler is further used to separate the transmitted light and the received light on the chip; Continue to adjust the phase modulator so that the light emitted from the optical antenna is emitted from a preset second direction, and continue to adjust the voltage or current of the phase modulator unchanged so that the balanced detector outputs the detected electrical signal, until the phase modulator is adjusted so that the object to be measured is scanned at least once by the phased array lidar.

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