CN114690150A

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

Info

Publication number: CN114690150A
Application number: CN202011603608.5A
Authority: CN
Inventors: 王鹏飞; 徐洋; 张冶金; 于红艳; 潘教青; 邓永强
Original assignee: Beijing Wanji Technology Co Ltd
Current assignee: Wuhan Wanji Photoelectric Technology Co Ltd
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2022-07-01

Abstract

The embodiment of the application provides a continuous wave frequency modulation phased array laser radar chip, a scanning method and a laser radar, wherein the chip comprises an input coupler, a scanning coupler and a scanning module, wherein the input coupler is used for coupling input light to the chip; the first coupler is used for transmitting the light coupled to the chip for emission to the beam splitter; the beam splitter is used for splitting the light for emission 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 waves to the space and receiving reflected light waves reflected by a measured object in the space, and transmitting the reflected light waves to the received light processing layer through the phase modulator, the beam splitter and the first coupler; the first coupler is used for receiving received light received on the chip through the optical antenna and transmitting the received light to the received light processing layer; and the receiving light processing layer is used for carrying out signal processing on the receiving light and outputting an electric signal. The performance of the phased array system is consistent with that of a traditional transceiving discrete phased array system, and the complexity of the whole system is reduced.

Description

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

Technical Field

The embodiment of the application relates to the technical field of radars, in particular to a continuous wave frequency modulation phased array laser radar chip, a scanning method and a laser radar.

Background

The concept of continuous wave frequency modulated phased array lidar has been proposed for a long time, and various design schemes are being developed. The basic modules in the existing continuous wave frequency modulation phased array laser radar are mature, such as a light source module, a beam splitting module, a phase modulation module, a balance detection module, an optical antenna and the like on a laser radar chip. In order to transmit and receive light, a continuous wave frequency modulation phased array lidar chip generally transmits and receives light through two independent phased array systems (the phased array systems may include a beam splitting module, a phase modulation module, an optical antenna, and the like).

For example, one phased array system adjusts the phase through the phase modulation module to realize the emission of light with different angles, and the other phased array system follows the emission angle of the emission system on the laser radar chip to detect the light reflected back to the chip by the original circuit with the emission angle. However, the number of devices on the chip is doubled, which results in complicated devices on the chip, and the driving circuit for driving the chip to operate normally in the laser radar system also needs to be increased by one time, which is disadvantageous for the whole laser radar system.

In the prior art, no scheme is provided for reducing the complexity of the whole system while ensuring the performance of the phased array system which is separated from the traditional transceiving system to be consistent.

Disclosure of Invention

The embodiment of the application provides a continuous wave frequency modulation phased array laser radar chip, a scanning method and a laser radar, and can reduce the complexity of the whole system while ensuring that the performance of the phased array system which is separated from the traditional receiving and transmitting system is consistent.

In a first aspect, an embodiment of the present application provides a continuous wave frequency modulation phased array laser radar 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 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 is used for transmitting the light coupled to the chip for emission into the beam splitter;

the beam splitter is used for splitting the light for emission 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 the received light received on the chip through the optical antenna 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.

In one possible design, the continuous wave frequency modulation phased array lidar chip as described above, 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.

In one possible design, the continuous wave frequency modulated phased array lidar chip as described above, the receive light processing layer comprising: 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.

In one possible design, the continuous wave frequency modulation phased array lidar chip as described above, 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.

In one possible design, the waveguide in the chip is a single-mode waveguide of the TE mode, which is shaped as a ridge waveguide or a strip waveguide.

In one possible design, the power divider is an optical switch type power divider, such as the above-described cw fm phased array lidar chip.

In one possible design, the balanced detector is two waveguide-type sige detectors, such as the above-described cw fm phased array lidar chip.

In one possible design, the above-mentioned cw fm phased array lidar chip has a structure of a 2 × 1 multimode interference coupler or a 2 × 2 multimode interference coupler, and the second coupler is a 50:50 directional coupler or a 2 × 2 multimode interference coupler.

In a second aspect, embodiments of the present application provide a phased array lidar chip including a continuous wave frequency modulated phased array lidar chip as described in any 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 lidar chip of the continuous wave frequency modulation phased array lidar chip, where the scanning method includes:

when the 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.

The embodiment of the application provides a continuous wave frequency modulation phased array laser radar chip, a scanning method and a laser radar, and the continuous wave frequency modulation phased array laser radar chip comprises the following steps: the optical coupler comprises 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 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 coupled into the chip for emission 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. Because this continuous wave frequency modulation phased array laser radar chip will be used for the signal light and the received signal light of transmission to part on the chip through first coupler, simultaneously beam splitter, phase modifier and optical antenna collaborative work have realized the transmission and the receipt of different angle light in the space, have realized receiving and dispatching integration to this continuous wave frequency modulation phased array laser radar chip's transmission and receipt use same set of phased array system, compact structure has simplified the complexity of whole system greatly.

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

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

Fig. 1 is a schematic structural diagram of a continuous wave frequency modulation phased array lidar chip according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a continuous wave frequency modulation phased array lidar chip according to yet another embodiment of the present application;

fig. 3 is a schematic structural diagram of a continuous wave frequency modulation phased array lidar chip according to yet another embodiment of the present application;

fig. 4 is a schematic structural diagram of a continuous wave frequency modulation phased array lidar chip according to another embodiment of the present application;

FIG. 5 is a schematic diagram of an SOI substrate with a protective layer in a CW FM phased array lidar according to yet another embodiment of the present application;

fig. 6 is a schematic flowchart of a scanning method according to an embodiment of the present application;

fig. 7 is a schematic diagram illustrating an emission process in a scanning method according to yet another embodiment of the present application;

fig. 8 is a schematic diagram of a receiving process in a scanning method according to another embodiment of the present application.

Reference numerals:

10-input coupler 20-first coupler 30-beam splitter 40-phase modulator 50-optical antenna 60-receiving light treatment 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

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 should 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 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 illustration purposes only and are not intended to limit the scope of the present application.

The terms "first," "second," "third," "fourth," and the like in the description and in the claims of the embodiments of the application and in the drawings described above, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.

Fig. 1 is a schematic structural diagram of a continuous wave frequency modulation phased array laser radar chip provided in an embodiment of the present application. As shown in fig. 1, the continuous wave frequency modulation phased array laser radar chip provided by 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 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 sequentially connected through a waveguide.

In particular, the input coupler 10 is used to couple input light onto the chip. The first coupler 20 for transmitting the light coupled into the chip for emission into the beam splitter. The beam splitter 30 is used for splitting the emitted light and outputting a plurality of beams of emitted light waves; the phase modulator 40 is configured to phase modulate the transmission light wave; the optical antenna 50 is configured to emit the phase-modulated transmitted light wave into a space, receive a reflected light wave reflected by an object to be measured in the space, and transmit the reflected light wave to the received-light processing layer 60 through the phase modulator 40, the beam splitter 30 and the first coupler 20; 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; the received light processing layer 60 is configured to perform signal processing on the received light and output an electrical signal. Wherein the chip further comprises: an SOI substrate; the input coupler 10, first coupler 20, beam splitter 30, phase modulator 40, optical antenna 50, and receive light handling layer 60 are located on the top silicon layer 13 of the SOI substrate. And the reflected light wave is reflected back after the emitted light wave reaches the object to be measured in the space.

In practical application, the continuous wave frequency modulation phased array laser radar chip can be integrated on a standard substrate compatible with a CMOS (complementary metal oxide semiconductor) process, namely an SOI (silicon on insulator) substrate, and all devices on the chip can be connected through waveguides. The SOI substrate comprises the following components from bottom to top: a substrate silicon layer 11, a buried oxide layer 12 and a top silicon layer 13. Among them, 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, etc. 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. If the material and thickness of each layer can be customized according to different requirements, an SOI substrate product of a conventional standard CMOS process can also be adopted, for example, the material of the substrate silicon layer 11 is silicon, and the thickness of the substrate silicon layer is 400-800 μm; the buried oxide layer 12 is made of silicon dioxide and has a thickness of 2 μm; the material of the top silicon layer 13 is silicon with a thickness of 220 nm.

The input coupler 10 is configured to couple laser light emitted by an off-chip laser to a chip, where the laser light emitted by the off-chip laser can be used as input light, and the frequency of the input light is linearly modulated, and the laser is a laser whose frequency is periodically and linearly changed. Because the existing continuous wave frequency modulation phased array laser radar chip usually realizes the transmission and the reception through two sets of independent phased array systems in order to realize the transmission and the reception of light, devices on the chip are doubled, so that the devices on the chip are complicated, and similarly, a driving circuit for driving the chip to normally work in the laser radar system also needs to be doubled in control quantity, which is disadvantageous to the whole laser radar 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 in cooperation to realize the transmission and reception of light at different angles in space, so that the same set of phased array system is used for the transmission and reception of the continuous wave frequency modulation phased array lidar chip, and the complexity of the whole system is reduced due to the compact structure on the chip while the transmission and reception are integrated.

In particular, beam splitter 30, phase modulator 40 and optical antenna 50 are phased array modules of the phased array lidar. The beam splitter 30 may split one beam into a plurality of beams, and the specific number is not limited in this application.

For example, the first coupler 20 transmits light for emission, which is coupled into the chip by the input coupler 10, into the beam splitter 30, the beam splitter 30 splits the light into 8 beams, and each beam is then phase-modulated by the phase modulator 40 and emitted through the optical antenna 50; similarly, when the optical antenna 50 receives signals, the beam splitter 30, the phase modulator 40 and the optical antenna 50 work in the same manner, but the work sequence is reversed, that is, the light for transmission is transmitted from the optical antenna 50 from the free space, reflected by the object to be measured, received into the waveguide on the chip, phase modulated by the phase modulator 40, merged into one waveguide by the beam splitter, and transmitted to the first coupler. Through the cooperative work of all devices, the light emitting and receiving of different angles are realized, and the emitting and receiving share one group of devices, namely a receiving and transmitting module.

The input coupler 10 is used for coupling light waves to a chip, and can couple high-power input light into the chip, then transmit light for emission in the light coupled to the chip to the beam splitter 30 through the first coupler 20, and the beam splitter 30 splits the light for emission, so that the light for emission in the light coupled into the input coupler 10 is split into a plurality of light waves after passing through the beam splitter 30, and then the phase of each light wave or each light wave after splitting is adjusted through the phase adjuster 40, that is, the phase of the light waves in the waveguide is changed. The light wave in the waveguide is phase-adjusted by the phase modulator 40, transmitted to the optical antenna 50 through the waveguide, and emitted to the space, the emitted light is reflected by the object to be measured and received onto the chip through the optical antenna 50, and transmitted to the output port of the second coupler 601, i.e., the port connected to the beam splitter 30, through the phase modulator 40 and the beam splitter 30, and then reversely transmitted to one input port of the second coupler 601, i.e., the port connected to the received-light processing layer 60, and transmitted 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 modulation phased array laser radar chip that this embodiment provided 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 input coupler 10 and the receiving 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 is used for coupling input light onto the chip; the first coupler 20 for transmitting the light coupled into the chip for emission into the beam splitter 30; the beam splitter 30 is used for splitting the emitted light and outputting a plurality of beams of emitted light waves; the phase modulator 40 is used for phase modulating the emitted light wave; the optical antenna 50 is configured to emit the phase-modulated transmitted light wave into a space, receive a reflected light wave reflected by an object to be measured in the space, and transmit the reflected light wave to the received-light processing layer 60 through the phase modulator 40, the beam splitter 30 and the first coupler 20; 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; the received light processing layer 60 is configured to perform signal processing on the received light and output an electrical signal. Because the continuous wave frequency modulation phased array laser radar chip separates the signal light and the received signal light used for transmitting on the chip through the first coupler 20, and the beam splitter 30, the phase modulator 40 and the optical antenna 50 work cooperatively, the transmission and the reception of the light with different angles in the space are realized, the receiving and the transmitting are integrated, and the same phased array system is used for the transmission and the reception of the continuous wave frequency modulation phased array laser radar chip, the structure is compact, and the complexity of the whole system is greatly simplified.

In order to precisely adjust the energy of the emitted light and the local light in the scenes of different intensities of the light sources, the emitted light or the light for emission is transmitted to the first coupler 20, the beam splitter 30, the phase modulator 40 and the optical antenna 50 in sequence and emitted into the space, referring to fig. 2, fig. 2 is a schematic structural diagram of a continuous wave frequency modulation phased array laser radar chip provided by another embodiment of the present application. The present embodiment describes details of a continuous wave frequency modulation phased array lidar chip on the basis of the above embodiments. This continuous wave frequency modulation phased array laser radar chip still includes: a power divider 70.

Wherein 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 distribute energy of light coupled onto the chip, resulting in emitted light and local light, the emitted light is transmitted to the first coupler 20, and the local light is transmitted to the received light processing layer 60.

In this embodiment, the front end of the power splitter 70 is connected to the input coupler 10 through a waveguide, and the rear end of the power splitter 70 is connected to the front end of the first coupler 20 (i.e., one input end of the first coupler 20) and the front end of the received-light processing layer 60 (one input end of the received-light processing layer 60) through waveguides, respectively. Wherein the power divider 70 may be an optical switch type power divider, and may precisely adjust a ratio of energy of the light for emission to energy of the local light processed by the receiving light processing layer 60, and transmit the adjusted light for emission (or the emitted light) to the beam splitter 30, and transmit the adjusted local light to the receiving light processing layer 60. Since the power divider 70 can be replaced by a directional coupler with a specific structure, but 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 is not adjustable, and therefore, the flexibility of the continuous wave frequency modulation phased array laser radar for transmitting and receiving integration is influenced to a certain extent, so that an adjustable power divider 70 can be adopted to finely divide the power of the emitted light and the local light.

In order to implement signal processing on the received light and output a detected electrical signal, refer to fig. 3, where fig. 3 is a schematic structural diagram of a continuous wave frequency modulation phased array lidar chip according to yet another embodiment of the present application, and this embodiment describes in detail the continuous wave frequency modulation phased array lidar chip based on the above-described embodiment, for example, based on the embodiment described in fig. 2. 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 with the output end of the power divider 70 and the first coupler 20 through a waveguide, and the output end of the second coupler 601 is connected with the balanced detector 602 through a waveguide; the second coupler 601 is configured to beat frequency of the local light and the reflected light wave, and transmit the beat frequency light wave to the balanced detector 602; the balance detector 602 is configured to detect the beat frequency of the optical wave and output an electrical signal of the detected optical wave.

In this embodiment, the second coupler 601 has two input ends and one output end, the second coupler 601 may be a 50:50 directional coupler or a 2 × 2 multimode interference coupler, and different types of second couplers 601 may be selected according to different scenarios. One input end, i.e., a first input end, of the second coupler 601 is connected to the rear end of the power divider 70, the other input end, i.e., a second input end, of the second coupler 601 is connected to the first coupler 20, and an output end, i.e., a second coupler output end, of the second coupler 601 is connected to the balanced detector 602.

In one possible design, the second coupler output end comprises two first output ports; the balanced detector 602 is two waveguide type sige detectors.

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

Specifically, a first input port is used for inputting local light distributed by the power divider 70 for balanced detection, and a second input port is used for inputting received light of the input port of the first coupler 20 reversely transmitted from the output port of the first coupler 20. Two beams of light have different frequencies, beat frequency is performed in the second coupler 601, and a beat frequency signal is transmitted to the balanced detector 602 through two first output ports of the second coupler 601, so that the balanced 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, the structure of the first coupler 20 may be a 2 × 1 multimode interference coupler or a 2 × 2 multimode interference coupler, and different types of the second coupler 601 may be selected according to different scenarios.

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

Specifically, the first coupler 20 is specifically configured to: the light for emission adjusted by the power divider 70 is transmitted to the beam splitter 30 through the third input end, the received light received by the optical antenna 50 on the chip and transmitted sequentially through the phase modulator 40 and the beam splitter 30 is received through the first coupler output end, and is transmitted to the fourth input end in a reverse direction, and the received light is transmitted to the second input end through the fourth input end.

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

Specifically, the first coupler 20 is used for separating light for emission and received light on a chip, wherein a third input end of the first coupler 20 is used for transmitting the light for emission distributed by the power divider 70 connected with the third input end into the beam splitter 30 connected with the first coupler output end of the first coupler 20, and the light for emission is emitted into the space through the phase shifter 40 and the optical antenna 50; the emitted light is reflected back through the object to be measured and received on the chip via the optical antenna 50 and transmitted via the phase modulator 40 and the beam splitter 30 to the first coupler output, through the first coupler output to the other input port of the first coupler 20, i.e. the fourth input port, and through the fourth input port to said second coupler 601.

It should be noted that the first coupler output terminal may include one output port or may include two output ports. If the first coupler 20 is a 2 × 1 multimode interference coupler, the output end of the first coupler includes an output port, as shown in any one of fig. 1 to 3, and the connection relationship of the first coupler 20 on the chip is the same as that described in the above embodiments, and is not described herein again. If the first coupler is a 2 x 2 multimode interference coupler, the first coupler output comprises two output ports, and the first coupler 20 has the function of a first stage splitter in addition to the functions of the embodiments described above with reference to fig. 1-3.

Specifically, referring to fig. 4, fig. 4 is a schematic structural diagram of a continuous wave frequency modulation phased array lidar chip according to another embodiment of the present application. The two output ports are respectively connected to the beam splitter 30, and the first coupler 20 also includes a function of a one-to-two beam splitter in addition to the functions described in the above embodiments, that is, two output waveguides respectively output from the two output ports of the first coupler 20 are directly split in the beam splitter 30 at the next stage, while the beam splitter 30 in the above embodiments needs to split from one waveguide. The overall working efficiency of the laser radar system is improved.

In a possible design, in order to implement optical path connection between the devices, on the basis of the foregoing embodiment, the waveguide in the continuous wave fm phased array lidar chip provided by this embodiment 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. A single mode waveguide using the TE mode enables a structure for directionally guiding an optical wave in the waveguide. With each device disposed on the top silicon layer 13 of the SOI substrate.

In a possible design, the present embodiment describes each device on the continuous wave frequency modulation phased array lidar chip in detail on the basis of the foregoing embodiments. 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 cascade of 1 x 2 multimode interference couplers); the optical antenna 50 is a grating-type optical antenna. Wherein the grating is a second order diffraction grating.

Specifically, in the present embodiment, the light waves in each waveguide are phase-adjusted by the phase modulator 40, and then transmitted to the optical antenna 50 by the waveguide to be emitted into space. The optical antenna 50 in this embodiment may be a grating-type optical antenna, which is a second-order diffraction grating etched on a silicon array waveguide. The specific parameters of the grating, such as 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 second-order diffraction grating of the optical antenna 50 is designed to have a shallow etching depth of 20-100 nm. Because the wave band of the light wave is 1.5-1.6 μm, the effective refractive index of the waveguide array for the wave band is about 2.38, the period of the second-order diffraction grating is 600-680 nm according to the formula of the second-order diffraction grating, namely, the grating etching is uniformly carried out on the silicon waveguide at the distance of each grating period. The width of the grating is determined by the duty cycle, i.e. the ratio of the grating width to the grating period. The calculation shows that the outward radiation efficiency is highest when the wave band of the light wave is 1.5-1.6 mu m and the duty ratio of the second-order diffraction grating is 0.4-0.6.

In this embodiment, the input coupler 10 may be selected as an end-face coupler or a grating coupler, and then after the end-face coupler or the grating coupler couples the light waves to the chip, the light waves are transmitted to the waveguide corresponding to any one of the beam splitters 30 of the multimode interference coupler, the star coupler or the directional coupler through the single-mode waveguide of the TE mode, the light waves are divided into a sufficient number of parts, and the light waves are phase-modulated by the phase modulator 40 and then transmitted to the optical antenna 50, so that the optical antenna 50 transmits the light waves with the phases changed by the phase modulator 40 into a space, thereby realizing the transmission and reception of light at different angles, and simplifying the structure of the whole laser radar system while ensuring the performance of the phased array system consistent with that of the conventional transceiver.

In a possible design, the present embodiment provides a detailed description of the phase inverter 40 based on the above-described embodiments. The phase modulator 40 in a continuous wave frequency modulated phased array lidar chip as described above may be a thermo-optic phase modulator or an electro-optic phase modulator.

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

Specifically, the thermo-optic phase modulator may be a top heating type or a two-side heating type, that is, a heating electrode is disposed on the top or two sides of the waveguide, and heat generated by the heating electrode is transferred to the waveguide (which may be a silicon waveguide) by applying current or voltage bias. It should be noted that in order to avoid that the heating electrode is too close to the waveguide and absorbs light in the waveguide, thereby causing large losses, the heating electrode needs to be at a distance from the waveguide, typically larger than 2 um. In this embodiment, the material of the heater electrode and the metal lead is not limited, but the resistivity of the heater electrode is generally approximately one order of magnitude greater than that of the metal lead. The electro-optic phase modulator injects current into the waveguides, and when current flows through the electro-optic phase modulator, the refractive index of silicon can be adjusted, so that the phase of light waves in each waveguide can be changed.

In a possible design, the present embodiment describes a continuous wave frequency modulation phased array lidar chip in detail on the basis of any of the above embodiments. The continuous wave frequency modulation phased array laser radar chip as described above further includes: and a protective layer 14. The 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 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 cw 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 2-5 um. Wherein the thickness of the protective layer 14 is matched to the operating wavelength.

Specifically, referring to fig. 3 or fig. 4 in combination with fig. 5, fig. 5 is a schematic structural diagram of an SOI substrate including a protective layer in a continuous wave frequency modulation phased array laser radar according to still another embodiment of the present application. The phased array lidar may include: the phased array laser radar includes: input coupler 10, balanced detector 602, power splitter 70, two couplers (i.e., first coupler 20 and second coupler 601), beam splitter 30, phase modulator 40, and optical antenna 50; all the above devices are disposed 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 for coupling laser emitted by an off-chip laser to a chip; the balanced detector 602 is used for detecting a received signal, and may be a waveguide-type sige detector, and two waveguide interfaces are provided at the input; the power divider 70 is for adjusting a ratio of energy of the light for emission and energy for balanced detection of the local light; then, the two distributed optical waves are respectively and correspondingly transmitted to a first coupler 20 and a second coupler 601, wherein the second coupler 601 is used for beating the received light and the local light as on-chip signals and outputting the signals to the balanced detector 602, and the balanced detector 602 outputs detected electrical signals; the first coupler 20 is used for separating light for emission and received light on a chip, the light for emission is emitted into space through the beam splitter 30, the phase modulator 40 and the optical antenna 50 in sequence, the emitted light is reflected back through an object to be tested and received on the chip through the optical antenna 50, and is transmitted to the second coupler output end of the second coupler 601 through the phase modulator 40 and the beam splitter 30, and then is transmitted to the fourth input end of the second coupler 601 in a reverse direction and is transmitted to the first coupler 20. By the cooperation 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 is achieved. Because the same phased array system is used for transmitting and receiving the continuous wave frequency modulation phased array laser radar chip integrating receiving and transmitting, the structure is compact, the complexity of the whole phased array laser system is greatly simplified, and especially for the phased array laser radar of a large array, the improvement effect is more remarkable.

The embodiment of the application provides a phased array laser radar, which comprises the continuous wave frequency modulation phased array laser radar chip in any one of the above embodiments.

In this embodiment, this phased array laser radar includes continuous wave frequency modulation phased array laser radar chip, because this chip 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 input coupler 10 and the receiving 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 is used for coupling input light onto the chip; the first coupler 20 for transmitting the light coupled into the chip for emission into the beam splitter 30; the beam splitter 30 for splitting the light for emission; the phase modulator 40 is used for adjusting the phase of each beam of light wave after beam splitting; the optical antenna 50 is configured to emit the light wave whose phase is changed by the phase modulator 40 into a space, and receive the light wave reflected by the object to be measured from the emitted light into the space onto the chip; the first coupler 20 is further configured to receive the received light received by the optical antenna 50 on the chip, and transmit the received light to the received light processing layer 60. Because this continuous wave frequency modulation phased array laser radar chip will be used for the signal light and the received signal light of transmission to part on the chip through first coupler 20, simultaneously beam splitter 30, phase modulator 40 and optical antenna 50 collaborative work have realized the transmission and the receipt of different angle light in the space, have realized the receiving and dispatching integration to this continuous wave frequency modulation phased array laser radar chip's transmission and receipt are with same set of phased array system, compact structure has simplified the complexity of whole phased array laser radar system greatly.

In order to facilitate understanding of the structure of the continuous wave frequency modulation phased array laser radar chip and how to work specifically, so as to achieve the purpose of ensuring that the performance of the continuous wave frequency modulation phased array laser radar chip is consistent with that of a traditional transceiving discrete phased array system, and at the same time, reduce the complexity of the whole system, which can be described in the following manner, it should be noted that, in the following manner, the applicable scene and implementation manner of the continuous wave frequency modulation phased array laser radar chip are not limited.

Referring to fig. 6, fig. 6 is a schematic flowchart of a scanning method according to an embodiment of the present disclosure. The present embodiment describes the scanning method in detail with reference to fig. 3 and 4. The method comprises the following steps:

step S101, when the light source is turned on, the power divider 70 is adjusted to adjust the light for emission and the local light for balanced detection to a preset ratio, wherein the light source is a laser whose frequency is periodically and linearly changed, and the light of the light source is coupled to the chip through an input coupler.

In this embodiment, the method is applied to the phased array lidar chip of the continuous wave frequency modulation phased array lidar chip. Firstly, a light source is turned on, wherein the light source is a laser with the frequency changing periodically and linearly, namely, the linear frequency modulation laser is turned on firstly, and the light source is coupled into the phased array laser radar chip through an input coupler. The power divider 70 is then adjusted to divide the emitted optical power and the local optical power through the power divider 70. Specifically, the power splitter 70 is adjusted to adjust the light for emission and the local light for balanced detection to a suitable ratio, for example, the intensity of the light for emission is 10 times the intensity of the local light for balanced detection.

Step S102, adjusting the phase modulator to enable the light emitted from the optical antenna to be emitted from a preset first direction.

In this embodiment, the voltage or the current of the phase modulator 40 is adjusted, the emission light spot is optimized through an optimization algorithm, and the emission light is emitted toward a specific direction, i.e., a preset first direction, where the direction of the emission light (the preset first direction) is denoted as direction 1, a schematic diagram of the emission process is shown in fig. 7, and fig. 7 is a schematic diagram of the emission process in the scanning method provided in another embodiment of the present application. The type of the device in fig. 7 is not particularly 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. Specifically, the light distributed for emission 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 this order. The optimization algorithm may be an exhaustive method, a gradient descent method, a random gradient descent method, or other optimization algorithms, as long as an optimal result of convergence can be obtained, and the embodiment does not limit the algorithm for optimizing the light spot.

Step S103, adjusting the voltage or current of the phase modulator to be unchanged, so that while the optical antenna transmits, the received light reflected by the object to be measured sequentially passes through the phase modulator and the beam splitter, reversely transmits to the fourth input end of the first coupler through the first coupler output end of the first coupler, and transmits to the second input end of the second coupler 601 through the fourth input end, wherein the received light and the local light perform beat frequency in the second coupler 601, the beat frequency light is transmitted to the balance detector 602, and the detected electrical signal is output by the balance detector 602.

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

The received light (i.e., the received signal or received signal light) is then beat-clocked with the local light in the second coupler 601 via the on-chip phase modulator 40, the beam splitter 30, the first coupler, etc. The beat frequency of the optical signal (i.e., the beat frequency of the optical wave) is transmitted to the balanced detector 602, and the optical signal is detected and output as an electrical signal.

Specifically, referring to fig. 8, fig. 8 is a schematic diagram of a receiving process in a scanning method according to another embodiment of the present application. The beat frequency of the optical signal is transmitted to two input waveguides of the balanced detector 602, and the balanced detector 602 may remove a portion of the noise signal and finally output the detected electrical signal. In this embodiment, the type of the device in fig. 8 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.

S104, continuously adjusting the phase modulator to enable the light emitted from the optical antenna to be emitted from a preset second direction, and continuously adjusting the voltage or the current of the phase modulator to be unchanged to enable the balance detector to output the detected electric signal until the phase modulator is adjusted to enable the object to be detected to be scanned at least by the phased array laser radar 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 completely scanned by the phased array laser radar at least once, and the profile information of a plurality of the object to be measured is obtained.

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 (a preset second direction) and is recorded as the direction 2, the operations in the steps S102 to S103 are continuously repeated, a new detection signal is detected, and so on, until the object to be measured is completely scanned by the laser radar at least once, and sufficient profile information of the object to be measured is obtained.

In this embodiment, the beam splitter 30, the phase modulator 40 and the optical antenna 50 cooperate to transmit and receive light at different angles in space. Because the same phased array system is used for transmitting and receiving the continuous wave frequency modulation phased array laser radar chip integrating receiving and transmitting, the structure is compact, the complexity of the whole phased array laser system is greatly simplified, and especially for the phased array laser radar of a large array, the improvement effect is more remarkable.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims

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 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 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;

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

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;

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