CN114690150A - Continuous wave frequency modulation phased array laser radar chip, scanning method and laser radar - Google Patents

Abstract

Embodiments of the present application provide a continuous wave frequency-modulated phased array laser radar chip, a scanning method, and a laser radar. The chip includes an input coupler for coupling input light to the chip; The transmitted light is transmitted to the beam splitter; the beam splitter is used to split the light used for transmission and output multiple beams of transmitted light waves; the phase modulator is used to phase modulate the transmitted light waves; the optical antenna is used to The transmitted light wave is transmitted to the space and the reflected light wave reflected by the measured object in the receiving space is transmitted, and the reflected light wave is transmitted to the receiving light processing layer through the phase modulator, the beam splitter and the first coupler; the first coupler is used for receiving through the optical antenna. The received light on the chip is received and the received light is transmitted to the received light processing layer; the received light processing layer is used to perform signal processing on the received light and output an electrical signal. While ensuring the performance of the traditional discrete phased array system, the complexity of the entire system is reduced.

Description

Continuous wave frequency modulation phased array lidar chip, scanning method and lidar

technical field

The embodiments of the present application relate to the technical field of radar, and in particular, to a continuous wave frequency-modulated phased array laser radar chip, a scanning method, and a laser radar.

Background technique

The concept of continuous wave FM phased array lidar has been proposed for a long time, and various design schemes are constantly being developed. The basic modules in the current continuous wave FM phased array lidar are also mature, such as the light source module, beam splitting module, phase modulation module, balanced detection module, and optical antenna on the lidar chip. Among them, in order to realize the transmission and reception of light, the continuous wave frequency modulation phased array lidar chip usually uses two independent phased array systems (phased array systems can include beam splitting modules, phase modulation modules, optical antennas, etc.) To achieve transmission and reception.

For example, one phased array system adjusts the phase through the phase modulation module to realize the emission of light at different angles, and another phased array system follows the emission angle of the emission system on the lidar chip to detect the same emission angle and reflect back to the chip. of light. However, the number of devices on the chip is doubled in this way, resulting in complicated devices on the chip. Similarly, the driving circuit used to drive the normal operation of the chip in the lidar system also needs to double the amount of control, which affects the entire lidar. The system is bad.

There is no solution in the prior art that reduces the complexity of the entire system while ensuring the performance consistent with the traditional phased array system with discrete transceivers.

SUMMARY OF THE INVENTION

Embodiments of the present application provide a continuous-wave frequency-modulated phased array laser radar chip, a scanning method, and a laser radar, which can reduce the complexity of the entire system while ensuring the same performance as a traditional phased array system with discrete transceivers.

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

The input coupler and the received light processing layer are respectively connected with the first coupler through waveguides, and the first coupler, beam splitter, phase modulator and optical antenna are sequentially connected through waveguides;

the input coupler for coupling input light to the chip;

the first coupler for transmitting light coupled to the chip for emission into the beam splitter;

the beam splitter, for splitting the light for emission, and outputting multiple emission light waves;

the phase modulator, used for phase modulation of the emitted light wave;

The optical antenna is used to transmit the phase-modulated emitted light wave to the space, receive the reflected light wave reflected by the measured object in the space, and pass the reflected light wave through the phase modulator, the the beam splitter and the first coupler are transmitted to the received light processing layer;

the first coupler is further configured to receive the received light received on the chip through the optical antenna, and transmit the received light to the received light processing layer;

The received light processing layer is used for performing signal processing on the received light and outputting an electrical signal.

In a possible design, the continuous wave FM phased array lidar chip as described above further includes: a power divider;

The input end of the power divider is connected to the input coupler through a waveguide, and the output end of the power divider is connected to the first coupler and the received light processing layer;

The power divider is used for energy distribution 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 The received light processing layer.

In a possible design, in the continuous wave frequency modulation phased array lidar chip described above, the received 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 used to beat the local light and the reflected light wave, and transmit the beat frequency light wave to the balanced detector;

The balanced detector is used for detecting the light wave after the beat frequency, and outputting an electrical signal of the detected light wave.

In a possible design, the continuous-wave frequency-modulated phased array lidar chip as described above further includes: an SOI substrate;

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

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

In a possible design, for the continuous wave frequency modulation phased array lidar chip described above, the power divider is an optical switch type power divider.

In a possible design, in the above-mentioned continuous-wave frequency-modulated phased array lidar chip, the balanced detectors are two waveguide-type silicon germanium detectors.

In a possible design, in the continuous wave FM phased array lidar chip described above, the structure of the first coupler is a 2*1 multimode interference coupler or a 2*2 multimode interference coupler, so The second coupler is a 50:50 directional coupler or a 2*2 multimode interference coupler.

In a second aspect, an embodiment of the present application provides a phased array laser radar, including the continuous wave frequency-modulated phased array laser radar chip according to any one of the first aspects above.

In a third aspect, an embodiment of the present application provides a scanning method, which is applied to the phased array laser radar of the continuous wave frequency modulation phased array laser radar chip described above, and the method includes:

When the light source is turned on, the power divider is adjusted to adjust the ratio of the light used for emission and the local light used for balanced detection to a preset ratio, wherein the light source is a laser whose frequency changes periodically and linearly through the input a coupler couples the light of the light source onto the chip;

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

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 measured object passes through the phase modulator and the beam splitter in sequence, and passes through the phase modulator and the beam splitter. The first coupler output terminal of the first coupler is reversely transmitted to the fourth input terminal of the first coupler, and then transmitted to the second input terminal of the second coupler through the fourth input terminal, Wherein, in the second coupler, the received light and the local light are beat frequency, the beat frequency light wave is transmitted to the balance detector, and the detected electrical signal is output through the balance detector;

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 output of the balanced detector detects until the phase modulator is adjusted, so that the object to be measured is scanned at least once by the phased array lidar.

Embodiments of the present application provide a continuous wave frequency-modulated phased array laser radar chip, a scanning method, and a laser radar. The continuous-wave frequency-modulated phased array laser radar chip includes: an input coupler, a first coupler, a beam splitter, a a phaser, an optical antenna, and a received light processing layer; the input coupler and the received light processing layer are respectively connected with the first coupler through a waveguide, and the first coupler, the beam splitter, and the phase modulator are connected to The optical antennas are in turn connected by waveguides; the input coupler is used to couple the input light to the chip; the first coupler is used to transmit the light for emission coupled into the chip to In the beam splitter; the beam splitter is used for splitting the emitted light to output multiple beams of emitted light waves; the phase modulator is used for phase modulation of the emitted light waves; The optical antenna is used to transmit the phase-modulated emitted light wave to the space, and receive the reflected light wave reflected from the measured object in the space, and transmit the reflected light wave through the phase modulator, the splitter The beamer and the first coupler are transmitted to the receiving light processing layer; the first coupler is also used to receive the received light received on the chip through the optical antenna, and transmit the received light to The received light processing layer; the received light processing layer is used for performing signal processing on the received light and outputting an electrical signal. Because the continuous wave frequency modulated phased array lidar chip separates the signal light for transmission and the signal light for reception on the chip through the first coupler, and at the same time the beam splitter, the phase modulator and the optical antenna work together, realizing the The emission and reception of light from different angles in space realizes the integration of transceivers, and the CW FM phased array lidar chip uses the same phased array system for transmission and reception, with a compact structure, which greatly simplifies the complexity of the entire system .

It should be understood that the content described in the above summary section is not intended to limit the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become readily understood from the following description.

Description of drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present application, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

1 is a schematic structural diagram of a continuous-wave frequency-modulated phased array laser radar chip provided by an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a continuous wave FM phased array lidar chip provided by another embodiment of the present application;

FIG. 3 is a schematic structural diagram of a continuous wave FM phased array lidar chip provided by still another embodiment of the present application;

4 is a schematic structural diagram of a continuous wave FM phased array lidar chip provided by another embodiment of the present application;

FIG. 5 is a schematic structural diagram of an SOI substrate containing a protective layer in a continuous-wave frequency-modulated phased-array lidar provided by yet another embodiment of the present application;

6 is a schematic flowchart of a scanning method provided by an embodiment of the present application;

FIG. 7 is a schematic diagram of a transmission process in a scanning method provided by still another embodiment of the present application;

FIG. 8 is a schematic diagram of a receiving process in a scanning method provided by another embodiment of the present application.

Reference number:

10-input coupler 20-first coupler 30-beam splitter 40-phase modulator 50-optical antenna 60-received light processing layer 70-power splitter 601-second coupler 602-balanced detector 11-liner Bottom silicon layer 12 - buried oxide layer 13 - top silicon layer 14 - protective layer

Detailed ways

Embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present application are shown in the drawings, it is to be understood that the present application may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but rather are provided for the purpose of A more thorough and complete understanding of this application. It should be understood that the drawings and embodiments of the present application are only used for exemplary purposes, and are not used to limit the protection scope of the present application.

The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims of the embodiments of the present application and the above-mentioned drawings are used to distinguish similar objects, while It is not necessary to describe a particular order or sequence. It is to be understood that data so used may be interchanged under appropriate circumstances such that the embodiments of the application described herein can, for example, be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having", and any variations thereof, are intended to cover non-exclusive inclusion.

FIG. 1 is a schematic structural diagram of a continuous-wave frequency-modulated phased array laser radar chip provided by an embodiment of the present application. As shown in FIG. 1 , the continuous wave FM phased array lidar 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 received light processing unit Layer 60.

Wherein, the input coupler 10 and the received light processing layer 60 are respectively connected with the first coupler 20 through waveguides, the first coupler 20 , the beam splitter 30 , the phase modulator 40 and the optical antenna 50 connected in turn through waveguides.

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 into the chip into the beam splitter. The beam splitter 30 is used for splitting the light used for emission to output multiple beams of emission light waves; the phase modulator 40 is used for phase modulation of the emission light waves; the optical antenna 50, It is used to transmit the phase-modulated emitted light wave to the space, receive the reflected light wave reflected by the measured object in the space, and pass the reflected light wave through the phase modulator 40 and the beam splitter 30 and the first coupler 20 is transmitted to the received light processing layer 60; the first coupler 20 is also used to receive the received light received on the chip through the optical antenna 50, and to transmit the received light It is transmitted to the received light processing layer 60; the received light processing layer 60 is used to perform signal processing on the received light and output an electrical signal. Wherein, 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 SOI substrate on the top silicon layer 13. The reflected light wave is the light wave reflected back after the emitted light wave reaches the measured object in the space.

In practical applications, the continuous-wave frequency-modulated phased array lidar chip can be integrated on a standard substrate compatible with CMOS technology, that is, an SOI substrate, and the devices on the chip can be connected by waveguides. The SOI substrate includes 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. The material and thickness of each layer of the SOI substrate are not limited in this embodiment. For example, the material and thickness of each layer can be customized according to different needs, and SOI substrate products of conventional standard CMOS process can also be used. For example, the material of the substrate silicon layer 11 is silicon, and its thickness is 400-800 μm; the buried oxide layer The material of 12 is silicon dioxide, and its thickness is 2 μm; the material of the top silicon layer 13 is silicon, and its thickness is 220 nm.

The input coupler 10 is used to couple the laser light emitted by the off-chip laser to the chip, where the laser light emitted by the off-chip laser can be used as input light, and its frequency is linearly modulated, and the laser is a frequency Lasers that do periodic linear changes. Since the current continuous-wave frequency-modulated phased array lidar chip usually uses two independent phased array systems to transmit and receive light, the number of devices on the chip is doubled. The devices on the lidar are complicated. Similarly, the driving circuit used to drive the normal operation of the chip in the lidar system also needs to double the amount of control, which is not good for the entire lidar system.

In order to solve the above problems, in this embodiment, the first coupler 20, the beam splitter 30, the phase modulator 40, and the optical antenna 50 are used to work cooperatively to realize the emission and reception of light at different angles in space, so that the continuous wave frequency modulation is achieved. The phased array lidar chip uses the same phased array system for transmission and reception, which realizes the integration of transceivers and reduces the complexity of the entire system due to the compact structure on the chip.

Specifically, the beam splitter 30, the phase modulator 40 and the optical antenna 50 are the phased array modules of the phased array lidar. The beam splitter 30 can divide a beam of light into several beams, and the specific number is not limited in this application.

For example, the first coupler 20 will use the input coupler 10 to couple the input light into the chip for emission and transmit it to the beam splitter 30, which splits the light into 8 beams, Then each beam of light is modulated in phase by the phase modulator 40 and transmitted through the optical antenna 50; similarly, when the optical antenna 50 receives the signal, the beam splitter 30, the phase modulator 40 and the optical antenna 50 are also in the same form work, but the working order is reversed, that is, the light used for emission is emitted from the free space from the optical antenna 50 and reflected by the object to be measured, and then received into the waveguide on the chip, and is phase-modulated by the phase modulator 40 and then split into beams. The couplers are combined into a waveguide and transmitted to the first coupler. Through the cooperative work of each device, the emission and reception of light from different angles are realized, and the emission and reception share a group of the above-mentioned devices, that is, the same module for transceiver.

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

The continuous wave frequency modulated phased array lidar 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 received light processing layer 60; the The input coupler 10 and the received light processing layer 60 are respectively connected with the first coupler 20 through waveguides, and the first coupler 20 , the beam splitter 30 , the phase modulator 40 and the optical antenna 50 are sequentially connected through waveguides ; the input coupler 10 for coupling the input light to the chip; the first coupler 20 for transmitting the light for emission coupled into the chip to the splitter In the device 30; the beam splitter 30 is used for splitting the emitted light to output multiple beams of emitted light waves; the phase modulator 40 is used for phase modulation of the emitted light waves; the The optical antenna 50 is used for transmitting the phase-modulated emitted light wave to space, and receiving the reflected light wave reflected by the measured object in the space, and passing the reflected light wave through the phase modulator 40, the The beam splitter 30 and the first coupler 20 are transmitted to the received light processing layer 60; the first coupler 20 is also used to receive the received light received on the chip through the optical antenna 50, and to The received light is transmitted to the received light processing layer 60; the received light processing layer 60 is used to perform signal processing on the received light and output an electrical signal. Since the continuous wave frequency modulated 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, the phase modulator 40 and the optical antenna 50 cooperate with each other It works, realizes the emission and reception of light from different angles in space, realizes the integration of transceiver, and the continuous wave frequency modulation phased array lidar chip uses the same set of phased array system for transmission and reception, with a compact structure, which greatly simplifies the whole process. the complexity of the system.

In order to precisely adjust the energy of the emitted light and the local light in the scenarios of different intensities of the light source, the emitted light or the light used for emission is transmitted to the first coupler 20 , the beam splitter 30 , the phase modulator 40 and the optical device in turn. The antenna 50 is launched into the space. Referring to FIG. 2 , FIG. 2 is a schematic structural diagram of a continuous-wave frequency-modulated phased array laser radar chip provided by another embodiment of the present application. Based on the above-mentioned embodiments, this embodiment provides a detailed description of the continuous-wave frequency-modulated phased array lidar chip. The continuous wave frequency modulation phased array lidar chip further includes: a power divider 70 .

The input end of the power divider 70 is connected to the input coupler 10 through a waveguide, and the output end of the power divider 70 is connected to the first coupler 20 and the received light processing layer 60 . Specifically, the power divider 70 is configured to perform energy distribution on the light coupled to the chip to obtain emission light and local light, the emission light is transmitted to the first coupler 20, and the local light Light is transmitted to the received light processing layer 60 .

In this embodiment, the front end of the power divider 70 is connected to the input coupler 10 through a waveguide, and the rear end of the power divider 70 is respectively connected to the front end of the first coupler 20 (ie, one input end of the first coupler 20 ) through the waveguide. It is connected to the front end of the received light processing layer 60 (one input end of the received light processing layer 60). The power divider 70 can be an optical switch type power divider, which can precisely adjust the ratio of the energy of the emitted light to the energy of the local light processed by the received light processing layer 60, After the emitted light (or emitted light) is transmitted to the beam splitter 30 , the conditioned local light is transmitted to the received light processing layer 60 . In general, the power divider 70 can be replaced by a directional coupler with a specific structure, but once the structure of the directional coupler is determined, the energy ratio of the emitted light and the local light is fixed, so the energy ratio The ratio is not adjustable, so this will affect the flexibility of the continuous wave FM phased array lidar used for transceiver integration to a certain extent, so an adjustable power divider 70 can be used to finely distribute the transmitted light and the local light. power.

In order to realize the signal processing of the received light and output the detected electrical signal, see FIG. 3 , which is a schematic structural diagram of a continuous-wave frequency-modulated phased array lidar chip provided by yet another embodiment of the present application. On the basis of the example, for example, on the basis of the embodiment described in FIG. 2 , the continuous wave FM phased array lidar chip is described in detail. The received 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 through a waveguide. connection, the output end of the second coupler 601 is connected to the balanced detector 602 through a waveguide; the second coupler 601 is used to beat the local light and the reflected light wave, and the beat frequency The beat frequency light wave is transmitted to the balance detector 602; the balance detector 602 is used to detect the beat frequency light wave, and output the electrical signal of the detected light wave.

In this embodiment, the second coupler 601 has two input ends and one output end, and the second coupler 601 may be a 50:50 directional coupler or a 2*2 multimode interference coupler, and may be based on different scenarios Different types of second couplers 601 are selected. Wherein, one input end of the second coupler 601, namely the first input end, is connected to the rear end of the power divider 70, and the other input end of the second coupler 601, namely the second input end, is connected to the first coupler 20, and the first The output end of the two couplers 601 , that is, the output end of the second coupler, is connected to the balanced detector 602 .

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

Therein, two input waveguide ports may be provided. The two input waveguide ports in the balanced detector 602 are respectively connected with the two first output ports of the output end of the second coupler through waveguides.

Specifically, the first input port is used for inputting the local light distributed by the power divider 70 for balanced detection, and the second input port is used for reverse transmission from the output port of the first coupler 20 to The received light input of the input port of the first coupler 20 comes in. The two beams of light have different frequencies, beat frequencies in the second coupler 601 and transmit the beat-frequency signal to the balanced detector 602 through the two first output ports of the second coupler 601, so that the balanced The detector 602 detects the beat frequency light wave (signal), and outputs an electrical signal of the detected light wave.

In a possible design, the first coupler 20 is provided with a third input end, a fourth input end and a first coupler output end, and the structure of the first coupler 20 may be 2*1 multi-mode interference coupling or a 2*2 multimode interference coupler, and different types of second couplers 601 can be selected according to different scenarios.

Wherein, the third input end is a port connected to the power divider 70, the fourth input end is a port connected to the received light processing layer 60, and the first coupler output end is a port connected to the received light processing layer 60. The port to which the beam splitter 30 is connected.

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

In this embodiment, the first coupler 20 has two input ports and one output port. Wherein, one input port of the first coupler 20 ie the third input port is connected to the rear end of the power divider 70 , and the other input port of the first coupler 20 ie the fourth input port is connected to the second input port of the second coupler 601 . The input end is connected, and the output end of the first coupler 20 , that is, the output end of the first coupler, is connected to the beam splitter 30 .

Specifically, the first coupler 20 is used to separate the light used for emission and the light received on the chip, wherein the third input end of the first coupler 20 is used to distribute the power divider 70 connected thereto. The light used for emission is transmitted to the beam splitter 30 connected with the output end of the first coupler of the first coupler 20, and the light used for emission is emitted into the space through the phase modulator 40 and the optical antenna 50; The light is reflected back by the measured object and received on the chip through the optical antenna 50, and is transmitted to the output end of the first coupler through the phase modulator 40 and the beam splitter 30, and is reversely transmitted to the first coupler through the output end of the first coupler Another input port of the coupler 20, that is, the fourth input terminal, is transmitted to the second coupler 601 through the fourth input terminal.

It should be noted that, the output end of the first coupler may include one output port, or may include two output ports. If the first coupler 20 is a 2*1 multi-mode interference coupler, the output end of the first coupler includes an output port, as shown in any of FIG. 1 to FIG. 3 , the first coupler 20 is on the chip. The positional connection relationship is the same as that described in the foregoing embodiment, and is not repeated here. If the first coupler is a 2*2 multi-mode interference coupler, the output end of the first coupler includes two output ports. In addition to the functions of the embodiments described in the above-mentioned FIGS. 1-3 , the first coupler 20 , Also has the function of a first-stage beam splitter.

Specifically, referring to FIG. 4 , FIG. 4 is a schematic structural diagram of a continuous-wave frequency-modulated phased array laser radar chip provided by another embodiment of the present application. The two output ports are respectively connected to the beam splitter 30. In addition to the functions described in the above embodiments, the first coupler 20 also includes the function of a one-to-two beam splitter, that is, the The two output waveguides respectively output by the two output ports of a coupler 20 are used for beam splitting of the next stage, which is different from that in the above-mentioned embodiment where the beam splitter 30 needs to perform beam splitting from one waveguide. The overall work efficiency of the lidar system is improved.

In a possible design, in order to realize the optical path connection between various devices, on the basis of the above embodiment, the waveguide in the continuous wave frequency modulation phased array lidar chip provided by this embodiment is a single-mode waveguide of TE mode , the shape of the single-mode waveguide of the TE mode is a ridge waveguide or a strip waveguide. A single-mode waveguide using the TE mode is a structure capable of directionally guiding light waves in the waveguide. Wherein each device is arranged on the top silicon layer 13 of the SOI substrate.

In a possible design, on the basis of the above-mentioned embodiments, this embodiment describes in detail each device 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 multi-mode interference coupler (or a cascaded 1*2 multi-mode interference coupler); the optical antenna 50 is a grating type optical antenna. The grating is a second-order diffraction grating.

Specifically, in this embodiment, after the phase of the light waves in each waveguide is adjusted by the phase modulator 40, the light waves in the waveguide are transmitted to the optical antenna 50 to be emitted into space. In this embodiment, the optical antenna 50 may be a second-order diffraction grating engraved on the silicon array waveguide, that is, a grating-type optical antenna. The specific parameters of the grating, such as the grating period, duty cycle, etching depth, etc., are all related to the working wavelength. When grating etching is performed on the waveguide, the grating period needs to be calculated according to the etching depth. In order to obtain a small far-field divergence angle along the waveguide direction and a high longitudinal radar scanning resolution, the etching depth of the second-order diffraction grating of the optical antenna 50 is designed to be shallow, at 20-100 nm. Since the light wave band is 1.5-1.6μm, the effective refractive index of the waveguide array for this band is about 2.38. According to the formula of the second-order diffraction grating, the period of the second-order diffraction grating is 600-680nm, that is, on the silicon waveguide, each grating is uniformly distributed on each grating. The grating is etched over the distance of the period. The width of the grating is determined by the duty cycle, which is the ratio of the grating width to the grating period. It can be seen from the calculation that in the light wave band of 1.5-1.6 μm, when the duty ratio of the second-order diffraction grating is 0.4-0.6, the outward radiation efficiency is the highest.

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

In a possible design, the phase modulator 40 is described in detail in this embodiment on the basis of the above-mentioned embodiment. As mentioned above, the phase modulator 40 in the continuous wave frequency modulated phased array lidar chip may be a thermo-optic phase modulator or an electro-optic phase modulator.

Wherein, the thermo-optic phase modulator is used for heating the waveguide, and the refractive index of the waveguide is changed by the thermo-optic effect to change the phase of the light wave in the waveguide; the electro-optic phase modulator is used for injecting into the waveguide The electric current changes the phase of the light waves in the waveguide by changing the refractive index of the waveguide through the electro-optic effect.

Specifically, the thermo-optic phase modulator can be of a top heating type or a two-sided heating type, that is, the heating electrode is arranged on the top or both sides of the waveguide, and the heat generated by the heating electrode is transferred to the waveguide by applying current or voltage biasing (can be In the case of silicon waveguide), since silicon is a material with a high thermo-optic coefficient, it is easy to change the refractive index in the waveguide and change the phase of the light wave in each waveguide. It should be noted that, in order to avoid the heating electrode being too close to the waveguide, the light in the waveguide will be absorbed, resulting in a large loss, the heating electrode needs to be a certain distance from the waveguide, generally greater than 2um. The materials of the heating electrode and the metal lead wire are not limited in this embodiment, but generally, the resistivity of the heating electrode is larger than that of the metal lead wire by an order of magnitude. The electro-optical phase modulator injects current into the waveguide, and when the current passes through, the refractive index of silicon can be regulated, thereby changing the phase of the light waves in each waveguide.

In a possible design, this embodiment provides a detailed description of a continuous wave frequency-modulated phased array lidar chip on the basis of any of the above-mentioned embodiments. The continuous wave FM phased array lidar chip as described above further includes: a protective layer 14 . The protective layer 14 is located above and completely covers the top silicon layer 13 . The protective layer 14 is made of a material compatible with the CMOS process, and the refractive index of the protective layer 14 is lower than that of silicon.

In this embodiment, the protective layer 14 covers the entire continuous wave FM phased array lidar chip, and the protective layer 14 is a low-refractive index protective layer. The material of the low-refractive-index protective layer can be selected from silicon dioxide, and the thickness can be 2-5um. Wherein, the thickness of the protective layer 14 matches the working wavelength.

Specifically, referring to FIG. 3 or FIG. 4 , and in conjunction with FIG. 5 , FIG. 5 is a schematic structural diagram of an SOI substrate with a protective layer in a continuous-wave frequency-modulated phased array laser radar according to another embodiment of the present application. The phased array lidar may include: the phased array lidar includes: an input coupler 10 , a balanced detector 602 , a power divider 70 , and two couplers (ie, the first coupler 20 and the second coupler 601 ) , beam splitter 30, phase modulator 40 and optical antenna 50; all the above devices are arranged on SOI substrate, the substrate includes: substrate silicon layer 11, buried oxide layer 12 and top silicon layer 13; the input The coupler 10 is used to couple the laser light emitted by the off-chip laser to the chip; the balanced detector 602 is used to detect the received signal, its structure can be a waveguide type silicon germanium detector, and the input has two waveguide interfaces; the The power divider 70 is used to adjust the ratio of the energy used for the emitted light and the energy used to balance the detection of the local light; then the distributed two light waves are respectively correspondingly transmitted to the first coupler 20 and the second coupler 601 , wherein the second coupler 601 is used to make the signal beat frequency of the received light and the local light on-chip and output it to the balanced detector 602, and the balanced detector 602 outputs the detected electrical signal; the first coupler 20 It is used to separate the light for emission and the light for reception on the chip, the light for emission passes through the beam splitter 30, the phase modulator 40 and the optical antenna 50 in turn and is emitted into the space, and the emitted light is reflected by the measured object It is received on the chip through the optical antenna 50, and transmitted to the second coupler output of the second coupler 601 through the phase modulator 40 and the beam splitter 30, and then reversely transmitted to the fourth input of the second coupler 601 terminal, and transmitted to the first coupler 20. Through the cooperative work of the beam splitter 30, the phase modulator 40 and the optical antenna 50, the emission and reception of light at different angles in space are realized. Since the continuous wave frequency modulation phased array laser radar chip used for transceiver integration uses the same set of 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 the phased array of large arrays. Controlled array lidar, the improvement effect is more significant.

An embodiment of the present application provides a phased array laser radar, where the phased array laser radar includes the continuous wave frequency-modulated phased array laser radar chip described in any one of the foregoing embodiments.

In this embodiment, the phased array laser radar includes a continuous wave frequency-modulated phased array laser radar chip, because the chip includes: an input coupler 10, a first coupler 20, a beam splitter 30, a phase modulator 40, an optical The antenna 50 and the received light processing layer 60; the input coupler 10 and the received light processing layer 60 are respectively connected with the first coupler 20 through waveguides, the first coupler 20, the beam splitter 30, the modulator The phase device 40 and the optical antenna 50 are sequentially connected 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 used for emission is transmitted to the beam splitter 30; the beam splitter 30 is used to split the light used for emission; the phase modulator 40 is used to adjust the The phase of the beam of light waves; the optical antenna 50 is used to transmit the light waves whose phases are changed by the phase modulator 40 into the space, and receive the light waves reflected from the emitted light into the space through the object to be measured. On the chip; the first coupler 20 is further configured to receive the received light received on the chip through the optical antenna 50 , and transmit the received light to the received light processing layer 60 . Because the continuous wave frequency modulated 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, the phase modulator 40 and the optical antenna 50 cooperate with each other It works, realizes the emission and reception of light from different angles in space, and realizes the integration of transceivers, and the continuous wave FM phased array lidar chip uses the same set of phased array systems for transmission and reception, with a compact structure, which greatly simplifies the whole The complexity of the phased array lidar system.

In order to facilitate the understanding of the structure of the CW FM phased array lidar chip and how it works in order to ensure the performance of the traditional phased array system with discrete transceivers and reduce the complexity of the entire system, it can be explained in the following ways. Yes, in the following manner, the applicable scenarios and implementation manners of the CW FM phased array lidar chip are not limited.

Referring to FIG. 6 , FIG. 6 is a schematic flowchart of a scanning method provided by an embodiment of the present application. With reference to FIG. 3 and FIG. 4 , the scanning method is described in detail in this embodiment. The method includes:

Step S101, when the light source is turned on, adjust the power divider 70 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 frequency that changes periodically and linearly. The laser couples the light of the light source to the chip through an input coupler.

In this embodiment, the method is applied to the phased array laser radar of the continuous wave frequency modulation phased array laser radar chip as described above. First turn on the light source, which is a laser whose frequency changes periodically and linearly, that is, first turn on the chirp laser, and couple the light source to the phased array lidar chip through the input coupler. Then, the power divider 70 is adjusted, and the transmitted optical power and the local optical power are distributed through the power divider 70 . Specifically, the power divider 70 is adjusted to adjust the light used for emission and the local light used for balanced detection to an appropriate ratio, for example, the intensity of the light used for emission is 10 times the intensity of the local light used for balanced detection .

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

In this embodiment, the voltage or current of the phase modulator 40 is adjusted, and the emission light spot is optimized by an optimization algorithm, and the emission light is emitted in a specific direction, that is, a preset first direction. The first direction) is denoted as direction 1, and a schematic diagram of the emission process is shown in FIG. 7 , which is a schematic diagram of the emission process in the scanning method provided by still another embodiment of the present application. In this embodiment, the type of the device in FIG. 7 is not specifically limited. For example, the first coupler 20 may 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 is finally emitted into the space through the on-chip first coupler 20 , the beam splitter 30 , the phase modulator 40 and the optical antenna 50 in sequence. The optimization algorithm may be an exhaustive method, a gradient descent method, a stochastic gradient descent method, or other optimization algorithms, as long as a converged optimal result can be obtained, and the algorithm for optimizing the light spot is not limited in this embodiment.

Step S103: Adjust the voltage or current of the phase modulator to remain unchanged, so that the received light reflected by the object to be measured passes through the phase modulator and the beam splitter in sequence while the optical antenna transmits. The first coupler output terminal of the first coupler is reversely transmitted to the fourth input terminal of the first coupler, and then transmitted to all the second coupler 601 through the fourth input terminal. The second input end, wherein the received light and the local light are beat frequency in the second coupler 601, and the beat frequency light wave is transmitted to the balance detector 602, and passes through the balance detector 602 outputs the detected electrical signal.

In this embodiment, the voltage or current of the phase modulator 40 is kept unchanged, and the phased array lidar synchronously receives the light spot reflected by the object to be measured. Specifically, since the optical path is reversible, if the light emitted in step S102 needs to return to the chip through the same path and be combined into the first coupler with maximum power, it is necessary to keep the voltage or current of the phase modulator 40 and the step The voltage or current in S102 is the same, and the optical antenna 50 is also used for receiving while transmitting. Wherein, when the phase modulator 40 is a thermo-optical phase modulator, it is voltage driving, and when the phase modulator 40 is an electro-optical phase modulator, it is current driving.

Then the received light (ie the received signal or the received signal light) passes through the phase modulator 40 , the beam splitter 30 , the first coupler and other devices on the chip and the local light is beat frequency in the second coupler 601 . The beat-frequency optical signal (ie, the beat-frequency light wave) is transmitted to the balance detector 602 for detection and the detected electrical signal is output.

Specifically, referring to FIG. 8 , FIG. 8 is a schematic diagram of a receiving process in a scanning method provided by another embodiment of the present application. The beat-frequency optical signal is transmitted to the two input waveguides of the balanced detector 602, and the balanced detector 602 can eliminate a part of the noise signal, and finally output the detected electrical signal. The device types in FIG. 8 are not specifically limited in this embodiment. For example, the first coupler 20 may be a 2*1 multimode interference coupler or a 2*2 multimode interference coupler.

S104. 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, so that the balanced detector outputs The step of detecting the electrical signal, until the phase modulator is adjusted, so that the object to be measured is completely scanned by the phased array lidar at least once.

In this embodiment, the next position of the object to be measured is detected until all the positions of the object to be measured are scanned at least once by the phased array lidar to obtain contour information of multiple objects to be measured.

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), denoted as direction 2. Repeat the operations in steps S102 to S103 continuously to detect new detection signals, and so on, until the object to be measured is scanned by the lidar at least once, and enough outline information of the object to be measured is obtained.

In this embodiment, through the cooperative work of the beam splitter 30, the phase modulator 40 and the optical antenna 50, the emission and reception of light of different angles in space are realized. Since the continuous wave frequency modulation phased array laser radar chip used for transceiver integration uses the same set of 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 the phased array of large arrays. Controlled array lidar, the improvement effect is more significant.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present application. scope.

Claims (10)

1. A continuous wave frequency modulated phased array lidar chip, comprising: an input coupler, a first coupler, a beam splitter, a phase modulator, an optical antenna, and a received light processing layer;

the input coupler and the receiving light processing layer are respectively connected with the first coupler through waveguides, and the first coupler, the beam splitter, the phase modulator and the optical antenna are sequentially connected through waveguides;

the input coupler is used for coupling input light onto the chip;

the first coupler for transmitting light for emission coupled onto the chip into the beam splitter;

the beam splitter is used for splitting the emitted light and outputting a plurality of beams of emitted light waves;

the phase modulator is used for phase modulating the emitted light wave;

the optical antenna is used for transmitting the phase-modulated transmitted light wave to a space, receiving a reflected light wave reflected by a measured object in the space, and transmitting the reflected light wave to a received light processing layer through the phase modulator, the beam splitter and the first coupler;

the first coupler is also used for receiving received light received by the optical antenna on the chip and transmitting the received light to the received light processing layer;

and the received light processing layer is used for carrying out signal processing on the received light and outputting an electric signal.

2. The cw fm phased array lidar chip of claim 1, further comprising: a power divider;

the input end of the power divider is connected with the input coupler through a waveguide, and the output end of the power divider is connected with the first coupler and the received light processing layer;

the power divider is configured to perform energy division on the light coupled onto the chip to obtain an emission light and a local light, the emission light is transmitted to the first coupler, and the local light is transmitted to the received light processing layer.

3. The CW FM phased array lidar chip of claim 2, wherein the receive light handling layer comprises: a balanced detector and a second coupler;

the input end of the second coupler is connected with the output end of the power divider and the first coupler through a waveguide, and the output end of the second coupler is connected with the balanced detector through a waveguide;

the second coupler is used for beating the local light and the reflected light wave and transmitting the beated light wave to the balanced detector;

and the balance detector is used for detecting the light wave after the beat frequency and outputting an electric signal of the detected light wave.

4. The cw fm phased array lidar chip of claim 1, further comprising: an SOI substrate;

the input coupler, the first coupler, the beam splitter, the phase modulator, the optical antenna, and the received light handling layer are located on a top silicon layer of the SOI substrate.

5. The chip of claim 1, wherein the waveguide in the chip is a single mode waveguide of the TE mode, and the single mode waveguide of the TE mode is in the shape of a ridge waveguide or a strip waveguide.

6. A cw fm phased array lidar chip according to claim 2 or claim 3, wherein the power divider is an optical switch type power divider.

7. The CW FM phased array lidar chip of claim 3, wherein the balanced detector is two waveguide type SiGe detectors.

8. The CW FM phased array lidar chip according to claim 3, wherein the first coupler is configured as a 2 x 1 multimode interference coupler or a 2 x 2 multimode interference coupler, and the second coupler is a 50:50 directional coupler or a 2 x 2 multimode interference coupler.

9. A phased array lidar chip comprising the continuous wave frequency modulated phased array lidar chip of any of claims 1-8.

10. A scanning method, for a phased array lidar chip having a continuous wave frequency modulated phased array lidar chip according to claim 3, the method comprising:

when a light source is turned on, adjusting the power divider to adjust the light for emission and the local light for balanced detection to a preset ratio, wherein the light source is a laser with a frequency which is periodically and linearly changed, and the light of the light source is coupled onto the chip through an input coupler;

adjusting the phase modulator such that light emitted from the optical antenna is emitted from a preset first direction;

adjusting the voltage or current of the phase modulator to be unchanged, so that while the optical antenna transmits, received light reflected by a measured object sequentially passes through the phase modulator and the beam splitter, reversely transmits the received light to a fourth input end of the first coupler through a first coupler output end of the first coupler, and transmits the received light to a second input end of the second coupler through the fourth input end, wherein the received light and the local light in the second coupler are subjected to beat frequency, a beat frequency light wave is transmitted to the balance detector, and a detected electric signal is output through the balance detector;

and continuing to adjust the phase modulator so that the light emitted from the optical antenna is emitted from a predetermined second direction, and continuing to adjust the voltage or current of the phase modulator so that the balance 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 laser radar.

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