CN115639543A

CN115639543A - Frequency modulated continuous wave laser radar and autopilot equipment

Info

Publication number: CN115639543A
Application number: CN202211599679.1A
Authority: CN
Inventors: 汪敬; 邱纯鑫; 刘乐天
Original assignee: Suteng Innovation Technology Co Ltd
Current assignee: Suteng Innovation Technology Co Ltd
Priority date: 2022-12-14
Filing date: 2022-12-14
Publication date: 2023-01-24
Anticipated expiration: 2042-12-14
Also published as: CN115639543B

Abstract

The application discloses frequency modulation continuous wave laser radar and autopilot equipment. The frequency modulation continuous wave laser radar comprises a frequency modulation light source, a light guide module, a silicon optical chip and a transceiver module; the light source module is used for emitting frequency-modulated continuous wave laser beams; the silicon optical chip comprises a light splitting module, a transmitting module, a coupling module and a receiving module, wherein the light splitting module receives a laser beam coupled into the silicon optical chip and divides the laser beam into detection light and local oscillation light, the detection light is emitted outwards through the transmitting module, the local oscillation light enters the receiving module, the coupling module receives echo light reflected by a target object and sends the echo light to the receiving module, and the receiving module is used for receiving the local oscillation light and the echo light; the light guide lens group is used for receiving and collimating the detection light output by the emission module and is also used for receiving and converging the echo light to the coupling module. The frequency modulation continuous wave laser radar system is simple in structure and low in scanning blind area.

Description

Frequency modulated continuous wave laser radar and autopilot equipment

Technical Field

The application relates to the technical field of radars, in particular to a frequency modulation continuous wave laser radar and an automatic driving device.

Background

Lidar is one of the core sensors widely used in autonomous driving scenarios, and can be used to collect three-dimensional information of the external environment. The lidar is mainly divided into two types of lidar, time of Flight (ToF) and Frequency Modulated Continuous Wave (FMCW), according to the detection principle. The FMCW laser radar adopts a coherent detection mode, a detection result is obtained by resolving after a receiving module performs coherent beat frequency on signal light reflected by local oscillator light and a target object, external environment light interference can be effectively reduced, and the laser radar ranging performance is improved. Simultaneously, FMCW laser radar can provide the information of testing the speed in addition to providing the space coordinate information.

FMCW laser radar usually adopts large-scale optical devices such as optical circulator to split light, the design of the light path is complicated, it is difficult to integrate miniaturization; the laser radar does not adopt a light splitting device for direct receiving, and the distance between the transmitting end and the receiving end is long, so that the receiving efficiency of the laser radar is low, and the detection blind area is large.

Disclosure of Invention

The embodiment of the application provides frequency modulation continuous wave laser radar and automatic driving equipment, and the problems that the frequency modulation continuous wave laser radar is complex in light path design and large in scanning blind area can be solved.

In a first aspect, an embodiment of the present application provides a frequency modulated continuous wave lidar, including:

the light source module is used for emitting frequency-modulated continuous wave laser beams;

the silicon optical chip comprises a light splitting module, a transmitting module, a coupling module and a receiving module, wherein the light splitting module receives the laser beam coupled into the silicon optical chip and divides the laser beam into detection light and local oscillation light, the detection light is emitted outwards through the transmitting module, the local oscillation light enters the receiving module, the coupling module receives echo light reflected by a target object and sends the echo light to the receiving module, and the receiving module is used for receiving the local oscillation light and the echo light; and

and the light guide mirror group is used for receiving and collimating the detection light output by the emission module and is also used for receiving and converging the echo light to the coupling module.

In some exemplary embodiments, the transmitting module includes a transmitting waveguide, the coupling module includes at least one receiving waveguide, and the transmitting waveguide and the receiving waveguide are disposed adjacent to a main optical axis of the light guiding mirror group.

In some exemplary embodiments, an end of the transmitting waveguide facing the light guiding lens group is a first transmitting end surface, and an end of the receiving waveguide facing the light guiding lens group is a first receiving end surface;

the first emitting end face and the first receiving end face are arranged on a focal plane of the light guide mirror group.

In some exemplary embodiments, the emitting mode field size of the emitting waveguide is equal to or different from the receiving mode field size of the receiving waveguide by a preset range, and the emitting waveguide and the receiving waveguide share the light guiding mirror group.

In some exemplary embodiments, the frequency modulated continuous wave lidar further comprises:

the first amplification module is arranged corresponding to the emission module and is used for receiving the detection light emitted by the emission module, amplifying the detection light to form first amplified light and then emitting the first amplified light;

and the auxiliary lens group is arranged corresponding to the first amplification module and is used for receiving the first amplified light and changing the light path direction of the first amplified light so that the first amplified light can be emitted to the center of the light guide lens group.

In some exemplary embodiments, the coupling module includes M reception waveguides, M being an integer greater than or equal to 2, and the coupling module further includes:

the beam combining module comprises at least one multi-port coupler, the multi-port coupler is provided with N first access ports and a first output port, N is an integer larger than or equal to 2, and at least two first access ports of the multi-port coupler are connected with the receiving waveguide one by one, so that the echo light transmitted by the receiving waveguide enters the multi-port coupler through the first access ports and is output to the receiving module through the first output port after being combined.

In some exemplary embodiments, the beam combining module further includes at least one through waveguide having a second access port and a second output port, where the second access port is connected to the receiving waveguide, and the second output port is connected to the receiving module, so that the echo light transmitted by the receiving waveguide is transmitted to the receiving module through the through waveguide.

In some exemplary embodiments, the sum of the number of the first access ports and the number of the second access ports is equal to the number of the reception waveguides.

In some exemplary embodiments, the transmitting waveguide and the receiving waveguide are sequentially arranged along a direction parallel to the surface of the silicon optical chip, the receiving waveguide on a side close to the transmitting waveguide is connected with at least one of the multiport couplers, and the receiving waveguide on a side far from the transmitting waveguide is connected with at least one of the through waveguides.

In some exemplary embodiments, the receiving module comprises:

the polarization beam splitting converter is used for receiving the echo light transmitted by the coupling module and splitting the echo light into two beams of polarized echo light in different polarization states;

each two optical mixers are connected with the same polarization beam splitting converter, and each optical mixer is used for receiving the polarization echo light output by the polarization beam splitting converter, receiving the local oscillator light, and mixing the received polarization echo light and the local oscillator light to obtain mixed light;

and the first balance detector is connected with the optical mixer to receive the mixed light for detection.

the packaging shell is provided with a first channel for the probe light to pass through and a second channel for the echo light to pass through.

In a second aspect, an embodiment of the present application provides an autopilot device, including an autopilot body and a frequency modulated continuous wave lidar as described above, the frequency modulated continuous wave lidar being mounted to the autopilot body.

Frequency modulation continuous wave laser radar and autopilot equipment based on this application embodiment through with emission module and coupling module integration on same silicon optical chip, makes silicon optical chip have the function of transmitted light and received light concurrently to frequency modulation continuous wave laser radar realizes off-axis receiving and dispatching function. The distance between the transmitting module and the coupling module can be smaller, the overlapping degree of the transmitting view field of the transmitting module and the receiving view field of the coupling module is improved, the coverage area of a scanning blind area is reduced, and even when the frequency modulation continuous wave laser radar is installed at a position, higher than the ground, of the automatic driving equipment, the frequency modulation continuous wave laser radar still can have a lower scanning blind area. In addition, the transmitting module and the coupling module are integrated on the same silicon optical chip, and the direction of light entering and exiting the silicon optical chip is adjusted by arranging the light guide lens group, so that a large optical device with large volume and high cost is not needed, and the volume of the whole frequency modulation continuous wave laser radar can be effectively reduced.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic diagram of a system architecture of a frequency modulated continuous wave lidar according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a frequency modulated continuous wave lidar according to an embodiment of the present application;

fig. 3 is a schematic view illustrating a transmitting angle of a transmitting module and a receiving angle of a receiving module according to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of a receiving module connected to a polarization beam splitter through a multiport coupler according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a portion of a waveguide array coupled to a multiport coupler according to an embodiment of the present application;

FIG. 6 is a schematic diagram of a structure in which a receiving module is connected to a polarization beam splitter through a star coupler according to an embodiment of the present application;

FIG. 7 is a schematic structural diagram of a receiving module connected to a polarization beam splitter through a multi-mode interference coupler according to an embodiment of the present application;

fig. 8 is a schematic structural diagram of a light guide module including an optical input amplifier according to an embodiment of the present application.

Reference numerals:

10. frequency modulated continuous wave lidar;

200. a light source module; 210. a collimating lens; 220. an isolator; 230. a first light guide lens; 240. an optical amplifier; 250. a second light guide mirror; 260. a frequency modulated light source;

300. a silicon optical chip;

320. a transmitting module; 321. an emission field of view; 322. an emission waveguide; 3221. a first emitting end face; 330. a coupling module; 331. receiving a field of view; 332. receiving a waveguide; 3321. a first receiving end face; 30a, scanning a blind area;

340. a light splitting module; 341. a first beam splitter; 342. a second beam splitter; 343. a third optical splitter; 344. a spot size converter;

350. a receiving module; 351. a polarization beam splitting converter; 352. an optical mixer; 353. a first balanced detector;

354. a nonlinear calibration light path of a light source; 3541. a coupler; 3542. calibrating the balance detector; 3543. an optical delay line;

360. a beam combining module; 361. a multi-port coupler; 3611. a first access port; 3612. a first output port; 362. a through waveguide; 3621. a second access port; 3622. a second output port;

410. a light guide lens group; 420. a first amplification module; 430. an auxiliary lens;

500. a light scanning module;

600. a signal processing circuit; 700. a temperature control module;

800. and (6) packaging the shell.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of and not restrictive on the broad application.

The inventor finds that FMCW lidar often requires the use of optical fibers to receive optical signals reflected back from an object due to the need for coherent detection. The efficiency of receiving the signal light reflected by the target can be improved significantly by using multimode fiber for receiving, but since coherent detection usually only works in a single mode, the light in multiple modes must be converted into a single mode before coherent detection. Such mode conversion in optical fibers is difficult and not easily controllable, resulting in leakage of higher order modes and significant optical loss. When the FMCW laser radar adopts the multimode optical fiber to receive a received echo optical signal, the waveguide array is coupled with the multimode optical fiber, and the optical loss can be effectively reduced by adjusting the size of the coupling end face of the waveguide array to be matched with the end face of the optical fiber. And the waveguide array and other photoelectric devices of the FMCW laser radar can be integrated on the same chip (such as a silicon optical chip) by adopting the coupling of the waveguide array and the optical fiber, so that higher integration level is realized. However, in the coaxial receiving scheme, the transmitting module and the coupling module use waveguide arrays, and need to use large optical devices such as a free space optical circulator or a polarization beam splitting crystal, which results in large volume, high cost and difficulty in mass production; in the off-axis receiving scheme, although an expensive large optical device is not needed to correspond to the transmitting module and the coupling module, the FMCW laser radar is usually far away from the ground when being installed on the automatic driving equipment, and the blind area of the transmitting module and the coupling module is large.

In addition, due to the influence of the walk-off effect, compared with the static state, after the laser radar dynamically scans, the echo light can generate a certain displacement. And as the distance increases, the displacement further increases. Thus, to cover such a large displacement, and to ensure that the mode fields of 1 or several of the waveguides can receive part of the echo signal at the maximum displacement, it is required that the mode field size of each waveguide individually add up to the maximum displacement. If the individual mode field for each waveguide is small, then the number of waveguides required is large. Resulting in a significant increase in the number of detectors at the back end of the waveguide, further resulting in a significant increase in subsequent hardware and signal processing resources.

In order to solve the above problem, an embodiment of the present application provides a frequency modulated continuous wave lidar and an automatic driving device. As shown in fig. 1, for the frequency modulated continuous wave lidar 10 according to an embodiment of the present disclosure, the frequency modulated continuous wave lidar 10 includes a light source module 200, a silicon optical chip 300, and an optical guiding mirror group 410.

The light source module 200 is used for emitting a laser beam, the silicon optical chip 300 is disposed on the light emitting side of the light source module 200, the light guide mirror group 410 is disposed corresponding to the silicon optical chip 300, and the laser beam emitted by the light source module 200 is emitted through the silicon optical chip 300 and the transceiver module to be projected to a target object.

As shown in fig. 2, the light source module 200 includes a frequency-modulated light source 260, a collimating lens 210, an isolator 220, and a first light guide 230. The frequency-modulated light source 260 may be a laser, the collimating lens 210 and the first light guide 230 are both disposed on the light emitting side of the frequency-modulated light source 260, the isolator 220 is disposed between the collimating lens 210 and the first light guide 230, and a laser beam emitted by the frequency-modulated light source 260 sequentially passes through the collimating lens 210, the isolator 220 and the first light guide 230. The collimating lens 210 is configured to collimate and project the laser beam to the isolator 220, and the isolator 220 is configured to project the collimated laser beam to the first light guide 230, and is configured to prevent light on one side of the first light guide 230 from projecting to one side of the isolator 220 facing the collimating lens 210, so as to prevent the light from interfering with normal operation of the frequency-modulated light source 260. The first light guide 230 receives the collimated laser beam transmitted by the isolator 220 and focuses and projects the collimated laser beam to the silicon optical chip 300. Specifically, the silicon optical chip 300 includes a light splitting module 340, and the light splitting module 340 is disposed corresponding to the first light guide mirror 230 to couple the laser beam focused by the first light guide mirror 230.

The silicon optical chip 300 further includes an emitting module 320 connected to the light splitting module 340, the light splitting module 340 receives the laser beam coupled into the silicon optical chip 300 and splits the laser beam into probe light and local oscillator light, and the emitting module 320 receives the probe light and emits the probe light. The silicon optical chip 300 further includes a coupling module 330 and a receiving module 350, the coupling module 330 receives the echo light reflected by the target object and sends the echo light to the receiving module 350, and the receiving module 350 is configured to receive the local oscillator light and the echo light for distance detection and the like. The light guiding mirror group 410 is used for receiving and collimating the detection light output by the emitting module 320, and is further used for receiving and converging the echo light to the coupling module 330.

As shown in fig. 3, the emission module 320 has an emission field of view 321, and the object in the emission field of view 321 can be scanned by the light from the emission module 320, and the object can also reflect the light. The coupling module 330 has a receiving field of view 331, and light reflected by the object within the receiving field of view 331 can be received by the coupling end face of the coupling module 330. The higher the overlapping degree of the transmitting visual field 321 and the receiving visual field 331 is, the smaller the scanning blind area 30a of the transmitting module 320 and the coupling module 330 is, and because there is a gap between the transmitting module 320 and the coupling module 330, the distance between the transmitting module 320 and the coupling module 330 needs to be set as small as possible to reduce the coverage area of the scanning blind area 30a. In the embodiment of the present application, the transmitting module 320 and the coupling module 330 are integrated on the same silicon optical chip 300, so that the silicon optical chip 300 has both functions of transmitting light and receiving light, so as to adjust the frequency of the continuous wave laser radar 10 to realize the off-axis transceiving function. The distance between the transmitting module 320 and the coupling module 330 can be small, the overlapping degree of the transmitting view field 321 and the receiving view field 331 is improved, the coverage area of the scanning blind area 30a is reduced, and even when the frequency modulation continuous wave laser radar 10 is installed at a position higher than the ground of the automatic driving equipment, the frequency modulation continuous wave laser radar 10 still can have a low scanning blind area 30a. In addition, the transmitting module 320 and the coupling module 330 are integrated on the same silicon optical chip 300, and the direction of light entering and exiting the silicon optical chip 300 is adjusted by arranging the light guide mirror group 410, so that large optical devices with large volume and high cost, such as an optical circulator, a beam splitter prism and the like, are not needed for light splitting, and the volume of the whole frequency modulation continuous wave laser radar 10 can be effectively reduced.

The transmitting module 320 includes a transmitting waveguide 322, the coupling module 330 includes at least one receiving waveguide 332, and the transmitting waveguide 322 and the receiving waveguide 332 are disposed adjacent to a main optical axis of the light guiding lens group 410. The transmitting waveguide 322 and at least one receiving waveguide 332 form a waveguide array, which enables the transmitting module 320 and the coupling module 330 to be integrated in the silicon optical chip 300, and also facilitates the reduction of the distance between the transmitting module 320 and the coupling module 330, so as to reduce the scan dead zone 30a between the transmitting module 320 and the coupling module 330.

The diameter of the light guide lens group 410 is centimeter, and the sizes of the transmitting waveguide 322 and the receiving waveguide 332 are smaller than that of the light guide lens group 410, for example, the sizes of the transmitting waveguide 322 and the receiving waveguide 332 are usually tens of micrometers to hundreds of micrometers. Optionally, the transmitting waveguide 322 and the receiving waveguide 332 are disposed adjacent to the main optical axis of the light guiding mirror group 410. For example, the transmitting waveguide 322 and all the receiving waveguides 332 are adjacent to the main optical axis of the light guiding mirror assembly 410, so that the light guiding mirror assembly 410 can adjust the propagation direction of the light, so that the light guiding mirror assembly 410 can collimate the probe light from the transmitting module 320, and can receive the echo light reflected from the target object and focus the echo light to project the echo light to the coupling module 330 for coupling. For example, the transmitting waveguides 322 and all the receiving waveguides 332 are sequentially laid in parallel along the surface of the silicon photonic chip 300, the end surfaces of the transmitting waveguides 322 and the receiving waveguides 332 are flush with the side edges of the silicon photonic chip 300, the principal optical axis of the light guiding lens group 410 may be disposed between the transmitting waveguides 322 and the receiving waveguides 332 closest to the transmitting waveguides 322, and the principal optical axis of the light guiding lens group 410 may also be disposed at the middle waveguide of the waveguide array or between the middle two waveguides. Optionally, the light guiding lens group 410 includes at least one lens with bending power, and the number of the lenses can be specifically selected according to actual requirements to meet the requirements of the light converging and collimating functions of the light guiding lens group 410.

Optionally, both the transmitting waveguide 322 and the receiving waveguide 332 are disposed towards the light guiding mirror group 410. The end of the transmitting waveguide 322 facing the light guiding lens assembly 410 is a first transmitting end 3221, and the end of the receiving waveguide 332 facing the light guiding lens assembly 410 is a first receiving end 3321, wherein the first transmitting end 3221 and the first receiving end 3321 are disposed on a focal plane of the light guiding lens assembly 410, the transmitting waveguide 322 of the transmitting module 320 and the receiving waveguide 332 of the coupling module 330 are closely spaced in a first direction, although the transmitting optical path and the receiving optical path are disposed off-axis, the receiving optical path is offset from the transmitting optical path due to the walk-off effect, the transmitting field of view and the receiving field of view are almost completely overlapped, the dead zone 30a between the transmitting module 320 and the coupling module 330 is very small, and the first direction is the arrangement direction of the transmitting waveguide 322 and the receiving waveguide 332. The detection light is emitted from the first emission end surface 3221 of the emission waveguide 322 to the light guide lens group 410, and the echo light reflected from the target is projected to the first emission end surface 3221 through the light guide lens group 410 to enter the receiving waveguide 332.

When the coupling module 330 includes at least three receiving waveguides 332, the distances between the adjacent two receiving waveguides 332 in the first direction may be equal or unequal. In addition, when the adjacent two waveguide arrays forming the coupling module 330 have the same pitch in the first direction and are a, the pitch in the first direction between the transmitting waveguide 322 of the transmitting module 320 and the receiving waveguide 332 of the coupling module 330 is b, and the pitch a and the pitch b may be the same or different. The first receiving end surfaces 3321 of the receiving waveguides 332 forming the coupling module 330 may or may not be equal in size. When the first receiving end surfaces 3321 of the receiving waveguides 332 forming the coupling module 330 are equal in size, the first transmitting end surfaces 3221 of the transmitting waveguides 322 forming the transmitting module 320 may be equal in size to or different in size from the first receiving end surfaces 3321. The space between two adjacent receiving waveguides 332, the receiving waveguides 332 and the transmitting waveguide 322 in the first direction is not limited, and the sizes of the first transmitting end face 3221 and the first receiving end face 3321 are not limited, and can be specifically selected according to actual requirements.

Among other things, the size of the first emission end face 3221 of the emission waveguide 322 affects the emission mode field size of the emission waveguide 322, and the size of the first reception end face 3321 of the reception waveguide 332 affects the reception mode field size of the reception waveguide 332. Optionally, the size of the transmission mode field of the transmission waveguide 322 is equal to or differs from the size of the reception mode field of the reception waveguide 332 by a preset range, the fm cw lidar 10 includes a group of light guide lens sets 410, that is, the transmission module 320 and the coupling module 330 share the same group of light guide lens sets 410, the first end surfaces of the plurality of waveguides of the waveguide array are all located near the main optical axis of the light guide lens sets 410, and light splitting is not required to be performed by using a large optical device, so that the light path design and structure of the whole fm cw lidar 10 are simplified.

Optionally, the fm continuous wave lidar 10 includes two light guide lens sets 410, one light guide lens set 410 is disposed corresponding to the emission module 320 and is used for collimating the detection light emitted from the emission module 320, and the other light guide lens set 410 is disposed corresponding to the coupling module 330 and is used for converging the echo light to the coupling module 330. The two light guiding lens sets 410 may be disposed at intervals, and each of the two light guiding lens sets 410 independently includes at least one lens, so as to flexibly adjust the number of the lenses of each light guiding lens set 410, and to flexibly adjust the positions of the two light guiding lens sets 410, so as to plan the installation space.

The fm continuous wave lidar 10 further includes a light scanning module 500, the light scanning module 500 is disposed on a side of the light guiding lens assembly 410 facing the target object, and the light scanning module 500 is configured to receive the light transmitted by the light guiding lens assembly 410 and emit the light to the outside for scanning. The optical scanning module 500 may be a galvanometer, a turning mirror, a MEMS micro galvanometer, or a combination thereof. Optionally, the light scanning module 500 includes a one-dimensional galvanometer and a one-dimensional rotating galvanometer, the one-dimensional galvanometer is configured to provide a scanning view field of the second direction for the frequency modulated continuous wave laser radar 10, and the one-dimensional rotating galvanometer is configured to provide a scanning view field of the first direction for the frequency modulated continuous wave laser radar 10, where the first direction is perpendicular to the second direction, for example, when the frequency modulated continuous wave laser radar 10 is installed in an automatic driving device, the second direction is a vertical direction, and the first direction is a horizontal direction.

As shown in fig. 2, the receiving module 350 includes a polarization beam splitter 351, and the polarization beam splitter 351 is connected to the receiving waveguide 332 of the coupling module 330 to receive the echo light transmitted by the coupling module 330 and convert the echo light into a plurality of polarized echo lights with the same polarization state.

Optionally, the coupling module 330 includes M receive waveguides 332, where M is an integer greater than or equal to 2. When the coupling module 330 includes M receiving waveguides 332, the receiving module 350 includes M polarization beam splitting converters 351 which are connected in a one-to-one correspondence manner and have the same number as the M receiving waveguides 332, and each polarization beam splitting converter 351 receives the echo light transmitted by the corresponding receiving waveguide 332 and performs polarization conversion to form a plurality of polarization echo lights. The receiving module 350 further includes an optical mixer 352, one input end of the optical mixer 352 is connected to the optical splitting module 340 and receives the local oscillator light, and the other input end of the optical mixer 352 is further connected to the polarization beam splitting converter 351 to receive a beam of polarized echo light and mix the polarized echo light and the local oscillator light to form mixed light. Specifically, the input end of the polarization beam splitting converter 351 is connected to the receiving waveguide 332, the polarization beam splitting converter 351 may include two output ends, for example, the received echo light is divided into P-polarization echo light and S-polarization echo light, the number of the optical mixers 352 corresponding to the same polarization beam splitting converter 351 at this time may be two, and the two optical mixers 352 are connected to the two output ends of the polarization beam splitting converter 351 in a one-to-one correspondence manner, one optical mixer 352 is used for mixing the P-polarization echo light with the local oscillator light, and the other optical mixer 352 is used for mixing the S-polarization echo light with the local oscillator light. Of course, the polarization beam splitter 351 may perform polarization diversity on the echo light in another manner, and output the polarization-diverse echo light separately and mix the polarization-diverse echo light with the local oscillation light.

The receiving module 350 further includes a first balanced detector 353, and the first balanced detector 353 is connected to the optical mixer 352 to receive the mixed light for balanced detection. Specifically, the optical mixer 352 has two outputs, and the first balanced detector 353 is connected to the two outputs of the optical mixer 352 to receive the mixed light for processing to form a corresponding coherent electrical signal, which can then be output to the other signal processing circuit 600 for further signal processing. For example, the signal processing circuit 600 may be a trans-impedance amplifier (TIA).

Optionally, as shown in fig. 4, when the coupling module 330 includes M receiving waveguides 332, the coupling module 330 further includes a beam combining module 360, and the beam combining module 360 includes at least one multiport coupler 361. As shown in fig. 5-7, the multi-port coupler 361 has N first access ports 3611 and one first output port 3612, N being an integer equal to or greater than 2. A first output port 3612 of the multi-port coupler 361 is connected to the receiving module 350, at least two first access ports 3611 of the multi-port coupler 361 are connected to the plurality of receiving waveguides 332 in a one-to-one correspondence manner, so that the echo light transmitted by the receiving waveguides 332 enters the multi-port coupler 361 from the first access port 3611 and is output to the receiving module 350 from the first output port 3612 after being combined by the multi-port coupler 361, and specifically, the first output port 3612 is connected to the polarization beam splitter 351 of the receiving module 350. Thus, when the coupling module 330 includes M receiving waveguides 332, the multiport coupler 361 couples the multiple optical signals from the M receiving waveguides 332 into one optical signal and outputs the optical signal to the corresponding polarization beam splitter 351, and only one polarization beam splitter 351 is needed to be connected to perform polarization conversion on the multiple signal lights transmitted by the multiple receiving waveguides 332, so as to save the usage of the optical mixer 352 and the first balanced detector 353, and simplify the system architecture of the entire silicon optical chip 300.

When the number of the receiving waveguides 332 connected to the same multi-port coupler 361 is large, optical loss tends to occur in the transmission of light between the plurality of receiving waveguides 332 and the multi-port coupler 361. Optionally, as shown in fig. 5, the silicon photonic chip 300 is configured to include a plurality of multi-port couplers 361, each multi-port coupler 361 being independently connected to a corresponding plurality of receiving waveguides 332 to reduce optical loss when one multi-port coupler 361 is connected to a large number of receiving waveguides 332.

Wherein, for longer distance, when the fm continuous wave lidar 10 is in the middle-short distance to the target, because the optical power of the echo light reflected by the target itself is relatively strong, the echo light can meet the detection requirement when entering the receiving module 350 through the receiving waveguide 332 and the multiport coupler 361, at this time, all the receiving waveguides 332 of the coupling module 330 can be set to be connected with the polarization beam splitting converter 351 through the multiport coupler 361, so as to reduce the usage amount of the following hardware such as the optical mixer 352 and the first balanced detector 353.

When the fm cw lidar 10 is at a longer distance from the target, the power of the echo light reaching the receiving waveguide 332 is smaller, and the echo light may also generate a certain offset due to the walk-off effect, and the offset is larger the farther the distance from the fm cw lidar 10 to the target is. Optionally, as shown in fig. 5, the beam combining module 360 is further configured to include at least one through waveguide 362, where the through waveguide 362 has a second access port 3621 and a second output port 3622, the second access port 3621 is connected to the receiving waveguide 332, and the second output port 3622 is connected to the receiving module 350, so that the receiving waveguide 332 is transmitted to the receiving module 350 through the through waveguide 362, and the loss of the optical signal transmitted through the through waveguide 362 is small. Specifically, the second output port 3622 of each straight waveguide 362 is connected to one polarization splitting converter 351. For example, when the receiving module 350 includes 9 receiving waveguides 332, the energy of the echo becomes smaller and smaller in the direction away from the transmitting waveguide 322, the beam combining module 360 includes two multi-port couplers 361 and three through waveguides 362, the two multi-port couplers 361 are disposed adjacent to the transmitting waveguide 322, one of the multi-port couplers 361 is connected to the three receiving waveguides 332 for receiving the short-distance echo light, the other multi-port coupler 361 is connected to the three receiving waveguides 332 for receiving the middle-distance echo light, and the three through waveguides 362 are connected to the three receiving waveguides 332 for receiving the long-distance echo light in a one-to-one correspondence.

Optionally, the sum of the number of the first access ports 3611 and the number of the second access ports 3621 is equal to the number of the receiving waveguides 332, a part of the receiving waveguides 332 are connected with the first access ports 3611 of the multi-port coupler 361 in a one-to-one correspondence manner, and the remaining part of the receiving waveguides 332 are connected with the second access ports 3621 of the through waveguides 362, so as to meet the requirement of multi-channel transmission.

Alternatively, the silicon photonic chip 300 has a first surface facing the light guiding mirror assembly 410, the first surface may be disposed at a focal plane of the light guiding mirror assembly 410, when the transmitting waveguide 322 and the receiving waveguide 332 are sequentially arranged along a direction parallel to the first surface (i.e. the first direction), the receiving waveguide 332 near the transmitting waveguide 322 is connected to at least one multiport coupler 361, and the receiving waveguide 332 far from the transmitting waveguide 322 is connected to at least one through waveguide 362, so as to prevent the occurrence of insufficient optical power of the edge light of the echo light transmitted to the receiving module 350 via the multiport coupler 361. Further, when the number of the receiving waveguides 332 is large, the beam combining module 360 may be configured to include a plurality of multi-port couplers 361, and the plurality of multi-port couplers 361 are each independently connected with the plurality of receiving waveguides 332 near one side of the transmitting waveguide 322.

The multi-port coupler 361 may be a star coupler, a multi-mode interference coupler, or the like. As shown in fig. 6, which is a schematic structural diagram of the coupling module 330 according to an embodiment of the present application, wherein the receiving waveguides 332 are connected to the polarization beam splitter 351 through star couplers, in fig. 6, a plurality of receiving waveguides 332 of the coupling module 330 are located between DD-BB; the spacing between the plurality of receive waveguides 332 between CC and BB is varied, for example, to adapt to the size of the multi-port coupler 361, the spacing between two adjacent receive waveguides 332 is gradually reduced in the direction from CC to BB, so as to realize transition between the plurality of receive waveguides 332 and the multi-port coupler 361, and reduce loss; and a star coupler is arranged between BB and AA and is used for combining multiple paths of optical signals transmitted by the waveguide array connected with the star coupler into one path of optical signal. Fig. 7 is a schematic structural diagram illustrating a receiving waveguide 332 of a coupling module 330 in an embodiment of the present application is connected to a polarization beam splitter 351 through a multi-mode interference coupler, which is different from fig. 6 in that a multi-mode interference coupler is shown between BB and AA in fig. 7, and the multi-mode interference coupler is used for combining multiple optical signals transmitted by a waveguide array connected to the multi-mode interference coupler into one optical signal.

The optical splitting module 340 is further configured to split the laser beam coupled into the silicon optical chip 300 into calibration light, and the silicon optical chip 300 further includes a light source nonlinear calibration optical path 354, where the light source nonlinear calibration optical path 354 is connected to the optical splitting module 340 and receives the calibration light, so as to calibrate the laser beam emitted by the frequency modulation light source 260. The light source nonlinear calibration optical path 354 includes a coupler 3541 and a calibration balance detector 3542, the light splitting module 340 splits light to two calibration lights, the two calibration lights have different delays, specifically, one of the calibration lights enters the coupler 3541, the other calibration light enters the coupler 3541 through an optical delay line 3543, the calibration light passing through the optical delay line 3543 can be delayed, the coupler 3541 is configured to mix the two calibration lights with different delays, and the calibration balance detector 3542 is configured to receive the mixed light output by the coupler 3541 and perform balance detection. Coupler 3541 is a 3dB coupler, although other couplers 3541 capable of performing the above-described functions may be used. In use, the output signal of the calibrated balanced detector 3542 may be further processed as a basis for calibration of the frequency modulated light source 260. By adopting the frequency modulation continuous wave laser radar 10 provided by the embodiment, the frequency modulation light source 260 can be calibrated in real time, so that an operator can find problems in time to adjust the problem, and the accuracy of a detection result is further ensured.

Alternatively, as shown in fig. 2, 4 and 8, the light splitting module 340 includes a spot size converter 344, a first optical splitter 341, a second optical splitter 342 and a third optical splitter 343. The spot size converter 344 receives a laser beam emitted by the light source module 200, the first optical splitter 341 is connected to the spot size converter 344 to receive the laser beam emitted by the light source module 200, the first optical splitter 341 is further connected to the emission module 320, the second optical splitter 342, and the third optical splitter 343, respectively, the first optical splitter 341 splits the laser beam emitted by the light source module 200 into probe light and transmits the probe light to the emission module 320, splits the probe light and transmits the first light to the second optical splitter 342, and splits the probe light and transmits the third light to the third optical splitter 343, the second optical splitter 342 is connected to the light source nonlinear calibration optical path 354 and transmits the first light into two calibration lights and transmits the two calibration lights to the light source nonlinear calibration optical path 354, and the third optical splitter 343 is connected to the plurality of optical mixers 352 and outputs a plurality of local oscillator lights from the third light and transmits the plurality of local oscillator lights to the plurality of optical mixers 352 in a one-to-one correspondence. Of course, the setting manner of the optical splitting module 340 in the embodiment of the present application includes, but is not limited to, the setting manner described above, and may be specifically selected according to actual requirements.

Optionally, the spot converter 344 includes a first waveguide that is a tapered waveguide, a cantilever waveguide, or a multilayer waveguide. The first waveguide and the emission waveguide 322 may be made of the same material, and at this time, the optical power that the first waveguide and the emission waveguide 322 can transmit is equal, and the first waveguide and the emission waveguide 322 may be disposed on the same layer, and the first waveguide and the emission waveguide 322 are directly conducted through the first optical splitter 341 to transmit light, so as to simplify the structure of the silicon optical chip 300. The material of the transmitting waveguide 322 may be the same as that of the receiving waveguide 332, so as to simplify the process for preparing the transmitting waveguide 322 and the receiving waveguide 332.

Optionally, when the optical power that the first waveguide can accommodate is equal to the optical power that the receiving waveguide 332 can accommodate, it is described that the power of the probe light that the silicon optical chip 300 can transmit is limited, the energy of the probe light emitted by the transmitting waveguide 322 is limited, and it is difficult to meet the transmission energy requirement of long-distance ranging, as shown in fig. 2 and fig. 4, the fm continuous wave lidar 10 further includes a first amplification module 420 and an auxiliary lens 430, the first amplification module 420 is disposed corresponding to the transmitting module 320, and the first amplification module 420 is configured to receive the probe light emitted by the transmitting module 320, amplify the probe light to form first amplified light, and then emit the first amplified light. The first amplifying module 420 may include a first Amplifier, which may be a Semiconductor Optical Amplifier (SOA) chip. The auxiliary lens 430 is disposed corresponding to the first amplifying module 420, and the auxiliary lens 430 is configured to receive the first amplified light and change a light path direction of the first amplified light, so that the first amplified light is emitted to the center of the light guide lens group 410, the first amplified light can be collimated by the light guide lens group 410 and then emitted, and meanwhile, an emitting position of the first amplified light is located near a central optical axis of the light guide lens group 410, a distance between the emitting light path and the receiving light path is small, and a scanning blind area 30a between the emitting module 320 and the coupling module 330 is reduced.

In other embodiments, when the optical power of the laser beam entering the first waveguide of the spot size converter 344 is larger, correspondingly, the first waveguide made of a material capable of accommodating larger optical power needs to be selected, in this case, the materials of the first waveguide and the emission waveguide 322 may be set to be different, and the optical power that the first waveguide can accommodate is larger than the optical power that the emission waveguide 322 can accommodate, and the silicon optical chip 300 further includes an interlayer mode converter (not shown in the drawings), in which the laser beam guided by the first waveguide is subjected to interlayer conversion to the emission waveguide 322 through evanescent wave coupling in the interlayer mode converter, in this case, optionally, as shown in fig. 8, the light source module 200 is set to include an optical input amplifier 240 and a second optical guide mirror 250, the second optical guide mirror 250 is set corresponding to the optical input light source 260, the optical input amplifier 240 is set on an optical path between the second optical guide mirror 250 and the collimating lens 210, the second optical guide mirror 250 is configured to receive the laser beam emitted by the frequency-modulated light source 260 and project the laser beam to the optical input amplifier 240, and the second optical guide mirror 250 is further configured to adjust the projection size of the laser beam to match the size of the optical input amplifier 240, for example, and the optical input amplifier 240 is configured to focus the optical input optical amplifier 240, and the optical amplifier 240 is configured to focus the optical amplifier 240 is smaller size of the optical input end of the optical amplifier 240. The light input amplifier 240 is configured to amplify the laser beam transmitted by the second light guide mirror 250, so that the laser beam transmitted to the first waveguide has a larger optical power and enters the collimating lens 210, so as to meet a subsequent optical power detection requirement.

When the first waveguide and the receiving waveguide 332 are made of the same material, the first waveguide and the receiving waveguide 332 may be made of silicon material, so as to simplify the manufacturing process for forming the first waveguide and the receiving waveguide 332. When the optical power that the first waveguide can accommodate is larger than that of the receiving waveguide 332, the first waveguide may be made of a silicon nitride material, and the receiving waveguide 332 may be made of a silicon material.

The frequency modulated continuous wave lidar 10 further comprises a package body 800, and the light source module 200, the silicon optical chip 300 and the first amplification module 420 are all arranged in the inner space of the package body 800. Alternatively, as shown in fig. 2, the light guiding lens assembly 410 is mounted on a structural member outside the package housing 800. The auxiliary lens 430 may be installed in the inner space of the package case 800, or, as shown in fig. 4, the auxiliary lens 430 may be installed on a structural member outside the package case 800. The package body 800 has a first channel through which the probe light passes, and also has a second channel through which the echo light passes. The light source module 200 further includes a light source housing, and the collimating lens 210, the isolator 220, the first light guide 230, the light input amplifier 240, the second light guide 250, and the frequency-modulated light source 260 may be packaged in the light source housing to form a whole, and then packaged in the packaging housing 800.

The frequency modulated continuous wave lidar 10 further comprises a temperature control module 700, the temperature control module 700 may also be packaged in the internal space of the package housing 800, and the temperature control module 700 is configured to monitor the temperature change inside the package housing 800, so as to observe the working states of the optical devices such as the light source module 200 and the silicon optical chip 300 inside the package housing 800. The embodiment of the application integrates the transmitting module 320 and the coupling module 330 into the silicon optical chip 300, and the light guide mirror group 410 is arranged for receiving and collimating the detection light output by the transmitting module 320 and for receiving and converging the echo light to the coupling module 330, so that the system architecture of the whole frequency modulation continuous wave laser radar 10 is simplified, a plurality of optical devices such as the silicon optical chip 300 and the light source module 200 can be integrally installed in the same packaging shell 800, the structure is compact, and the size of the whole frequency modulation continuous wave laser radar 10 is convenient to reduce.

The embodiment of the application also provides automatic driving equipment, wherein the automatic driving equipment comprises one of an automobile, an airplane and other equipment related to intelligent sensing and detection by using the laser radar. The autopilot device comprises an autopilot body and a frequency modulated continuous wave lidar 10 as described above. The frequency modulated continuous wave lidar 10 is provided to an autonomous driving body, for example, when the autonomous driving apparatus is a car, the autonomous driving body includes a roof, and the frequency modulated continuous wave lidar 10 is mounted to the roof of the car.

The same or similar reference numerals in the drawings of the present embodiment correspond to the same or similar components; in the description of the present application, it is to be understood that if there is an orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not intended to indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and are not to be construed as limitations of the present patent, and specific meanings of the above terms may be understood by those skilled in the art according to specific situations.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A frequency modulated continuous wave lidar comprising:

2. A fm cw lidar as claimed in claim 1, wherein the transmit module includes a transmit waveguide, the coupling module includes at least one receive waveguide, and the transmit waveguide and the receive waveguide are disposed adjacent to a principal optical axis of the set of light guiding mirrors.

3. Frequency modulated continuous wave lidar according to claim 2,

the end of the transmitting waveguide facing the light guide lens group is a first transmitting end surface, and the end of the receiving waveguide facing the light guide lens group is a first receiving end surface;

4. A fm cw lidar according to claim 2, wherein the size of the transmit mode field of the transmit waveguide is equal to or within a predetermined range of the size of the receive mode field of the receive waveguide, and the transmit waveguide and the receive waveguide share the set of light guiding mirrors.

5. A frequency modulated continuous wave lidar according to claim 2, further comprising:

6. A frequency modulated continuous wave lidar according to claim 2, wherein the coupling module comprises M receive waveguides, M being an integer greater than or equal to 2, the coupling module further comprising:

the beam combining module comprises at least one multi-port coupler, the multi-port coupler is provided with N first access ports and a first output port, N is an integer greater than or equal to 2, and the at least two first access ports of the multi-port coupler are connected with the receiving waveguide one by one so that the echo light transmitted by the receiving waveguide enters the multi-port coupler through the first access ports and is output to the receiving module through the first output port after being combined.

7. An FMCW lidar according to claim 6 wherein said beam combining module further comprises at least one through waveguide having a second access port and a second output port, said second access port being coupled to said receive waveguide, said second output port being coupled to said receive module such that said echo light transmitted by said receive waveguide is transmitted to said receive module via said through waveguide.

8. A frequency modulated continuous wave lidar according to claim 7, wherein a sum of the number of the first access ports and the number of the second access ports is equal to the number of the receive waveguides.

9. An FHSCW lidar according to claim 7, wherein said transmitting waveguide and said receiving waveguide are arranged in series in a direction parallel to a surface of said silicon photonic chip, said receiving waveguide on a side close to said transmitting waveguide being connected to at least one of said multiport couplers, and said receiving waveguide on a side remote from said transmitting waveguide being connected to at least one of said pass-through waveguides.

10. Frequency modulated continuous wave lidar according to claim 2,

the receiving module includes:

11. A frequency modulated continuous wave lidar according to claim 1, further comprising:

12. An autopilot apparatus, comprising:

a frequency modulated continuous wave lidar as claimed in any of claims 1-9; and

and the frequency modulation continuous wave laser radar is arranged on the automatic driving main body.