FMCW lidar and optical chip

Abstract

The embodiment of the invention discloses an FMCW laser radar and an optical chip. The FMCW laser radar comprises a light source module, a transmitting module, a receiving module and a photoelectric detection module. The transmitting module comprises a polarization rotation beam combiner, the polarization rotation beam combiner comprises a first input end, a second input end and a first output end, and the polarization direction of an optical signal input through the first input end and output through the first output end is kept unchanged. The polarization direction of the optical signal input through the second input end and output through the first output end is rotated by 90 degrees. The polarization rotation beam combiner is adopted to combine the first detection light and the second detection light, and the first detection light and the second detection light are detected in different polarization directions after being combined. Compared with beam combination through a wavelength division multiplexer, the polarization rotation beam combiner has the advantage of being insensitive to temperature.

Description

Technical Field

[0001] This application relates to the field of laser detection equipment technology, and in particular to an FMCW lidar and optical chip. Background Technology

[0002] FMCW (Frequency Modulated Continuous Wave) lidar is a high-performance lidar based on linear frequency modulated light source and coherent reception technology. It has advantages such as high receiving sensitivity, providing target velocity information in real time, and resistance to ambient light interference.

[0003] To achieve real-time velocity and range decoupling, FMCW lidar typically emits two different wavelengths of probe light simultaneously at the transmitting end and receives the two different wavelengths of echo light at the receiving end. Specifically, the transmitting end needs to combine the two probe light beams of different wavelengths before emitting them. This ensures that both beams fall on the same target object, guaranteeing that the range beat frequency component and the Doppler beat frequency component of the two beams are consistent. This allows for the calculation of the target object's distance and velocity based on the beat frequencies of the two probe light beams. Summary of the Invention

[0004] In related technologies, wavelength division multiplexers are typically used at the transmitting end to combine two probe beams with different wavelengths. However, wavelength division multiplexers are temperature sensitive and their coupling efficiency can be affected by temperature drift.

[0005] This application provides an FMCW lidar and optical chip to improve the current situation in related technologies where the coupling efficiency of two probes with different wavelengths is easily affected by temperature drift when using a wavelength division multiplexer to combine them.

[0006] In a first aspect, embodiments of this application provide an FMCW lidar, including a light source module, a transmitting module, a receiving module, and a photoelectric detection module. The light source module outputs a first detection light and a second detection light with different wavelengths but the same polarization direction. The transmitting module includes a polarization rotating beam combiner, which has a first input end, a second input end, and a first output end. The polarization direction of the light signal input through the first input end and output through the first output end remains unchanged, while the polarization direction of the light signal input through the second input end and output through the first output end is rotated by 90 degrees. The first input end receives the first detection light, the second input end receives the second detection light, and the first output end outputs a combined detection light comprising the first and second detection lights. The receiving module receives the combined echo light, which includes a first echo light and a second echo light. The first echo light is formed by reflection of the first detection light from a target object, and the second echo light is formed by reflection of the second detection light from a target object. The photoelectric detection module is used to receive the first local oscillator light, the first echo light, the second local oscillator light, and the second echo light. The first local oscillator light and the first detection light have the same wavelength and polarization direction, and the second local oscillator light and the second detection light have the same wavelength and polarization direction.

[0007] Secondly, embodiments of this application provide an optical chip, including a cladding layer, a transmitting module, a receiving module, and a photodetector module. The transmitting module is embedded in the cladding layer and includes a polarization rotating beam combiner and a transmitting waveguide. The polarization rotating beam combiner includes a first input terminal, a second input terminal, and a first output terminal. The polarization direction of the optical signal input through the first input terminal and output through the first output terminal remains unchanged, while the polarization direction of the optical signal input through the second input terminal and output through the first output terminal is rotated by 90 degrees. The first input terminal is used to receive a first probe light, the second input terminal is used to receive a second probe light, and the first output terminal is used to output a combined probe light including the first and second probe lights. One end of the transmitting waveguide is connected to the first output terminal, and the other end is used to emit the combined probe light. The first and second probe lights have different wavelengths but the same polarization direction. The receiving module is embedded in the cladding layer and is used to receive the combined echo light. The combined echo light includes a first echo light and a second echo light. The first echo light is formed by the reflection of the first probe light from a target object, and the second echo light is formed by the reflection of the second probe light from a target object. The photoelectric detection module is located in the cladding and is used to receive the first local oscillator light, the first echo light, the second local oscillator light, and the second echo light. The first local oscillator light and the first detection light have the same wavelength and polarization direction, and the second local oscillator light and the second detection light have the same wavelength and polarization direction.

[0008] The FMCW lidar and optical chip of this application embodiment employ a polarization rotating beam combiner to combine a first probe light and a second probe light. After beam combining, the first and second probe lights are detected with different polarization directions. Compared to beam combining using wavelength division multiplexers in related technologies, the polarization rotating beam combiner has the advantage of being insensitive to temperature. Therefore, its coupling efficiency for optical signals is less affected by temperature changes, meeting the application requirements of automotive-grade environments. Furthermore, compared to beam combining schemes using wavelength division multiplexers, the polarization rotating beam combiner does not have particularly strict requirements on the wavelength misalignment of the first and second probe lights and has the advantage of lower insertion loss. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the structure of the FMCW lidar provided in the first embodiment of this application;

[0011] Figure 2 This is a schematic diagram of the structure of the FMCW lidar provided in the second embodiment of this application;

[0012] Figure 3 This is a schematic diagram of the structure of the FMCW lidar provided in the third embodiment of this application;

[0013] Figure 4 This is a partial structural schematic diagram of the FMCW lidar provided in the fourth embodiment of this application.

[0014] Explanation of reference numerals in the attached figures:

[0015] 1. FMCW LiDAR;

[0016] 10. Light source module; 11. First light source module; 111. First laser; 112. First optical amplifier; 113. Third beam splitter; 12. First beam splitter; 13. Second light source module; 131. Second laser; 132. Second optical amplifier; 133. Fourth beam splitter; 14. Second beam splitter; 15. Light source module; 151. Laser; 152. Optical amplifier; 16. Beam processing unit;

[0017] 20. Transmitting module; 21. Polarization rotating beam combiner; 211. First input terminal; 212. Second input terminal; 213. First output terminal; 22. Transmitting waveguide;

[0018] 30. Receiving module; 31. Polarization beam splitter rotator; 311. Third input terminal; 312. Second output terminal; 313. Third output terminal; 32. Receiving waveguide;

[0019] 40. Photoelectric detection module; 41. First photoelectric detection module; 411. First mixer; 412. First balanced photodetector; 42. Second photoelectric detection module; 421. Second mixer; 422. Second balanced photodetector;

[0020] 50. Optical chip; 51. Cladding; 52. First coupler; 53. Second coupler. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0022] In the following description, when referring to the accompanying drawings, the same numbers in different drawings denote the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0023] Example 1

[0024] Please see Figure 1 This application provides an FMCW lidar 1, which includes a light source module 10, a transmitting module 20, a receiving module 30, and a photoelectric detection module 40.

[0025] The light source module 10 is used to output a first probe light and a second probe light with different wavelengths but the same polarization direction. The transmitting module 20 includes a polarization rotating beam combiner 21, which includes a first input terminal 211, a second input terminal 212, and a first output terminal 213. The polarization direction of the light signal input through the first input terminal 211 and output through the first output terminal 213 remains unchanged, while the polarization direction of the light signal input through the second input terminal 212 and output through the first output terminal 213 is rotated by 90 degrees. The first input terminal 211 is used to receive the first probe light, the second input terminal 212 is used to receive the second probe light, and the first output terminal 213 is used to output the combined probe light including the first probe light and the second probe light. The receiving module 30 is used to receive the combined echo light, which includes the first echo light and the second echo light. The first echo light is formed by the reflection of the first probe light from the target object, and the second echo light is formed by the reflection of the second probe light from the target object. The photoelectric detection module 40 is used to receive the first local oscillator light, the first echo light, the second local oscillator light, and the second echo light. The first local oscillator light and the first detection light have the same wavelength and polarization direction, and the second local oscillator light and the second detection light have the same wavelength and polarization direction.

[0026] The aforementioned transmitting module 20 uses a polarization rotating beam combiner 21 to combine the first and second probe beams. After beam combining, the first and second probe beams are detected with different polarization directions. Compared to beam combining using a wavelength division multiplexer in related technologies, the polarization rotating beam combiner 21 has the advantage of being less sensitive to temperature. Therefore, its coupling efficiency for optical signals is less affected by temperature changes, meeting the application requirements of automotive-grade environments. Furthermore, compared to beam combining schemes using wavelength division multiplexers, the polarization rotating beam combiner 21 does not have particularly strict requirements on the degree of wavelength misalignment between the first and second probe beams. However, due to the characteristics of coherent beat frequencies, the wavelengths of the first and second probe beams cannot be too close to avoid direct beat frequencies, or the first local oscillator (or second local oscillator) beats with the second echo (or first echo) to obtain a beat frequency signal whose beat frequency falls within the bandwidth of the photoelectric detection module. In addition, the polarization rotating beam combiner 21 also has the advantage of lower insertion loss.

[0027] The light source module 10 outputs a first probe light, a first local oscillator light, a second probe light, and a second local oscillator light. The first probe light is used to detect a target object. The first local oscillator light has the same wavelength and polarization direction as the first probe light. This first local oscillator light serves as the local reference signal for the first echo light after the first probe light is reflected from the target object. The first probe light and the first local oscillator light can be generated from the same first optical signal or from different laser sources; this application does not specifically limit this. The second probe light is also used to detect a target object. The second local oscillator light has the same wavelength and polarization direction as the second probe light. This second local oscillator light serves as the local reference signal for the second echo light after the second probe light is reflected from the target object. The second probe light and the second local oscillator light can be generated from the same second optical signal or from different laser sources; this application does not specifically limit this. The first optical signal and the second optical signal have different wavelengths but the same polarization direction. This serves two purposes: firstly, to stagger their wavelengths and prevent coherence during their common propagation; and secondly, to allow them to be combined via the polarization rotation combiner 21 with the same polarization direction. For example, in this embodiment, the first optical signal is a TE-polarized optical signal with a first wavelength, denoted as TE1; and the second optical signal is a TE-polarized optical signal with a second wavelength, denoted as TE2. As another example, in some other embodiments, the first optical signal is a TM-polarized optical signal with a first wavelength, denoted as TM1; and the second optical signal is a TM-polarized optical signal with a second wavelength, denoted as TM2.

[0028] In one exemplary solution, see [reference] Figure 1 The light source module 10 includes a first light source module 11, a first beam splitter 12, a second light source module 13, and a second beam splitter 14. The first light source module 11 generates a first optical signal, and the first beam splitter 12 receives the first optical signal and splits it into a first local oscillator beam and a first probe beam. The second light source module 13 generates a second optical signal; the second beam splitter 14 receives the second optical signal and splits it into a second local oscillator beam and a second probe beam. That is, the light source module 10 includes two light source modules, the first light source module 11 and the second light source module 13, allowing for relatively independent control of the two light source modules.

[0029] In this exemplary solution, see Figure 1The first light source module 11 may include a first laser 111 and a first optical amplifier 112. The first laser 111 is used to generate a first source light signal, and the first optical amplifier 112 is used to receive and amplify the first source light signal. The first light signal is at least a portion of the amplified first source light signal, thereby increasing the detection range of the FMCW lidar 1. The placement of the first optical amplifier 112 between the first laser 111 and the first beam splitter 12 ensures that both the first local oscillator light and the first probe light output from the first beam splitter 12 propagate with sufficient optical power, reducing the number of optical amplifiers and lowering assembly and manufacturing costs. It is understood that... Figure 1 The first optical amplifier 112 is replaced by an optical amplifier connected to each output terminal of the first optical splitter 12. That is, the split signals output by the first optical splitter 12 are amplified respectively. At this time, the optical amplifier can be a lower power optical amplifier than the first optical amplifier 112.

[0030] In this exemplary solution, see Figure 1 The second light source module 13 includes a second laser 131 and a second optical amplifier 132. The second laser 131 generates a second source light signal, and the second optical amplifier 132 receives and amplifies the second source light signal. The second light signal is at least a portion of the amplified second source light signal, thereby increasing the detection range of the FMCW lidar 1. By placing the second optical amplifier 132 between the second laser 131 and the second beam splitter 14, both the second local oscillator light and the second probe light output from the second beam splitter 14 can propagate with sufficient optical power, reducing the number of optical amplifiers and lowering assembly and manufacturing costs. It is understood that... Figure 1 The second optical amplifier 132 is replaced by an optical amplifier connected to each output terminal of the second beam splitter 14. That is, the split signals output by the second beam splitter 14 are amplified respectively. In this case, the optical amplifier can be a lower power optical amplifier than the second optical amplifier 132.

[0031] In another exemplary solution, see [reference] Figure 2 The light source module 10 includes a light source module 15, a beam processing unit 16, a first beam splitter 12, and a second beam splitter 14. The light source module 15 generates an optical signal, and the beam processing unit 16 receives the optical signal generated by the light source module 15 and processes it to form a first optical signal and a second optical signal with different wavelengths. The first beam splitter 12 receives the first optical signal and splits it into a first local oscillator beam and a first probe beam. The second beam splitter 14 receives the second optical signal and splits it into a second local oscillator beam and a second probe beam. That is, the light source module 10 includes only one light source module 15, which helps reduce the number of light source modules used and lowers the manufacturing cost of the light source module 10.

[0032] In this exemplary scheme, the beam processing unit 16 can be any optical device capable of outputting dual-wavelength light; for example, the beam processing unit 16 may include a dual-wavelength fundamental frequency light generation unit and a dual-wavelength signal light generation unit. The dual-wavelength fundamental frequency light generation unit includes a first resonant cavity and a laser gain medium located inside the first resonant cavity. The laser gain medium and the first resonant cavity absorb light and generate dual-wavelength fundamental frequency light through stimulated emission. The dual-wavelength signal light generation unit includes a second resonant cavity and a nonlinear crystal located inside the second resonant cavity. The nonlinear crystal and the second resonant cavity are used to perform wavelength conversion on the dual-wavelength fundamental frequency light to generate dual-wavelength light.

[0033] In this exemplary solution, see Figure 2 The light source module 15 includes a laser 151 and an optical amplifier 152. The laser 151 generates a source light signal, and the optical amplifier 152 receives and amplifies the source light signal. The light signal received by the beam processing unit 16 is at least a portion of the amplified source light signal, thereby increasing the detection range of the FMCW lidar 1. By placing the optical amplifier 152 between the laser 151 and the beam processing unit 16, both the first and second light signals output by the beam processing unit 16 can propagate with sufficient optical power, reducing the number of optical amplifiers and lowering assembly and manufacturing costs. It is understood that... Figure 2 The optical amplifier 152 in the beam processing unit 16 is replaced by connecting one optical amplifier to each output terminal of the beam processing unit 16. That is, the first optical signal and the second optical signal output by the beam processing unit 16 are amplified respectively. In this case, the optical amplifier can be a lower power optical amplifier than the optical amplifier 152. It is understood that it is also possible to replace the optical amplifier 152 with an optical amplifier 152. Figure 2 The optical amplifier 152 is replaced by an optical amplifier connected to each output terminal of the first beam splitter 12 and each output terminal of the second beam splitter 14. That is, the beam splitting signals output by the first beam splitter 12 and the beam splitting signals output by the second beam splitter 14 are amplified respectively. In this case, the optical amplifier can be a lower power optical amplifier than the optical amplifier 152.

[0034] The aforementioned lasers (first laser 111, second laser 131, laser 151, etc.) can be various types of lasers; for example, carbon dioxide lasers, neodymium-doped yttrium aluminum garnet lasers, semiconductor lasers, wavelength-tunable solid-state lasers, and fiber frequency-modulated lasers, without limitation. The frequency-modulated continuous wave generated by the aforementioned lasers can be internally modulated or externally modulated, and can have a nonlinear calibration path or not.

[0035] The aforementioned optical amplifiers (first optical amplifier 112, second optical amplifier 132, optical amplifier 152, etc.) can be of various forms, such as fiber optic amplifiers and semiconductor amplifiers, without limitation. These optical amplifiers (first optical amplifier 112, second optical amplifier 132, optical amplifier 152, etc.) can be integrated with their corresponding lasers (first laser 111, second laser 131, laser 151, etc.) or can operate independently.

[0036] For the aforementioned transmitting module 20, the polarization direction of the first probe light TE1 in the combined probe light output via its polarization rotating beam combiner 21 remains unchanged. Thus, the polarization direction of the first probe light TE1 in the combined probe light is the same as the polarization direction of the first local oscillator light TE1. In the first echo light formed by the reflection of the first probe light TE1 from the target object, due to the diffuse reflection caused by the uneven surface of the target object, the first echo light may no longer have a single polarization direction. For example, it may include a component in the TE polarization direction (hereinafter referred to as the first echo light principal component TE1), a component in the TM polarization direction (hereinafter referred to as the first echo light secondary component TM1), and components in other polarization directions. Generally, the first echo light is still dominated by the component in the TE polarization direction, i.e., the first echo light principal component TE1, and also includes some components in other polarization directions. For ease of explanation, this embodiment will describe the first echo light as including the first echo light principal component TE1 and the first echo light secondary component TM1.

[0037] The polarization direction of the second probe light TM2 in the combined probe light output by its polarization rotating beam combiner 21 is rotated by 90 degrees. Thus, the polarization direction of the second probe light TM2 in the combined probe light will differ from the polarization direction of the second local oscillator light TE2 by 90 degrees. In the second echo light formed by the reflection of the second probe light TM2 from the target object, due to diffuse reflection caused by the uneven surface of the target object, the second echo light may no longer have a single polarization direction. For example, it may include a component in the TM polarization direction (hereinafter referred to as the principal component TM2 of the second echo light), a component in the TE polarization direction (hereinafter referred to as the secondary component TE2 of the second echo light), and components in other polarization directions. Generally, the second echo light is still dominated by the component in the TM polarization direction, i.e., the principal component TM2 of the second echo light, and also includes components in some other polarization directions. For ease of explanation, this embodiment will describe the second echo light as including the principal component TM2 and the secondary component TE2 of the second echo light.

[0038] In the embodiments of this application, see the following: Figure 1 and Figure 2The receiving module 30 includes a polarization beam splitter rotator 31, which includes a third input terminal 311, a second output terminal 312, and a third output terminal 313. The polarization direction of the optical signal input through the third input terminal 311 and output through the second output terminal 312 remains unchanged, while the polarization direction of the optical signal input through the third input terminal 311 and output through the third output terminal 313 is rotated by 90 degrees. The third input terminal 311 is used to receive the combined echo light, the second output terminal 312 is used to output the first beam, and the third output terminal 313 is used to output the second beam. The polarization directions of the first beam and the second beam are the same as those of the first probe light. The photoelectric detection module 40 is used to receive the first local oscillator light, the second local oscillator light, the first beam, and the second beam.

[0039] Based on the above analysis, the combined echo light received by the third input terminal 311 includes a first echo light principal component TE1, a first echo light secondary component TM1, a second echo light principal component TM2, and a second echo light secondary component TE2. The first echo light principal component TE1 and the second echo light secondary component TE2 can be output via the second output terminal 312 while maintaining their polarization direction; that is, the first beam includes the first echo light principal component TE1 and the second echo light secondary component TE2. Similarly, the first echo light secondary component TM1 and the second echo light principal component TM2 can be output via the third output terminal 313 with their polarization direction rotated by 90 degrees; that is, the second beam includes the second echo light principal component TE2 and the first echo light secondary component TE1.

[0040] The aforementioned receiving module 30 uses a polarization beam splitter rotator 31 to split the combined echo light. The polarization direction of the optical signals output through the second output terminal 312 and the third output terminal 313 is the same as that of the first and second local oscillator lights, thus enabling coherent beat frequency response. Compared to beam splitting via wavelength demultiplexers in related technologies, the polarization beam splitter rotator 31 does not require a specific wavelength misalignment for the optical signals of different wavelengths in the combined echo light and has the advantage of being insensitive to temperature, meeting the application requirements of automotive-grade environments.

[0041] The photoelectric detection module 40 includes a first photoelectric detection module 41 and a second photoelectric detection module 42. The first photoelectric detection module 41 is used to receive one of a first beam and a second beam along with a first local oscillator beam, and the second photoelectric detection module 42 is used to receive the other of the first beam and the second beam along with a second local oscillator beam. That is, in one exemplary embodiment, the first photoelectric detection module 41 is used to receive both the first local oscillator beam and the first beam, and the second photoelectric detection module 42 is used to receive both the second local oscillator beam and the second beam; in another exemplary embodiment, the first photoelectric detection module 41 is used to receive both the first local oscillator beam and the second beam, and the second photoelectric detection module 42 is used to receive both the second local oscillator beam and the first beam.

[0042] Based on the above analysis, refer to Figure 1 and Figure 2 The first beam includes a first echo light principal component TE1 and a second echo light secondary component TE2. The second beam includes a second echo light principal component TE2 and a first echo light secondary component TE1. When the first photoelectric detection module 41 is used to receive the first local oscillator light TE1 and the first beam, and the second photoelectric detection module 42 is used to receive the second local oscillator light TE2 and the second beam, the first photoelectric detection module 41 can mix the first local oscillator light TE1 with the first echo light principal component TE1 in the first beam, with high mixing efficiency; the second photoelectric detection module 42 can mix the second local oscillator light TE2 with the second echo light principal component TE2 in the second beam, also with high mixing efficiency. When the first photoelectric detection module 41 is used to receive the first local oscillator light TE1 and the second beam, and the second photoelectric detection module 42 is used to receive the second local oscillator light TE2 and the first beam, the first photoelectric detection module 41 can mix the first local oscillator light TE1 with the first echo light subcomponent TE1 in the second beam; the second photoelectric detection module 42 can mix the second local oscillator light TE2 with the second echo light subcomponent TE2 in the first beam.

[0043] Next, the specific structures of the first photoelectric detection module 41 and the second photoelectric detection module 42 will be described. The first photoelectric detection module 41 includes a first mixer 411 and a first balanced photodetector 412, and the second photoelectric detection module 42 includes a second mixer 421 and a second balanced photodetector 422.

[0044] The mixers (first mixer 411 and second mixer 421) are optical mixers used for coherent optical communication. They can be implemented using spatial optical elements or silicon photonics materials, such as multimode interferometer (MMI) mixers or coupler array mixers. The first mixer 411 receives a first local oscillator light and a first beam (or a second beam) to beat the received first local oscillator light with the first beam (or the second beam) to generate two first beat frequency signals. Optionally, the first mixer 411 is a 180-degree mixer, such as a 3dB coupler; then the first mixer 411 can output two first beat frequency signals with a 180-degree phase difference. The first balanced photodetector 412 receives the two first beat frequency signals and performs balanced detection on them to convert them into a first electrical signal.

[0045] The second mixer 421 is used to receive the second local oscillator light and the second beam (or the first beam) to make the received second local oscillator light and the second beam (or the first beam) beat at the same frequency to generate two second beat frequency signals. Optionally, the second mixer 421 is a 180-degree mixer, such as a 3dB coupler; then the second mixer 421 can output two second beat frequency signals with a phase difference of 180 degrees. The second balanced photodetector 422 is used to receive the two second beat frequency signals and perform balanced detection on the two second beat frequency signals to convert them into a second electrical signal.

[0046] The first and second electrical signals are related to parameters such as the speed and distance of the target object. Therefore, after appropriate processing of the first and second electrical signals, the speed and distance of the target object can be obtained. This application will not elaborate on this.

[0047] It should be understood that although the above embodiments are described using the first photodetector module 41 including the first mixer 411 and the first balanced photodetector 412 as an example, this application is not limited to this. As long as it can be used to receive the first local oscillator light and the first beam (or the second beam) so that the first local oscillator light and the first beam (or the second beam) beat, and the beat frequency signal is received and converted into a related electrical signal, it is acceptable. For example, in some other embodiments of this application, the first photodetector module 41 may also include only the first photodetector; the first photodetector is used to receive the first local oscillator light and the first beam (or the second beam), which can beat in free space, and the first photodetector is used to receive the beat frequency signal and convert it into a related electrical signal. The second photodetector module 42 is similar and will not be described in detail here.

[0048] See Figure 1 and Figure 2 The FMCW lidar 1 can be configured as a single-channel system. (See also...) Figure 3 The FMCW lidar 1 can also be a multi-detection channel system architecture. It should be noted that each "detection channel" described in this application includes a transmitting module for transmitting combined detection light, a receiving module for receiving combined echo light, and a photoelectric detection module for coherent beat frequency.

[0049] Specifically, see Figure 3If the FMCW lidar 1 is a multi-detection channel system architecture, the first light source module 11 is used to generate multiple first light signals, and the second light source module 13 is used to generate multiple second light signals. The FMCW lidar 1 includes multiple first beam splitters 12, multiple second beam splitters 14, multiple transmitting modules 20, multiple receiving modules 30, and multiple photoelectric detection modules 40; the first beam splitters 12, second beam splitters 14, transmitting modules 20, receiving modules 30, and photoelectric detection modules 40 correspond one-to-one. Each first beam splitter 12 is used to receive a first light signal, and each second beam splitter 14 is used to receive a second light signal. Each first beam splitter 12, along with its corresponding second beam splitter 14, transmitting module 20, receiving module 30, and photoelectric detection module 40, constitutes a detection channel of the FMCW lidar 1, and each detection channel is independent of the others. The purpose of setting up multiple detection channels is to improve the detection resolution of the FMCW lidar 1 under the same detection field of view, or to improve the detection field of view of the FMCW lidar 1 under the same detection resolution.

[0050] It should be noted that, in order for the first light source module 11 to generate multiple first light signals, refer to... Figure 3 The first light source module 11 may further include a third beam splitter 113. A first optical amplifier 112 may be located upstream of the third beam splitter 113 to amplify the optical signal at the input of the third beam splitter 113; alternatively, the first optical amplifier 112 may be replaced by connecting one optical amplifier to each output of the third beam splitter 113. To enable the second light source module 13 to generate multiple second optical signals, refer to... Figure 3 The second light source module 13 may also include a fourth beam splitter 133. The second optical amplifier 132 may be located upstream of the fourth beam splitter 133 to amplify the optical signal at the input of the fourth beam splitter 133; the second optical amplifier 132 may also be replaced by connecting an optical amplifier to each output of the fourth beam splitter 133.

[0051] See Figures 1 to 3 The aforementioned light source module 10, transmitting module 20, receiving module 30, and photoelectric detection module 40 can be formed by combining discrete optical devices, and can transmit optical signals between them through optical fibers, spatial optical paths, etc. (See also...) Figure 4 At least some of the aforementioned light source module 10, transmitting module 20, receiving module 30, and photoelectric detection module 40 can also be integrated together, and optical signals can be transmitted between them through waveguides or other means. Wherein, if at least some of the light source module 10, transmitting module 20, receiving module 30, and photoelectric detection module 40 are integrated together, the FMCW lidar 1 can be a single-detection-channel system architecture or a multi-detection-channel system architecture.

[0052] See Figure 4 The FMCW lidar 1 includes an optical chip 50, which includes a cladding 51 and a transmitting module 20, a receiving module 30, and a photoelectric detection module 40 embedded in the cladding 51. The transmitting module 20 includes a polarization rotating beam combiner 21 and a transmitting waveguide 22. One end of the transmitting waveguide 22 is connected to a first output terminal 213, and the other end is used to emit combined detection light. The receiving module 30 includes a receiving waveguide 32 and a polarization beam splitter rotator 31. One end of the receiving waveguide 32 is used to receive the combined echo light, and the other end is connected to a third input terminal 311. The photoelectric detection module 40 is connected to the polarization beam splitter rotator 31 and is used to receive a first local oscillator light, a second local oscillator light, a first beam, and a second beam. The aforementioned design includes a polarization rotating beam combiner 21 in the transmitting module 20 and a polarization beam splitter rotator 31 in the receiving module 30. These devices combine or split optical signals of different wavelengths using different polarization directions. Compared to related technologies that use wavelength multiplexers and demultiplexers for beam combining or splitting, the polarization rotating beam combiner 21 and the polarization beam splitter rotator 31 have the advantage of being insensitive to temperature. Therefore, their coupling efficiency for optical signals is less affected by temperature changes, meeting the application requirements of automotive-grade environments. Furthermore, compared to schemes using wavelength multiplexers and demultiplexers for beam combining or splitting, the polarization rotating beam combiner 21 and the polarization beam splitter rotator 31 do not have particularly strict requirements on the wavelength misalignment between the first and second probe lights, and they have the advantage of lower insertion loss, which can be less than 0.2 dB.

[0053] See Figure 4 The optical chip 50 also includes a first coupler 52, a second coupler 53, a first beam splitter 12, and a second beam splitter 14 embedded in the cladding layer 51. The first coupler 52 receives a first optical signal from outside the optical chip 50, allowing the first optical signal to enter the optical chip 50. The first beam splitter 12 is connected to the first coupler 52 and receives the first optical signal, splitting it into a first probe beam and a first local oscillator beam. The second coupler 53 receives a second optical signal from outside the optical chip 50, allowing the second optical signal to enter the optical chip 50. The second beam splitter 14 is connected to the second coupler 53 and receives the second optical signal, splitting it into a second probe beam and a second local oscillator beam.

[0054] It should be noted that at least some of the transmitting module 20 and the receiving module 30 can also be integrated into one optical chip, the photoelectric detection module 40 can be integrated into another optical chip, and the two optical chips can be connected to each other, etc. The specific integration method of the light source module 10, the transmitting module 20, the receiving module 30 and the photoelectric detection module 40 is not limited in the embodiments of this application.

[0055] In summary, the FMCW lidar 1 of this application includes a light source module 10, a transmitting module 20, a receiving module 30, and a photoelectric detection module 40. The transmitting module 20 includes a polarization rotating beam combiner 21, which combines a first probe light and a second probe light, resulting in the first and second probe lights being detected with different polarization directions after beam combining. The receiving module 30 includes a polarization beam splitter 31, which splits the combined echo light. The polarization direction of the optical signal output from the second output terminal 312 and the third output terminal 313 of the polarization beam splitter 31 is the same as that of the first and second local oscillator lights, achieving coherent beat frequency. Compared to related technologies that use wavelength multiplexers and demultiplexers for beam combining or splitting, the polarization rotating beam combiner 21 and the polarization beam splitter 31 have the advantage of being insensitive to temperature. Therefore, their coupling efficiency for optical signals is less affected by temperature changes, meeting the application requirements of automotive-grade environments. Furthermore, compared with the scheme using wavelength multiplexers and wavelength demultiplexers, the polarization rotating beam combiner 21 and the polarization rotating beam splitter 31 do not have particularly strict requirements on the wavelength misalignment of the first probe light and the second probe light, and have the advantage of lower insertion loss, which can be less than 0.2dB.

[0056] Example 2

[0057] The difference between this embodiment and Embodiment 1 is that, as shown in the following... Figure 4This embodiment requests protection for an optical chip 50, which includes a cladding 51 and a transmitting module 20, a receiving module 30, and a photodetector module 40 embedded in the cladding 51. The transmitting module 20 includes a polarization rotating beam combiner 21 and a transmitting waveguide 22. The polarization rotating beam combiner 21 includes a first input terminal 211, a second input terminal 212, and a first output terminal 213. The polarization direction of the optical signal input through the first input terminal 211 and output through the first output terminal 213 remains unchanged, while the polarization direction of the optical signal input through the second input terminal 212 and output through the first output terminal 213 is rotated by 90 degrees. The first input terminal 211 is used to receive a first probe light, the second input terminal 212 is used to receive a second probe light, and the first output terminal 213 is used to output a combined probe light including the first and second probe lights. One end of the transmitting waveguide 22 is connected to the first output terminal 213, and the other end is used to emit the combined probe light; wherein the first and second probe lights have different wavelengths but the same polarization direction. The receiving module 30 is used to receive the combined echo light, which includes a first echo light and a second echo light. The first echo light is formed by the reflection of the first probe light from the target object, and the second echo light is formed by the reflection of the second probe light from the target object. The photoelectric detection module 40 is used to receive the first local oscillator light, the first echo light, the second local oscillator light, and the second echo light. The first local oscillator light and the first probe light have the same wavelength and polarization direction, and the second local oscillator light and the second probe light have the same wavelength and polarization direction. The above-mentioned transmitting module 20 includes a polarization rotating beam combiner 21, which uses different polarization directions to combine two optical signals of different wavelengths. Compared with the beam combining using a wavelength multiplexer in related technologies, the polarization rotating beam combiner 21 has the advantage of being insensitive to temperature. Therefore, its coupling efficiency for optical signals is less affected by temperature changes, which can meet the application requirements of automotive-grade environments. Furthermore, compared to the scheme of using a wavelength multiplexer for beam combining, the polarization rotation beam combiner does not have particularly strict requirements on the degree of wavelength misalignment between the first and second probe beams, and has the advantage of lower insertion loss, which can be less than 0.2dB.

[0058] The receiving module 30 includes a receiving waveguide 32 and a polarization beam splitter rotator 31. One end of the receiving waveguide 32 is used to receive the combined echo light, and the other end is connected to the polarization beam splitter rotator 31. The polarization beam splitter rotator 31 includes a third input terminal 311, a second output terminal 312, and a third output terminal 313. The polarization direction of the optical signal input through the third input terminal 311 and output through the second output terminal 312 remains unchanged, while the polarization direction of the optical signal input through the third input terminal 311 and output through the third output terminal 313 is rotated by 90 degrees. The third input terminal 311 is connected to the receiving waveguide 32, the second output terminal 312 is used to output a first beam, and the third output terminal 313 is used to output a second beam. The polarization directions of both the first and second beams are the same as those of the first probe light. The photoelectric detection module 40 is used to receive the first local oscillator light, the second local oscillator light, the first beam, and the second beam. The aforementioned receiver module 30 includes a polarization beam splitter rotator 31, which uses different polarization directions to split two optical signals of different wavelengths. Compared to beam splitting using wavelength demultiplexers in related technologies, the polarization beam splitter rotator 31 has the advantage of being insensitive to temperature. Therefore, its coupling efficiency for optical signals is less affected by temperature changes, meeting the application requirements of automotive-grade environments. Furthermore, compared to beam combining schemes using wavelength demultiplexers, the polarization rotating beam combiner does not have particularly strict requirements on the wavelength misalignment of the first and second probe beams, and has the advantage of lower insertion loss, which can be less than 0.2 dB.

[0059] The photoelectric detection module 40 includes a first photoelectric detection module 41 and a second photoelectric detection module 42. The first photoelectric detection module 41 is used to receive a first local oscillator light and one of a first beam and a second beam. The second photoelectric detection module 42 is used to receive a second local oscillator light and another of the first beam and the second beam.

[0060] The optical chip 50 also includes a first coupler 52, a second coupler 53, a first beam splitter 12, and a second beam splitter 14 embedded in the cladding 51. The first coupler 52 receives a first optical signal from outside the optical chip 50, allowing the first optical signal to enter the optical chip 50. The second coupler 53 receives a second optical signal from outside the optical chip 50, allowing the second optical signal to enter the optical chip 50. The first and second optical signals have different wavelengths but the same polarization direction. The first beam splitter 12 is connected to the first coupler 52 and receives the first optical signal, splitting it into a first probe beam and a first local oscillator beam. The second beam splitter 14 is connected to the second coupler 53 and receives the second optical signal, splitting it into a second probe beam and a second local oscillator beam.

[0061] In summary, the optical chip 50 of this application includes a transmitting module 20, a receiving module 30, and a photodetector module 40. The transmitting module 20 includes a polarization rotating beam combiner 21, which combines a first probe light and a second probe light, resulting in the first and second probe lights being detected with different polarization directions after beam combining. The receiving module 30 includes a polarization beam splitter 31, which splits the combined echo light. The polarization direction of the optical signal output from the second output terminal 312 and the third output terminal 313 of the polarization beam splitter 31 is the same as that of the first and second local oscillator lights, achieving coherent beat frequency. Compared to related technologies that use wavelength multiplexers and demultiplexers for beam combining or splitting, the polarization rotating beam combiner 21 and the polarization beam splitter 31 have the advantage of being insensitive to temperature. Therefore, their coupling efficiency for optical signals is less affected by temperature changes, meeting the application requirements of automotive-grade environments. Furthermore, compared with the method of using wavelength division multiplexers for beam combining, the polarization rotation beam combiner does not have particularly strict requirements on the degree of wavelength misalignment between the first and second probe beams, and has the advantage of lower insertion loss, which can be less than 0.2dB.

[0062] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, in the description of this application, unless otherwise stated, "multiple" means at least two, for example, two, three, four, etc. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0063] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with the claims of this application shall still fall within the scope of this application.

Claims

1. An FMCW lidar, characterized in that, include: The light source module is used to output a first probe light and a second probe light with different wavelengths but the same polarization direction; The transmitting module includes a polarization rotating beam combiner, which includes a first input terminal, a second input terminal, and a first output terminal. The polarization direction of the optical signal input through the first input terminal and output through the first output terminal remains unchanged, while the polarization direction of the optical signal input through the second input terminal and output through the first output terminal is rotated by 90 degrees. The first input terminal is used to receive the first probe light, the second input terminal is used to receive the second probe light, and the first output terminal is used to output a combined probe light including the first probe light and the second probe light. A receiving module is used to receive multiplexed echo light, wherein the multiplexed echo light includes a first echo light and a second echo light, wherein the first echo light is formed by the reflection of the first probe light by the target object, and the second echo light is formed by the reflection of the second probe light by the target object; as well as The photoelectric detection module is used to receive a first local oscillator light, a first echo light, a second local oscillator light, and a second echo light. The first local oscillator light and the first detection light have the same wavelength and polarization direction, and the second local oscillator light and the second detection light have the same wavelength and polarization direction.

2. The FMCW lidar according to claim 1, characterized in that, The receiving module includes a polarization beam splitter rotator; The polarization beam splitter includes a third input terminal, a second output terminal, and a third output terminal. The polarization direction of the optical signal input through the third input terminal and output through the second output terminal remains unchanged, while the polarization direction of the optical signal input through the third input terminal and output through the third output terminal is rotated by 90 degrees. The third input terminal is used to receive the combined echo light, the second output terminal is used to output a first beam, and the third output terminal is used to output a second beam. The polarization directions of the first beam and the second beam are the same as those of the first probe light. The photoelectric detection module is used to receive the first local oscillator light, the second local oscillator light, the first beam light, and the second beam light.

3. The FMCW lidar according to claim 2, characterized in that, The photoelectric detection module includes a first photoelectric detection module and a second photoelectric detection module; The first photoelectric detection module is used to receive the first local oscillator light and the first beam, and the second photoelectric detection module is used to receive the second local oscillator light and the second beam.

4. The FMCW lidar according to claim 2, characterized in that, The photoelectric detection module includes a first photoelectric detection module and a second photoelectric detection module; The first photoelectric detection module is used to receive the first local oscillator light and the second beam light, and the second photoelectric detection module is used to receive the second local oscillator light and the first beam light.

5. The FMCW lidar according to claim 1, characterized in that, The light source module includes: The first light source module is used to generate the first light signal; The first beam splitter is used to receive the first optical signal and split it into a first local oscillator beam and a first probe beam. A second light source module is used to generate a second optical signal, which has a different wavelength but the same polarization direction as the first optical signal; and The second beam splitter is used to receive the second optical signal and split it into a second local oscillator beam and a second probe beam.

6. The FMCW lidar according to claim 5, characterized in that, The first light source module is used to generate multiple first light signals, and the second light source module is used to generate multiple second light signals; The FMCW lidar includes multiple first beam splitters, multiple second beam splitters, multiple transmitting modules, multiple receiving modules, and multiple photoelectric detection modules. The first beam splitter, the second beam splitter, the transmitting module, the receiving module, and the photoelectric detection module correspond one-to-one. Each first beam splitter is used to receive a first optical signal, and each second beam splitter is used to receive a second optical signal.

7. The FMCW lidar according to claim 5, characterized in that, The first light source module includes a first laser and a first optical amplifier. The first laser is used to generate a first source light signal, and the first optical amplifier is used to receive and amplify the first source light signal. The first light signal is at least a portion of the amplified first source light signal. The second light source module includes a second laser and a second optical amplifier. The second laser is used to generate a second source light signal, and the second optical amplifier is used to receive and amplify the second source light signal. The second light signal is at least a portion of the amplified second source light signal.

8. The FMCW lidar according to any one of claims 2 to 7, characterized in that, Includes an optical chip, the optical chip comprising: Cladding; The transmitting module is embedded in the cladding and includes the polarization rotating beam combiner and the transmitting waveguide. One end of the transmitting waveguide is connected to the first output end, and the other end is used to emit the beam combiner probe light. The receiving module, embedded in the cladding, includes a receiving waveguide and the polarization beam splitter. One end of the receiving waveguide is used to receive the combined echo light, and the other end is connected to the third input terminal. The photoelectric detection module is embedded in the cladding and connected to the polarization beam splitter, and is used to receive the first local oscillator light, the second local oscillator light, the first beam light, and the second beam light.

9. An optical chip, characterized in that, include: Cladding; A transmitting module, embedded in the cladding, includes a polarization rotating beam combiner and a transmitting waveguide. The polarization rotating beam combiner includes a first input terminal, a second input terminal, and a first output terminal. The polarization direction of the optical signal input through the first input terminal and output through the first output terminal remains unchanged. The polarization direction of the optical signal input through the second input terminal and output through the first output terminal is rotated by 90 degrees. The first input terminal is used to receive a first probe light, the second input terminal is used to receive a second probe light, and the first output terminal is used to output a combined probe light including the first probe light and the second probe light. One end of the transmitting waveguide is connected to the first output terminal, and the other end is used to emit the combined probe light. The first probe light and the second probe light have different wavelengths but the same polarization direction. A receiving module, embedded in the cladding, is used to receive combined echo light, the combined echo light including a first echo light and a second echo light, wherein the first echo light is formed by the reflection of the first probe light from a target object, and the second echo light is formed by the reflection of the second probe light from the target object; and A photoelectric detection module is disposed in the cladding and is used to receive a first local oscillator light, a first echo light, a second local oscillator light, and a second echo light. The first local oscillator light and the first detection light have the same wavelength and polarization direction, and the second local oscillator light and the second detection light have the same wavelength and polarization direction.

10. The optical chip according to claim 9, characterized in that, The receiving module includes a receiving waveguide and the polarization beam splitter. One end of the receiving waveguide is used to receive the combined echo light, and the other end is connected to the polarization beam splitter. The polarization beam splitter includes a third input terminal, a second output terminal, and a third output terminal. The polarization direction of the optical signal input through the third input terminal and output through the second output terminal remains unchanged, while the polarization direction of the optical signal input through the third input terminal and output through the third output terminal is rotated by 90 degrees. The third input terminal is connected to the receiving waveguide. The second output terminal is used to output a first beam, and the third output terminal is used to output a second beam. The polarization directions of the first beam and the second beam are the same as those of the first probe beam. The photoelectric detection module is used to receive the first local oscillator light, the second local oscillator light, the first beam light, and the second beam light.

11. The optical chip according to claim 10, characterized in that, The photoelectric detection module includes a first photoelectric detection module and a second photoelectric detection module; The first photoelectric detection module is used to receive the first local oscillator light and the first beam, and the second photoelectric detection module is used to receive the second local oscillator light and the second beam.

12. The optical chip according to claim 9, characterized in that, Also includes: A first coupler, embedded in the cladding, is used to receive a first optical signal from outside the optical chip, so that the first optical signal enters the optical chip; A second coupler, embedded in the cladding, is used to receive a second optical signal from outside the optical chip, so that the second optical signal enters the optical chip. The first optical signal and the second optical signal have different wavelengths but the same polarization direction. The first beam splitter, embedded in the cladding and connected to the first coupler, is used to receive the first optical signal and split it into a first probe beam and a first local oscillator beam. as well as The second beam splitter, embedded in the cladding and connected to the second coupler, is used to receive the second optical signal and split it into a second probe beam and a second local oscillator beam.

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