Frequency modulated continuous wave lidar and autonomous driving device

Abstract

The application discloses a silicon optical chip, a frequency-modulated continuous wave laser radar and an automatic driving device. The silicon optical chip comprises at least one transceiving unit and a receiving module. The transceiving unit is used for emitting probe light outward and receiving echo light and transmitting the echo light to the receiving module to form a detection channel. The transceiving unit comprises a coupling module comprising a plurality of receiving waveguides, which are used for receiving echo light from a receiving end face; and a beam combining module, which is used for receiving echo light output by the coupling module and outputting the echo light after beam combining. The silicon optical chip has high coupling efficiency for receiving echo light, saves the number of devices of the receiving module and simplifies the system architecture of the whole silicon optical chip.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radar, in particular to a frequency-modulated continuous wave laser radar and an automatic driving device. BACKGROUND

[0002] The laser radar is one of the core sensors widely used in the automatic driving scene, and can be used to collect three-dimensional information of the external environment. According to the detection mechanism, the laser radar can be mainly divided into two kinds of laser radars, namely, Time of Flight (ToF) and Frequency Modulated Continuous Wave (FMCW). The FMCW laser radar adopts a coherent detection mode, and through the balanced detection of the local oscillator light and the signal light reflected by the target object at the receiving end, the interference of the external environmental light on the performance of the laser radar can be effectively reduced, and the ranging performance of the laser radar is improved. Meanwhile, the FMCW laser radar can additionally provide speed information in addition to providing spatial coordinate information.

[0003] In the related art, the FMCW laser radar cannot adjust the position of the optical path in two directions, and it is difficult to improve the detection field of view and the resolution of the laser radar. SUMMARY

[0004] Embodiments of the present application provide a frequency-modulated continuous wave laser radar and an automatic driving device, which can solve the problem of poor detection performance of the FMCW laser radar.

[0005] In a first aspect, the embodiments of the present application provide a frequency-modulated continuous wave laser radar, comprising:

[0006] A light source module is configured to emit a frequency-modulated continuous wave laser beam.

[0007] A silicon optical chip includes a light splitting module, a receiving module and a plurality of transceiver units. The end faces of the plurality of transceiver units are arranged along a first direction. The light splitting module receives the laser beam coupled into the silicon optical chip and splits the laser beam into a plurality of detection beams. The plurality of detection beams are transmitted to the corresponding plurality of transceiver units. The transceiver units emit the received detection beams outward and also transmit the received echo beams to the receiving module to form a detection channel.

[0008] An optical folding module is configured to fold the detection beams emitted by the plurality of transceiver units to make the plurality of detection beams deviate from each other in a second direction, and to fold the plurality of echo beams deviated from each other in the second direction and project the echo beams to the corresponding transceiver units. The second direction is perpendicular to the end faces of the transceiver units.

[0009] In some example embodiments, the light folding module comprises at least one of a first light reflecting element and a first light folding prism, the first light reflecting element is at least one in number, and the first light folding prism is at least one in number.

[0010] In some example embodiments, the light folding module comprises a plurality of first light reflecting elements arranged correspondingly to a plurality of the transceiving units.

[0011] Each of the first light reflecting elements is configured to reflect the optical path of the probe light emitted by the corresponding transceiving unit and the echo light received thereby, and the first light reflecting element and the end face of the corresponding transceiving unit are arranged in the second direction with a spacing therebetween, and a plurality of the first light reflecting elements are arranged in the second direction with a staggered arrangement.

[0012] In some example embodiments, the light folding module comprises a plurality of the first light folding prisms.

[0013] The probe light emitted by a plurality of the transceiving units is projected to the corresponding first light folding prisms, and after being deflected by the first light folding prisms, the probe light is emitted in the second direction with a staggered arrangement.

[0014] After a plurality of the echo light emitted in the second direction with a staggered arrangement is deflected by the corresponding first light folding prisms, each of the echo light is returned to the corresponding transceiving unit via the corresponding probe channel.

[0015] In some example embodiments, the frequency-modulated continuous wave laser radar further comprises a plurality of collimating mirror groups arranged correspondingly to the front side of the end face of a plurality of the transceiving units, configured to collimate the probe light emitted by the transceiving units, and configured to converge the echo light towards the transceiving units.

[0016] In some example embodiments, each of the transceiving units comprises a transmitting module and a coupling module; the transmitting module is configured to emit the received probe light outwards from a transmitting end face; the coupling module is configured to receive the echo light from a receiving end face and transmit the echo light to the coupling module; and the transmitting end face of the transmitting module and the receiving end face of the coupling module constitute the end face of the transceiving unit.

[0017] In some example embodiments, the frequency-modulated continuous wave laser radar further comprises a plurality of first amplifying modules arranged correspondingly to the transmitting modules, configured to amplify the probe light emitted by the corresponding transmitting modules.

[0018] In some example embodiments, the light folding module further comprises:

[0019] A light adjusting mirror group configured to expand the probe light deflected by the light folding module and emit the probe light outwards, and configured to shrink the echo light and emit the echo light towards the light folding module.

[0020] In some example embodiments, the plurality of transceiver units are configured to emit the probe light or receive the echo light through the same set of light modulation mirrors.

[0021] In some example embodiments, the light splitting module is further configured to split the laser beam into a plurality of local light beams, and the receiving module comprises:

[0022] a polarization beam splitting converter configured to receive the echo light transmitted by the transceiver unit and split the echo light into two beams of polarized echo light having different polarization states;

[0023] a plurality of optical mixers, each of the optical mixers being connected to the polarization beam splitting converter and configured to receive the polarized echo light output by the polarization beam splitting converter and the local light, and mix the received polarized echo light and the local light to obtain mixed light;

[0024] a first balanced detector connected to the optical mixer and configured to receive the mixed light for detection.

[0025] In some example embodiments, the frequency-modulated continuous wave lidar further comprises:

[0026] a first packaging shell, the light source module and the silicon optical chip being packaged in an inner space of the first packaging shell;

[0027] a second packaging shell, the light splitting module being packaged in an inner space of the second packaging shell;

[0028] The second packaging shell is connected to the first packaging shell, the first packaging shell is provided with a plurality of first light transmission holes, the second packaging shell is provided with a plurality of second light transmission holes, and the first light transmission holes and the second light transmission holes are correspondingly arranged to allow the probe light and the echo light to pass through.

[0029] In a second aspect, the embodiments of the present application provide an automatic driving device, comprising an automatic driving main body and the frequency-modulated continuous wave lidar as described above, the horizontal direction being the first direction and the vertical direction being the second direction, and the frequency-modulated continuous wave lidar being installed on the automatic driving main body.

[0030] The frequency-modulated continuous wave laser radar and the automatic driving device based on the embodiment of the application are characterized in that a plurality of groups of transceiving units are integrated in a silicon optical chip and used for detecting target objects; meanwhile, each group of transceiving units is provided with a corresponding light refraction module, the direction of multi-channel light path propagation and arrangement is changed through the light refraction module, even if the plurality of groups of transceiving units are designed along the surface of the silicon optical chip, the multi-channel light path extends in the direction perpendicular to the end surface of the transceiving unit, the multi-channel light path can be staggered in the direction perpendicular to the end surface of the transceiving unit, the number of lines of the laser radar in the direction is increased, and then the detection resolution and the field of view are increased, the silicon optical chip is simple in design and high in integration, and is convenient for tape-out production. In addition, the plurality of groups of transceiving units are integrated in the silicon optical chip, a separate transmitting module does not need to be separately provided, high integration is realized, and the complexity of the photoelectric device assembly of the frequency-modulated continuous wave laser radar is effectively reduced. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0032] Figure 1 The system architecture schematic diagram of the frequency-modulated continuous wave laser radar of one embodiment of the application;

[0033] Figure 2 The system architecture schematic diagram of the light refraction module corresponding to two groups of transceiving units of one embodiment of the application;

[0034] Figure 3 The structure schematic diagram of the light refraction module including two first reflecting elements of one embodiment of the application;

[0035] Figure 4 The structure schematic diagram of the one-dimensional galvanometer and the one-dimensional rotating mirror corresponding to the light adjusting mirror group arrangement of one embodiment of the application;

[0036] Figure 5 The structure schematic diagram of the light refraction module including the first reflecting element and the first light refraction prism of one embodiment of the application;

[0037] Figure 6 The schematic diagram of the transmitting field of view of the transmitting module and the receiving field of view of the coupling module of one embodiment of the application;

[0038] Figure 7 The structure schematic diagram of the receiving waveguide connected with the polarization beam splitting rotator through the multi-port coupler of one embodiment of the application;

[0039] Figure 8 A structure diagram of a beam combining module for an embodiment of the present application includes a plurality of multi-port couplers and a plurality of through waveguides.

[0040] Reference signs:

[0041] 10, frequency-modulated continuous wave laser radar;

[0042] 200, light source module; 210, first light guide mirror; 220, isolator; 230, second light guide mirror; 240, frequency-modulated light source;

[0043] 300, silicon optical chip;

[0044] 320, light splitting module; 321, first light splitter; 322, second light splitter; 323, third light splitter; 324, mode spot converter;

[0045] 330, transceiver unit; 331, transmitting module; 3311, transmitting waveguide; 331a, transmitting field of view; 331b, transmitting end face; 332, coupling module; 3321, receiving waveguide; 332a, receiving field of view; 332b, receiving end face; 330a, scanning blind area;

[0046] 350, receiving module; 351, polarization beam splitting rotator; 360, optical frequency mixer; 370, first balanced photodetector; 340, light source nonlinear calibration optical path; 341, coupler; 342, calibration balanced photodetector; 343, optical delay line;

[0047] 400, light folding module; 411, first light reflecting element; 412, first light folding prism; 413, second light reflecting element;

[0048] 420, beam scanning module; 421, one-dimensional galvanometer; 4211, galvanometer; 422, one-dimensional rotating mirror; 4221, rotating mirror; 430, first amplification module; 440, collimating mirror group; 450, light adjusting mirror group;

[0049] 510, first packaging shell; 520, second packaging shell;

[0050] 600, temperature control module; 700, signal processing circuit;

[0051] 810, multi-port coupler; 820, through waveguide; 811, first access port; 812, first output port; 821, second access port; 822, second output port;

[0052] Y, first direction; X, second direction. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0054] The inventors discovered that the FMCW lidar suffers from a walk-off effect due to the movement of the scanning device, which significantly impacts its receiving efficiency. To mitigate the degrading effect of the walk-off effect on lidar performance, the scanning speed of the scanning device cannot be significantly increased. Consequently, the improvement of the lidar's equivalent line count is limited, directly affecting the lidar's resolution and field of view.

[0055] To address the aforementioned issues, this application provides a frequency-modulated continuous wave lidar and an autonomous driving device.

[0056] like Figure 1 The diagram shown is a system architecture diagram of a frequency-modulated continuous wave lidar 10 according to an embodiment of this application. The frequency-modulated continuous wave lidar 10 includes a light source module 200, a silicon photonics chip 300, and a refractive module 400. The light source module 200 is used to emit a laser beam. The silicon photonics chip 300 is disposed on the light-emitting side of the light source module 200. The laser beam emitted by the light source module 200 passes through the silicon photonics chip 300, the refractive module 400, and the beam scanning module 420 before being emitted and projected onto the target object. The echo light reflected back from the target object passes through the beam scanning module 420 and the refractive module 400 before entering the silicon photonics chip 300.

[0057] like Figure 2 As shown, the light source module 200 includes a frequency-modulated light source 240, a first light guide mirror 210, an isolator 220, and a second light guide mirror 230. The frequency-modulated light source 240 can be a frequency-modulated laser, used to emit a frequency-modulated continuous wave laser beam. The first light guide mirror 210 and the second light guide mirror 230 are both disposed on the light-emitting side of the frequency-modulated light source 240. The isolator 220 is disposed between the first light guide mirror 210 and the second light guide mirror 230. The laser beam emitted by the frequency-modulated light source 240 passes through the first light guide mirror 210, the isolator 220, and the second light guide mirror 230 in sequence. The first light guide mirror 210 is used to collimate the laser beam before projecting it onto the second light guide mirror 230. An isolator 220 is also disposed between the first light guide mirror 210 and the second light guide mirror 230. The isolator 220 is used to prevent light from the second light guide mirror 230 side from being back-transmitted to the side of the isolator 220 facing the first light guide mirror 210, thereby preventing the laser beam from interfering with the normal operation of the frequency-modulated light source 240. The second light guide mirror 230 receives the collimated laser beam transmitted from the isolator 220, focuses the collimated laser beam, and couples it into the silicon photonic chip 300. Specifically, the silicon photonic chip 300 includes a beam splitting module 320, and the laser beam coupled into the silicon photonic chip 300 is transmitted to the beam splitting module 320.

[0058] The silicon optical chip 300 further comprises a plurality of groups of transceiver units 330, end faces of the plurality of transceiver units 330 are arranged along the first direction Y, light enters and exits the transceiver units 330 from the end faces of the transceiver units 330, and the end faces of the transceiver units 330 are parallel to the first direction Y. The light splitting module 320 receives the laser beam coupled into the silicon optical chip 300 and splits the laser beam into a plurality of probe lights, and the plurality of probe lights are transmitted to the corresponding plurality of transceiver units 330 respectively, the transceiver units 330 emit the received probe lights outward, and also transmit the received echo lights to the coupling module 332 to form a detection channel.

[0059] The light folding module 400 is configured to fold the probe lights emitted by the plurality of transceiver units 330 to make the plurality of probe lights be emitted in the second direction X staggered, and fold the plurality of echo lights staggered in the second direction X and project the plurality of echo lights to the corresponding transceiver units 330, and the second direction X is a direction perpendicular to the end face of the transceiver unit 330. By changing the direction of propagation and arrangement of the multi-channel optical path through the light folding module 400, even if the plurality of groups of transceiver units 330 are designed along the surface parallel to the silicon optical chip 300, the multi-channel optical path extends in the direction perpendicular to the end face of the transceiver unit, the multi-channel optical path can be staggered in the direction perpendicular to the end face of the transceiver unit 330, the number of channels of the low-frequency continuous wave laser radar 10 in the direction is increased, and the detection resolution and the field of view angle of the low-frequency continuous wave laser radar 10 are increased, the silicon optical chip 300 is simple in design, high in integration, and convenient for tape-out production. In addition, the plurality of groups of transceiver units 330 are integrated in the silicon optical chip 300, and a separate emission module is not needed to emit the probe light outward, high integration is achieved, and the complexity of assembling and light adjustment of the photoelectric devices inside the low-frequency continuous wave laser radar 10 is effectively reduced.

[0060] Specifically, as shown in Figure 3 the probe lights emitted by each transceiver unit 330 are projected to the light folding module 400 along the second direction X, and the light folding module 400 is configured to change the propagation direction of the probe lights emitted by the plurality of transceiver units 330 to make the plurality of probe lights be emitted in the second direction X staggered. In addition, the plurality of echo lights reflected by the target object return along the light path approximately overlapping with the probe lights and are projected to the light folding module 400, so that the probe light emitted by each transceiver unit 330 and the echo light received thereby propagate in the corresponding detection channel to meet the multi-channel detection requirement.

[0061] As shown in Figure 3 and Figure 4As shown, the refraction module 400 includes at least one of the first light reflecting element 411 for reflecting the probe light or the echo light and the first refraction prism 412 for refracting the probe light or the echo light, which can both correspondingly change the propagation direction of the probe light or the echo light. The number of the first light reflecting element 411 is at least one, and the number of the first refraction prism 412 is at least one.

[0062] Optionally, as Figure 3 As shown, the refraction module 400 includes a plurality of first light reflecting elements 411 corresponding to the plurality of transceiving units 330, and the number of the plurality of transceiving units 330 is the same as the number of the plurality of first light reflecting elements 411. Each first light reflecting element 411 is used to reflect the light path of the probe light emitted by the corresponding transceiving unit 330 and the echo light received, and the end face of the first light reflecting element 411 and the corresponding transceiving unit 330 are spaced apart in the second direction X, and the plurality of first light reflecting elements 411 are arranged staggered in the second direction X, that is, when the end faces of the plurality of transceiving units 330 are flush, the distances from the plurality of first light reflecting elements 411 to the end faces of the corresponding transceiving units 330 in the second direction X are different. In the process of the echo light reaching the transceiving unit 330 after being reflected by the first light reflecting element 411, the special design of the plurality of first light reflecting elements 411 being staggered in position in the second direction X can correspondingly receive a plurality of beams of echo light and reflect the corresponding echo light to propagate along the second direction X and project to the corresponding transceiving unit 330, so that the frequency-modulated continuous wave laser radar 10 has a plurality of detection channels in the second direction X, thereby improving the detection resolution and expanding the field of view of the frequency-modulated continuous wave laser radar 10.

[0063] Taking the vertical direction as the second direction X and the horizontal direction as the first direction Y, when the frequency-modulated continuous wave laser radar 10 is installed on the automatic driving body of the automatic driving device, the plurality of first light reflecting elements 411 arranged staggered in the vertical direction can correspondingly emit the probe light emitted by the silicon optical chip 300 in the vertical direction, receive a plurality of beams of echo light staggered in the vertical direction, and reflect the plurality of beams of echo light to the corresponding transceiving unit 330, thereby forming a plurality of detection channels in the vertical direction, improving the equivalent line number in the vertical direction, and enabling the frequency-modulated continuous wave laser radar 10 installed on the automatic driving body to also have better resolution and a larger field of view.

[0064] Optionally, the light refraction module 400 includes a plurality of first light refraction prisms 412; the end surface of the plurality of transceiver units 330 arranged in the first direction Y emits probe light which is projected to the corresponding first light refraction prism 412 and is deflected by the first light refraction prism 412 to be emitted in the second direction X; the plurality of echo lights arranged in the second direction X are deflected by the corresponding first light refraction prism 412, and each echo light returns to the corresponding transceiver unit 330 along the optical path of the same detection channel. For example, when the silicon optical chip 300 includes two transceiver units 330, the light refraction module 400 is provided with one first light refraction prism 412 corresponding to one of the transceiver units 330, and the probe light or the returned echo light emitted by the other transceiver unit 330 directly propagates, and the first light refraction prism 412 deflects the probe light or the returned echo light emitted by the corresponding transceiver unit 330 to adjust the optical path position of the light emitted or received by the transceiver unit 330, so that the two detection channels of the two transceiver units 330 are changed from staggered in the first direction Y to staggered in the second direction X. Of course, the two transceiver units 330 can also be provided with first light refraction prisms 412 respectively for adjusting the mutual arrangement relationship of the optical paths of the two channels.

[0065] The light refraction module 400 changes the propagation direction of the probe light, so that the optical paths of the plurality of channels are arranged staggered in the second direction X. Further, the light refraction module 400 can also include a second light reflection element 413 for adjusting the direction of the optical path. In order to save the space inside the laser radar, the placement position of the silicon optical chip 300 cannot necessarily make the optical paths of the plurality of channels arranged in the first direction Y and emitted to the corresponding first light refraction prism 412, and the placement angle of the silicon optical chip 300 affects the direction of the light emitted from the end surface of the transceiver unit. In order to adjust the direction of the optical path, the second light reflection element 413 is provided. The number of the second light reflection element 413 can be multiple. For example, as shown in Figure 5 The light refraction module 400 includes one second light reflection element 413 and one first light refraction prism 412, one of the transceiver units 330 emits probe light which is directly reflected by the second light reflection element 413 to form first emitted light which is directly emitted, and the probe light emitted by the other transceiver unit 330 is reflected by the second light reflection element 413 to enter the first light refraction prism 412 and is refracted by the first light refraction prism 412 to form second emitted light which is emitted, at this time, the two emitted lights staggered in the second direction are changed to the first emitted light and the second emitted light which exist with an interval in the second direction X, and the arrangement direction of the optical paths of the plurality of channels is changed.

[0066] As shown in Figure 4 and Figure 5As shown, the frequency-modulated continuous wave laser radar 10 further comprises a beam scanning module 420 arranged on the side of the light folding module 400 facing the target object. The beam scanning module 420 is configured to receive the probe light passing through the light folding module 400 and project the probe light to the target object, and receive the echo light reflected by the target object and project the echo light to the light folding module 400. The beam scanning module 420 can be a galvanometer, a rotating mirror, a MEMS micro galvanometer, or a combination of the above. As shown, the beam scanning module 420 can optionally comprise a one-dimensional galvanometer 421 and a one-dimensional rotating mirror 422.

[0067] The one-dimensional galvanometer 421 has a galvanometer 4211 reciprocatingly rotating in the second direction X. The galvanometer 4211 is configured to reflect the echo light from the one-dimensional rotating mirror 422 to the light folding module 400, or reflect the probe light from the light folding module 400 to the one-dimensional rotating mirror 422, so that the one-dimensional galvanometer 421 can provide a scanning field of view in the second direction X for the frequency-modulated continuous wave laser radar 10. For example, the second direction X is the vertical direction.

[0068] The one-dimensional rotating mirror 422 has a rotating mirror 4221 and a rotating mirror rotation axis (not shown in the figure). The rotating mirror rotation axis extends along the second direction X and is connected to the rotating mirror to drive the rotating mirror 4221 to rotate around the rotating mirror rotation axis. The rotating mirror 4221 has a plurality of rotating mirror reflecting surfaces. The rotating mirror 4221 is configured to reflect the probe light from the one-dimensional galvanometer 421 to the target object, or reflect the echo light from the target object to the one-dimensional galvanometer 421. During the rotation of the one-dimensional rotating mirror 422, the angle between the optical path and the rotating mirror reflecting surface continuously changes, thereby achieving scanning. The one-dimensional rotating mirror 422 can provide a scanning field of view in the first direction Y for the frequency-modulated continuous wave laser radar 10. For example, the first direction Y is the horizontal direction.

[0069] During the rotation of the one-dimensional rotating mirror 422, a part of the displacement caused by the walk-off effect will be generated along the arrangement direction of the transmission waveguide and the receiving waveguide of the transceiver unit 330 (i.e., the first direction Y). Therefore, the optical path of the transmission and reception of the transceiver unit also needs to be transmitted along the direction perpendicular to the end surface of the transmission waveguide and the receiving waveguide (i.e., the second direction X). The optical paths of the plurality of transceiver units 330 are difficult to be staggered in the second direction and are also difficult to improve the equivalent line number in the second direction. At this time, the light folding module 400 changes the direction of light propagation, converts the direction of the optical path of the transceiver unit from the second direction to the first direction Y, and makes the optical paths of the multiple channels staggered in the second direction. After the optical paths of the plurality of transceiver units pass through the beam scanning module and are scanned, a plurality of scanning tracks staggered in the second direction can be formed in the field of view, thereby improving the equivalent line number.

[0070] Each transceiver unit 330 comprises a transmitting module 331 and a coupling module 332, the transmitting module 331 comprises a transmitting waveguide 3311 having a transmitting end face 331b, the coupling module 332 comprises at least one receiving waveguide 3321, each receiving waveguide 3321 has a receiving end face 332b, the transmitting end face 331b of the transmitting module 331 and the receiving end face 332b of the coupling module 332 are parallel and constitute the end face of the transceiver unit 330. The transmitting module 331 emits the received probe light outward from the transmitting end face 331b; the coupling module 332 receives the echo light from the receiving end face 332b and transmits the echo light to the coupling module 332. The transmitting waveguide 3311 and the plurality of receiving waveguides 3321 can extend in a direction perpendicular to the end face of the transceiver unit 330, or can extend in a direction at an angle to the end face of the transceiver unit 330.

[0071] As shown in Figure 2 and Figure 3 , the frequency-modulated continuous wave laser radar 10 further comprises a plurality of collimating mirror groups 440, which are correspondingly arranged on the front side of the end face of the plurality of transceiver units 330, for collimating and projecting the probe light emitted by the transceiver units 330 to the light folding module 400, and for focusing and projecting the echo light passing through the light folding module 400 to the transceiver units 330, thereby reducing light loss.

[0072] As shown in Figure 6 , the transmitting module 331 has a transmitting field of view 331a, a target object within the transmitting field of view 331a can be scanned by light from the transmitting module 331, and the target object can reflect the light. The coupling module 332 has a receiving field of view 332a, the light reflected by the target object within the receiving field of view 332a can be received by the coupling end face 332b of the coupling module 332. Among them, the higher the overlap degree of the transmitting field of view 331a and the receiving field of view 332a, the smaller the scanning blind area 330a of the transmitting module 331 and the coupling module 332. Since there is a gap between the transmitting module 331 and the coupling module 332, the distance between the transmitting module 331 and the coupling module 332 is set as small as possible to reduce the coverage area of the scanning blind area 330a.

[0073] The frequency-modulated continuous wave laser radar 10 further comprises a plurality of first amplification modules 430, which are correspondingly arranged with the transmitting modules 331 of the plurality of transceiver units 330, and are configured to amplify the probe light emitted by the corresponding transmitting modules 331, so that the amplified probe light has sufficient energy to meet the ranging requirements of long distances. The first amplification module 430 can comprise a first amplification chip, which can be a semiconductor optical amplifier (SOA) chip. The probe light amplified by the first amplification module 430 is emitted towards the collimating lens group 440, and the amplified probe light is collimated by the collimating lens group 440 and then emitted.

[0074] Optionally, the light folding module 400 further comprises a light adjusting lens group 450, which is arranged on the optical path between the light folding module 400 and the beam scanning module 420, and is configured to expand the beam of the probe light folded by the light folding module 400 and then emit it outward, so that the distance between the probe light emitted by the plurality of channels is increased, and the probe light can cover a larger field of view when emitted outward through the beam scanning module 420. The light adjusting lens group 450 is also configured to shrink the beam of the return light and then emit it towards the light folding module 400, so that the return light can pass through the light folding module 400 and the collimating lens group 440 in sequence with a small light area, so as to match the small size of the light folding module 400 and the collimating lens group 440, and facilitate the reduction of the volume of the frequency-modulated continuous wave laser radar 10.

[0075] The light adjusting lens group 450 corresponds to a plurality of transceiver units 330, that is, the plurality of transceiver units 330 emit probe light or receive return light through the same set of light adjusting lens groups 450. Among them, the diameter of the light adjusting lens group 450 is in centimeter level, and the size of the transmitting waveguide 3311 and the receiving waveguide 3321 is relatively small relative to the light adjusting lens group 450, for example, the size of the transmitting waveguide 3311 and the receiving waveguide 3321 is usually tens of microns to hundreds of microns. Optionally, the transmitting waveguide 3311 and the receiving waveguide 3321 are arranged adjacent to the main optical axis of the light adjusting lens group 450. For example, the transmitting waveguide 3311 and all the receiving waveguides 3321 are adjacent to the main optical axis of the light adjusting lens group 450, so that the light adjusting lens group 450 adjusts the direction of light propagation. For example, the transmitting waveguide 3311 and all the receiving waveguides 3321 are sequentially and parallelly laid along the surface of the silicon optical chip 300, the end face of the transmitting waveguide 3311 and the end face of the receiving waveguide 3321 are flush with the side of the silicon optical chip 300, the main optical axis of the light adjusting lens group 450 can be arranged between the transmitting waveguide 3311 and the receiving waveguide 3321 closest to the transmitting waveguide 3311, or the main optical axis of the light adjusting lens group 450 can be arranged at the middle waveguide or between the two middle waveguides. Optionally, the light adjusting lens group 450 comprises at least one lens with tortuosity, and the number of lenses can be selected according to actual needs to meet the light converging and collimating function requirements of the light adjusting lens group 450.

[0076] The receiving module 350 includes a polarization beam splitter 351, which is connected to the receiving waveguide 3321 of the coupling module 332 to receive the echo light transmitted by the coupling module 332 and convert the echo light into multiple polarized echo light with the same polarization state.

[0077] Optionally, the coupling module 332 includes M receiving waveguides 3321, where M is an integer greater than or equal to 2. When the coupling module 332 includes M receiving waveguides 3321, the receiving module 350 includes M polarization beam splitters 351, which are connected one-to-one with the M receiving waveguides 3321. Each polarization beam splitter 351 receives the echo light transmitted from the corresponding receiving waveguide 3321 and performs polarization conversion to form multiple beams of polarized echo light. The receiving module 350 also includes an optical mixer 360. One input of the optical mixer 360 is connected to the beam splitter module 320 and the receiving local oscillator light. The other input of the optical mixer 360 is also connected to the polarization beam splitter 351 to receive a beam of polarized echo light and mix the polarized echo light with the local oscillator light to form mixed light. Specifically, the input terminal of the polarization beam splitter 351 is connected to the receiving waveguide 3321. The polarization beam splitter 351 may include two output terminals, for example, splitting the received echo light into P-polarized echo light and S-polarized echo light. In this case, the number of optical mixers 360 corresponding to the same polarization beam splitter 351 can be two, and the two optical mixers 360 are connected one-to-one with the two output terminals of the polarization beam splitter 351. One optical mixer 360 mixes the P-polarized echo light with the local oscillator light, and the other optical mixer 360 mixes the S-polarized echo light with the local oscillator light. Of course, the polarization beam splitter 351 can also use other methods to polarize the echo light and output the polarization-dividered echo light separately for mixing with the local oscillator light.

[0078] The receiving module 350 also includes a first balanced detector 370, which is connected to the optical mixer 360 to receive the mixed light for balanced detection. Specifically, the optical mixer 360 has two output terminals, and the first balanced detector 370 is connected to the two output terminals of the optical mixer 360 to receive the mixed light for processing, forming a corresponding coherent electrical signal. This coherent electrical signal can then be output to other signal processing circuits 700 for further signal processing. For example, the signal processing circuit 700 can be a trans-impedance amplifier (TIA).

[0079] Optionally, such as Figure 7 As shown, when the coupling module 332 includes M receiving waveguides 3321, the coupling module 332 also includes a beam combiner module, which includes at least one multiport coupler 810. Figure 8As shown, the multi-port coupler 810 has N first access ports 811 and one first output port 812, N is an integer greater than or equal to 2. The first output port 812 of the multi-port coupler 810 is connected with the coupling module 332, and at least two first access ports 811 of the multi-port coupler 810 are connected with the plurality of receiving waveguides 3321 one by one, so that the echo light transmitted by the receiving waveguides 3321 enters the multi-port coupler 810 through the first access ports 811, and is output from the first output port 812 to the coupling module 332 after being combined by the multi-port coupler 810, and specifically, the first output port 812 is connected with the polarization beam splitting and converting device 351 of the coupling module 332. In this way, in the case that the coupling module 332 includes M receiving waveguides 3321, the multi-port coupler 810 couples the multi-channel optical signals from the M receiving waveguides 3321 into one optical signal and outputs the one optical signal to the corresponding polarization beam splitting and converting device 351, so that the polarization conversion of the multi-channel signal light transmitted by the plurality of receiving waveguides 3321 can be realized by accessing only one polarization beam splitting and converting device 351, thereby saving the use amount of the optical frequency mixer 360 and the first balanced detector 370 and simplifying the system architecture of the entire silicon optical chip 300.

[0080] When the number of receiving waveguides 3321 connected with the same multi-port coupler 810 is large, the light transmission between the plurality of receiving waveguides 3321 and the multi-port coupler 810 is prone to light loss. Alternatively, as shown in FIG. 8B, the silicon optical chip 300 is provided with a plurality of multi-port couplers 810, and each multi-port coupler 810 is independently connected with the plurality of receiving waveguides 3321, so as to reduce the light loss when one multi-port coupler 810 is connected with a large number of receiving waveguides 3321. Figure 8

[0081] When the frequency-modulated continuous wave laser radar 10 is at a medium or short distance from the target object, the light power of the echo light reflected by the target object itself is relatively strong, and the echo light can meet the detection requirements when entering the coupling module 332 through the receiving waveguides 3321 and the multi-port coupler 810. At this time, the plurality of receiving waveguides 3321 of the coupling module 332 can be all connected with the polarization beam splitting and converting device 351 through the multi-port coupler 810, so as to reduce the use amount of the subsequent hardware such as the optical frequency mixer 360 and the first balanced detector 370.

[0082] When the frequency-modulated continuous wave laser radar 10 is at a long distance from the target object, the light power of the echo light reaching the receiving waveguides 3321 is small, and the echo light also produces a certain offset due to the walk-off effect. The farther the distance between the frequency-modulated continuous wave laser radar 10 and the target object, the greater the offset. Alternatively, as shown in FIG. 9B, the silicon optical chip 300 is provided with a plurality of multi-port couplers 810, and each multi-port coupler 810 is independently connected with the plurality of receiving waveguides 3321, so as to reduce the light loss when one multi-port coupler 810 is connected with a large number of receiving waveguides 3321. Figure 8 ​As shown, the beam combining module further includes at least one straight waveguide 820, the straight waveguide 820 having a second access port 821 and a second output port 822, the second access port 821 being connected with the receiving waveguide 3321, and the second output port 822 being connected with the coupling module 332, so that the receiving waveguide 3321 is transmitted to the coupling module 332 through the straight waveguide 820, and the optical signal transmitted through the straight waveguide 820 has a small loss. Specifically, the second output port 822 of each straight waveguide 820 is connected with a polarization beam splitter 351. For example, when the coupling module 332 includes nine receiving waveguides 3321, the energy of the echo becomes smaller and smaller in the direction away from the transmitting waveguide 3311, the beam combining module includes two multi-port couplers 810 and three straight waveguides 820, the two multi-port couplers 810 are arranged adjacent to the transmitting waveguide 3311, and one of the multi-port couplers 810 is connected with three receiving waveguides 3321 receiving close-range echo light, the other multi-port coupler 810 is connected with three receiving waveguides 3321 receiving medium-range echo light, and the three straight waveguides 820 are one-to-one corresponding to the three receiving waveguides 3321 receiving far-range echo light.

[0083] The beam splitting module 320 is also used to split the calibration light from the laser beam coupled into the silicon optical chip 300, and the silicon optical chip 300 further includes a light source nonlinear calibration light path 340 connected with the beam splitting module 320 and receiving the calibration light to calibrate the laser beam emitted by the frequency-modulated light source 240. The light source nonlinear calibration light path 340 includes a coupler 341 and a calibration balanced detector 342, the beam splitting module 320 splits two beams of calibration light, the two beams of calibration light have different delays, and specifically, one of the beams of calibration light enters the coupler 341, and the other beam of calibration light enters the coupler 341 through an optical delay line 343, the calibration light passing through the optical delay line 343 can be delayed, the coupler 341 is used to mix the two beams of calibration light with different delays, and the calibration balanced detector 342 is used to receive the mixed light output by the coupler 341 and perform balanced detection. The coupler 341 is a dB coupler 341, and of course, other couplers 341 capable of achieving the above functions can also be used. In use, the output signal of the calibration balanced detector 342 can be further processed as the basis for calibration of the frequency-modulated light source 240. By using the frequency-modulated continuous wave laser radar 10 provided in the embodiment, the frequency-modulated light source 240 can be calibrated in real time, so that the operator can timely find problems and adjust them, thereby ensuring the accuracy of the detection result.

[0084] Optionally, the light splitting module 320 comprises a mode spot converter 324, a first light splitter 321, a second light splitter 322 and a third light splitter 323. The mode spot converter 324 receives the laser beam emitted by the light source module 200, the first light splitter 321 is connected with the mode spot converter 324 to receive the laser beam emitted by the light source module 200, the first light splitter 321 is further connected with the emission module 331, the second light splitter 322 and the third light splitter 323 respectively, and the first light splitter 321 splits the laser beam emitted by the light source module 200 into a detection light transmitted to the emission module 331, a first light transmitted to the second light splitter 322 and a third light transmitted to the third light splitter 323. The second light splitter 322 is connected with the light source nonlinear calibration light path 340 and splits the first light into two calibration lights transmitted to the light source nonlinear calibration light path 340. The third light splitter 323 is connected with the plurality of light mixers 360 and splits the third light into a plurality of local oscillation lights, and the plurality of local oscillation lights are transmitted to the plurality of light mixers 360 one by one. Of course, the arrangement mode of the light splitting module 320 of the embodiment of the present application includes but is not limited to the arrangement mode described above, and can be selected according to actual needs.

[0085] Optionally, the mode spot converter 324 comprises a first waveguide, and the first waveguide is a tapered waveguide, a cantilever beam waveguide or a multi-layer waveguide. The first waveguide and the emission waveguide 3311 can be made of the same material, at this time, the light power that the first waveguide and the emission waveguide 3311 can transmit is equal, and the first waveguide and the emission waveguide 3311 can be arranged in the same layer, and the first waveguide and the emission waveguide 3311 are directly connected through the first light splitter 321 to transmit the light, which is convenient for simplifying the structure of the silicon optical chip 300. The material of the emission waveguide 3311 can be the same as that of the receiving waveguide 3321, which is convenient for simplifying the process of preparing the emission waveguide 3311 and the receiving waveguide 3321.

[0086] When the light power that the first waveguide can accommodate is equal to the light power that the receiving waveguide 3321 can accommodate, it indicates that the power of the detection light that the silicon optical chip 300 can transmit is limited, the energy of the detection light emitted by the emission waveguide 3311 is limited, and it is difficult to meet the emission energy demand of long-distance ranging. Optionally, the frequency-modulated continuous wave laser radar 10 comprises a first amplification module 430.

[0087] In some other embodiments, when the light power of the laser beam entering the first waveguide of the mode spot converter 324 is large, the material of the first waveguide is selected to be able to accommodate the large light power. In this case, the material of the first waveguide and the material of the emission waveguide 3311 are different, and the light power that the first waveguide can accommodate is greater than the light power that the emission waveguide 3311 can accommodate. The silicon optical chip 300 further includes an interlayer mode converter (not shown in the figure), and the laser beam conducted by the first waveguide is converted to the emission waveguide 3311 by evanescent wave coupling in the interlayer mode converter.

[0088] When the material of the first waveguide is the same as the material of the receiving waveguide 3321, the first waveguide and the receiving waveguide 3321 can both be made of silicon material, so as to simplify the preparation process of forming the first waveguide and the receiving waveguide 3321. When the light power that the first waveguide can accommodate is greater than the light power that the receiving waveguide 3321 can accommodate, the first waveguide can be made of silicon nitride material, and the receiving waveguide 3321 can be made of silicon material.

[0089] The frequency-modulated continuous wave laser radar 10 further includes a first packaging shell 510 and a second packaging shell 520, and the light source module 200, the silicon optical chip 300, and the first amplification module 430 are arranged in the internal space of the first packaging shell 510. Optionally, as shown in the figure, the light folding module 400, the beam scanning module 420, and the light adjusting mirror group 450 are arranged in the internal space of the second packaging shell 520. The collimating mirror group 440 can be arranged in the internal space of the first packaging shell 510, or the collimating mirror group 440 can be arranged in the internal space of the second packaging shell 520. The first packaging shell 510 and the second packaging shell 520 each have a first channel through which the probe light passes, and a second channel through which the echo light passes. The light source module 200 further includes a light source shell, and the first light guide mirror 210, the isolator 220, the second light guide mirror 230, the light-in amplifying device, the second light guide mirror 230, and the frequency-modulated light source 240 are integrally encapsulated in the light source shell and then encapsulated in the first packaging shell 510.

[0090] The frequency-modulated continuous wave laser radar 10 further includes a temperature control module 600, which can also be encapsulated in the internal space of the first packaging shell 510. The temperature control module 600 is used to monitor the temperature change in the internal space of the first packaging shell 510, so as to observe the working state of the optical devices such as the light source module 200 and the silicon optical chip 300 in the internal space of the first packaging shell 510.

[0091] The embodiments of the present application also provide an automatic driving device, which is one of a car, an airplane, and other devices related to intelligent sensing and detection using a laser radar. The automatic driving device comprises an automatic driving body and the frequency-modulated continuous wave laser radar 10 as described above. The frequency-modulated continuous wave laser radar 10 is arranged on the automatic driving body, for example, when the automatic driving device is a car, the automatic driving body comprises a roof, and the frequency-modulated continuous wave laser radar 10 is installed on the roof of the car.

[0092] In the drawings of the embodiments of the present application, the same or similar reference numerals correspond to the same or similar components; in the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationships in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present patent, and for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0093] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A frequency modulated continuous wave lidar, characterized in that, Comprising: a light source module for emitting a frequency-modulated continuous wave laser beam; a silicon optical chip comprising a transceiver unit and a receiving module, the transceiver unit is used for emitting probe light outwardly, and is also used for receiving echo light and transmitting to the receiving module, forming a probe channel, the number of the transceiver units is greater than or equal to 2, and the end faces of the plurality of transceiver units are arranged along a first direction; and a light deflection module for deflecting the probe light emitted by the plurality of transceiver units so that a plurality of the probe light is emitted in a second direction, and for deflecting a plurality of the echo light in the second direction and projecting it to the corresponding transceiver unit, the second direction being perpendicular to the end face of the transceiver unit; the transceiver unit comprises: a coupling module comprising a plurality of receiving waveguides for receiving the echo light from the receiving end face; a beam combining module for receiving the echo light output by the coupling module and outputting the echo light after beam combining; the beam combining module comprises at least one multi-port coupler and at least one straight-through waveguide; the multi-port coupler comprises N first access ports and a first output port, at least two first access ports are connected to the receiving waveguides one by one, and the first output port is connected to the receiving module, wherein N is an integer greater than or equal to 2; the straight-through waveguide comprises a second access port and a second output port, the second access port is connected to the receiving waveguide, and the second output port is connected to the receiving module.

2. The frequency-modulated continuous wave lidar of claim 1, wherein, The sum of the number of the first access ports of at least one multi-port coupler and the number of the second access ports of at least one straight-through waveguide is the same as the number of the receiving waveguides, and they are arranged one by one.

3. The frequency-modulated continuous wave lidar of claim 1, wherein, At least one multi-port coupler is connected to the receiving waveguide for receiving near and medium distance echo light one by one, and at least one straight-through waveguide is connected to the receiving waveguide for receiving far distance echo light one by one.

4. The frequency-modulated continuous wave lidar of claim 1, wherein, The transceiver unit further comprises a transmitting module for emitting the probe light outwardly from the transmitting end face; at least one multi-port coupler and at least one straight-through waveguide are arranged on the same side of the transmitting module along the first direction, at least one multi-port coupler is arranged close to the transmitting module, and at least one straight-through waveguide is arranged away from the transmitting module.

5. The frequency-modulated continuous wave lidar of claim 1, wherein, The silicon optical chip further comprises: a light splitting module for receiving a laser beam coupled into the silicon optical chip and splitting into a plurality of probe light transmitted to a plurality of corresponding transmitting modules.

6. An automatic driving apparatus characterized by comprising: Comprising: a frequency-modulated continuous wave laser radar according to any one of claims 1-5; and an automatic driving subject, the horizontal direction being the first direction and the vertical direction being the second direction, the frequency-modulated continuous wave laser radar being installed on the automatic driving subject.

Images