Optical components and silicon photonic chips that can be used for radar

Abstract

The present invention provides an optical component that can be used in radar, including: a polarization beam splitter, configured so that a first port can receive first polarized light from a laser and output the first polarized light from a second port; a phase retarder, configured to receive the first polarized light output from the second port of the polarization beam splitter, the first polarized light passing through the phase retarder and then being emitted; the phase retarder is also configured to receive the radar echo, which is adjusted to second polarized light after passing through the phase retarder and is incident on the polarization beam splitter from the second port and output from a third port, wherein the polarization direction of the first polarized light is perpendicular to the polarization direction of the second polarized light. Embodiments of the present invention can effectively reduce crosstalk and stray light, improve the ranging accuracy of the radar, and reduce blind spots.

Description

Technical Field

[0001] The present invention generally relates to the field of optoelectronic technology, and in particular to an optical component and a silicon photonic chip that can be used in lidar. Background Art

[0002] Silicon photonics is a next-generation technology based on silicon and silicon-based substrate materials (such as SiGe / Si and SOI), utilizing existing CMOS processes for the development and integration of optical devices. It combines the ultra-large-scale, ultra-high-precision manufacturing capabilities of integrated circuit technology with the ultra-high speed and ultra-low power consumption of photonic technology. Silicon photonics architecture primarily consists of silicon-based lasers, silicon-based optoelectronic integrated chips, active optical components, and fiber packaging. LiDAR (Light Detection and Ranging) requires multiple laser sources and receivers, or uses multi-path signal control. Silicon photonics' high degree of integration and electro-optical phase tuning capabilities are well-suited for LiDAR applications.

[0003] LiDARs that use pulse ranging have high pulse peak power, while silicon photonics devices are extremely small. This results in high power density within the device, leading to laser power loss and heat generation, which can easily cause nonlinearity. Compared to pulse ranging LiDARs, the peak power of frequency modulated continuous wave (FMCW) radars is the continuous power of the light emitted, which is much lower than the pulse peak power and does not result in excessive power density in silicon photonics devices. Therefore, silicon photonics technology is well-suited for FMCW radars.

[0004] Coaxial FMCW radar generally uses a circulator as a beam splitter. The circulator has a magneto-optical effect, which causes the polarized light to undergo Farady deflection in the circulator. The beam transmission is controlled by the 2-port and 3-port polarization isolation devices. Figure 1 The schematic diagram of the circulator shown in the figure shows that the probe light enters the circulator from port 1 and can only be output from port 2. The echo beam enters the circulator from port 2 and can only be output from port 3, thus achieving isolation between the transmit and receive light paths. However, the circulator has a certain amount of crosstalk, approximately -60dB. This means that a small portion of the probe light is emitted from port 3, resulting in stray light. If the circulator is integrated on a silicon photonics chip, the crosstalk will reach -30dB. Using a high-pass filter to filter out stray light signals will result in a close-range blind spot of more than 2 meters. If the stray light is too strong, it will also generate various higher-order harmonics, expanding the blind spot and significantly affecting the close-range detection of the lidar. Therefore, the circulator has become a major obstacle to the integration of FMCW radar optical components into chips.

[0005] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the existing technologies in this field. Summary of the Invention

[0006] The embodiments of the present invention solve the problems of crosstalk and stray light caused by using a circulator as a beam splitting device in the prior art by using a silicon photonic chip including a polarization beam splitter or an optical coupler.

[0007] In view of at least one drawback of the prior art, the present invention provides an optical component that can be used for radar, comprising:

[0008] a polarization beam splitter configured such that a first port can receive first polarized light from a laser and output the first polarized light from a second port;

[0009] A phase delay plate is configured to receive the first polarized light output from the second port of the polarization beam splitter, and the first polarized light is emitted after passing through the phase delay plate. The phase delay plate is also configured to receive the echo of the radar, and the echo is adjusted to the second polarized light after passing through the phase delay plate, and is incident on the polarization beam splitter from the second port and output from the third port.

[0010] The polarization direction of the first polarized light is perpendicular to the polarization direction of the second polarized light.

[0011] According to one aspect of the present invention, the polarization beam splitter further includes a mode converter, the second polarized light is incident on the polarization beam splitter, is converted into a third polarized light by the mode converter and is output from the third port, and the polarization direction of the third polarized light is the same as that of the first polarized light.

[0012] According to one aspect of the present invention, it also includes a collimating lens arranged between the polarization beam splitter and the phase delay plate, and a scanning unit arranged in the optical path downstream of the phase delay plate, the collimating lens is configured to receive the first polarized light from the polarization beam splitter, collimate it and make it incident on the phase delay plate, the collimated first polarized light passes through the phase delay plate and is scanned by the scanning unit and then emitted, and the scanning unit is configured to receive the echo and return it to the phase delay plate.

[0013] According to one aspect of the present invention, it also includes a collimating lens and a scanning unit sequentially arranged downstream of the phase delay plate, the first polarized light is emitted after passing through the phase delay plate, the collimating lens, and the scanning unit respectively, and the echo is scanned by the scanning unit and converged by the collimating lens before being incident on the phase delay plate.

[0014] According to one aspect of the present invention, the polarization beam splitter is integrated on a silicon photonic chip, and the phase delay plate is arranged outside the silicon photonic chip.

[0015] According to one aspect of the present invention, the polarization beam splitter and the phase delay plate are integrated on a silicon photonic chip.

[0016] According to one aspect of the present invention, the phase retarder is a quarter-wave plate.

[0017] The present invention also relates to a silicon photonic chip that can be used for radar, comprising

[0018] Chip body;

[0019] an optical beam splitter, which receives a light beam emitted by a light source, splits it into local oscillator light and probe light in a certain ratio, and receives an echo of the probe light reflected by a target object, wherein the probe light is polarized light; and

[0020] a mixer for mixing the local oscillator light and the echo;

[0021] The chip body has at least two ports, one of which outputs the detection light and receives the echo, and the other port outputs the beat signal obtained by the mixer mixing the local oscillator light and the echo.

[0022] According to one aspect of the present invention, the optical beam splitter further comprises a mode converter for converting the polarization state of the echo to be the same as that of the detection light.

[0023] According to one aspect of the present invention, the silicon photonic chip is combined with a phase delay plate to perform phase modulation on the detection light and the echo.

[0024] According to one aspect of the present invention, the phase retarder is integrated into the silicon photonic chip.

[0025] According to one aspect of the present invention, the optical beam splitter is a polarization beam splitter.

[0026] According to one aspect of the present invention, the optical beam splitter is an optical coupler.

[0027] According to one aspect of the present invention, the light-emitting surface of the silicon photonic chip is provided with an antireflection film.

[0028] According to one aspect of the present invention, the light-emitting surface of the silicon photonic chip is set as an inclined surface, so that the angle between the transmission direction of the detection light emitted by the silicon photonic chip and the light-emitting surface is not 90 degrees.

[0029] The embodiments of the present invention use a polarization beam splitter or an optical coupler instead of a circulator integrated on a silicon photonic chip, eliminating the need for a high-crosstalk circulator for optical path isolation, greatly reducing stray light, and thereby lowering filtering requirements, improving the signal-to-noise ratio, and reducing close-range blind spots. Furthermore, optical path control for coaxial transmission and reception is implemented within the chip, enabling radar to realize optical device chipization, increase signal transmission speed, and significantly improve the integration of devices, which is beneficial to reducing the size of the lidar, and reducing power consumption and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 A schematic diagram of a circulator in the prior art is shown;

[0032] Figure 2 FIG2 is a schematic diagram showing an optical component that can be used for FMCW radar according to one embodiment of the present invention;

[0033] Figure 3 FIG2 is a schematic diagram showing an optical component that can be used for FMCW radar according to another embodiment of the present invention;

[0034] Figure 4 A schematic diagram of a silicon photonic chip according to an embodiment of the present invention is shown;

[0035] Figure 5 shows a schematic diagram of a polarization beam splitter according to one embodiment of the present invention; and

[0036] Figure 6 FIG. 1 is a schematic diagram showing an optical coupler according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0038] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for the purpose of facilitating the description of the present invention and simplifying the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of the aforementioned features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0039] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, removable, or integral connections; mechanical, electrical, or intercommunication connections; direct or indirect connections through an intermediary; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0040] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may also include the first and second features not being in direct contact but being in contact via another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a lower level than the second feature.

[0041] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0042] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0043] Figure 2 A schematic diagram of an optical assembly for a laser radar (LIDAR), particularly an FMCW radar, according to one embodiment of the present invention is shown. As shown, the optical assembly 100 includes a polarization beam splitter 110 and a phase retarder 120. The polarization beam splitter 110 has multiple ports, each capable of receiving only polarized light of a predetermined polarization direction. Incident polarized light of the predetermined polarization direction is emitted from another predetermined port. For example, the polarization beam splitter 110 is configured such that a first port 110-1 receives first polarized light, such as TE mode light, and outputs the first polarized light from a second port 110-2. The phase retarder 120 is configured to receive the first polarized light output from the second port 110-2 of the polarization beam splitter 110. The first polarized light passes through the phase retarder 120 and is then emitted. The phase retarder 120 is also configured to receive the echo from the FMCW radar. The echo is adjusted to a second polarized light after passing through the phase retarder 120, where the polarization direction of the first polarized light is perpendicular to that of the second polarized light. The second polarized light is incident from the second port 110-2 of the polarization beam splitter 110, modulated into a third polarized light and output from the third port 110-3. Optionally, a coupler (not shown in the figure) is further provided downstream of the optical path of the light source (e.g., a laser) of the first polarized light. The coupler divides the laser light emitted by the light source into local oscillator light and a first polarized light for detection according to a certain preset ratio. The first polarized light for detection is incident from the first port 110-1 of the polarization beam splitter 110. The optical component 100 further includes a mixer 230. The mixer 230 receives the local oscillator light and the third polarized light output from the third port 110-3 of the polarization beam splitter 110. The mixer 230 mixes the local oscillator light and the third polarized light (echo) to obtain a beat signal and outputs it. Based on the beat signal, information such as the distance and speed of the target object can be calculated.

[0044] According to one embodiment of the present invention, Figure 2 As shown, the polarization beam splitter 110 further includes a mode converter 111. The second polarized light adjusted by the phase retarder 120 is incident on the second port 110-2 of the polarization beam splitter 110, converted by the mode converter 111 into a third polarized light and output from the third port 110-3. The polarization direction of the third polarized light is the same as that of the first polarized light. Preferably, the polarization state of the first polarized light incident from the first port 110-1 remains unchanged after passing through the mode converter 111.

[0045] According to one embodiment of the present invention, Figure 2 As shown, the optical component 100 further includes a collimating lens 130 and a scanning unit 140. The collimating lens 130 is arranged between the polarization beam splitter 110 and the phase delay plate 120. The scanning unit 140 is arranged downstream of the optical path of the phase delay plate 120. The collimating lens 130 is configured to receive the first polarized light from the polarization beam splitter 110, collimate it and make it incident on the phase delay plate 120 as parallel light. The collimated first polarized light is modulated by the phase delay plate 120. The echo is scanned by the scanning unit 140 and then emitted so as to reach a certain field of view. The scanning unit 140 is configured to receive the echo and scan it to the phase delay plate 120. The echo passes through the phase delay plate 120 and is converged by the collimating lens 130. The converged echo, i.e., the second polarized light, is incident from the second port 110-2 of the polarization beam splitter 110, is converted into the third polarized light by the mode converter 111, and is emitted from the third port 110-3 of the polarization beam splitter 110.

[0046] According to one embodiment of the present invention, the phase retarder 120 is a quarter-wave plate. The function of the phase retarder is explained here: if the phase retarder is not provided, it is assumed that the first polarized light (probe light) received from the light source (e.g., a laser) is a transverse electric mode (TE mode), which is incident from the first port 110-1 of the polarization beam splitter 110, and is emitted from the second port 110-2 of the polarization beam splitter 110 while maintaining the TE mode. After being collimated by the collimating lens 130, the parallel light is emitted and irradiated to the scanning unit 140. After being reflected by the scanning unit 140, it reaches a certain FOV. With the TE mode light as the probe light (first polarized light), the echo light beam reflected by the target object is polarized and degraded, but it is likely still TE mode light. The polarization beam splitter 110 cannot deflect the echo light beam incident from the 110-2 end to an output port other than 110-1, causing the echo light beam to overlap with the probe light emission optical path and failing to effectively achieve polarization splitting. Due to the presence of phase retarder 120 (e.g., a quarter-wave plate), the probe light and the echo light each pass through phase retarder 120. After two deflections, the TE mode light becomes transverse magnetic mode (TM mode) light. At this point, the echo beam has a different polarization state from the probe light. After passing through the polarization beam splitter, the polarization splitting effect deflects the echo beam to the third port and outputs it to mixer 230. This solution achieves the integration of a coaxial transceiver solution and effectively reduces crosstalk and stray light.

[0047] According to another embodiment of the present invention, Figure 3 A schematic diagram of an optical component that can be used for an FMCW radar is shown, wherein the collimating lens 130 and the scanning unit 140 of the optical component 100 are respectively arranged in sequence downstream of the optical path of the phase delay plate 120, the first port 110-1 of the polarization beam splitter 110 receives the first polarized light from the light source and outputs the first polarized light from the second port 110-2, the output first polarized light is collimated by the phase delay plate 120 and the collimating lens 130, and scanned by the scanning unit 140 before being emitted, the scanning unit 140 receives and reflects the echo of the FMCW radar, and the reflected echo is converged by the collimating lens 130 and incident on the phase delay plate 120 to become the second polarized light, the second port 110-2 of the polarization beam splitter 110 receives the incident second polarized light, converts it into the third polarized light through the mode converter 111 inside it, and emits it from the third port 110-3.

[0048] According to one embodiment of the present invention, Figure 2As shown, the polarization beam splitter 110 is integrated on the silicon photonic chip 200, and the phase retarder 120 is disposed outside the silicon photonic chip 200. Specifically, the collimating lens 130, the phase retarder 120, and the scanning unit 140 are sequentially disposed downstream of the optical path of the polarization beam splitter 110, and are all located outside the silicon photonic chip 200. Preferably, the mixer 230 is also disposed on the silicon photonic chip 200.

[0049] According to one embodiment of the present invention, Figure 3 As shown, the polarization beam splitter 110 and the phase retarder 120 are integrated on a silicon photonic chip 200, and the collimating lens 130 and the scanning unit 140 are sequentially arranged downstream of the optical path of the phase retarder 120 and are both located outside the silicon photonic chip 200. Preferably, the mixer 230 is also arranged on the silicon photonic chip 200.

[0050] The present invention also relates to a silicon photonic chip, which can be used for FMCW radar. Figure 4 A schematic diagram of a silicon photonic chip according to an embodiment of the present invention is shown. The silicon photonic chip 200 includes a chip body 210, an optical beam splitter 220, and a mixer 230, wherein the optical beam splitter 220 and the mixer 230 are both integrated on the chip body 210. The optical beam splitter 220 receives the probe light transmitted from the light source (not shown in the figure), and a portion of the light emitted by the light source is also separated as local oscillation light, which is directly output to the mixer 230. Preferably, an optical coupler 150 can be used to connect to the light source to divide the light emitted by the light source into two parts: probe light and local oscillation light. The optical beam splitter 220 emits the probe light and receives the echo of the probe light reflected by the target object. The mixer 230 mixes the local oscillation light and the echo to obtain a beat frequency signal and output it. The local oscillation light and the probe light are both polarized light, and the local oscillation light and the echo output by the optical beam splitter 220 have the same polarization direction.

[0051] According to one embodiment of the present invention, the optical beam splitter 220 is a polarization beam splitter 110. Figure 2 As shown, the polarization beam splitter 110 receives the detection light, i.e., the first polarized light. The detection light is emitted through the polarization beam splitter 110, and the echo reflected by the target object, i.e., the second polarized light, is received by the polarization beam splitter 110, and outputs the third polarized light. The third polarized light is mixed with the local oscillator light from the light source in the mixer 230 to output a beat signal.

[0052] According to one embodiment of the present invention, a phase delay plate is further provided inside the silicon photonic chip 210. Figure 3As shown, if the phase retarder is not provided, assuming that the first polarized light (probe light) received from the light source (e.g., a laser) is in the TE mode, it is incident on the first port 110-1 of the polarization beam splitter 110, and is emitted from the second port 110-2 of the polarization beam splitter 110 while maintaining the TE mode. After being collimated by the collimating lens 130, it is emitted as parallel light, irradiated to the scanning unit 140, and after being reflected by the scanning unit 140, reaches a certain FOV. With the TE mode light as the probe light (first polarized light), the echo light beam reflected by the target object, although polarization is degraded, is likely still TE mode light. The polarization beam splitter 110 cannot deflect the echo light beam incident on the 110-2 end, whose main component is the TE mode, to an output port other than 110-1, causing the echo light beam to overlap with the probe light path, and thus failing to effectively achieve polarization splitting. A phase retarder 120 is provided within the silicon photonic chip 210. The TE-mode probe light originally output by the polarization beam splitter 110 undergoes deflection by the phase retarder 120, changing its polarization state. Subsequently, the corresponding echo beam is deflected again by the phase retarder 120 and becomes TM-mode light. At this point, the echo beam input to the polarization beam splitter 110 has a different polarization state than the output probe light. After passing through the polarization beam splitter, the polarization splitting effect deflects the echo beam to the third port and outputs it to the mixer 230. The phase retarder can optionally be a quarter-wave plate. This solution enables the integration of a coaxial transceiver solution and effectively reduces crosstalk and stray light.

[0053] Figure 5 FIG. 1 shows a schematic diagram of a polarization beam splitter according to an embodiment of the present invention. Figure 5 As shown, the polarization beam splitter 110 has three ports, namely a first port 110-1, a second port 110-2 and a third port 110-3. Figure 5 As shown, the first port 110-1 receives the detection light, which is the first polarized light. In this embodiment, the detection light is the TE mode. The TE mode detection light (first polarized light) is directly emitted after passing through the polarization beam splitter 110, for example, it is emitted after passing through the phase delay plate 120 downstream of the optical path of the polarization beam splitter 110 (as shown in FIG. Figure 2 or Figure 3 As shown), in this case, the returned echo beam is TM mode, that is, the second polarized light. The TM mode echo beam (second polarized light) is input into the polarization beam splitter 110 from the second port 110-2. According to one embodiment of the present invention, as Figure 5As shown, the mode converter 111 of the polarization beam splitter 110 includes a first mode converter 111-1 and a second mode converter 111-2. The first mode converter 111-1 converts the received TM mode echo (second polarization light) into the TE1 mode. The TE1 mode light is coupled to the second mode converter 111-2, thereby separating the optical path from the probe light (first polarization light). The second mode converter 111-2 converts the TE1 mode light into the TE mode, thereby obtaining a TE mode echo light with the same polarization state as the probe light (first polarization light), i.e., third polarization light, which is output from the third port 110-3.

[0054] The polarization beam splitter 110 of this embodiment is integrated into the silicon photonic chip 210 . The polarization beam splitter 110 and the mode converters 111 - 1 and 111 - 2 are all composed of silicon waveguides.

[0055] By using the polarization beam splitter including the mode converter of this embodiment, the first polarization light of the detection light is different from the polarization state of the obtained echo, so that the optical path of the echo and the detection light can be separated, and the coaxial transmission and reception of the laser radar can be realized. The polarization state of the echo is converted to be the same as the first polarization light, and then the polarization state of the echo light output to the detector is the same as the local oscillator light, ensuring that the detector obtains the beat frequency signal, and processes it to obtain distance and / or speed data. The polarization beam splitter of this embodiment is composed of a silicon waveguide in a silicon photonic chip. The parameter design of the silicon waveguide can realize splitting and mode conversion, giving full play to the advantages of the high integration of the silicon photonic chip, reducing the crosstalk caused by traditional splitting components such as circulators, thereby effectively reducing stray light and reducing the range of radar blind spots.

[0056] According to an embodiment of the present invention, the optical beam splitter 220 is an optical coupler 221 . Figure 6 A schematic diagram of an optical coupler according to an embodiment of the present invention is shown. As shown in the figure, the optical coupler 221 has two inputs and two outputs, and the wave splitting ratio can be set in advance to detect the target. Optionally, the wave splitting ratio is 99:1, that is, all the light emitted by the light source is input from A, and after passing through the optical coupler 221, 99% of the light from the light source is output from C for detection, that is, the detection light, and 1% of the light from the light source is output from D as the local oscillator light. The echo of the detection light after being reflected by the target is incident on the optical coupler 221 from C, wherein 99% of the echo is output from B, which can be used for subsequent coherent detection, and 1% of the echo is output from A. The energy of the echo light beam itself is relatively low, and only 1% of the echo energy is output from A. The influence of this small amount of light on the light source can be ignored. Refer to Figure 4 The optical coupler 221 can be fully integrated on the silicon photonic chip 200, which improves the chip's integration while reducing costs. Under the same transmission power, it can be used for short-range FMCW radar ranging.

[0057] In this embodiment, the probe light and the local oscillator light can also use polarized light with the same polarization state, and the echo light beam and the local oscillator light also have the same polarization state. After being coupled out through the optical coupler, it can still maintain the original polarization state and can be mixed with the local oscillator light to obtain a beat frequency signal.

[0058] According to one embodiment of the present invention, to mitigate or avoid the effects of stray light, an antireflection coating is applied to the light-emitting surface of the silicon photonic chip. This surface may produce partial reflections, with the reflected light returning along its original path also forming stray light. The antireflection coating has a reflectivity of approximately 1‰. By applying this coating to the light-emitting surface of the silicon photonic chip, the reflection caused by stray light can be reduced to an acceptable level, effectively minimizing the effects of stray light.

[0059] According to one embodiment of the present invention, in order to reduce or avoid the influence of stray light, the light-emitting surface of the silicon photonic chip is set to a slope, so that the angle between the light beam emitted by the silicon photonic chip and the light-emitting surface is not 90 degrees. In this way, even if a part of the light is reflected on the light-emitting surface, this part of the light cannot return to the transmitting end along the original path, and therefore has no influence or very little influence on the detection light path.

[0060] The embodiments of the present invention integrate an optical beam splitter, such as a polarization beam splitter or an optical coupler, on a silicon photonic chip to achieve the integration of coaxial transmission and reception of detection light in the silicon photonic chip, thereby improving the chip integration, effectively reducing crosstalk and stray light, reducing light loss, and reducing costs. This solves the problem of large crosstalk when the circulator used in the prior art is integrated on a silicon photonic chip, enables FMCW radar to realize chip-based optical devices, improves the stability of the optical path, and can significantly increase the integration of the device, which is conducive to reducing the size of the lidar and reducing power consumption and cost.

[0061] Those skilled in the art will appreciate that the technical solution of the present invention is not only applicable to FMCW radars, but can also be applied to other optical waveguide-based radars, such as radars or scanners using absolute range finders (ADMs). The technical solution provided by the present invention can be adopted to achieve isolation of the transmit and receive light paths, while achieving the technical effects of low crosstalk, low cost, and high integration.

[0062] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A laser radar comprising: A silicon photonic chip, comprising: Chip body; an optical coupler, wherein the optical coupler receives a light beam emitted by a light source and splits the light beam into a local oscillation light and a detection light according to a certain ratio, wherein the detection light is a first polarized light; a polarization beam splitter having at least three ports, wherein a first port of the polarization beam splitter receives the probe light, a second port of the polarization beam splitter outputs the probe light, and the second port is further adapted to receive an echo of the probe light reflected by an object, the echo being output from a third port of the polarization beam splitter; and a mixer, adapted to mix the local oscillator light and the echo, The laser radar also includes a scanning unit, which is arranged outside the silicon photonic chip, and the scanning unit is suitable for reflecting the detection light and the echo.

2. The laser radar as claimed in claim 1, wherein the laser radar further comprises a phase delay plate, wherein the phase delay plate receives the first polarized light output from the second port, and the first polarized light is emitted after passing through the phase delay plate, and the phase delay plate also receives the echo, and the echo is adjusted to the second polarized light after passing through the phase delay plate, and is incident on the polarization beam splitter from the second port and output from the third port, wherein the polarization direction of the first polarized light is perpendicular to the polarization direction of the second polarized light.

3. The laser radar as described in claim 2 further includes a collimating lens arranged between the polarization beam splitter and the phase delay plate, and the collimating lens is configured to receive the first polarized light from the polarization beam splitter, collimate it and make it incident on the phase delay plate, and the collimated first polarized light passes through the phase delay plate and is scanned by the scanning unit and then emitted, and the scanning unit is configured to receive the echo and return it to the phase delay plate.

4. The laser radar as described in claim 2 further includes a collimating lens arranged downstream of the phase delay plate, and the first polarized light is emitted after passing through the phase delay plate, the collimating lens, and the scanning unit respectively, and the echo is scanned by the scanning unit and converged by the collimating lens and then incident on the phase delay plate.

5. The laser radar as claimed in claim 1, wherein the silicon photonic chip further comprises a phase delay plate, wherein the phase delay plate is arranged downstream in the optical path of the second port, and the phase delay plate is configured to adjust the polarization state of the first polarized light.

6. The laser radar according to any one of claims 2 to 5, wherein the polarization beam splitter further includes a mode converter, the second polarized light is incident on the polarization beam splitter, is converted into a third polarized light by the mode converter and is output from the third port, and the polarization direction of the third polarized light is the same as that of the first polarized light.

7. The laser radar according to any one of claims 2 to 5, wherein the phase delay plate is a quarter-wave plate.

8. The laser radar according to any one of claims 1 to 5, wherein the light-emitting surface of the silicon photonic chip is provided with an anti-reflection film.

9. The laser radar according to any one of claims 1 to 5, wherein the light-emitting surface of the silicon photonic chip is set as an inclined surface, so that the angle between the transmission direction of the detection light emitted by the silicon photonic chip and the light-emitting surface is not 90 degrees.

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