Compact LIDAR system with super lens

Abstract

An optical ranging and detection (LiDAR) system is provided. The LiDAR system includes a meta-surface based optical device. The system includes a transmitter that includes one or more transmitter optics. The emitter is configured to provide one or more transmitted light beams. The system also includes a beam steering device optically coupled to the transmitter. The beam directing device includes one or more steering optics configured to scan the one or more transmitted beams to a field of view in at least one of a horizontal direction and a vertical direction, and direct return light formed based on the scanned one or more transmitted beams. The system also includes a receiver that includes one or more receiver optics. At least one of the one or more transmitter optics, the one or more steering optics, and the one or more receiver optics includes the one or more meta-surface based optics.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application Serial No. 18 / 373,252, filed on September 26, 2023, entitled “COMPACT LIDAR SYSTEM WITH METALENSES” and U.S. Provisional Patent Application Serial No. 63 / 410,608, filed on September 27, 2022, entitled “COMPACT LIDAR SYSTEM WITH METALENSES”. The contents of both applications are hereby incorporated by reference in their entirety for all purposes. Technical Field

[0003] The present disclosure relates generally to a light ranging and detection (LiDAR) system, and more particularly to a compact LiDAR system using a metasurface-based lens, also known as a metalens. Background Art

[0004] Light detection and ranging (LiDAR) systems use light pulses to create images or point clouds of the external environment. LiDAR systems can be scanning or non-scanning systems. Some typical scanning LiDAR systems include a light source, a light emitter, a light steering system, and a light detector. The light source generates a light beam, which is guided in a specific direction by the light steering system when emitted from the LiDAR system. When the emitted light beam is scattered or reflected by an object, a portion of the scattered light or reflected light returns to the LiDAR system to form a return light pulse. The light detector detects the return light pulse. Using the difference between the time when the return light pulse is detected and the time when the corresponding light pulse in the light beam is emitted, the LiDAR system can determine the distance to the object based on the speed of light. This technique for determining distance is called time of flight (ToF) technology. The light steering system can guide the light beam along different paths to allow the LiDAR system to scan the surrounding environment and generate an image or point cloud. A typical non-scanning LiDAR system illuminates the entire field of view (FOV) instead of scanning the entire FOV. An example of a non-scanning LiDAR system is a flash LiDAR, which can also use ToF technology to measure the distance to an object. LiDAR systems can also use techniques other than time-of-flight and scanning to measure their surroundings. Summary of the invention

[0005] Transceivers in current LiDAR systems are typically designed with optical lenses or lens groups, such as glass-based lenses. In order to provide a large receiving aperture with a large FOV coverage (e.g., a horizontal FOV of 120° or greater, and / or a vertical FOV of 70° or greater), the size of these optical lenses is typically large. A superlens is an optical component that uses a metasurface to guide light (e.g., focus light). A superlens is sometimes also referred to as a metamaterial lens, which is an advanced type of lens that uses metamaterials to manipulate and control light in a specific way. For example, a superlens can achieve the same focusing and collimation functions with a flat geometry, thereby significantly reducing the thickness or overall size of the LiDAR system compared to a system using a glass-based lens or lens group. In addition, superlenses can be mass-produced using mature silicon wafer manufacturing processes. Superlenses can also compete with traditional aspheric lenses in production costs, making LiDAR systems more compact and cost-effective.

[0006] In one embodiment, a light ranging and detection (LiDAR) system including one or more metasurface-based optical devices is provided. The system includes a transmitter, which includes one or more transmitter optical devices. The transmitter is configured to provide one or more transmitted light beams. The system also includes a beam steering device optically coupled to the transmitter. The beam steering device includes one or more steering optical devices, which are configured to: scan the one or more transmitted light beams to the field of view in at least one of the horizontal direction and the vertical direction, and guide the return light generated based on the scanned one or more transmitted light beams. The system also includes a receiver, which includes one or more receiver optical devices. The receiver is configured to receive the return light guided by the beam steering device. At least one of the one or more transmitter optical devices, the one or more steering optical devices, and the one or more receiver optical devices includes the one or more metasurface-based optical devices. At least one of the metasurface-based optical devices has a subwavelength structure disposed on a semiconductor wafer substrate. The feature of the subwavelength structure has a size smaller than the operating wavelength of the LiDAR system. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present application may be best understood by referring to the embodiments described below in conjunction with the accompanying drawings, in which like components may be represented by like reference numerals.

[0008] Figure 1 One or more exemplary LiDAR systems disposed or included in a motor vehicle are illustrated.

[0009] Figure 2is a block diagram illustrating the interaction between an exemplary LiDAR system and a number of other systems including a vehicle perception and planning system.

[0010] Figure 3 is a block diagram illustrating an exemplary LiDAR system.

[0011] Figure 4 is a block diagram illustrating an exemplary fiber-based laser source.

[0012] FIG. 5A to FIG. 5C An exemplary LiDAR system that uses pulse signals to measure the distance to objects disposed in a field of view (FOV) is illustrated.

[0013] Figure 6 is a block diagram illustrating an exemplary apparatus for implementing the systems, apparatus, and methods in various embodiments.

[0014] Fig. 7A An exemplary wafer including a metalens is illustrated according to one embodiment.

[0015] FIG. 7B to FIG. 7E Illustrated are examples of forming different patterns of sub-wavelength structures for use in metasurface-based optical devices according to some embodiments.

[0016] Figure 8 is a diagram illustrating the use of artificial phase shifts from a metasurface of a metalens to simulate a spherical wavefront for beam focusing, according to some embodiments.

[0017] Fig. 9 Included are diagrams illustrating lenses designed to remove various aberrations of traditional optical lenses and achieve better focusing results according to some embodiments.

[0018] Fig. 10A is a perspective view of an exemplary transceiver assembly of a LiDAR system including one or more metasurface-based optics, according to some embodiments.

[0019] Fig. 10B is a block diagram of an exemplary transmitter according to some embodiments, which includes an optical device based on a transmitter metasurface configured to collimate a transmitted light beam.

[0020] Fig.11 is a block diagram of another exemplary transmitter according to some embodiments, which transmitter includes one or more transmitter metasurface-based optical devices for collimating and shifting a transmitted light beam.

[0021] Fig. 12A is a perspective view of an exemplary transceiver assembly of a LiDAR system including one or more receiver element surface-based optics, according to some embodiments.

[0022] Fig. 12B is a block diagram of an exemplary receiver including one or more receiver element surface-based optics for directing return light to a detector, according to some embodiments.

[0023] Fig. 12C is a block diagram of another exemplary receiver including one or more receiver element surface-based optics for directing return light to a detector, according to some embodiments.

[0024] Fig.13A is a diagram illustrating another exemplary LiDAR system including one or more emitter metasurface-based optics according to some embodiments.

[0025] Fig. 13B is a diagram illustrating an exemplary emitter including an emitter metalens for collimating a transmitted light beam according to some embodiments.

[0026] Fig. 13C is a diagram illustrating a glass-based lens assembly for collimating a transmitted light beam according to some embodiments.

[0027] Fig.14A is a perspective view of another exemplary LiDAR system including a receiver metalens for beam homogenization, according to some embodiments.

[0028] FIG. 14B to FIG. 14E Another exemplary receiver including a receiver metalens for beam homogenization is illustrated in accordance with some embodiments.

[0029] Fig.14F Illustrated is an exemplary typical glass-based lens set that may be replaced with a metalens according to some embodiments.

[0030] Figure 14G An exemplary cylindrical lens array that may be replaced with a metalens is illustrated in accordance with some embodiments.

[0031] Fig.15A An exemplary steering mechanism comprising one or more metalenses according to some embodiments is illustrated.

[0032] Fig. 15B Another exemplary steering mechanism including a metalens is illustrated in accordance with some embodiments.

[0033] Fig. 15C Another exemplary steering mechanism including a metalens is illustrated in accordance with some embodiments. DETAILED DESCRIPTION

[0034] In order to provide a more thorough understanding of various embodiments of the present invention, the following description sets forth many specific details, such as specific configurations, parameters, examples, etc. However, it should be appreciated that this description is not intended to limit the scope of the present invention, but is intended to provide a better description of exemplary embodiments.

[0035] Throughout the specification and claims, unless the context clearly dictates otherwise, the following terms have the meanings explicitly associated herein:

[0036] As used herein, the phrase "in one embodiment" does not necessarily refer to the same embodiment, even though it may. Thus, as described below, the various embodiments of the present disclosure can be easily combined without departing from the scope or spirit of the invention.

[0037] As used herein, the term "or" is an inclusive "or" operator and is equivalent to the term "and / or" unless the context clearly dictates otherwise.

[0038] Unless the context clearly dictates otherwise, the term "based on" is not exclusive and allows for being based on additional factors not described.

[0039] As used herein, and unless the context dictates otherwise, the term "coupled to" is intended to include both direct coupling (where two elements coupled to each other are in contact with each other) and indirect coupling (where at least one additional element is located between the two elements). Therefore, the terms "coupled to" and "coupled with" are used synonymously. In the context of a networked environment where two or more components or devices are able to exchange data, the terms "coupled to" and "coupled with" are also used to mean "communicatively coupled with" possibly via one or more intermediate devices. The components or devices may be optical, mechanical and / or electrical devices.

[0040] Although the following description uses the terms "first," "second," etc. to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the various described examples, a first metalens may be referred to as a second metalens, and similarly, a second metalens may be referred to as a first metalens. Both the first metalens and the second metalens may be sensors, and in some cases, may be separate and different sensors.

[0041] In addition, throughout the specification, the meanings of “a,” “an,” and “the” include plural forms, and the meaning of “in” may include “in” and “on.”

[0042] Although some of the various embodiments provided herein constitute a single combination of inventive elements, it should be understood that the inventive subject matter is considered to include all possible combinations of disclosed elements. Thus, if one embodiment includes elements A, B, and C, and another embodiment includes elements B and D, the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if this paper does not explicitly discuss. In addition, the transition term "comprising" means having parts or components, or those parts or components. As used herein, the transition term "comprising" is inclusive or open-ended, and does not exclude additional, unlisted elements or method steps.

[0043] As used in the description herein and throughout the claims that follow, when a system, engine, server, device, module, or other computing element is described as being configured to perform or execute functions on data in a memory, the meaning of "configured to" or "programmed to" is defined as one or more processors or cores of the computing element being programmed by a set of software instructions stored in the memory of the computing element to perform the set of functions on target data or data objects stored in the memory.

[0044] It should be noted that any language for computers should be understood to include any suitable combination of computing devices or network platforms (including servers, interfaces, systems, databases, agents, peers, engines, controllers, modules, or other types of computing devices operating alone or together). It should be understood that the computing device includes a processor configured to execute software instructions stored on a tangible, non-transitory computer-readable storage medium (e.g., a hard drive, FPGA, PLA, solid-state drive, RAM, flash memory, ROM, or any other volatile or non-volatile storage device). The software instructions configure or program the computing device to provide roles, responsibilities, or other functions, as discussed below with respect to the disclosed apparatus. In addition, the disclosed technology can be embodied as a computer program product, which includes a non-transitory computer-readable medium storing software instructions that cause the processor to perform the disclosed steps associated with the implementation of a computer-based algorithm, process, method, or other instructions. In some embodiments, various servers, systems, databases or interfaces exchange data using standardized protocols or algorithms, which may be based on HTTP, HTTPS, AES, public-private key exchange, web service API, known financial transaction protocols or other electronic information exchange methods. Data exchange between devices can be carried out through the following: packet switching networks, the Internet, LAN, WAN, VPN or other types of packet switching networks; circuit switching networks; cell switching networks; or other types of networks.

[0045] The transceivers in current LiDAR systems are designed with typical optical lenses and lens groups. In order to provide a large receiving aperture for achieving large FOV coverage (e.g., a horizontal FOV of 120° or greater, and / or a vertical FOV of 70° or greater), the size of these optical lenses or lens groups is usually large. A superlens is an optical component that uses a metasurface to guide light (e.g., focus light). A superlens is sometimes also called a metamaterial lens, which is an advanced type of lens that uses metamaterials to manipulate and control light in a specific way. Metamaterials have a subwavelength structure that has specific electromagnetic properties. The subwavelength structure of a superlens can be designed to have a specific pattern, thereby manipulating the behavior of light and other electromagnetic waves.

[0046] Typical optical lenses, such as those based on glass, rely on the curvature of their surfaces to focus light. Metalenses, on the other hand, are flat and made of a series of subwavelength structures that can interact with light in ways that typical optical lenses can or cannot. This allows metalenses to overcome some of the flaws and limitations of traditional optical lenses, such as chromatic aberration (color distortion) and bulkiness.

[0047] For example, metalenses can be designed to focus light based on its wavelength, polarization, and other properties. They offer the potential for compact and lightweight optics in a variety of applications, such as LiDAR systems and other imaging systems. Because metalenses are made using nanoscale fabrication techniques, they are easier to integrate into a variety of devices, systems, and platforms than traditional optical lenses.

[0048] In some examples, metalenses can achieve the same focusing and collimation functions with a flat geometry, significantly reducing the thickness or overall size of the LiDAR system compared to systems using glass-based lenses or lens arrays. In addition, metalenses can be mass-produced using mature silicon wafer manufacturing processes. Metalenses can also compete with traditional aspheric lenses in production costs, making LiDAR systems more compact and cost-effective.

[0049] In the present disclosure, a lens can be a glass-based optical lens or a metasurface-based lens (superlens). Similarly, a mirror can be a traditional optical mirror or a metasurface-based mirror (supermirror). Unless otherwise specified, other optical components can also be traditional glass-based optics or metasurface-based optics.

[0050] Embodiments of the invention are described below. In various embodiments of the invention, a light ranging and detection (LiDAR) system is provided that includes one or more metasurface-based lenses (metalenses).

[0051] The system includes a transmitter, which includes one or more transmitter optical devices. The transmitter is configured to provide one or more transmitted light beams. The system also includes a beam steering device optically coupled to the transmitter. The beam steering device includes one or more steering optical devices, which are configured to: scan the one or more transmitted light beams to the field of view in at least one of the horizontal direction and the vertical direction, and guide the return light generated based on the scanned one or more transmitted light beams. The system also includes a receiver, which includes one or more receiver optical devices. The receiver is configured to receive the return light guided by the beam steering device. At least one of the one or more transmitter optical devices, the one or more steering optical devices, and the one or more receiver optical devices includes the one or more metasurface-based lenses (super lenses). One of the one or more super lenses includes a subwavelength structure disposed on a semiconductor wafer substrate, wherein the subwavelength structure is preconfigured to modulate light according to the optical requirements of the LiDAR system.

[0052] Figure 1 One or more exemplary LiDAR systems 110 and 120A-120I are illustrated as being arranged or included in a motor vehicle 100. The vehicle 100 may be a car, a sport utility vehicle (SUV), a truck, a train, a van, a bicycle, a motorcycle, a tricycle, a bus, a motor scooter, a tram, a ship, a boat, an underwater vehicle, an airplane, a helicopter, an unmanned aerial vehicle (UAV), a spacecraft, and the like. The motor vehicle 100 may be a vehicle having any level of automation. For example, the motor vehicle 100 may be a partially automated vehicle, a highly automated vehicle, a fully automated vehicle, or an unmanned vehicle. A partially automated vehicle may perform some driving functions without human driver intervention. For example, a partially automated vehicle may perform blind spot monitoring, lane keeping and / or lane change operations, automatic emergency braking, smart cruise control, and / or traffic following, and the like. Certain operations of a partially automated vehicle may be limited to specific applications or driving scenarios (e.g., limited to highway driving). A highly automated vehicle may generally perform all operations of a partially automated vehicle, but with fewer restrictions. Highly automated vehicles can also detect their own limits when operating the vehicle and request the driver to take over control of the vehicle when necessary. Fully automated vehicles can perform all vehicle operations without driver intervention, but can also detect their own limits and request the driver to take over when necessary. Driverless vehicles can operate autonomously without any driver intervention.

[0053] In a typical configuration, the motor vehicle 100 includes one or more LiDAR systems 110 and 120A-120I. Each of the LiDAR systems 110 and 120A-120I can be a scanning-based LiDAR system and / or a non-scanning LiDAR system (e.g., flash LiDAR). A scanning-based LiDAR system scans one or more light beams in one or more directions (e.g., horizontal and vertical directions) to detect objects in a field of view (FOV). A non-scanning-based LiDAR system emits a laser to illuminate the FOV without scanning. For example, a flash LiDAR is a type of non-scanning-based LiDAR system. A flash LiDAR can emit a laser to illuminate the FOV simultaneously using a single light pulse or light beams.

[0054] LiDAR systems are common sensors used in at least partially automated vehicles. Figure 1 As shown, the motor vehicle 100 may include a single LiDAR system 110 (e.g., without LiDAR systems 120A-120I) disposed at the highest position of the vehicle (e.g., on top of the vehicle). Placing the LiDAR system 110 on top of the vehicle facilitates 360-degree scanning around the vehicle 100. In some other embodiments, the motor vehicle 100 may include multiple LiDAR systems, including two or more of the systems 110 and / or 120A-120I. Figure 1 As shown, in one embodiment, multiple LiDAR systems 110 and / or 120A-120I are attached to the vehicle 100 at different locations of the vehicle. For example, LiDAR system 120A is attached to the vehicle 100 at the right front corner; LiDAR system 120B is attached to the vehicle 100 at the front center location; LiDAR system 120C is attached to the vehicle 100 at the left front corner; LiDAR system 120D is attached to the vehicle 100 at the right side mirror; LiDAR system 120E is attached to the vehicle 100 at the left side mirror; LiDAR system 120F is attached to the vehicle 100 at the rear center location; LiDAR system 120G is attached to the vehicle 100 at the right rear corner; LiDAR system 120H is attached to the vehicle 100 at the left rear corner; and / or LiDAR system 120I is attached to the vehicle 100 at the center toward the rear end (e.g., the rear end of the top of the vehicle). It should be understood that one or more LiDAR systems may be distributed and attached to a vehicle in any desired manner, and Figure 1Only one embodiment is illustrated. As another example, LiDAR systems 120D and 120E can be attached to the B-pillars of vehicle 100 instead of rearview mirrors. As another example, LiDAR system 120B can be attached to the windshield of vehicle 100 instead of the front bumper.

[0055] In some embodiments, LiDAR systems 110 and 120A-120I are independent LiDAR systems with their respective laser sources, control electronics, transmitters, receivers and / or steering mechanisms. In other embodiments, some of LiDAR systems 110 and 120A-120I can share one or more components to form a distributed sensor system. In one example, optical fiber is used to deliver lasers from a centralized laser source to all LiDAR systems. For example, system 110 (or another system positioned in the center or any position of vehicle 100) includes a light source, a transmitter and a light detector, but no steering mechanism. System 110 can distribute transmitted light to each of systems 120A-120I. Transmitted light can be distributed via optical fiber. Optical connectors can be used to couple optical fibers to each of systems 110 and 120A-120I. In some examples, one or more systems in systems 120A-120I include a steering mechanism, but no light source, transmitter or light detector. The steering mechanism may include one or more movable mirrors, such as one or more polygonal mirrors, one or more single plane mirrors, one or more multi-plane mirrors, etc. The embodiments of the light source, the transmitter, the steering mechanism and the light detector will be described in more detail below. Via the steering mechanism, one or more systems in the system 120A-120I scan the light into one or more corresponding FOVs and receive the corresponding return light. The return light is formed by scattering or reflecting the transmitted light by one or more objects in the FOV. The system 120A-120I may also include a collecting lens and / or other optical devices to focus and / or guide the return light into an optical fiber, and the optical fiber delivers the received return light to the system 110. The system 110 includes one or more light detectors for detecting the received return light. In some examples, the system 110 is arranged inside the vehicle so that it is in a temperature-controlled environment, and one or more systems 120A-120I may be at least partially exposed to the external environment.

[0056] Figure 22 is a block diagram 200 illustrating the interaction between a vehicle-mounted LiDAR system 210 and a plurality of other systems including a vehicle perception and planning system 220. The LiDAR system 210 may be mounted on or integrated with a vehicle. The LiDAR system 210 includes a sensor that scans laser light into the surrounding environment to measure the distance, angle, and / or velocity of an object. Based on the scattered light returned to the LiDAR system 210, the sensor may generate sensor data (e.g., image data or 3D point cloud data) representing the perceived external environment.

[0057] The LiDAR system 210 may include one or more of a short-range LiDAR sensor, a mid-range LiDAR sensor, and a long-range LiDAR sensor. Short-range LiDAR sensors measure objects up to about 20-50 meters from the LiDAR sensor. Short-range LiDAR sensors can be used, for example, to monitor nearby moving objects (e.g., pedestrians crossing the road in a school zone), parking assistance applications, etc. Mid-range LiDAR sensors measure objects up to about 70-200 meters from the LiDAR sensor. Mid-range LiDAR sensors can be used, for example, to monitor road intersections, assist in merging into or exiting a highway, etc. Long-range LiDAR sensors measure objects located 200 meters and above. Long-range LiDAR sensors are typically used when the vehicle is traveling at high speeds (e.g., on a highway), so that the vehicle's control system may only have a few seconds (e.g., 6-8 seconds) to respond to any situation detected by the LiDAR sensor. Figure 2 As shown, in one embodiment, LiDAR sensor data can be provided to vehicle perception and planning system 220 via communication path 213 for further processing and control of vehicle operation. Communication path 213 can be any wired or wireless communication link capable of transmitting data.

[0058] Still reference Figure 2, in some embodiments, other onboard sensors 230 are configured to interact with multiple other systems of the LiDAR system 210 alone or with a block diagram 200. The other onboard sensors 230 may include, for example, one or more cameras 232, one or more radars 234, one or more ultrasonic sensors 236, and / or other sensors 238. The camera 232 can capture images and / or videos of the external environment of the vehicle. The camera 232 can capture, for example, high-definition (HD) video with millions of pixels in each frame. The camera includes an image sensor that facilitates the generation of monochrome or color images and videos. Color information may be important when interpreting data in certain situations (e.g., interpreting images of traffic lights). Color information may not be available from other sensors (such as LiDAR or radar sensors). The camera 232 may include one or more of a narrow focal length camera, a wide focal length camera, a side camera, an infrared camera, a fisheye camera, etc. The image and / or video data generated by the camera 232 may also be provided to the vehicle perception and planning system 220 via a communication path 233 for further processing and control of vehicle operation. The communication path 233 may be any wired or wireless communication link capable of transmitting data. The camera 232 may be mounted or integrated into the vehicle at any location (eg, rearview mirror, pillar, front grille and / or rear bumper, etc.).

[0059] Other on-board sensors 230 may also include radar sensors 234. Radar sensors 234 use radio waves to determine the distance, angle, and speed of an object. Radar sensors 234 generate electromagnetic waves in the radio or microwave spectrum. Electromagnetic waves are reflected by objects, and some of the reflected waves return to the radar sensor, thereby providing information about the position and speed of the object. Radar sensors 234 may include one or more of short-range radars, medium-range radars, and long-range radars. Short-range radars measure objects about 0.1-30 meters from the radar. Short-range radars are useful in detecting objects near vehicles (such as other vehicles, buildings, walls, pedestrians, cyclists, etc.). Short-range radars can be used to detect blind spots, assist in lane changes, provide rear-end collision alerts, assist in parking, provide emergency braking, etc. Medium-range radars measure objects about 30-80 meters from the radar. Long-range radars measure objects located at about 80-200 meters. Medium-range and / or long-range radars can be used, for example, for traffic tracking, adaptive cruise control, and / or highway automatic braking. Sensor data generated by radar sensor 234 may also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and control of vehicle operation. Radar sensor 234 may be mounted or integrated into the vehicle at any location (e.g., rearview mirror, pillar, front grille and / or rear bumper, etc.).

[0060] Other on-board sensors 230 may also include ultrasonic sensors 236. Ultrasonic sensors 236 use sound waves or pulses to measure objects located outside the vehicle. The sound waves generated by ultrasonic sensors 236 are emitted to the surrounding environment. At least some of the emitted waves are reflected by the object and returned to the ultrasonic sensor 236. Based on the return signal, the distance of the object can be calculated. Ultrasonic sensors 236 can be used, for example, to check blind spots, identify parking spaces, provide lane change assistance in traffic, etc. The sensor data generated by ultrasonic sensors 236 can also be provided to the vehicle perception and planning system 220 via the communication path 233 for further processing and control of vehicle operation. Ultrasonic sensors 236 can be installed or integrated into the vehicle at any location (e.g., rearview mirrors, pillars, front grilles and / or rear bumpers, etc.).

[0061] In some embodiments, one or more other sensors 238 may be attached to the vehicle and may also generate sensor data. Other sensors 238 may include, for example, a global positioning system (GPS), an inertial measurement unit (IMU), etc. The sensor data generated by the other sensors 238 may also be provided to the vehicle perception and planning system 220 via the communication path 233 for further processing and control of vehicle operation. It should be understood that the communication path 233 may include one or more communication links to transmit data between the various sensors 230 and the vehicle perception and planning system 220.

[0062] In some embodiments, such as Figure 2 As shown, a block diagram 200 of the interaction between multiple other systems through which sensor data from other onboard sensors 230 can be transmitted via a communication path 231. The LiDAR system 210 can process the sensor data from the other onboard sensors 230. For example, sensor data from a camera 232, a radar sensor 234, an ultrasonic sensor 236, and / or other sensors 238 can be correlated or fused with the sensor data LiDAR system 210, thereby at least partially clearing the sensor fusion process performed by the vehicle perception and planning system 220. It should be understood that other configurations for transmitting and processing sensor data from various sensors can also be implemented (e.g., the data can be transmitted to a cloud or edge computing service provider for processing, and the processing results can then be transmitted back to the vehicle perception and planning system 220 and / or the LiDAR system 210).

[0063] Still reference Figure 2In some embodiments, sensors on other vehicles 250 are used to provide additional sensor data alone or in conjunction with the LiDAR system 210. For example, two or more nearby vehicles may have their own LiDAR sensors, cameras, radar sensors, ultrasonic sensors, etc. Nearby vehicles can communicate and share sensor data with each other. Communication between vehicles is also known as V2V (vehicle-to-vehicle) communication. For example, Figure 2 As shown, sensor data generated by other vehicles 250 can be transmitted to vehicle perception and planning system 220 and / or onboard LiDAR system 210 via communication path 253 and / or communication path 251, respectively. Communication paths 253 and 251 can be any wired or wireless communication links capable of transmitting data.

[0064] Sharing sensor data facilitates better perception of the environment outside the vehicle. For example, the first vehicle may not sense a pedestrian that is behind the second vehicle but is approaching the first vehicle. The second vehicle can share sensor data related to the pedestrian with the first vehicle, so that the first vehicle can have additional reaction time to avoid colliding with the pedestrian. In some embodiments, similar to the data generated by sensor 230, the data generated by sensors on other vehicles 250 can be correlated or fused with sensor data generated by LiDAR system 210 (or other LiDAR systems located in other vehicles), thereby at least partially offloading the sensor fusion process performed by the vehicle perception and planning system 220.

[0065] In some embodiments, the smart infrastructure system 240 is used to provide sensor data alone or in conjunction with the LiDAR system 210. Certain infrastructures may be configured to communicate with vehicles to transfer information, and vice versa. Communication between vehicles and infrastructure is generally referred to as V2I (vehicle to infrastructure) communication. For example, the smart infrastructure system 240 may include a smart traffic light that can communicate its status to approaching vehicles with messages such as "turn yellow in 5 seconds". The smart infrastructure system 240 may also include its own LiDAR system installed near the intersection so that it can transmit traffic monitoring information to the vehicle. For example, a vehicle turning left at an intersection may not have sufficient sensing capabilities because some of its own sensors may be blocked by traffic in the opposite direction. In this case, the sensors of the smart infrastructure system 240 can provide useful data to the vehicle turning left. Such data may include, for example, traffic conditions, object information in the direction of vehicle turning, traffic light status and predictions, etc. These sensor data generated by the smart infrastructure system 240 can be provided to the vehicle perception and planning system 220 and / or the onboard LiDAR system 210 via communication paths 243 and / or 241, respectively. Communication paths 243 and / or 241 may include any wired or wireless communication links capable of transmitting data. For example, sensor data from the smart infrastructure system 240 can be transmitted to the LiDAR system 210 and correlated or fused with sensor data generated by the LiDAR system 210, thereby at least partially offloading the sensor fusion process performed by the vehicle perception and planning system 220. The above-mentioned V2V and V2I communications are examples of vehicle-to-X (V2X) communications, where "X" represents any other device, system, sensor, infrastructure, etc. that can share data with the vehicle.

[0066] Still reference Figure 2, a block diagram 200 of the interaction between multiple other systems of the vehicle perception and planning system 220 from the LiDAR system 210, other onboard sensors 230, other vehicles 250, and / or the smart infrastructure system 240 via various communication paths. In some embodiments, the sensor fusion subsystem 222 correlates and / or integrates different types of sensor data. For example, the sensor fusion subsystem 222 can use multiple images or videos captured by multiple cameras set at different locations of the vehicle to generate a 360-degree model. The sensor fusion subsystem 222 obtains sensor data from different types of sensors and uses the combined data to more accurately perceive the environment. For example, the onboard camera 232 may not capture a clear image because it is directly facing the sun or a light source (e.g., the headlights of another vehicle during night time). The LiDAR system 210 may not be affected too much, so the sensor fusion subsystem 222 can combine the sensor data provided by both the camera 232 and the LiDAR system 210, and use the sensor data provided by the LiDAR system 210 to compensate for the unclear image captured by the camera 232. As another example, in rainy or foggy weather, radar sensor 234 may work better than camera 232 or LiDAR system 210. Therefore, sensor fusion subsystem 222 may use sensor data provided by radar sensor 234 to compensate for sensor data provided by camera 232 or LiDAR system 210.

[0067] In other examples, the sensor data generated by other onboard sensors 230 may have a lower resolution (e.g., radar sensor data) and therefore may need to be correlated with and confirmed by the LiDAR system 210, which typically has a higher resolution. For example, a manhole cover (also known as a manhole cover) may be detected by the radar sensor 234 as a target that the vehicle is approaching. Due to the low-resolution nature of the radar sensor 234, the vehicle perception and planning system 220 may not be able to determine whether the target is an obstacle that the vehicle needs to avoid. Therefore, the high-resolution sensor data generated by the LiDAR system 210 can be used to correlate and confirm that the target is a manhole cover and will not cause harm to the vehicle.

[0068] The vehicle perception and planning system 220 also includes a target classifier 223. The target classifier 223 can use the raw sensor data and / or the related / fused data provided by the sensor fusion subsystem 222, and use any computer vision technology to detect and classify the target and estimate the position of the target. In some embodiments, the target classifier 223 can use machine learning-based techniques to detect and classify the target. Examples of machine learning-based techniques include using algorithms such as region-based convolutional neural network (R-CNN), fast R-CNN, faster R-CNN, histogram of oriented gradient (HOG), region-based fully convolutional network (R-FCN), singleshot detector (SSD), spatial pyramid pooling (SPP-net) and / or You Only Look Once (Yolo).

[0069] The vehicle perception and planning system 220 also includes a road detection subsystem 224. The road detection subsystem 224 locates the road and identifies objects and / or signs on the road. For example, the road detection subsystem 224 can build a 3D model of the road based on the original or fused sensor data provided by the radar sensor 234, the camera 232 and / or the LiDAR system 210, based on machine learning techniques (e.g., a pattern recognition algorithm for identifying lanes). The road detection subsystem 224 can use the 3D model of the road to identify objects (e.g., obstacles or debris on the road) and / or signs (e.g., lane lines, turn signs, crosswalk signs, etc.) on the road.

[0070] The vehicle perception and planning system 220 also includes a positioning and vehicle attitude subsystem 225. The positioning and vehicle attitude subsystem 225 can determine the position of the vehicle and the attitude of the vehicle based on the original or fused sensor data. For example, the positioning and vehicle attitude subsystem 225 can use the sensor data and / or GPS data from the LiDAR system 210, the camera 232 to determine the precise position of the vehicle on the road and the six degrees of freedom of the vehicle (for example, whether the vehicle moves forward or backward, upward or downward, and left or right). In some embodiments, a high-definition (HD) map is used to locate the vehicle. The HD map can provide a highly detailed three-dimensional computerized map that accurately determines the position of the vehicle. For example, the positioning and vehicle attitude subsystem 225 can use the HD map to accurately determine the current position of the vehicle (for example, which lane of the road the vehicle is currently located on, how close it is to the curb or sidewalk) and predict the future position of the vehicle.

[0071] The vehicle perception and planning system 220 also includes an obstacle predictor 226. The target identified by the target classifier 223 can be stationary (e.g., a light pole, a road sign) or dynamic (e.g., a moving pedestrian, a bicycle, another car). For moving targets, predicting their movement path or future position can be important for avoiding collisions. The obstacle predictor 226 can predict the trajectory of obstacles and / or warn the driver or the vehicle planning subsystem 228 of potential collisions. For example, if there is a high probability that the trajectory of the obstacle intersects the current movement path of the vehicle, the obstacle predictor 226 can generate such a warning. The obstacle predictor 226 can use various techniques to make such predictions. Such technologies include, for example, constant speed or acceleration models, constant turning rate and speed / acceleration models, models based on Kalman Filter and Extended Kalman Filter, models based on recurrent neural network (RNN), models based on long short-term memory (LSTM) neural network, encoder-decoder RNN models, etc.

[0072] Still reference Figure 2In some embodiments, the vehicle perception and planning system 220 also includes a vehicle planning subsystem 228. The vehicle planning subsystem 228 may include one or more planners, such as a route planner, a driving behavior planner, and a motion planner. The route planner may plan the route of the vehicle based on the vehicle's current position data, target position data, traffic information, etc. The driving behavior planner uses the obstacle prediction results provided by the obstacle predictor 226 to adjust the timing and planned movements based on how other objects may move. The motion planner determines the specific operations that the vehicle needs to follow. The planning results are then transmitted to the vehicle control system 280 via the vehicle interface 270. Communications may be performed via communication paths 227 and 271, which include any wired or wireless communication links that can transmit data.

[0073] The vehicle control system 280 controls the vehicle's steering mechanism, throttle, brakes, etc. to operate the vehicle according to the planned route and movement. In some examples, the vehicle perception and planning system 220 may also include a user interface 260, which provides the user (e.g., the driver) with access to the vehicle control system 280, for example, to override or take over control of the vehicle when necessary. The user interface 260 and the vehicle perception and planning system 220 may also be separate. The user interface 260 can communicate with the vehicle perception and planning system 220, for example to obtain and display raw or fused sensor data, identified targets, the position / attitude of the vehicle, etc. These displayed data can help the user better operate the vehicle. The user interface 260 can communicate with the vehicle perception and planning system 220 and / or the vehicle control system 280 via communication paths 221 and 261, respectively, and such communication paths include any wired or wireless communication links that can transmit data. It should be understood that Figure 2 The various systems, sensors, communication links and interfaces in the can be configured in any desired manner and are not limited to Figure 2 Configuration shown.

[0074] Figure 3 is a block diagram illustrating an exemplary LiDAR system 300. The LiDAR system 300 may be used to implement Figure 1 and Figure 2 The LiDAR systems 110, 120A-120I and / or 2101 and Figure 2, and / or 210. In one embodiment, the LiDAR system 300 includes a laser source 310, a transmitter 320, an optical receiver and light detector 330, a steering system 340, and a control circuit system 350. As described below, one or more components of the transmitter 320, the optical receiver and light detector 330, and the steering system 340 can be implemented using metasurface-based lenses or reflectors. Communication paths 312, 314, 322, 332, 342, 352, and 362 are used to couple these components together. These communication paths include communication links (wired or wireless, bidirectional or unidirectional) between various LiDAR system components, but do not need to be physical components themselves. Although the communication paths can be implemented by one or more wires, buses, or optical fibers, the communication paths can also be wireless channels or free space optical paths so that there is no physical communication medium. For example, in one embodiment of the LiDAR system 300, the communication path 314 between the laser source 310 and the transmitter 320 can be implemented using one or more optical fibers. Communication paths 332 and 352 can represent optical paths implemented using free space optics and / or optical fibers. Also, communication paths 312, 322, 342, and 362 can be implemented using one or more wires carrying electrical signals. The communication paths can also include one or more of the above types of communication media (e.g., they can include optical fibers and free space optics, or include one or more optical fibers and one or more wires).

[0075] In some embodiments, the LiDAR system 300 may be a coherent LiDAR system. One example is a frequency modulated continuous wave (FMCW) LiDAR. Coherent LiDAR detects a target by mixing the return light from the target with the light from a coherent laser emitter. Thus, Figure 3 As shown, if the LiDAR system 300 is a coherent LiDAR, it can include a route 372 that provides a portion of the transmitted light from the transmitter 320 to the optical receiver and light detector 330. Route 372 may include one or more optical devices (e.g., optical fibers, lenses, mirrors, etc.) for providing light from the transmitter 320 to the optical receiver and light detector 330. The transmitted light provided by the transmitter 320 may be modulated light and may be divided into two parts. One part is emitted to the FOV, while the second part is sent to the optical receiver and light detector of the LiDAR system. The second part is also referred to as light kept locally (LO) in the LiDAR system. The transmitted light is scattered or reflected by various objects in the FOV, and at least a portion of it forms return light. The return light is then detected and recombined by interference with the second part of the transmitted light that remains local. Coherent LiDAR provides a mechanism for optically sensing the range of objects and their relative speed along the line of sight (LOS).

[0076] The LiDAR system 300 may also include Figure 3 Other components not shown in the diagram may include a power bus, power supplies, LED indicators, switches, etc. Additionally, there may be other communication connections between components, such as a direct connection between the light source 310 and the optical receiver and light detector 330 to provide a reference signal so that the time from the emission of a light pulse to the detection until the return light pulse can be accurately measured.

[0077] The light source 310 outputs a laser for irradiating an object in the field of view (FOV). The laser can be an infrared light having a wavelength in the range of 700nm to 1mm. The light source 310 can be, for example, a semiconductor-based laser (e.g., a diode laser) and / or an optical fiber-based laser. The semiconductor-based laser can be, for example, an edge-emitting laser (EEL), a vertical cavity surface-emitting laser (VCSEL), an external cavity diode laser, a vertical external cavity surface-emitting laser, a distributed feedback (DFB) laser, a distributed Bragg reflector (DBR) laser, an interband cascade laser, a quantum cascade laser, a quantum well laser, a double heterostructure laser, etc. An optical fiber-based laser is a laser in which the activation gain medium is an optical fiber doped with rare earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium, and / or holmium. In some embodiments, the optical fiber laser is based on a double-clad optical fiber, in which the gain medium forms the core of an optical fiber surrounded by two layers of cladding. Double-clad fibers allow a high-power beam to be pumped into the core, enabling the laser source to become a high-power fiber laser source.

[0078] In some embodiments, the light source 310 includes a master oscillator (also called a seed laser) and a power amplifier (MOPA). The power amplifier amplifies the output power of the seed laser. The power amplifier can be a fiber amplifier, a bulk amplifier, or a semiconductor optical amplifier. The seed laser can be a diode laser (e.g., a Fabry-Perot cavity laser, a distributed feedback laser), a solid-state bulk laser, or an external cavity tunable diode laser. In some embodiments, the light source 310 can be an optically pumped microchip laser. A microchip laser is an alignment-free monolithic solid-state laser in which the laser crystal is directly in contact with the end mirror of the laser resonator. Microchip lasers are typically pumped by laser diodes (directly or using optical fibers) to obtain the desired output power. Microchip lasers can be based on neodymium-doped yttrium aluminum garnet (Y3Al5O 12) laser crystal (i.e., Nd:YAG) or neodymium-doped vanadate (i.e., ND:YVO4) laser crystal. In some examples, light source 310 can have multiple amplification stages to achieve high power gain so that the laser output can have high power, thereby enabling the LiDAR system to have a long scanning range. In some examples, the power amplifier of light source 310 can be controlled so that the power gain can be changed to achieve any desired laser output power.

[0079] Figure 4 4 is a block diagram illustrating an exemplary fiber-based laser source 400 having a seed laser and one or more pumps (eg, laser diodes) for pumping a desired output power. Figure 3 An example of a light source 310 is shown. In some embodiments, the fiber-based laser source 400 includes a seed laser 402 to generate initial light pulses of one or more wavelengths (e.g., an infrared wavelength such as 1550 nm), which are provided to a wavelength division multiplexer (WDM) 404 via an optical fiber 403. The fiber-based laser source 400 also includes a pump 406 for providing laser power (e.g., a different wavelength, such as 980 nm) to the WDM 404 via an optical fiber 405. The WDM 404 multiplexes the light pulses provided by the seed laser 402 and the laser power provided by the pump 406 onto a single optical fiber 407. The output of the WDM 404 can then be provided to one or more preamplifiers 408 via the optical fiber 407. The preamplifier 408 can be an optical amplifier (e.g., having a gain of about 10-30 dB) that amplifies the optical signal. In some embodiments, the preamplifier 408 is a low noise amplifier. The preamplifier 408 outputs to the optical combiner 410 via an optical fiber 409. Combiner 410 combines the output laser of preamplifier 408 with the laser power provided by pump 412 via optical fiber 411. Combiner 410 can combine optical signals having the same wavelength or different wavelengths. An example of a combiner is a WDM. Combiner 410 provides the combined optical signal to boost amplifier 414, which generates output optical pulses via optical fiber 415. Boost amplifier 414 provides further amplification of the optical signal (e.g., another 20-40 dB). The output optical pulses can then be transmitted to transmitter 320 and / or steering mechanism 340 (e.g., Figure 3 It should be understood that Figure 4 An exemplary configuration of a fiber-based laser source 400 is shown. The laser source 400 may have a Figure 4 One or more components shown in and / or Figure 4 Many other configurations of different combinations of other components not shown (e.g., other components such as power supplies, lenses, filters, splitters, combiners, etc.).

[0080] In some variations, the fiber-based laser source 400 can be controlled (e.g., by control circuitry 350) to generate pulses of varying amplitudes based on the fiber gain profile of the optical fiber used in the fiber-based laser source 400. The communication path 312 couples the fiber-based laser source 400 to the control circuitry 350 (e.g., Figure 3 350) so that the components of the fiber-based laser source 400 can be controlled by or otherwise communicate with the control circuit system. Alternatively, the fiber-based laser source 400 can include its own dedicated controller. Instead of the control circuit system 350 communicating directly with the components of the fiber-based laser source 400, the dedicated controller of the fiber-based laser source 400 communicates with the control circuit system 350 and controls and / or communicates with the components of the fiber-based laser source 400. The fiber-based laser source 400 may also include other components not shown, such as one or more power connectors, power sources, and / or power lines.

[0081] refer to Figure 3 , typical operating wavelengths of the light source 310 include, for example, about 850nm, about 905nm, about 940nm, about 1064nm, and about 1550nm. For laser safety, the upper limit of the maximum available laser power is set by the U.S. Food and Drug Administration (FDA) regulations. The optical power limit of the 1550nm wavelength is much higher than the optical power limits of the other wavelengths mentioned above. In addition, at 1550nm, the optical power loss in the optical fiber is very low. These characteristics of the 1550nm wavelength make it more conducive to long-distance LiDAR applications. The amount of optical power output from the light source 310 can be characterized by its peak power, average power, pulse energy, and / or pulse energy density. Peak power is the ratio of pulse energy to pulse width (e.g., full width at half maximum or FWHM). Therefore, for a fixed amount of pulse energy, a smaller pulse width can provide a larger peak power. The pulse width can be in the range of nanoseconds or picoseconds. The average power is the product of the pulse energy and the pulse repetition rate (PRR). As described in more detail below, PRR represents the frequency of the pulsed laser. In general, the smaller the time interval between pulses, the higher the PRR. The PRR generally corresponds to the maximum range that the LiDAR system can measure. The light source 310 can be configured to generate pulses with a high PRR to meet the desired number of data points in the point cloud generated by the LiDAR system. The light source 310 can also be configured to generate pulses with a medium or low PRR to meet the desired maximum detection distance. Wall plug efficiency (WPE) is another factor in evaluating the total power consumption, which can be a useful metric for evaluating the efficiency of the laser. For example, if Figure 1As shown, multiple LiDAR systems can be attached to a vehicle, which can be an electric vehicle or a vehicle with limited fuel or battery power. Therefore, high WPE and intelligent ways of using laser power are often important considerations when selecting and configuring light sources 310 and / or designing laser delivery systems for vehicle-mounted LiDAR applications.

[0082] It should be understood that the above description provides non-limiting examples of light sources 310. Light source 310 can be configured to include many other types of light sources (e.g., laser diodes, short cavity fiber lasers, solid-state lasers, and / or external cavity tunable diode lasers) that are configured to generate one or more optical signals of various wavelengths. In some examples, light source 310 includes an amplifier (e.g., a preamplifier and / or a boost amplifier), which can be a doped fiber amplifier, a solid-state bulk amplifier, and / or a semiconductor optical amplifier. The amplifier is configured to receive and amplify the optical signal at a desired gain.

[0083] Return to reference Figure 3 , the LiDAR system 300 also includes a transmitter 320. The light source 310 provides laser light (e.g., in the form of a laser beam) to the transmitter 320. The laser light provided by the light source 310 can be an amplified laser with a predetermined or controlled wavelength, pulse repetition rate, and / or power level. The transmitter 320 receives the laser light from the light source 310 and emits the laser light to the steering mechanism 340 with a low divergence. In some embodiments, the transmitter 320 may include, for example, optical components (e.g., lenses, optical fibers, mirrors, etc.) for emitting one or more laser beams into the field of view (FOV) directly or via the steering mechanism 340. Although Figure 3 The transmitter 320 and the steering mechanism 340 are illustrated as separate components, but in some embodiments, they may be combined or integrated into a system. The steering mechanism 340 will be described in more detail below.

[0084] The laser beam provided by the light source 310 may diverge when it propagates to the emitter 320. Therefore, the emitter 320 generally includes a collimating lens, which is configured to collect the divergent laser beam and produce a more parallel beam with reduced or minimal divergence. The collimated beam can then be further directed through various optical devices, such as mirrors and lenses. The collimating lens can be, for example, a single plano-convex lens or a lens array. The collimating lens can be configured to achieve any desired characteristics, such as beam diameter, divergence, numerical aperture, focal length, etc. The beam propagation ratio or beam quality factor (also referred to as M 2 Factor) is used to measure the laser beam quality. In many LiDAR applications, it is important to have good laser beam quality in the generated transmitted laser beam. 2 The factor represents the degree of change of the beam relative to the ideal Gaussian beam. Therefore, M2 The factor reflects how well a collimated laser beam can be focused on a small spot, or how well a divergent laser beam can be collimated. Thus, the light source 310 and / or the emitter 320 can be configured to meet, for example, scanning resolution requirements while maintaining a desired M 2 factor.

[0085] One or more of the light beams provided by the transmitter 320 are scanned to the FOV by the steering mechanism 340. The steering mechanism 340 scans the light beam in multiple dimensions (e.g., in the horizontal dimension and the vertical dimension) so that the LiDAR system 300 can map the environment by generating a 3D point cloud. The horizontal dimension can be a dimension parallel to the horizon or a surface associated with the LiDAR system or vehicle (e.g., a road surface). The vertical dimension is perpendicular to the horizontal dimension (i.e., the vertical dimension forms a 90-degree angle with the horizontal dimension). The steering mechanism 340 will be described in more detail below. The laser light scanned to the FOV may be scattered or reflected by objects in the FOV. At least a portion of the scattered light or reflected light forms the return light returned to the LiDAR system 300. Figure 3 An optical receiver and light detector 330 configured to receive the return light is further illustrated. The optical receiver and light detector 330 include an optical receiver configured to collect the return light from the FOV. The optical receiver may include optics (e.g., lenses, optical fibers, mirrors, etc.) for receiving, redirecting, focusing, amplifying, and / or filtering the return light from the FOV. For example, the optical receiver typically includes a collection lens (e.g., a single plano-convex lens or a lens group) to collect the return light and / or focus the collected return light onto the light detector.

[0086] The photodetector detects the return light focused by the optical receiver and generates a current and / or voltage signal proportional to the incident intensity of the return light. Based on such current and / or voltage signals, the depth information of the object in the FOV can be derived. An exemplary method for deriving such depth information is based on direct TOF (time of flight), which will be described in more detail below. The photodetector can be characterized by its detection sensitivity, quantum efficiency, detector bandwidth, linearity, signal-to-noise ratio (SNR), overload resistance, interference resistance, etc. Based on the application, the photodetector can be configured or customized to have any desired characteristics. For example, the optical receiver and the photodetector 330 can be configured so that the photodetector has a large dynamic range while having good linearity. The linearity of the photodetector indicates the ability of the detector to maintain a linear relationship between the input optical signal power and the detector output. A detector with good linearity can maintain a linear relationship within a large dynamic input optical signal range.

[0087] In order to achieve the desired detector characteristics, the structure of the photodetector and / or the material system of the detector can be configured or customized. Various detector structures can be used for the photodetector. For example, the photodetector structure can be a PIN-based structure having an undoped intrinsic semiconductor region (i.e., an "I" region) between the p-type semiconductor and the n-type semiconductor regions. Other photodetector structures include, for example, APD (avalanche photodiode)-based structures, PMT (photomultiplier tube)-based structures, SiPM (silicon photomultiplier tube)-based structures, SPAD (single photon avalanche diode)-based structures and / or quantum wires. For the material system used in the photodetector, Si, InGaAs and / or Si / Ge-based materials can be used. It should be understood that many other detector structures and / or material systems can be used in the optical receiver and the photodetector 330.

[0088] The photodetector (e.g., an APD-based detector) may have an internal gain so that the input signal is amplified when the output signal is generated. However, due to the internal gain of the photodetector, noise may also be amplified. Common types of noise include signal shot noise, dark current shot noise, thermal noise, and amplifier noise. In some embodiments, the optical receiver and photodetector 330 may include a preamplifier of a low noise amplifier (LNA). In some embodiments, the preamplifier may also include a transimpedance amplifier (TIA) that converts the current signal into a voltage signal. For linear detector systems, the input equivalent noise or noise equivalent power (NEP) measures the sensitivity of the photodetector to weak signals. Therefore, they can be used as an indicator of overall system performance. For example, the NEP of the photodetector specifies the power of the weakest signal that can be detected, and therefore it in turn specifies the maximum range of the LiDAR system. It should be understood that various photodetector optimization techniques can be used to meet the requirements of the LiDAR system 300. Such optimization techniques may include selecting different detector structures, materials, and / or implementing signal processing techniques (e.g., filtering, noise reduction, amplification, etc.). For example, in addition to or instead of direct detection using a return signal (e.g., by using ToF), coherent detection can also be used for a light detector. Coherent detection allows the amplitude and phase information of the received light to be detected by interfering the received light with a local oscillator. Coherent detection can improve detection sensitivity and noise immunity.

[0089] Figure 3The LiDAR system 300 is further illustrated to include a steering mechanism 340. As described above, the steering mechanism 340 guides the light beam from the transmitter 320 to scan the FOV in multiple dimensions. The steering mechanism is called a grating mechanism, a scanning mechanism, or simply a light scanner. Scanning the light beam in multiple directions (e.g., in the horizontal direction and the vertical direction) helps the LiDAR system to draw the environment by generating an image or a 3D point cloud. The steering mechanism can be based on mechanical scanning and / or solid-state scanning. Mechanical scanning uses a rotating mirror to steer the laser beam or physically rotates the LiDAR transmitter and receiver (collectively referred to as a transceiver) to scan the laser beam. Solid-state scanning guides the laser beam to various positions through the FOV without mechanically moving any macroscopic components, such as a transceiver. The solid-state scanning mechanism includes, for example, steering based on an optical phased array and steering based on a flash LiDAR. In some embodiments, because the solid-state scanning mechanism does not physically move the macroscopic components, the steering performed by the solid-state scanning mechanism can be referred to as effective steering. A LiDAR system using solid-state scanning may also be referred to as a non-mechanical scanning or simply a non-scanning LiDAR system (a flash LiDAR system is an exemplary non-scanning LiDAR system).

[0090] The steering mechanism 340 can be used with a transceiver (e.g., a transmitter 320 and an optical receiver and a light detector 330) to scan the FOV for generating an image or a 3D point cloud. As an example, to implement the steering mechanism 340, a two-dimensional mechanical scanner can be used with a single point or several single point transceivers. The single point transceiver transmits a single beam or a small number of beams (e.g., 2-8 beams) to the steering mechanism. The two-dimensional mechanical steering mechanism includes, for example, a polygon mirror, an oscillating mirror, a rotating prism, a rotating tilt mirror, a single plane or a multi-plane mirror, or a combination thereof. In some embodiments, the steering mechanism 340 may include a non-mechanical steering mechanism, such as a solid-state steering mechanism. For example, the steering mechanism 340 can be based on the tuned wavelength of a laser combined with a refraction effect, and / or based on a reconfigurable grating / phase array. In some embodiments, the steering mechanism 340 can use a single scanning device to achieve two-dimensional scanning, or use a combination of multiple scanning devices to achieve two-dimensional scanning.

[0091] As another example, to implement the steering mechanism 340, a one-dimensional mechanical scanner can be used with an array or a large number of single-point transceivers. Specifically, the transceiver array can be mounted on a rotating platform to achieve a 360-degree horizontal field of view. Alternatively, a static transceiver array can be combined with a one-dimensional mechanical scanner. The one-dimensional mechanical scanner includes a polygon mirror, an oscillating mirror, a rotating prism, a rotating tilt mirror, or a combination thereof to obtain a forward horizontal field of view. A steering mechanism using a mechanical scanner can provide robustness and reliability in mass production for automotive applications.

[0092] As another example, to implement the steering mechanism 340, a two-dimensional transceiver can be used to directly generate a scanned image or a 3D point cloud. In some embodiments, a stitching or micro-displacement method can be used to increase the resolution of the scanned image or the scanned field of view. For example, using a two-dimensional transceiver, a signal generated in one direction (e.g., horizontally) and a signal generated in another direction (e.g., vertically) can be integrated, interleaved, and / or matched to generate a higher or full resolution image or 3D point cloud representing the scanned FOV.

[0093] Some embodiments of the steering mechanism 340 include one or more optical redirecting elements (e.g., mirrors or lenses) that redirect the return light signal along the receive path (e.g., by rotation, vibration, or guidance) to direct the return light signal to the optical receiver and light detector 330. The optical redirecting elements that direct the light signal along the transmit path and the receive path can be the same component (e.g., shared), separate components (e.g., dedicated), and / or a combination of shared and separate components. This means that in some cases, the transmit path and the receive path are different, although they may partially overlap (or in some cases, substantially overlap or completely overlap).

[0094] Still reference Figure 3 , the LiDAR system 300 also includes a control circuit system 350. The control circuit system 350 can be configured and / or programmed to control various parts of the LiDAR system 300 and / or perform signal processing. In a typical system, the control circuit system 350 can be configured and / or programmed to perform one or more control operations, including, for example, controlling the light source 310 to obtain the desired laser pulse timing, pulse repetition rate and power; controlling the steering mechanism 340 (e.g., controlling speed, direction and / or other parameters) to scan the FOV and maintain pixel registration and / or alignment; controlling the optical receiver and light detector 330 (e.g., controlling sensitivity, noise reduction, filtering and / or other parameters) so that it is in an optimal state; and monitoring the overall system health / functional safety status (e.g., monitoring the safety of the laser output power and / or steering mechanism operation status).

[0095] The control circuit system 350 can also be configured and / or programmed to perform signal processing on the raw data generated by the optical receiver and light detector 330 to obtain distance and reflectivity information, and to package and communicate the data with the vehicle perception and planning system 220 (e.g., Figure 2For example, control circuit system 350 determines the time taken from transmitting a light pulse to receiving a corresponding return light pulse; determines when a return light pulse is not received for an transmitted light pulse; determines the direction (e.g., horizontal and / or vertical information) of the transmitted light pulse / return light pulse; determines an estimated range in a particular direction; derives reflectivity of objects in the FOV, and / or determines any other type of data related to LiDAR system 300.

[0096] The LiDAR system 300 can be set in a vehicle that can operate in many different environments, including hot or cold weather, rough road conditions that may cause strong vibrations, high or low humidity, dusty areas, etc. Therefore, in some embodiments, the optical and / or electronic components of the LiDAR system 300 (e.g., the optical devices in the transmitter 320, the optical receiver and light detector 330, and the steering mechanism 340) are arranged and / or configured in a manner to maintain long-term mechanical and optical stability. For example, the components in the LiDAR system 300 can be fixed and sealed so that they can operate under all conditions that the vehicle may encounter. As an example, a moisture-proof coating and / or an airtight seal can be applied to the optical components of the transmitter 320, the optical receiver and light detector 330, and the steering mechanism 340 (as well as other components susceptible to moisture). As another example, a housing, a cover, a fairing, and / or a window can be used in the LiDAR system 300 to provide desired properties, such as hardness, foreign object protection level (IP), self-cleaning ability, chemical resistance, and impact resistance. Additionally, efficient and economical methods for assembling the LiDAR system 300 may be used to meet LiDAR operational requirements while keeping costs low.

[0097] Those skilled in the art should understand that Figure 3 The above description is for illustrative purposes only, and the LiDAR system may include other functional units, blocks, or segments, and may include variations or combinations of the above functional units, blocks, or segments. For example, the LiDAR system 300 may also include Figure 3 Other components not depicted in the drawings may include a power bus, power supplies, LED indicators, switches, etc. Additionally, there may be other connections between components, such as a direct connection between the light source 310 and the optical receiver and light detector 330 so that the light detector 330 can accurately measure the time from when the light source 310 emits a light pulse until the light detector 330 detects a returning light pulse.

[0098] Figure 3The components are shown coupled together using communication paths 312, 314, 322, 332, 342, 352, and 362. These communication paths represent communications (bidirectional or unidirectional) between the various LiDAR system components, but are not necessarily the physical components themselves. Although communication paths can be implemented by one or more wires, buses, or optical fibers, communication paths can also be wireless channels or open-air optical paths so that no physical communication medium is present. For example, in one exemplary LiDAR system, communication path 314 includes one or more optical fibers; communication path 352 represents an optical path; and communication paths 312, 322, 342, and 362 are all wires that carry electrical signals. Communication paths can also include more than one of the above-mentioned types of communication media (e.g., they can include optical fibers and optical paths, or one or more optical fibers and one or more wires).

[0099] As mentioned above, some LiDAR systems use the time of flight (ToF) of light signals (e.g., light pulses) to determine the distance to objects in the light path. Figure 5A , an exemplary LiDAR system 500 includes a laser light source (e.g., a fiber laser), a steering mechanism (e.g., a system of one or more moving mirrors), and a light detector (e.g., a photodetector having one or more optical devices). The LiDAR system 500 can be implemented using, for example, the LiDAR system 300 described above. The LiDAR system 500 emits light pulses 502 along an optical path 504 determined by the steering mechanism of the LiDAR system 500. In the depicted example, the light pulses 502 generated by the laser light source are short pulses of laser light. In addition, the signal manipulation mechanism of the LiDAR system 500 is a pulse signal steering mechanism. However, it should be understood that the LiDAR system can operate by generating, emitting, and detecting non-pulsed light signals, and using techniques other than time of flight to derive the distance to objects in the surrounding environment. For example, some LiDAR systems use frequency modulated continuous waves (i.e., "FMCW"). It should also be understood that any of the techniques described herein for time-of-flight-based systems using pulsed signals can also be applied to LiDAR systems that do not use one or both of these techniques.

[0100] Return to reference Figure 5A(e.g., a time-of-flight LiDAR system using light pulses is illustrated), when light pulse 502 reaches object 506, light pulse 502 is scattered or reflected to form return light pulse 508. Return light pulse 508 may return to system 500 along optical path 510. The time from when the emitted light pulse 502 leaves LiDAR system 500 to when the return light pulse 508 returns to LiDAR system 500 may be measured (e.g., by a processor or other electronic device within the LiDAR system, such as control circuitry 350). This time of flight, combined with knowledge of the speed of light, may be used to determine the distance / distance from LiDAR system 500 to the portion of object 506 where light pulse 502 was scattered or reflected.

[0101] By directing many light pulses, such as Figure 5B As depicted, LiDAR system 500 scans the external environment (e.g., by directing light pulses 502, 522, 526, 530 along optical paths 504, 524, 528, 532, respectively). Figure 5C As depicted, the LiDAR system 500 receives return light pulses 508, 542, 548 (corresponding to transmitted light pulses 502, 522, 530, respectively). The return light pulses 508, 542, and 548 are formed by scattering or reflecting the transmitted light pulses by one of the objects 506 and 514. The return light pulses 508, 542, and 548 may return to the LiDAR system 500 along optical paths 510, 544, and 546, respectively. Based on the direction of the transmitted light pulses (as determined by the LiDAR system 500) and the calculated distance from the LiDAR system 500 to the portion of the object that scattered or reflected the light pulses (e.g., the portion of objects 506 and 514), the external environment within the detectable range (e.g., the field of view between the paths 504 and 532, inclusive) may be accurately mapped or mapped (e.g., by generating a 3D point cloud or image).

[0102] If a corresponding light pulse is not received for a particular emitted light pulse, the LiDAR system 500 may determine that there is no object within the detectable range of the LiDAR system 500 (e.g., the object is outside the maximum scanning distance of the LiDAR system 500). Figure 5B In the example, light pulse 526 may not have a corresponding return light pulse (e.g. Figure 5C 528 within the detectable range of the LiDAR system 500).

[0103] exist Figure 5B , light pulses 502, 522, 526, and 530 may be emitted in any order, serially, in parallel, or based on other timings relative to each other. Additionally, although Figure 5B The emitted light pulses are depicted as being directed in one dimension or plane (e.g., the plane of the paper), but the LiDAR system 500 may also direct the emitted light pulses along other dimensions or planes. For example, the LiDAR system 500 may also direct the emitted light pulses in a direction perpendicular to the plane of the paper. Figure 5B The emitted light pulses are guided in the dimension or plane of the dimension or plane shown, thereby forming a 2-dimensional transmission of the light pulses. This 2-dimensional transmission of the light pulses can be performed point by point, line by line, once or in other ways. That is, the LiDAR system 500 can be configured to perform point scanning, line scanning, single scanning without scanning, or a combination thereof. A point cloud or image (e.g., a single horizontal line) from a one-dimensional transmission of a light pulse can generate 2-dimensional data (e.g., (1) data from the horizontal transmission direction and (2) the range or distance to the object). Similarly, a point cloud or image from a 2-dimensional transmission of a light pulse can generate 3-dimensional data (e.g., (1) data from the horizontal transmission direction, (2) data from the vertical transmission direction, and (3) the range or distance to the object). Typically, a LiDAR system that performs n-dimensional transmission of light pulses generates (n+1)-dimensional data. This is because the LiDAR system can measure the depth of an object or the distance to an object, which provides an additional data dimension. Therefore, a 2D scan performed by a LiDAR system can generate a 3D point cloud that is used to map the external environment of the LiDAR system.

[0104] The density of a point cloud refers to the number of measurements (data points) per region performed by a LiDAR system. The point cloud density is related to the LiDAR scan resolution. Typically, at least for regions of interest (ROIs), a greater point cloud density is desired, and therefore a higher resolution is required. The point density in a point cloud or image generated by a LiDAR system is equal to the number of pulses divided by the field of view. In some embodiments, the field of view may be fixed. Therefore, in order to increase the density of points generated by a set of transmit-receive optical devices (or transceiver optical devices), the LiDAR system may need to generate pulses more frequently. In other words, the light source in the LiDAR system may have a higher pulse repetition rate (PRR). On the other hand, by generating and transmitting pulses more frequently, the farthest distance that a LiDAR system can detect may be limited. For example, if a return signal from a distant object is received after the system transmits the next pulse, the return signal may be detected in a different order from the order in which the corresponding signal was transmitted, resulting in ambiguity if the system cannot correctly associate the return signal with the transmitted signal.

[0105] To illustrate, consider an exemplary LiDAR system that can emit laser pulses with a pulse repetition rate between 500kHz and 1MHz. Based on the time it takes for the pulses to return to the LiDAR system, and to avoid confusion of return pulses from consecutive pulses in typical LiDAR designs, the maximum distance that the LiDAR system can detect can be 300 meters and 150 meters for 500kHz and 1MHz, respectively. The point density of a LiDAR system with a repetition rate of 500kHz is half that of 1MHz. Therefore, this example shows that if the system cannot correctly associate return signals that arrive out of order, increasing the repetition rate from 500kHz to 1MHz (and thus increasing the point density of the system) may reduce the detection range of the system. Various techniques are used to mitigate the tradeoff between higher PRR and limited detection range. For example, multiple wavelengths can be used to detect objects within different ranges. Optical and / or signal processing techniques (e.g., pulse coding techniques) are also used to associate between the emitted light signal and the returned light signal.

[0106] The various systems, devices, and methods described herein may be implemented using digital circuits or using one or more computers utilizing well-known computer processors, memory units, storage devices, computer software, and other components. Typically, a computer includes a processor for executing instructions and one or more memories for storing instructions and data. A computer may also include or be coupled to one or more mass storage devices, such as one or more magnetic disks, internal hard disks and removable disks, magneto-optical disks, optical disks, and the like.

[0107] The various systems, devices, and methods described herein can be implemented using computers operating in a client-server relationship. Typically, in such a system, a client computer is located remotely from a server computer and interacts via a network. The client-server relationship can be defined and controlled by computer programs running on the respective client and server computers. Examples of client computers may include desktop computers, workstations, portable computers, cellular smartphones, tablet computers, or other types of computing devices.

[0108] The various systems, apparatuses, and methods described herein may be implemented using a computer program product tangibly embodied in an information carrier, such as in a non-transitory machine-readable storage device, for execution by a programmable processor; and the method processes and steps described herein (including Figure 1 to Figure 15) can be implemented using one or more computer programs executable by such a processor. A computer program is a set of computer program instructions that can be used directly or indirectly in a computer to perform a specific activity or produce a specific result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0109] Figure 6 A high-level block diagram of an exemplary apparatus that can be used to implement the systems, apparatus, and methods described herein is illustrated. Apparatus 600 includes a processor 610 that is operably coupled to a persistent storage device 620 and a main memory device 630. Processor 610 controls the overall operation of apparatus 600 by executing computer program instructions that define these operations. The computer program instructions may be stored in persistent storage device 620 or other computer-readable medium and loaded into main memory device 630 when execution of the computer program instructions is desired. For example, processor 610 may be used to implement one or more components and systems described herein, such as control circuit system 350 ( Figure 3 As shown), vehicle perception and planning system 220 ( Figure 2 shown) and the vehicle control system 280 ( Figure 2 Therefore, Figure 1 to Figure 1 At least some of the method steps in the embodiment of the present invention may be defined by computer program instructions stored in the main memory device 630 and / or the persistent storage device 620, and performed by the processor 610 executing the computer program instructions. For example, the computer program instructions may be implemented as computer executable codes programmed by a person skilled in the art to perform the method described in conjunction with the present invention. Figure 1 to Figure 1 5 . Accordingly, by executing computer program instructions, the processor 610 performs the algorithm defined by the method steps of these aforementioned figures. The device 600 also includes one or more network interfaces 680 for communicating with other devices via a network. The device 600 may also include one or more input / output devices 690 that enable a user to interact with the device 600 (e.g., a display, keyboard, mouse, speaker, buttons, etc.).

[0110] The processor 610 may include general and special purpose microprocessors and may be the sole processor of the device 600 or one of multiple processors. The processor 610 may include one or more central processing units (CPUs) and one or more graphics processing units (GPUs), which may, for example, work separately from the one or more CPUs and / or perform multitasking with the one or more CPUs to accelerate processing, for example, for various image processing applications described herein. The processor 610, the persistent storage device 620, and / or the main memory device 630 may include one or more application specific integrated circuits (ASICs) and / or one or more field programmable gate arrays (FPGAs), or may be supplemented by one or more ASICs and / or one or more FPGAs, or may be incorporated into one or more ASICs and / or one or more FPGAs.

[0111] The persistent storage device 620 and the main memory device 630 each include a tangible, non-transitory computer-readable storage medium. The persistent storage device 620 and the main memory device 630 may each include a high-speed random access memory, such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a double data rate synchronous dynamic random access memory (DDR RAM), or other random access solid-state memory devices, and may include non-volatile memory, for example, one or more disk storage devices, such as internal hard disks and removable disks, magneto-optical disk storage devices, optical disk storage devices, flash memory devices, semiconductor storage devices (such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM)), compact disk read-only memory (CD-ROM), digital versatile disk read-only memory (DVD-ROM) disks, or other non-volatile solid-state storage devices.

[0112] Input / output devices 690 may include peripheral devices such as printers, scanners, display screens, etc. For example, input / output devices 690 may include a display device (such as a cathode ray tube (CRT), plasma or liquid crystal display (LCD) monitor, keyboard) for displaying information to a user, and a pointing device (such as a mouse or trackball) that a user may use to provide input to apparatus 600.

[0113] Any or all of the functionality of the systems and devices discussed herein may be performed by the processor 610, and / or incorporated into a device or system such as the LiDAR system 300. Additionally, the LiDAR system 300 and / or device 600 may utilize one or more neural networks or other deep learning techniques performed by the processor 610 or other systems or devices discussed herein.

[0114] Those skilled in the art will recognize that the actual computer or computer system implementation may have other structures and may also include other components, and Figure 6 is a high-level representation of some of the components of such a computer for purposes of illustration.

[0115] Fig. 7A An exemplary wafer 700 including a metalens according to one embodiment is shown. Wafer 700 may include a thin, flat sheet or disk of dielectric and / or semiconductor material. Wafer 700 includes a substrate for fabricating a subwavelength structure that forms a metalens or other optical device based on a metasurface. Wafer 700 may be a glass wafer, a silicon-based wafer, a gallium arsenide (GaAs)-based wafer, a silicon carbide (SiC)-based wafer, or a wafer based on any other dielectric and / or semiconductor material. The diameter of wafer 700 may be any size (e.g., 300 mm or 12 inches). Wafer 700 may be flat and thin (e.g., having a thickness in the order of microns or millimeters). Wafer 700 may also include various subwavelength structures formed in or on a substrate. These subwavelength structures may form a two-dimensional (2D) or three-dimensional (3D) pattern. In some embodiments, wafer 700 may have a repeating pattern of subwavelength structures, each pattern forming an optical device based on a metasurface (e.g., a metalens, a super reflector, etc.). In some embodiments, wafer 700 may include different patterns of sub-wavelength structures, such as FIG. 7B to FIG. 7D Those shown.

[0116] FIG. 7B to FIG. 7D Examples of subwavelength structures forming different patterns 702, 704, or 706 for metasurface-based optical devices according to some embodiments are illustrated. Subwavelength structures refer to patterns or features whose size is smaller than the wavelength of the light or electromagnetic wave with which they interact. For example, the size of these subwavelength structures is nanometer-scale, which is usually much smaller than the wavelength of light (such as visible light or infrared light). When light encounters an object or structure much larger than its wavelength, it behaves in the way predicted by the laws of classical optics. However, when light interacts with structures on the order of its wavelength or smaller, it behaves differently due to diffraction, interference, and other wave phenomena. Subwavelength structures can be configured using a variety of materials and manufacturing techniques to achieve specific optical effects. These effects can include bending, focusing, collimation, transmission, filtering, beam homogenization, and manipulating light in ways that are possible or impossible with conventional optical lenses and macroscopic structures. Metamaterials are typical examples of subwavelength structures and are often used to make metasurface-based optical devices, such as superlenses. These metamaterials are designed to have properties derived from the arrangement of their subwavelength components, such as nanoscale metal or dielectric elements. By manipulating the arrangement of these elements, the behavior of light can be controlled at scales smaller than its wavelength, enabling the creation of metasurface-based optical systems such as superlenses.

[0117] FIG. 7B to FIG. 7D Several examples of subwavelength structures (sometimes also referred to as nanostructures) for use in metasurface-based optical devices (e.g., metalenses) are illustrated. These nanostructures can be nanoslits, nanorods, nanodisks, etc. The nanostructures are specifically configured to resonate with incident light of a specific wavelength and angle. As described in more detail below, metasurface-based optical devices (e.g., metalenses) can achieve phase modulation of incident light. The resonant interaction between the subwavelength structure and the incident light results in the manipulation of the phase of the light wave. By controlling the phase, metasurface-based optical devices (e.g., metalenses) can redirect or focus light so that any desired wavefront (e.g., a wavefront of converging light or any complex wavefront) can be generated. Also as described in more detail below, metasurface-based optical devices (e.g., metalenses) can be configured to have different resonant modes for different wavelengths. This property can reduce or eliminate chromatic aberration, which is a common problem in traditional optical lenses, where different colors of light are focused at slightly different points. A metalense with a suitable resonant subwavelength structure can focus different wavelengths to a common focal point, thereby reducing or eliminating chromatic aberration. In addition, metasurface-based optical devices (e.g., metalenses) can be configured with subwavelength openings or slits. The resonant properties of subwavelength openings or slits in metasurface-based optical devices (e.g., metalenses) allow them to effectively transmit or block specific wavelengths of light, thereby achieving optical effects such as filtering, polarization control, and sensing. Specific applications of metasurface-based optical devices in LiDAR systems are described in more detail below.

[0118] Figure 7B A pattern 702 having subwavelength structures is shown, which can be used in a metasurface-based optical device. These structures can be, for example, nanoscale features having rectangular or any other desired shape. The features of these structures can have the same or different sizes. In one example, the nanoscale features can form one or more lines or arrays, such as Figure 7B The lines may or may not be straight lines, depending on the specific optical effect desired. The nanoscale features may form a periodic or non-periodic pattern along one or two directions. The nanoscale features in a line may or may not have the same or similar dimensions. For example, for beam homogenization described in detail below, the nanoscale features of the subwavelength structure may form a line and may have dimensions that reshape the light to fit the shape of a sensing element of a detector-like structure. In one example, Figure 7B The metasurface-based optical device shown in FIG. 4 can be a lead telluride (PbTe)-based superlens operating in the mid-infrared wavelength range (e.g., approximately 2.5 μm to 25 μm).

[0119] Figure 7C Another pattern 704 with sub-wavelength structures for implementing metasurface-based optical devices is shown. These structures in pattern 704 have pillars that are smaller than the wavelength of the incident light. The pillars in pattern 704 include cylindrical vertical structural elements. Figure 7C As shown, the pillars in pattern 704 can have the same or different diameters (e.g., 50nm to 70nm). They can also form an array, a matrix, or any other shape or pattern, depending on the specific optical effect desired. In one example, Figure 7C The metasurface-based optical device shown can be a silicon-based metalens operating in the near-infrared range (e.g., 700 nm to 2.5 μm).

[0120] Fig.7D Another pattern 706 with sub-wavelength structures for implementing metasurface-based optics is illustrated. These structures form a concentric ring pattern that can be used to implement the optical effects of a traditional spherical lens (or any other lens with curvature). Some of these lenses are shown in other figures of the present disclosure (e.g., collimating lenses, focusing lenses, beam homogenizers, etc.). For example, Fig.7D The metasurface-based optical device shown can be a silicon-based metalens operating in the near-infrared wavelength range (e.g., 700 nm to 2.5 μm).

[0121] The metasurface-based optical devices disclosed herein may include subwavelength structures having dielectric-based structures at the nanometer or micrometer scale. The subwavelength structures may include single-layer or multi-layer nanostructures. Multiple layers may be stacked, overlapped, disposed on different wafers, or bonded together by wafer bonding. The thickness of the metasurface-based optical device may be, for example, less than 1 micrometer or at the nanometer scale. It should be understood that FIG. 7C to FIG. 7D Only a few examples of sub-wavelength structures and patterns that can be used to implement metasurface-based optical devices (such as metalenses) are illustrated. Other structures and patterns can also be used to implement metasurface-based optics, depending on the requirements of the optical effect. Such metasurface-based optical devices can be used for visible light or other wavelengths of light. For example, the metasurface-based optical device can be a single crystal silicon-based metalens, a titanium monoxide (TiO)-based metalens, or a gallium nitride (GaN)-based metalens. These metalens can operate in the visible light wavelength range. As another example, the metalens can be a hafnium oxide (HfO)-based metalens that operates in the ultraviolet light wavelength range.

[0122] Fig. 7EA two-layer metasurface-based optical device is shown including a first layer 712 and a second layer 714. As described in more detail below, different layers in a multi-layer metasurface-based optical device (e.g., a metalens) can include nanostructures configured to perform similar or different functions. For example, one layer can be configured to perform optical collimation, while another layer can be configured to perform bandpass filtering. As another example, both layers can be configured to perform beam collimation, with one layer performing coarse collimation and the other layer performing fine tuning to obtain parallel light rays with good collimation quality. Although Fig. 7E Only two layers are illustrated, but it will be appreciated that metasurface-based optics may be configured with any number of layers.

[0123] Figure 8 is a diagram illustrating the use of artificial phase shifts from a metasurface of a metalens to simulate a spherical wavefront for beam focusing, according to some embodiments. Figure 8 , the superlens 804 has a subwavelength structure formed on the surface of the wafer substrate. The subwavelength structure can form a nanoscale pattern as described above. Light 802 is guided to the superlens 804. The superlens 804 is thin and receives the light 802 at one surface (e.g., the left surface that does not have the subwavelength structure). When the light 802 passes through a specific position of the superlens 804, the subwavelength structure can change the amount of phase it adds to the light 802. Figure 8 As shown, the phase of the light wave is modulated at the edge position of the metalens 804 and the center position of the metalens 804. The phase is modulated by the average refractive index change caused by a specific pattern, which includes a subwavelength structure at a specific position of the metalens 804. As described above, the metalens can have a specially designed nanoscale pattern including a subwavelength structure. At different positions of the metalens 804, the structure can be different, and the effective refractive index at a specific position can be different. Therefore, the phase modulation at different positions of the metalens 804 can be different.

[0124] In other examples, resonance effects can be used to enhance phase modulation. The resonance effects of the subwavelength structures of a metal lens can enhance the ability to manipulate and control light. The resonance effect may arise from the interaction between the incident light and specific nanostructures on the metal surface. The nanostructures can be configured to exhibit a specific response to incident light of a specific wavelength or angle, allowing the metalens to focus, bend, or otherwise manipulate light as desired. Figure 8As shown, when light 802 reaches different positions of the metalens 804, the phase of the light 802 at these positions is modulated, resulting in a change in the wavefront. For example, if the metalens 804 is specifically configured as a focusing lens for converging light, the nanostructure can modulate the light 802 so that the wavefront at the edge position of the metalens 804 propagates slightly faster than the wavefront at the center position of the metalens 804 (for example, the propagation time t2 is less than the propagation time t1). In this way, the wavefront of the light 802 passing through the metalens 804 has a curved shape. The nanostructure can also be further configured so that the curvature of the wavefront is appropriately designed to converge the light 802 to the desired convergence point 808. In contrast, a conventional glass-based focusing lens has a thicker center and a thinner edge. Therefore, when light passes through a conventional glass focusing lens, the wavefront of the light propagates slightly faster at the edge than at the center, thereby converging the light to the focus of the lens. Therefore, the metalens 804 can perform the same converging function as a conventional glass-based lens, with higher precision and better quality.

[0125] Fig. 9 Included are diagrams illustrating lenses designed to remove various optical aberrations of traditional glass-based optical lenses and achieve better focusing results according to some embodiments. The top four diagrams illustrate optical aberrations caused by traditional glass-based lenses. In one example, spherical aberration can be caused by traditional optical lens 902. Fig. 9 As shown, when light passes through lens 902 (or a curved mirror), the light does not converge to a single point, resulting in a blurred or distorted image. This is primarily because the shape of lens 902 is spherical, and light passing through the edge of lens 902 experiences a different focus than light passing through the center. For example, the wavefront of light passing through lens 902 may have an aspherical wavefront, such as Fig. 9 shown.

[0126] Optical coma is another optical aberration caused by conventional optical lenses 904. Fig. 9 In the example above, when light rays pass through a conventional glass-based lens 904, the light rays do not converge to a single point along the central axis (or desired axis) of the lens 904, resulting in distortion and comet-like shapes in the image. Because the lens 904 is not focusing, optical coma occurs when off-axis light rays are directed to a single point, resulting in an image that is elongated in one direction. Fig. 9 Comae becomes more pronounced when entering at the angles shown and focusing at different points on a line, causing an asymmetrical blur in the image.

[0127] Field curvature is another optical aberration caused by conventional optical lenses 906. Fig. 9In , when light passes through a conventional glass-based lens 906, the focal plane is not flat, but rather follows a curved surface. Therefore, when viewed through the lens 906, objects appear to be out of focus or curved. When the lens 906 has field curvature, different points in the field of view are focused at different distances from the lens 906. Therefore, when using a lens 906 with field curvature, the center may be in focus while the edges may be blurred, or vice versa. Fig. 9 As shown, field curvature aberrations can also be worse when the incident light rays enter at an angle.

[0128] Astigmatism is another optical aberration caused by conventional optical lenses 908. Fig. 9 In the optical lens 908, as light passes through the lens 908, the light does not converge to a single point. Instead, the light is focused along two or more different lines, axes, or focal planes, resulting in a blurred or distorted image. Astigmatism is caused by the mismatch in curvature of the different meridians (lines passing through the center of the lens) of the optical lens 908. Essentially, the lens 908 has different focal lengths in two perpendicular directions. This causes the image of a point source to appear stretched along one direction and compressed along the perpendicular direction.

[0129] Due to optical manufacturing limitations of conventional glass-based optical lenses, it may not be feasible or practical to reduce or eliminate the aberrations described above with respect to conventional lenses 902, 904, 906, and 908. Metasurface-based optics (e.g., metalenses) include sub-wavelength structures that can be customized or precisely configured to achieve a desired optical effect. Fig. 9 The four figures at the bottom of the middle illustrate the use of metalenses to reduce or eliminate the various optical aberrations described above. In one example, a metalens 912 can be used to replace a conventional optical lens 902 as a focusing lens without spherical aberration. The nanostructure of the metalens 912 can be configured so that the phase modulation of incident light at different locations of the metalens 912 produces an aberration-free spherical wavefront. As a result, light rays passing through the metalens 912 propagate at slightly different speeds to converge on a desired center point.

[0130] Similarly, metalenses 914, 916, and 918 can be used to replace conventional optical lenses 904, 906, and 908, respectively, to reduce and eliminate optical coma, field curvature, and astigmatism, respectively. Fig. 9As shown, even when incident light rays enter at an angle to metalens 914, the light rays can be focused on a single point because the nanostructures of metalens 914 are precisely configured at different locations of metalens 914. Therefore, metalens 914 can produce a precise wavefront to obtain coma-free convergence. Similarly, the nanostructures of metalens 916 can be precisely configured so that light rays entering at different incident angles can be focused on a single focal plane, rather than on different focal planes, thereby eliminating field curvature aberrations. Astigmatism aberrations can be eliminated by using metalens 918 with a precisely configured subwavelength structure so that different light rays are focused on the same focal plane, rather than on two or more different lines, axes, or focal planes, thereby eliminating any blurred or distorted images.

[0131] It should be understood that the metalenses disclosed herein may be configured with any subwavelength structure for reducing optical artifacts associated with non-metasurface based optics, such as conventional glass-based optical lenses, mirrors, prisms, etc. Optical artifacts may include spherical aberration, chromatic aberration, coma, astigmatism, field curvature, distortion, or a combination thereof.

[0132] Figure 7 Figure 8 and Fig. 9 Several exemplary metasurface-based optical devices (e.g., metalenses) that can be used in various imaging systems (such as LiDAR systems) are illustrated. It should also be understood that various changes can be implemented or configured for different applications to achieve different optical effects. For example, in LiDAR system applications, because the metasurface-based optical devices are sensitive to the operating wavelength, the subwavelength structure can be configured according to the operating wavelength of the LiDAR system. Therefore, the metal nanostructure used in the LiDAR with a wavelength of 795nm can be different (e.g., different pattern, size, shape, etc.) from the metalenses used in the LiDAR with a wavelength of 1550nm. In some embodiments, the LiDAR system has a wavelength between 750nm and 2000nm, and the metasurface-based optical device with the corresponding nanostructure can be configured to obtain the desired optical effect (e.g., collimation, divergence, convergence, filtering, etc.). As described above, the nanostructure has a subwavelength size feature. For the metasurface-based optical devices disclosed in the present disclosure, the subwavelength structures can have characteristic dimensions (e.g., width, height, length, diameter, etc.) between 1 / 20-9 / 10 of the operating wavelength of a particular LiDAR system. Thus, if the LiDAR system operates at a wavelength of 1550 nm, the characteristic dimensions of the subwavelength structures can be from about 70 nm to 1395 nm. If the operating wavelength of the LiDAR system changes, the dimensions of the subwavelength structures may change.

[0133] As described above, for the metasurface-based optical devices disclosed in the present disclosure, the subwavelength structures can form a 2-dimensional or 3-dimensional pattern that is configured to modularize light to have different optical phase changes at different locations of the subwavelength structure. Therefore, the light formed by the subwavelength structure is shaped and / or guided according to at least one optical requirement. These optical requirements relate to the direction, reflection, deflection, refraction, diffraction, focusing, collimation, separation, merging, convergence, steering, scattering, dispersion or polarization of light. Some examples of light redirection, focusing, collimation, filtering and steering using metasurface-based optical devices are shown and described in more detail below.

[0134] Fig. 10A 1 is a perspective view of an exemplary transceiver 1000 for a LiDAR system including one or more transmitter metalenses according to some embodiments. The transceiver 1000 can be used to implement the LiDAR system 300, any other LiDAR system, or a hybrid LiDAR imaging system (e.g., a hybrid LiDAR and camera imaging system). In some embodiments, the transceiver 1000 includes a transceiver housing 1002, a transmitter fiber array 1010, a transmitter metalens 1012, a collection lens 1022, a receiver fiber array 1020, a plurality of detectors (e.g., Fig. 12B and Fig. 12C 1002 ) and reference channel 1032. Transceiver housing 1002 may be made of metal, plastic, glass, composite materials, and / or any other desired material. Transceiver housing 1002 provides at least a partial housing for transmitter fiber array 1010, receiver fiber array 1020, collection lens 1022, and transmitter metalens 1012. Transceiver housing 1002 may be configured such that various components are positioned therein for proper operation. For example, Fig. 10A As shown, in one embodiment, the transmitter fiber array 1010, the collection lens 1022 and the transmitter metalens 1012 are arranged along the longitudinal direction of the transceiver housing 1002 toward its front end. The receiver fiber array 1020 and the detector (such as Fig. 12B and Fig. 12C At least a portion of the optical fiber 1026A-1026D (shown in FIG. 1 ) is disposed toward the rear end of the transceiver housing 1002. In addition, the transceiver housing 1002 is configured to have an appropriate size so that the transceiver 1000 can operate appropriately to achieve its optical function. For example, the distance between the collection lens 1022 and the receiver optical fiber array 1020 is configured to have a predetermined value so that each return light 1026A-1026D (for illustration, Fig. 10A Only the return light 1026A and 1026D are shown) can be appropriately directed from the collection lens 1022 to the corresponding receiver fibers of the receiver fiber array 1020. For example, in Fig. 10A, return light 1026A is focused by the collection lens 1022 onto the receiver fiber 1024A at the bottom of the receiver fiber array 1020. And return light 1026D is focused by the collection lens 1022 onto the receiver fiber 1024D at the top of the receiver fiber array 1020. It should be understood that the other return lights 1026B and 1026C can be similarly focused by the collection lens 1022 onto the other corresponding receiver channels 1024B and 1024C, respectively.

[0135] Still reference Fig. 10A , the transceiver 1000 includes a plurality of transmitter channels configured to transmit a plurality of transmit light beams 1014A-1014D (collectively referred to as 1014) to the FOV. In one embodiment, there are four such transmitter channels, using a transmitter fiber array 1010 configured to transmit light beams 1014A-1014D. In some embodiments, the transmitter channels of the fiber array 1010 are fiber-based transmitter channels. For example, the transmitter fiber array 1010 includes four transmitter fibers, each for one transmitter channel. The transmitter channel is configured to transmit an optical signal from, for example, a light source to other optical components (e.g., a lens) or the FOV. In one embodiment, the transmitter channel includes a transmitter fiber. Although four transmitter fibers are used for illustration herein, it should be understood that the transmitter fiber array 1010 may include any number of optical fibers that can be used for any number of transmitter channels. In some embodiments, the transmitter fiber array 1010 is optically coupled to a light source and an optical beam splitter (not shown). The light source and optical beam splitter can be integrated with the transceiver 1000, or can be independent components of the LiDAR system. In some embodiments, the light source is configured to generate a single light beam. The optical beam splitter receives the single light beam and forms multiple transmitted light beams. The multiple transmitted light beams are then directed to the transmitter fiber array 1010. In some embodiments, the light source can directly generate multiple light beams for multiple transmitted light beams.

[0136] In some embodiments, one or more transmitter fibers in the fiber array 1010 include one or more single-mode fibers. A single-mode fiber includes a core with a very small diameter (e.g., a few microns) that allows only one transverse mode of light at the design wavelength to pass through. Therefore, the output beam quality can be close to the diffraction limit (e.g., M 2 ≈1).

[0137] like Fig. 10A As shown, in some embodiments, the light beam from the transmitter fiber array 1010 is directed to one or more transmitter optical devices (e.g., a transmitter metalens 1012). The one or more transmitter optical devices can be used to direct the light beam to a steering mechanism (e.g., Figure 3The light beam is further processed before being directed to the steering mechanism 340 shown. In one example, the transmitter optical device includes one or more optical devices based on transmitter metasurfaces. Each of such optical devices based on transmitter metasurfaces can have a subwavelength structure as described above. Therefore, these metasurface-based optical devices can be configured to perform one or more of the shifting, shaping, separation and convergence of one or more transmitted light beams. For example, the nanostructures of the metasurface-based optical device can be configured to have specific shapes and sizes at specific locations, so that incident light beams at different locations are manipulated to change their phases to obtain any desired wavefront, thereby effectively shifting, shaping, separating and converging the transmitted light beams.

[0138] Fig. 10A and Fig. 10B An example of an emitter metasurface-based optical device is shown in . The metalens 1012 is disposed downstream of the emitter fiber array 1010 in the transmission light path, but upstream of any steering mechanism. In this embodiment, a single metalens 1012 is used to replace one or more conventional glass-based collimating lenses or lens groups. The emitter fiber array 1010 has multiple optical fibers that are capable of emitting multiple transmitted light beams at desired angular intervals. As described above, if each emitter channel has its own conventional collimating lens and / or other optical components, the size of the emitter will increase significantly, making it difficult to provide a compact LiDAR system. In addition, the emitter may include a greater number of optical components, making the emitter less robust or reliable. Fig. 10A and Fig. 10B An embodiment is illustrated in which multiple transmitter channels provided by a transmitter fiber array 1010 share a single metalens 1012 configured to perform beam collimation. The metalens 1012 is positioned to be optically coupled to the fiber array 1010 to receive transmitted beams 1014A-1014D (collectively 1014).

[0139] Continuing with the above example, the transmitter fiber array 1010 includes four transmitter fibers for four transmitter channels. Each of the four transmitter fibers is disposed in a slot that is positioned at a preconfigured spacing from an adjacent slot. Thus, each of the four transmitter fibers in the array 1010 is also positioned at a preconfigured spacing from an adjacent transmitter fiber. The four transmitter fibers, or at least their ends, are parallel or substantially parallel to each other ( Fig. 12BAn optical fiber array 1220 for receiving return light is shown, and the transmitter optical fiber array 1010 can be configured to be substantially the same or similar). In some embodiments, the ends of the four transmitter optical fibers are polished to be flat. Each transmitter optical fiber in the optical fiber array 1010 is used as at least a portion of a transmitter channel for emitting a transmitted light beam 1014A, 1014B, 1014C, or 1014D. In some embodiments, the transmitted light beams 1014A-1014D are transmitted to the transmitter metalens 1012 simultaneously. As the transmitted light beams 1014A-1014D propagate toward the metalens 1012 in free space, their spatial cross-sectional areas expand. As a result, the transmitted light beams 1014A-1014D begin to diverge and overlap each other spatially, as shown in FIG. Fig. 10B Thus, when they reach the transmitter metalens 1012, the transmitted light beams 1014A-1014D overlap spatially.

[0140] like Fig. 10B As shown, the emitter metalens 1012 receives the emission light beams 1014A-1014D. The emitter metalens 1012 is configured to perform light collimation so that the transmitted light beams 1014A-1014D from the optical fiber array 1010 are collimated. This can be achieved by configuring the nanostructure of the emitter metalens 1012 so that specific positions of the metalens 1012 have the same or different structures for collimating the light beams 1014A-1014D incident on the metalens 1012 at different angles. For example, at a specific position of the metalens 1012, the subwavelength structure of the metalens 1012 can be designed so that the phase modulation of the light from the same transmitted light beam makes the wavefronts of the light equal. Therefore, for the same transmitted light beam, the light rays of the same transmitted light beam (e.g., 1014A, 1014B, 1014C, or 1014D) coming out of the emitter metalens 1012 are substantially parallel (or collimated), as shown in FIG. Fig. 10B Different collimated beams have different angles, so adjacent collimated beams have an angular spacing. It should be understood that although Fig. 10B Different collimated light beams are illustrated as overlapping each other just out of the transmitter metalens 1012, but the different collimated light beams become spatially separated as they propagate to a distance. The angular spacing between adjacent light beams is determined by the properties of the transmitter fiber array 1010 (e.g., the spacing between the fibers in the fiber array) and / or the properties of the metalens 1012 (e.g., the effective focusing lens, as if the metalens 1012 were replaced by a conventional glass-based collimating lens to obtain the same angular spacing). In one example, the angular spacing is equal to the spacing of the fibers divided by the effective focal length of the transmitter metalens 1012.

[0141] Continue to refer Fig. 10B, the collimated light beam exiting the metalens 1012 can have a much smaller divergence than the light beam before collimation. The emitter metalens 1012 thus enables the emitted light beams 1014A-1014D to reach a greater distance with concentrated energy. Compared to conventional glass-based collimating lenses, the emitter metalens 1012 can be smaller and thinner in size, and thus more compact overall, while providing improved optical performance (e.g., light rays in the same light beam are more accurately collimated) by reducing or eliminating any of the optical aberrations described above.

[0142] As described above, transceiver 1000 includes a transmitter fiber array 1010 and one or more transmitter metasurface-based optical devices, such as a transmitter metalens 1012. Fig. 10A In the illustrated embodiment, the emitter metalens 1012 is at least partially located in an opening (e.g., slot, hole) of the collection lens 1022. The opening of the collection lens 1022 is located in the center or middle portion of the collection lens 1022 so that the transmitted light beam is directed to the FOV from the center of the optical aperture of the collection lens 1022. Thus, the collection lens 1022 is appropriately positioned to have an optimal optical aperture for collecting the return light 1026A-1026D.

[0143] Fig.11 is a block diagram of another example, in which the positions of the transmitter fiber array 1010 and the transmitter metalens 1012 are similar to Fig. 10B The positions shown are different. Fig.11 In the embodiment, unlike the collection lens 1022, the collection lens 1122 does not require an opening. The collection lens 1122 can be Fig. 10A The collection lens 1022 shown is substantially the same or similar except that there is no opening such as a slot or hole in the middle of its optical aperture. The transmitter fiber array 1010 and the transmitter metalens 1012 can be located on one side of the collection lens 1122, with a beam shifting system to move the transmitted beam to a desired position. The transmitter fiber array 1010, the transmitter metalens 102, and the beam shifting system including one or more optical devices can be used in the transceiver 1000 of the LiDAR system. Fig.11 As shown, similar to that described above, the transmitter fiber array 1010 provides a plurality of transmit light beams 1014, which are collimated by the transmitter metalens 1112. The transmitter metalens 1112 can be substantially the same as or similar to the metalens 1012, and therefore, the description is not repeated.

[0144] In some embodiments, Fig.11 The beam moving system shown uses a periscope device 1102. Fig.11, the transmitter fiber array 1010 is optically coupled to a metalens 1112, which is optically coupled to a periscope device 1102 for directing a collimated transmitted light beam 1114. In one embodiment, the collection lens 1122 may have a flat top and / or bottom surface, which makes it easier to assemble the collection lens 1122 into the transceiver housing. Fig.11 In the embodiment shown, Fig. 10A Unlike the embodiments in the embodiment, the emitter metalens 1112 is disposed on the side (e.g., at the bottom) of the collection lens 1122. In order to increase or maximize the optical collection aperture of the collection lens 1122, the periscope device 1102 can move the collimated transmission light beam 1114 so that it is located within the optical receiving aperture of the collection lens 1122. The periscope device 1102 may include, for example, a system of glass-based prisms, lenses, and / or mirrors to redirect the light beam through the tube. In one example, the periscope prism 1102 includes two parallel-arranged reflective surfaces 1104 and 1106 that change the direction of the light beam along the vertical tube. The reflective surface 1104 (similar to the reflective surface 1106) can be part of a mirror and / or a prism. Using the reflective surface 1104 of the periscope prism 1102, the collimated transmission light beam 1114 is redirected to below the periscope tube at an angle of approximately 90 degrees. The redirected light beam is redirected again by the reflective surface 1106 to make another approximately 90 degree turn and is then transmitted outward to the FOV as a redirected transmitted light beam 1124. The periscope device 1102 is configured to have appropriate dimensions so that the redirected transmitted light beam 1124 is positioned around the center of the optical aperture of the collection lens 1122, which allows the return light formed based on the redirected transmitted light beam 1124 to be properly collected by the collection lens 1122.

[0145] In another embodiment, one or more glass-based optical devices of the periscope device 1102 can be replaced with optical devices based on metasurfaces. For example, the reflective surfaces 1104 and 1106 can be implemented using a metamaterial including a wafer substrate and a subwavelength structure. The subwavelength structure is configured so that the phase, amplitude, and polarization of the incident light can be controlled in a desired manner. The reflective surface implemented by this metamaterial can also be called a super reflector. Due to the subwavelength structure, the super reflector can reflect light similar to a traditional reflector. They can also manipulate light in unconventional ways that traditional mirrors cannot do. For example, by using a super reflector and / or a super lens, the outgoing light and the incident light may not follow the traditional laws of reflection. Instead, the outgoing light can have any desired direction, phase, amplitude, and polarization. In this way, by using a super lens and / or a super reflector to implement the reflective surfaces 1104 and / or 1106, the periscope device 1102 can be more flexibly configured to move the collimated transmission beam 1114 to the center of the optical aperture of the collection lens 1122. The orientation and position of one or more metasurface-based optical devices in the periscope device 1102 include but are not limited to Fig.11 Because metasurface-based optics implementing reflective surfaces 1104 and / or 1106 can manipulate light in unconventional ways, they do not require Fig.11 , but may be positioned in other ways to make the system more compact or to meet any desired system configuration requirements.

[0146] Return to reference Fig. 10A , the transceiver 1000 can provide a reference signal 1032, which can be a signal derived or obtained directly from the transmitter fiber array 1010. As described above, the LiDAR system can measure the distance of an object based on the time of flight method. The reference signal 1032 can be used as a timestamp to set the starting point of the time of flight measurement. Using this timestamp and the time when the corresponding return light is received, the flight time can be calculated, and then the distance can be calculated.

[0147] Fig. 12A is a perspective view of an exemplary transceiver 1200 for a LiDAR system including one or more receiver metalenses according to some embodiments. The transceiver 1200 may be used with Fig. 10A The transceiver 1000 shown is substantially the same, except that one or more of the receive optics may be implemented using metasurface-based optics to receive and detect the return light 1226A-1226D (again, only 122A and 1226D are shown for illustration purposes). Fig. 10A , the transmission light path is described above. Fig. 12A Used to describe the receiving optical path in some embodiments.

[0148] When the transmitted light beam illuminates one or more objects in the FOV, return light may be generated due to scattering or reflection of the transmitted light beam by the objects. The return light can first be diverted by a steering mechanism (e.g., Figure 3 The steering mechanism 340 shown in FIG. 1 , or FIG. 15A to FIG. 15C The return light is received by the steering mechanism 1500, 1530, 1560 shown in FIG. The steering mechanism can then direct the return light to one or more receiver optical devices, which redirect the return light to a receiver fiber array and / or a detector. Fig. 12A Such a receiver fiber array 1220 is shown for detecting the return light guided by the receiver metalens 1222. The receiver fiber array 1220 can be connected to Fig. 10A The receiver fiber array 1020 shown is substantially the same. A receiver metalens 1222 is disposed between the steering mechanism and the receiver fiber array 1220 to receive the return light 1226A-1226D and redirect it to the receiver fiber array 1220. The receiver fiber array 1220 includes a plurality of receiver fibers, each corresponding to a receiver channel. The receiver channel is configured to transmit the optical signal from, for example, the FOV directly or indirectly via other optical components (e.g., a collection lens, an optical fiber, a mirror, a metalens, a super reflector, etc.) to one or more detectors. The receiver fibers 1224A-1224D in the fiber array 1220 are optically aligned based on the transmission angle of the corresponding transmitted light beam. As described above, each transmitted light beam is angularly separated from its adjacent transmitted light beam corresponding to the desired or predetermined angular channel spacing. Therefore, for a particular transmitted light beam, its corresponding return light also has an angular spacing from the return light corresponding to other transmitted light beams. In this way, different return lights 1226A-1226D formed by different transmitted light beams (e.g., light beams 1214A-1214D, respectively) can be directed by the receiver metalens 1222 to their respective receiver channels.

[0149] The receiver metalens 1222 can collect and focus the return light 1226A-1226D formed by the different transmitted light beams to their respective receiver fibers 1224A-1224D in the receiver fiber array 1220. The receiver metalens 1222 can have a metasurface similar to that described above for focusing light. For example, similar to Figure 8 804, the receiver metalens 1222 can introduce an artificial phase shift from its metasurface to simulate a spherical wavefront for beam focusing. For example, the receiver metalens 1222 can be configured to have a subwavelength structure formed on the surface of the wafer substrate. The subwavelength structure can form a nanoscale pattern (e.g., Fig.7D The circular pattern shown or any other desired pattern). Fig. 12AThe returned light 1226A-1226D is shown being directed to the receiver metalens 1222. The receiver metalens 1222 may be a thin sheet with a sub-wavelength structure. The thickness of the receiver metalens 1222 may be on the order of microns or millimeters and is therefore much smaller than a glass-based collection lens. The returned light 1226A-1226D is directed to the receiver metalens 1222 in a manner similar to Figure 8 The manner shown is through the receiver metalens 1222. When the light of each of the returning lights 1226A-1226D passes through a specific position of the metalens 1222, the subwavelength structure of the metalens 1222 can change the amount of phase it adds to the light of each of the returning lights 1226A-1226D. Therefore, the phase of the light wave of each of the returning lights 1226A-1226D is modulated at the edge position and the center position of the metalens 1222. The phase is modulated by the average refractive index change caused by a specific pattern including the subwavelength structure. As described above, the metalens can have a specially designed nanoscale pattern including the subwavelength structure. At different positions of the metalens 1222, the structure can be different, and the refractive index at a specific position can be different.

[0150] In other examples, the resonance effect can be used to enhance the phase modulation of the metalens 1222. The resonance effect of the subwavelength structure of the metalens 1222 can enhance the ability to manipulate and control light. The resonance effect may arise from the interaction between each of the returning lights 1226A-1226D and a specific nanostructure on the meta-surface of the metalens 1222. The nanostructures can be configured to exhibit a specific response to a specific wavelength or angle of the returning light 1226A-1226D, enabling the metalens 1222 to focus, bend, or otherwise manipulate the light as desired. Fig. 12A As shown, when different return lights 1226A-1226D arrive at different positions of the metalens 1222, the phase of the light rays of each return light 1226A-1226D at these positions is modulated, resulting in a change in the wavefront. Therefore, the nanostructure can modulate the light rays of each return light 1226A-1226D so that the wavefront at the edge position of the metalens 1222 propagates slightly faster than the wavefront at the center position of the metalens 1222. Using light 1226A as an example, the wavefront of the light rays of the return light 1226A passing through the metalens 1222 can be modulated to have a curved shape. The nanostructure can be further configured so that the curvature of the wavefront is appropriately designed to converge the light rays of the return light 1226A to a desired convergence point. Fig. 12A In the embodiment, the convergence point of the return light 1226A is configured at one end of the corresponding optical fiber 1224A of the receiver optical fiber array 1220, so that the light of the return light 1226A is precisely focused onto the optical fiber 1224A.

[0151] like Fig. 12A and Fig. 12B As shown, since the return lights 1226A-1226D are separated at an angle (for example, the return light 1226A and its adjacent return light 1226B are not parallel and may form an angle between them), the return light 1226A is focused by the metalens 1222 to the receiver fiber 1224A; the return light 1226B is focused by the metalens 1222 to the receiver fiber 1224B; and so on. Therefore, the metalens 1222 effectively collects and converges all the return lights 1226A-1226D to their respective receiver fibers. Although Fig. 12A Four receiver fibers 1224A-1224D in the receiver fiber array 1220 are illustrated, but it should be understood that the receiver fiber array 1220 may include any number of receiver fibers corresponding to any number of receiver channels (e.g., 2, 4, 6, 8, etc.). In one embodiment, multiple receiver fibers in the receiver fiber array 1220 may share a single receiver metalens 1222, such as Fig. 12A As shown, the size of the transceiver of the LiDAR system is reduced. This in turn makes the LiDAR system more compact. In some other embodiments, if more space is available for the LiDAR system, if the number of receiving channels is large (e.g., containing a large amount of return light), multiple metalenses can be used to collect the return light.

[0152] refer to Fig. 12A and Fig. 12B As described above, the receiver fiber array 1220 includes receiver fibers 1224A-1224D, which receive the converged return light 1226A-1226D from the metalens 1222, respectively. The receiver fibers 1224A-1224D can respectively transmit the return light 1226A-1226D to one or more detectors. In some embodiments, each of the receiver fibers 1224A-1224D includes a multimode fiber. Compared with single-mode fibers, the core diameter of multimode fibers is much larger (e.g., 50-1000 microns), which is much larger than the wavelength of light transmitted in the multimode fibers. Because the core is larger, it may have a larger numerical opening, and the multimode fiber has a greater light-gathering ability than the single-mode fiber. Therefore, the multimode fiber is more suitable for receiving the return light guided by the collection lens. Therefore, when multimode fibers are used for receiver channels, they generally perform better than single-mode fibers.

[0153] exist Fig. 12A and Fig. 12B In one embodiment shown, return light 1226A- 1226D can be emitted from the other ends of optical fibers 1224A- 1224D, respectively, and received by another receiver metalens 1242 . Fig. 12A and Fig. 12BA monolithic receiver metalens 1242 is illustrated for receiving all return light 1226A-1226D transmitted by the fiber array 1220. It should be understood that multiple receiver metalens may be used to receive return light. The number of receiver metalens used to receive return light delivered by the fiber array 1220 may be determined based on the physical location of the detector and / or crosstalk requirements.

[0154] like Fig. 12B As shown, since the optical fiber is physically flexible (e.g., the optical fiber can be bent into any shape or may not have a physical linear shape along its entire longitudinal direction), the detectors 1246A-1246D can be flexibly distributed (e.g., they do not need to be placed close to each other or form a network as shown in FIG. Fig. 12B Detectors 1246A-1246D may be positioned at any desired location while still being coupled to their respective receiver fibers 1224A-1224D through one or more receiver metalenses (such as metalenses 1242). Fig. 12B All detectors 1246A-1246D are shown forming an array and optically coupled to the same receiver metalens 1242. However, it should be understood that any relationship between these components can be configured. For example, the detectors 1246A-1246D can be located in a variety of different positions and not form a single array. Fig. 12B Thus, each detector can be optically coupled to a different receiver metalens, which in turn is coupled to a corresponding optical fiber 1224. In another example, one receiver metalens can be used to receive return light from two or more optical fibers 1224 and redirect the return light to one or more detectors 1246.

[0155] exist Fig. 12B As described above, adjacent detectors 1246 can be placed at different locations away from each other. Therefore, both optical and electrical crosstalk between adjacent detectors can be significantly reduced. In addition, the optical fiber 1224 has a core layer surrounded by a cladding material, thereby providing spatial filtering to further reduce optical crosstalk. Fig. 12B As shown, adjacent receiver fibers 1224 can be positioned at precise spacings from each other. The spacing is the spacing between the center lines of two adjacent optical fibers 1224 (e.g., 1224A and 1224B). This further reduces alignment errors so that the return light generated from different transmitted light beams is precisely aligned with the corresponding receiver fibers. Therefore, the return light 1226 can be properly received at the corresponding receiver fibers 1224 with reduced or minimal losses or crosstalk. In some embodiments, if the crosstalk is not significant, adjacent detectors (e.g., 1246A and 1246B) do not need to be placed farther away. Therefore, a single receiver metalens can be used for multiple optical fibers and / or multiple detectors. For example, as Fig. 12B As shown, a single metalens 1242 can be used to receive light from optical fibers 1224A and 1224B and redirect the light to detectors 1246A and 1246B. Other configurations are also contemplated.

[0156] like Fig. 12B As shown, a receiver metalens 1242 is disposed downstream of another receiver metalens 1222 (or glass-based collection lens) for directing return light 1226 to a detector 1246. The following description does not distinguish between any return light 1226A-1226D or any detector 1246A-1246D. Thus, any of the return light or detector will only be referred to as return light 1226 or detector 1246. Fig. 12B As shown, the metalens 1242 can be configured to perform one or more of the following: collimation, filtering, shifting, shaping, separation, and focusing of the return light 1226. In one embodiment, the metalens 1242 can collimate the incident return light 1226, perform bandpass filtering, and then focus the filtered return light to a corresponding detector 1246.

[0157] In one embodiment, metalens 1242 may include a multi-layer sub-wavelength structure for achieving different optical functions. The multi-layer structure may be Fig. 7E For example, metalens 1242 may include three layers, and the first layer of the subwavelength structure may be similar to that described above with respect to emitter metalens 1012 or 1212 (e.g., Fig. 10A 12) to collimate the received return light 1226. The collimated return light can pass through the second layer in the metalens 1242. The second layer of the subwavelength structure can be configured to perform optical filtering to filter out light with undesirable wavelengths (e.g., stray light, sunlight, or any other interfering light outside the operating wavelength of the LiDAR). In one example, the subwavelength structures in the second layer can be configured to have different phase responses for light of different wavelengths. This means that they can introduce a specific phase delay to light of one wavelength while allowing light of other wavelengths to pass with minimal phase change. As described above, different materials can be used for this purpose (e.g., a glass-based metalens layer for passing visible light, a silicon-based metalens layer for passing near-infrared light, a PbTe-based metalens layer for passing mid-infrared light, a HfO2-based metalens layer for passing ultraviolet light, etc.). Different patterns can also be used to enhance the wavelength-dependent phase modulation provided by the second layer of the metalens 1242. This wavelength-dependent phase operation can be used to selectively filter out or transmit certain colors or spectral bands.

[0158] In another embodiment, the second layer of the metalens 1242 can have a sub-wavelength structure to form a pattern exhibiting dispersion characteristics, which can be used to separate light with different wavelengths to achieve spectral filtering or dispersion compensation. Therefore, the sub-wavelength structure of the second layer can act as a glass-based prism to physically separate light with different wavelengths and direct them to different locations. The light signal with the desired wavelength can be directed to the detector 1246, while other light can be directed to other locations to be absorbed or filtered out.

[0159] Continuing with the above example of three layers of metalens 1242, when the second layer filters out unwanted light, the remainder of the return light 1226 is directed to the third layer, which has a subwavelength structure for focusing or converging the light to the detector 1246. The subwavelength structure of the third layer of metalens 1242 can be the same or similar to the subwavelength structure of the receiver metalens 1222 described above. It should be understood that metalens 1242 can be configured to concentrate light similar to metalens 1222, but one or more optical properties can be configured differently using the same or different types of nanostructures, the same or different feature sizes, and / or the same or different patterns of nanostructures. For example, receiver metalens 1242 can have a similar pattern (e.g., a ring pattern) as metalens 1222, but have different feature sizes, so that the effective focal length of metalens 1242 is different from that of metalens 1222. The different effective focal length may be the result of the focal point of metalens 1242 being much closer than the focal point of metalens 1222 because detector 1246 can be positioned close to metalens 1242. In contrast, the optical fiber array 1220 can be positioned away from the metalens 1222.

[0160] Fig. 12B The above-described embodiment of the metalens 1242 shown uses three layers of nanostructures. In other embodiments, fewer or more layers may be used. For example, the first layer of the subwavelength structure can be configured to perform collimation, and the second layer can be configured to focus the return light 1226 to the detector 1246 while filtering out certain undesirable wavelengths. Therefore, the metalens 1242 is very useful in compact optical systems while still providing the desired functionality. Compared to using glass-based optics (e.g., an assembly 1243 having a glass-based lens for collimation and focusing, and a bandpass filter disposed between the lenses), the metalens 1242 can significantly reduce the size of the receiver, thereby reducing the size of the entire LiDAR system. In addition, due to the precise configuration of the subwavelength structure, the metalens 1242 can improve the quality of collimation, focusing, and filtering, thereby providing a signal with better quality (e.g., reduced noise or interference, no optical aberrations, etc.) to the detector 1246. Therefore, the overall detection performance of the LiDAR system is improved.

[0161] Fig. 12C is a block diagram of another exemplary receiver that includes one or more receiver metalenses 1222 and 1252 for directing return light to a detector 1246, according to some embodiments. Fig. 12C The embodiment shown is similar to Fig. 12B The embodiment shown, except that in this embodiment, no fiber array is used to receive the return light 1226 from the receiver metalens 1222 (or glass-based collection lens). Instead, the return light 1226A-1226D is focused directly onto the metalens 1252, which is configured to perform one or more optical functions, including collimation, filtering, light distribution, and focusing. The light exiting the metalens 1252 is then directed to one or more detectors 1246. The metalens 1252 may include a sub-wavelength structure substantially the same or similar to the metalens 1242 described above, and therefore, will not be described again. In one embodiment, depending on the location of the detectors, the metalens 1222 may not need to be located in a substantially uniform manner. Fig. 12C The metalens 1222 can be configured to focus the return light 1226A-1226D in the manner shown. In contrast, the metalens 1222 can be configured to make the return light 1226A-1226D pass through the metalens 1252 more uniformly. For example, the light of the return light 1226A can be directed to the top of the metalens 1252; the light of the return light 1226D can be directed to the bottom of the metalens 1252; and the light of the return light 1226B and 1226C can be directed to the middle portion of the metalens 1252. The metalens 1252 can then perform various optical functions (e.g., collimation, filtering, and redirection) at various locations of the corresponding return light 1226A-1226D. After optical processing, the metalens 1252 directs the processed return light with improved signal quality to the detector 1246. Fig. 12C The embodiment shown eliminates the receiver fiber array, making the receiver more compact. This in turn reduces the overall size of the LiDAR system. This embodiment can be used when crosstalk between adjacent receiver channels is not significant or is controlled by other means.

[0162] In alternative embodiments, multiple instances of the metalens 1252 may be used. For example, each instance of the metalens 1252 may be positioned to receive different return lights 1226A-1226D from the metalens 1222 (or glass-based collection lens). Multiple instances of the metalens 1252 may be placed close to each other or far from each other, depending on the location of the detectors 1246 and crosstalk requirements. It should be understood that any configuration of one or more instances of the metalens 1252 may be provided to receive any number of return lights 1226 and direct the return lights 1226 to any number of detectors 1246 at any physical location.

[0163] Fig.13A is a diagram illustrating another exemplary LiDAR system 1300 including one or more emitter metasurface-based optics according to some embodiments. Fig.13A A perspective view of a LiDAR system 1300 having a stacked configuration is shown. The LiDAR system 1300 may be used to implement the above Figure 3 13. The LiDAR system 1300 includes a transmitter circuit board 1302, one or more transmitter metalenses 1304, a polygon mirror 1306, a combining mirror 1308, a receiver lens group 1310, a folding mirror 1312, a focusing lens 1314, and a detector circuit board 1316. The following description uses the transmitter metalenses 1304 as an example. However, one or more of the combining mirror 1308, the folding mirror 1312, the receiver lens group 1310, and the focusing lens 1314 can be replaced with a metasurface-based optical device, such as a metalenses or a superreflector as described above.

[0164] refer to Fig.13A In some embodiments, the emitter circuit board 1302 includes a laser source and circuits for generating output lasers of one or more channels in the form of multiple laser beams. The emitter circuit board 1302 may include a vertical cavity surface emitting laser (VCSEL) chip configured to provide, for example, 48 channels of emitted laser beams. The VCSEL chip can be arranged to have an array of emission zones (e.g., a 1x8 array) arranged in a row in the center of the chip. Each emission zone has multiple micro VCSEL emitters. Each emission zone corresponds to a laser channel and can be turned on and off individually. When the emission zone is turned on or off, the micro VCSEL emitters in the particular emission zone are turned on and off together. The emission zone can be connected to one or more electrodes. The electrode can control one or a group of emission zones by turning the emission zone on and off. The electrode can be of several different types, such as an anode, a cathode, etc. All emission zones on the VCSEL chip can share a common electrode. In other embodiments, multiple emission zones on the VCSEL chip can be connected to more than one electrode.

[0165] The laser beams provided by the transmitter circuit board 1302 are directed to one or more transmitter metalenses 1304. In one embodiment, a single metalens 1304 is used to receive and collimate all laser beams provided by the transmitter circuit board 1302. The metalens 1304 can be used in conjunction with the transmitter metalens 1304 as described above. Fig. 12A1304. In another embodiment, multiple metalenses 1304 can be used to collimate a large number of laser beams (e.g., 48 or more beams) provided by transmitter circuit board 1302. Multiple metalenses 1304 can be arranged in such a manner that each of multiple metalenses 1304 receives a subset of the laser beams (e.g., one metalense receives and collimates 12 beams, and another metalense receives and collimates another 12 beams, and so on).

[0166] In another embodiment, metalens 1304 can be used to effectively replace glass-based lens sets. Fig. 13B and Fig. 13C is shown in more detail in . Fig. 13B is a magnified view of the emitter circuit board 1302 and the emitter metalens 1304. As described above, in some examples, the emitter circuit board 1302 provides a large number of laser beams (e.g., 48 or more). Fig. 13C As shown in the figure, in order to collimate a large number of laser beams, if a conventional glass-based optical lens is used, a collimating lens group 1334 is usually required. The exemplary glass-based collimating lens group 1334 includes four glass-based collimating lenses and / or prisms, which are arranged in a specific manner to manipulate a large number of laser beams and generate parallel light for each laser beam at its output end. Therefore, the glass-based collimating lens group 1334 usually occupies a large space, making the LiDAR system bulky.

[0167] The large lens group 1334 can be used Fig. 13B The single thin sheet metal lens 1304 shown is replaced. Metalens 1304 includes a sub-wavelength structure configured to collimate a large number of laser beams. In one embodiment, metalens 1304 may include multiple layers stacked together, similar to Fig. 7EThe metalens shown. For example, the metalens 1304 can have two or more layers including nanostructures. The first layer receives the laser beam from the transmitter circuit board 1302 and includes a nanostructure configured to perform a rough phase modulation of all beams, thereby performing a rough collimation of all beams. Rough collimation can produce a high-quality collimated beam (for example, the light in the same beam has a smaller divergence angle or convergence angle than an uncollimated beam). The second layer receives the coarsely modulated beam and includes a nanostructure to fine-tune the coarse collimated beam. Therefore, the output of the second layer of the metalens 1304 can be a further collimated beam, thereby improving the collimation quality. If the collimation quality is to be further improved, more layers can be added. Ultimately, the output beam of the metalens 1304 can have very good collimation quality. As described above, a well-collimated beam can propagate farther and ensure proper alignment and focusing. In addition, the metalens 1304 can have a thickness of the order of microns (for example, 1 μm) or less. Thus, the bulky glass-based lens set 1334 can be replaced with a thin metalens 1304, making the LiDAR system significantly more compact. In other embodiments, the metalens 1304 can include multiple layers, each layer including a sub-wavelength structure for collimating a subset of laser beams.

[0168] Return to reference Fig.13A , continuing to refer to the emission light path, the metalens 1304 receives and collimates a large number of transmitted light beams (e.g., 48 light beams). The collimated light beams are directed to the combined mirror 1308. In one example, the combined mirror 1308 has one or more openings or transmissive portions to allow the transmitted light beams to pass through the mirror 1308. The one or more openings in the reflector 1308 can be a cutout, a hole, a groove, a lens, or a portion of the mirror 1308 with an anti-reflective coating, or anything that allows the transmitted light beam to pass through. The reflective surface of the combined mirror 1308 (on the opposite side of the transmitter circuit board 1302) redirects the return light to the light detector on the detector circuit board 1316 via other components of the LiDAR system 1300. In one embodiment, one or more openings are located in the center of the combined mirror 1308. In other embodiments, the openings can be located in other portions of the combined mirror 1308 that are not in the center (e.g., at a corner).

[0169] In other embodiments, the combined mirror 1308 can be an optical device based on a metasurface, including a super reflector, a super lens, or a combination thereof. For example, the combined mirror 1308 can have a subwavelength structure disposed on the surface of the super reflector (on the opposite side of the transmitter circuit board 1302). These subwavelength structures can be configured to reflect light by controlling the phase, polarization, and direction of the return light reflected by the polygonal mirror 1306. In one example, the combined mirror 1308 also includes a subwavelength structure at a specific position of the mirror 1308 for passing a transmitted light beam from the super lens 1304 to the polygonal mirror 1306. In another example, the reflector 1308 includes only a super reflector with an opening for passing a collimated transmitted light beam to the multi-faceted reflector 1306.

[0170] Still reference Fig.13A , the collimated transmission beam passes through the combination mirror 1300 and is then redirected to the polygon mirror 1306. In other embodiments, the emission beam from the transmitter circuit board 1302 can be redirected by one or more other intermediate reflectors before reaching the polygon mirror 1306. In other embodiments, the metalens 1304 can be located between the combination mirror 1308 and the polygon mirror 1306. In some embodiments, the polygon mirror 1306 can have multiple facets. For example, the polygon mirror 1306 can have 3 facets, 4 facets, 5 facets, 6 facets, and so on. When the polygon mirror 1306 rotates, the collimated transmission beam is reflected by the face of the polygon mirror 1306 at any time. The polygon mirror 1306 rotates around an axis perpendicular to its top and bottom surfaces. When the polygon mirror 1306 rotates, each of the multiple facets reflects all the transmission beams in turn and guides them to illuminate the field of view.

[0171] In some embodiments, according to one embodiment, the multi-faceted polygonal reflector 1306 is a variable angle multi-faceted polygon (VAMFP). The facets of the VAMFP do not have the same tilt angle. The tilt angle is the angle between the rotation axis of the polygonal mirror 1306 and the normal direction of the facet. Therefore, the different angles of different facets make the vertical area of ​​the scanning FOV different. VAMFP is described in more detail in U.S. non-provisional patent application No. 16 / 837,429, entitled "Variable Angle Polygon for LiDAR Systems" filed on April 1, 2020, the contents of which are incorporated by reference in their entirety.

[0172] If there is an object in the field of view, return light is formed based on the scattering or reflection of the transmitted light beam by the object and is directed back to the small facets of the polygon mirror 1306, such as Fig.13A The polygon mirror 1306 reflects the return light back to the combination mirror 1308, and the combination mirror guides the return light to the receiver lens group 1310. Fig.13AThe receiver lens assembly 1310 shown may include, for example, a collimating lens and a bandpass filter, similar to the glass-based collimating lens and bandpass filter in assembly 1243 described above ( Fig. 12B ). Therefore, in one embodiment, receiver lens group 1310 is implemented using glass-based lenses and filters. Due to the large number of transmitted beams, the return light may also include many rays corresponding to all transmitted beams. Therefore, using glass-based lenses and filters, lens group 1310 may include, for example, four or more lenses for processing all return light. Therefore, receiver lens group 1310 may also be bulky.

[0173] In another embodiment, receiver lens assembly 1310 can be replaced with another receiver metalens ( Fig.13A 1310). The receiver metalens can be substantially the same or similar to any of the receiver metalens described above. For example, the receiver metalens used to replace the lens group 1310 can also be a multi-layer metalens, including a layer for performing optical collimation and a layer for performing bandpass filtering. As another example, a single-layer metalens can be used to replace the lens group 1310, so that the nanostructure of the single-layer metalens is designed to perform collimation and filter undesirable optical signals at the same time. As described above, the receiver metalens can also be very thin (e.g., a thickness on the order of microns or less). Therefore, replacing the bulky glass-based lens group 1310 with a receiver metalens can further reduce the size of the LiDAR system 1300, making it more compact.

[0174] Still reference Fig.13A , the receiver lens assembly 1310 or a metalens in place of the lens assembly 1310 directs the return light to the detector circuit board 1316. The return light can be sent directly to the detector circuit board 1316, or sent through one or more receiver optical devices. Fig.13A , such receiver optics are shown to include a fold mirror 1312 and a focusing lens 1314. Fold mirror 1312 is used because the detector circuit board is located perpendicular to the side of lens group 1310 (or the metalens replacing lens group 1310), and therefore the direction of the return lights needs to be changed so that they are directed to the detector circuit board 1316. If the detector circuit board 1316 is positioned parallel to the optical surface of lens group 1310 (or the meta-surface of the metalens replacing lens group 1310), it can directly receive the return light without the need for fold mirror 1312.

[0175] The focusing lens 1314 focuses the return light into a small spot size and converges the light of the return light with each of the transmitted light beams to the detector (or detector element) on the board 1316. Similar to the above description, the focusing lens 1314 can also be a glass-based lens or a metalens similar to the metalens 804. In short, if the focusing lens 1314 uses a metalens, it also includes a nanostructure to converge the light to a focal point (similar to Figure 8 In one embodiment, focusing lens 1314 can be combined with lens group 1310. Lens group 1310 and focusing lens 1314 can be combined together and used with a monolithic metalens (e.g., similar to Fig. 12B The return light is then directed to and detected by one or more detectors on a detector circuit board 1316 using focusing lens 1314.

[0176] Thus, one or more components of the LiDAR system 1300 may use a metalens, including a transmitter collimating lens (composed of Fig.13A 1304), a combination mirror 1308, a receiver lens set 1310, and a focusing lens 1314. A combination of a metalens and glass-based optical components can also be used to implement the LiDAR system 1300.

[0177] Fig.14A is a perspective view of another exemplary LiDAR system 1400 including one or more metasurface-based optics, according to some embodiments. Fig.14A As shown, the LiDAR system 1400 includes a polygon mirror 1402, an oscillating mirror 1404, a transmitter circuit board 1406, one or more collimating lenses 1410 and 1411, one or more folding mirrors 1408 and 1412, a collecting lens 1418, a folding mirror 1414, a receiver metalens 1416, an optical slit 1420, and a detector 1422 (e.g., Fig. 14B As shown in FIG. 1 ). The LiDAR system 1400 can be used to implement the above Figure 3 The LiDAR system 300 described in . Similar to Fig.13A 1300, LiDAR system 1400 has a stacked configuration such that polygonal mirror 1402 is stacked vertically above at least a portion of the transmitter and receiver. As described above, in some embodiments, the stacked configuration provides a more compact LiDAR system that can be easily installed in a vehicle. Fig.13A Unlike the illustrated LiDAR system 1300 , the polygon mirror 1402 in LiDAR system 1400 is located above a transceiver including a transmitter circuit board 1406 , transmitter optics, receiver optics, and a detector.

[0178] refer to Fig.14A In some embodiments, the transmitter circuit board 1406 includes a laser source that emits one or more transmission beams. The transmitted light beam can be directed (directly or through other optical devices such as a folding mirror) to a collimating lens 1410. The collimating lens 1410 can be a glass-based lens or a metalens (e.g., similar to the above-described metalens 1012). The collimating lens 1410 collimates the transmitted light beams and directs them to the folding mirror 1408. The collimating lens 1410 can be a fast-axis collimating lens. In some examples, another collimating lens 1411 can be placed between the two folding mirrors 1410 and 1412 to perform further collimation. The collimating lens 1411 can be a slow-axis collimating lens. In Fig.14A In the embodiment shown, the collimating lens 1410 is placed on one side of the collecting lens 1418. Thus, similar to the above reference Fig.11 As described, using fold mirrors 1408 and 1412 to form a beam shifting system, the collimated transmitted light beam can be shifted to be positioned within the optical receiving aperture of the collection lens 1418. For example, the collimated transmitted light beam can be moved to align with the central portion of the collection lens 1418 to maximize the collection of return light using the optical receiving aperture of the collection lens 1418. The fold mirrors 1408 and 1412 can be glass-based reflectors with a reflective coating or similar to those described above with reference to Fig.11 Reflective surfaces 1104 and 1106 are depicted as super mirrors.

[0179] Next, the collimated transmission beam is directed to an oscillating mirror 1404, which can oscillate to enable scanning of the beam in the vertical direction. Oscillating mirror 1404 redirects the collimated transmission beam to polygon mirror 1402, which rotates to scan the beam in the horizontal direction. Thus, LiDAR system 1400 can scan the FOV in two dimensions. In some examples, oscillating mirror 1404 can be replaced by a fixed mirror, and polygon mirror 1402 can be configured as a variable angle polygon mirror, similar to the method described above using Fig.13A Those described with respect to polygon mirror 1306.

[0180] When the transmitted light beam illuminates one or more objects in the FOV, return light may be formed by scattering or reflecting the transmitted light beam. The return light is received by the polygon mirror 1402. The polygon mirror 1402 directs the return light to the oscillating mirror 1404, which redirects the return light to the collection lens 1418. The collection lens 1418 may be a glass-based lens or a lens similar to that used above. Fig. 12A The metalens of the collecting lens 1222 is described. Fig.14A In the embodiment shown, the collection lens 1418 can focus the return light onto the folding mirror 1414.

[0181] Reference Image Fig.14A and Fig. 14B , fold mirror 1414 can change the direction of the returning light and guide the returning light to optical slit 1420. In some examples, fold mirror 1414 can be a glass-based reflector or a super reflector with a reflective coating. Optical slit 1420 is configured to have a narrow opening along one dimension through which light can be transmitted. Optical slit 1420 is made with high precision to shape the light passing through along one dimension. Fig.14D An exemplary light pattern 1440 is shown passing through the optical slit 1420. Fig.14D As shown, the return light through the slit 1420 can include a plurality of rectangular light segments (e.g., 16 segments). Each of the light segments represents the return light corresponding to a different transmitted light beam in the plurality of transmitted light beams. The optical slit 1420 can be made of a metal material such as stainless steel, molybdenum, or tungsten, or made in a thin metal coating on a glass sheet.

[0182] Return to reference Fig.14A and Fig. 14B , the slit 1420 can be positioned and configured to block light other than the desired return light. As described above, the multiple transmitted light beams are angularly separated, and therefore the return light corresponding to the different transmitted light beams is also angularly separated. Therefore, the return light formed based on the multiple transmitted light beams is received at a specific angle. Noise, interference light and / or other undesirable light may be received by the LiDAR system 1400 at an incident angle different from that of the desired return light. Therefore, by appropriately positioning and configuring the size of the slit 1420, undesirable stray light can be blocked while allowing the desired return light to pass.

[0183] Continuing with reference to the receiving optical path, when the return light passes through the optical slit 1420, it is directed to the receiver metalens 1416 for beam homogenization before being detected by the detector 1422. Fig. 14B and Fig.14D , as described above, the return light through the optical slit 1420 may have Fig.14D Pattern 1440 is shown. Pattern 1440 may include an array of rectangular light segments corresponding to returned light formed based on different transmitted light beams. Fig.14D Also shown is an array of detector elements 1450. These detector elements 1450 may be included in Fig. 14B In the detector 1422 shown. Fig.14DAs shown, the shape of each of the detector elements 1450 may be different from the shape of the light segments in the light pattern 1440. For example, each of the detector elements 1450 may have a square shape (or other shape). Therefore, there may be a mismatch between the shape of the light segments in the return light passing through the slit 1420 and the shape of the detector elements 1450. The mismatch may reduce the detection efficiency because the light segments received at the detector elements 1450 have a profile that is not uniformly distributed according to the shape of the detector elements 1450.

[0184] To reduce or eliminate the non-uniformity of the portion of the returned light received at each of the detector elements 1450, Fig. 14B The receiver metalens 1416 in can be used to perform beam homogenization and thus act as Fig.14D The beam homogenizer 1446 shown in . The beam homogenizer 1446 can change the light distribution to make it more uniform. For example, in order to make the rectangular light segments in the light pattern 1440 more uniform so that the light segments received at the detector element 1450 better match the shape of the detector element 1450, the metalens 1416 can have a metasurface configured to introduce an artificial phase shift in one direction but not in another direction (or more in one direction but less in another direction), thereby expanding the light distribution of each returned light segment in the pattern 1440 in a longitudinal direction perpendicular to each returned light segment. For example, the receiver metalens 1416 can be configured to have a subwavelength structure formed on the surface of the wafer substrate. The subwavelength structure can form a nanoscale pattern (e.g., a 1D array pattern with varying feature sizes in a direction perpendicular to the longitudinal direction of the array, or any other desired pattern). Therefore, the receiver metalens 1416 increases a slight beam divergence in the longitudinal direction perpendicular to the light pattern 1440. The result of the beam homogenization can be seen in Fig.14E After passing through the receiver superlens 1416 (in Fig.14D After beam homogenization (shown as beam homogenizer 1446 in FIG. 1 ), the light profile of the return light received at the detector element 1450 can have a square shape that better matches the shape of the detector element (e.g., more uniform in all four directions).

[0185] Fig. 14C Another exemplary configuration of a receiver including a metalens 1416 for beam homogenization is illustrated in accordance with some embodiments. Fig. 14B , Fig. 14C The receiver is shown receiving the return light. The return light passes through an optical slit 1420 and is directed to a lens set before the return light is received by the receiver metalens 1416 for beam homogenization. Fig. 14CThe lens group shown includes a collimating lens 1424, a filter 1426, and a focusing lens 1428. The collimating lens 1424 further collimates the light rays of the return light formed based on the specific transmitted light beam to be more parallel. The filter 1426 can perform spectral filtering to remove or reduce light with undesirable wavelengths (e.g., light outside the operating wavelength of the LiDAR system). The focusing lens 1428 can better focus the return light to the receiver metalens 1416, and then to the detector 1422. Therefore, the lens group including the collimating lens 1424, the filter 1426, and the focusing lens 1428 can be used to further improve the quality of the return light before the return light is homogenized by the receiver metalens 1416, thereby further improving the detection accuracy and efficiency. In some examples, one or more of the collimating lens 1424, the filter 1426, and the focusing lens 1428 can be implemented using glass-based optics or metasurface-based optics, similar to those described above. In addition, one or more of the collimating lens 1424, the filter 1426, and the focusing lens 1428 may be omitted. The order of these optical elements may be changed, or additional optical elements may be added. When the metalens 1416 receives the return light from the lens group for further processing, it may perform beam homogenization similar to that described above. As a result, the return light received at the detector 1422 has a more uniform light distribution, which improves detection efficiency.

[0186] It should be understood that Fig. 14C The lens group shown is an example. Any other optical device, whether glass-based or metasurface-based, can be used to implement the lens group to further improve the light reception quality and detection efficiency. It should also be understood that the lens group (or one or more optical devices) can be placed downstream or upstream of the beam homogenizer (e.g., in Fig.14D either or both sides of the beam homogenizer 1446 as shown).

[0187] Fig.14F An exemplary conventional glass-based lens set is shown that may be replaced by a metalens in a receiver of a LiDAR system, according to some embodiments. Fig. 14C and Fig.14F , the exemplary lens set including collimating lens 1424, filter 1426, and focusing lens 1428 can be partially or entirely replaced by a multilayer metalens. The multilayer metalens can be similar to the multilayer metalens 1242 or 1252 described above (e.g., three layers for collimating, filtering, and focusing the return light; or two layers when filtering and focusing are combined). Using a metalens instead Fig.14F The lens set shown can further reduce the size of the receiver and, in turn, the size of the LiDAR system. As a result, the system can be more compact.

[0188] Figure 14G An exemplary lens array 1468 is illustrated according to some embodiments, which may be replaced by a metasurface-based beam homogenizer. The lens array 1468 may be, for example, a cylindrical lens array for expanding the beam profile and performing a degree of beam homogenization. The cylindrical lens array 1468 may use a glass-based optical lens or a microlens array. However, glass-based optical lenses may be bulky. In addition, each of the lenses in the array 1468 may need to be precisely configured to form a light distribution in a desired manner. Therefore, the cost of manufacturing such a glass-based lens array may be high. A metasurface-based beam homogenizer (e.g., 1446) may be used in place of a cylindrical lens array to reduce or eliminate these problems, while performing beam homogenization in a more precise manner using nanostructures as described above.

[0189] exist FIG. 14A to FIG. 14C In the illustrated embodiment, metalens 1416 is used to perform beam homogenization in LiDAR system 1400. However, it should be understood that the same or substantially similar metalens can be used in other LiDAR systems (e.g., systems 300, 1000, 1200, and 1300). In addition, each of systems 300, 1000, 1200, 1300, and 1400 can include a steering mechanism for scanning a transmitted beam to the FOV and receiving and redirecting return light. In some examples, the steering mechanism can be implemented using a metalens, a metal mirror, and / or other metasurface-based optical devices.

[0190] FIG. 15A to FIG. 15C Illustrated are exemplary steering mechanisms 1500, 1530, and 1560 according to some embodiments, which include one or more metalenses, metalmirrors, and / or other metasurface-based structures. Steering mechanisms 1500, 1530, or 1560 can be used to implement or replace steering mechanism 340, polygon mirror 1306, polygon mirror 1402, oscillating mirror 1404, and / or other optical scanners.

[0191] refer to Fig.15A, the steering mechanism 1500 includes two cylindrical structures 1502 and 1504, each of which includes a subwavelength structure disposed on the surface. These subwavelength structures can be nanoslits, nanorods, nanodisks, nanopillars, etc. The nanostructures are specifically configured to resonate with incident light of one or more specific wavelengths and angles. In one embodiment, the subwavelength structure is printed onto the surface of the cylindrical structures 1502 and 1504 to form a metasurface. For example, a silicon nanocomposite material can be used to provide a printable superlens. The nanocomposite material is synthesized by dispersing silicon nanoparticles in a thermally printable resin. The resin can be printed onto the base structure together with the silicon nanocomposite material to form cylindrical structures 1502 and 1504. The pattern of the subwavelength structure is configured to control the direction of the outgoing light. In one example, the cylindrical structure 1504 can have a pattern of subwavelength structures that are configured to receive incident light beams from the emitter 1506 and redirect them to the cylindrical structure 1502. The cylindrical structure 1502 may also have a pattern of sub-wavelength structures to receive the light beams from the cylindrical structure 1504 and redirect them to the FOV to form an outgoing light beam 1510, such as Fig.15A shown.

[0192] The patterns of the sub-wavelength structures printed on the surfaces of the cylindrical structures 1502 and 1504 may be the same or different. Fig.15A In the illustrated embodiment, cylindrical structures 1502 and 1504 can each control the scanning of light in one direction, thereby achieving two-dimensional scanning. Each of cylindrical structures 1502 and 1504 can be configured to rotate around their respective rotational axes 1505 and axes 1507. In some examples, cylindrical structure 1502 can be controlled to rotate around axis 1505 in one rotational direction (e.g., viewing structure 1502 clockwise along axis 1505), or oscillate around axis 1505 in the rotational direction and the opposite direction (e.g., clockwise and counterclockwise). Similarly, cylindrical structure 1504 can be controlled to rotate around axis 1507 in one rotational direction, or oscillate around axis 1507 in the rotational direction and the opposite direction.

[0193] In some embodiments, one or both metasurfaces of the cylindrical structures 1502 and 1504 can be divided into micro-regions, each of which is approximately a few square microns. Each micro-region is printed with a specific pattern of sub-wavelength structures, so that the angle between the incident light of the cylindrical structure and the corresponding outgoing light is controlled according to the rotation angle of the cylindrical structure. Therefore, when the cylindrical structures 1502 and 1504 rotate, the outgoing transmission light beam used to scan the FOV changes angle in two directions (each of the structures 1502 and 1504 controls one direction), thereby achieving 2D scanning.

[0194] In certain embodiments, cylindrical structures 1502 and 1504 control scanning in the vertical and horizontal directions, respectively. Thus, when cylindrical structure 1504 rotates, the horizontal angle of exit beam 1510 changes. When cylindrical structure 1502 rotates, the vertical angle of exit beam 1510 changes. It should be understood that cylindrical structures 1502 and 1504 can be reconfigured so that they scan in the horizontal and vertical directions, respectively.

[0195] In one example, the subwavelength structure printed on the surface of each of the cylindrical structures 1502 and 1504 can be patterned so that the surface is reflective. The subwavelength structure is configured so that the phase, amplitude, and polarization of the incident light can be controlled in a desired manner. The reflective surface implemented by this metamaterial is called a super mirror. Due to the subwavelength structure, the super mirror can reflect light similar to a traditional mirror. They can also manipulate light in unconventional ways that traditional mirrors cannot do. For example, by using a super mirror and / or a super lens, the outgoing light and the incident light may not follow the traditional laws of reflection. Instead, the outgoing light can have any desired direction, phase, amplitude, and polarization. In this way, by using a super lens, a super mirror, and / or other optical devices based on a meta surface, the steering mechanism 1500 can be more flexibly configured to scan the transmitted light beam 1510 to the FOV of the LiDAR system. Depending on the specific subwavelength structure configured for the steering mechanism 1500, the scanning can meet any horizontal FOV and vertical FOV requirements.

[0196] Fig. 15B Another example of a steering mechanism 1530 is shown, which includes a single cylindrical structure 1532 and a fixed reflector 1534. The cylindrical structure 1532 includes a subwavelength structure disposed on its surface. These subwavelength structures can be nanoslits, nanorods, nanodisks, nanopillars, etc. The nanostructure is specifically configured to resonate with incident light of one or more specific wavelengths and angles. In one embodiment, the subwavelength structure is printed onto the surface of the cylindrical structure 1532 to form a metasurface. Unlike the pattern used for the cylindrical structure 1502, the pattern of the subwavelength structure printed on the cylindrical structure 1532 is configured to control the two directions of the outgoing light beam. In one example, the immovable reflector 1534 receives incident light from the emitter 1536 and redirects the incident light toward the cylindrical structure 1532. The cylindrical structure 1532 can have a larger size than the structure 1502. Therefore, the cylindrical structure 1532 can have enough surface area to print the micro-region of the subwavelength structure. These micro-regions collectively encode all possible coordinate combinations of the 2D scan.

[0197] In one embodiment, the subwavelength structures printed on the surface of cylindrical structure 1532 can be patterned so that the surface is reflective, similar to those described above with respect to structure 1502. Using the printed subwavelength structures, cylindrical structure 1532 can redirect light from light source 1536 to the FOV, thereby forming an outgoing light beam 1540, such as Fig. 15B As shown. Fig. 15B In the illustrated embodiment, both the horizontal and vertical angles of the outgoing beam 1540 change as the cylindrical structure 1532 rotates about its rotational axis 1535 and / or translates along an axial direction 1537, thereby providing scanning coverage of the entire FOV. In some examples, the cylindrical structure 1532 can be controlled to rotate about the axis 1535 in one rotational direction (e.g., viewing the structure 1532 clockwise along the axis 1535), or to oscillate about the axis 1535 in the rotational direction and the opposite direction (e.g., clockwise and counterclockwise).

[0198] Fig. 15C Another example of a steering mechanism 1560 is illustrated which is a single disk-shaped structure having sub-wavelength structures printed on a flat surface. Fig. 15C The disk-shaped structure shown can have a size approximately the size of a compact disk (CD). The disk-shaped structure of the steering mechanism 1560 can include a micro-region of a subwavelength structure for reflecting or refracting the incident laser received from the light source 1566 (as a reflective disk or a transmissive disk). Super lenses, super reflectors, and / or other metasurface-based structures can be patterned to control the outgoing light 1568 at horizontal and vertical angles. In one embodiment, the disk-shaped structure of the steering mechanism 1560 has micro-regions in a circular or spiral track, similar to a CD. The disk-shaped structure can rotate around an axis of rotation 1564 and can be linearly moved in a radial direction 1562 relative to the light source 1566 so that the incident laser can move between the inner and outer tracks of the disk-shaped structure. Therefore, the steering mechanism 1560 can form an outgoing beam 1568 that scans the entire FOV in two directions. In some examples, the disc-shaped structure of steering mechanism 1560 can be controlled to rotate about axis 1564 in one rotational direction (e.g., clockwise) or to swing about axis 1564 in a rotational direction and its opposite direction (e.g., clockwise and counterclockwise).

[0199] The foregoing description should be understood to be illustrative and exemplary in every respect, rather than restrictive, and the scope of the invention disclosed herein is not determined by the description, but by the claims interpreted in accordance with the full breadth allowed by patent law. It should be understood that the embodiments shown and described herein are merely illustrations of the principles of the invention, and that various modifications may be made by those skilled in the art without departing from the scope and spirit of the invention. Various other feature combinations may be implemented by those skilled in the art without departing from the scope and spirit of the invention.

Claims

1. A light ranging and detection (LiDAR) system comprising one or more metasurface-based optical devices, the system comprising: a transmitter, the transmitter comprising one or more transmitter optics, the transmitter configured to provide one or more transmitted light beams; a beam steering device optically coupled to the emitter, the beam steering device comprising one or more steering optics configured to: scanning the one or more transmitted light beams to a field of view in at least one of a horizontal direction and a vertical direction, and directing return light formed based on the scanned one or more transmitted light beams; a receiver, the receiver comprising one or more receiver optics, the receiver configured to receive the return light directed by the beam steering device; Wherein at least one of the one or more transmitter optics, the one or more steering optics, and the one or more receiver optics comprises the one or more metasurface-based optics, at least one of the metasurface-based optics having a subwavelength structure disposed on a semiconductor wafer substrate, wherein features of the subwavelength structure have a size that is smaller than an operating wavelength of the LiDAR system.

2. The system of claim 1, wherein the subwavelength structure is preconfigured to modulate light according to one or more optical requirements associated with the transmitter, the beam steering device, or the receiver.

3. The system of claim 2, wherein the operating wavelength of the LiDAR system is between 750 nm and 2000 nm.

4. The system of any one of claims 1 to 3, wherein each of the sub-wavelength structures has a size between 1 / 20 and 9 / 10 of the operating wavelength of the LiDAR system.

5. A system according to any one of claims 1 to 4, wherein the subwavelength structure forms a 2-dimensional or 3-dimensional pattern, and the 2-dimensional or 3-dimensional pattern is configured to modularize the light to have different optical phase changes at different positions of the subwavelength structure, so that the light formed by the subwavelength structure is manipulated according to at least one optical requirement associated with the transmitter, the beam steering device or the receiver.

6. A system according to claim 5, wherein the at least one optical requirement includes one or more requirements related to: beam direction, reflection, deflection, refraction, diffraction, focusing, collimation, separation, merging, convergence, steering, scattering, dispersion or polarization of the one or more transmitted light beams and the return light.

7. The system of any one of claims 1 to 6, wherein the sub-wavelength structures comprise dielectric-based structures on the nanometer or micrometer scale.

8. The system according to any one of claims 1 to 7, wherein the sub-wavelength structure comprises a single layer or a multi-layer nanostructure.

9. The system of any one of claims 1 to 8, wherein at least one of the one or more metasurface-based optical devices has a thickness of less than one micron.

10. The system according to any one of claims 1 to 9, wherein the transmitter further comprises: a transmitter fiber array configured to transmit respective light beams from respective transmitter fibers of the transmitter fiber array to the light beam steering device, and Wherein the one or more metasurface-based optical devices include one or more first emitter metalenses disposed between the emitter optical fiber and the beam steering device.

11. The system of claim 10, wherein the one or more first emitter metalenses are configured as: collimating the light beam emitted from the transmitter optical fiber; and The collimated light beam is directed along different directions to form the one or more transmitted light beams, wherein adjacent transmitted light beams have a predetermined angular spacing.

12. The system of any one of claims 10 to 11, wherein the one or more metasurface-based optical devices further comprise one or more second emitter metalenses configured to: One or more of shifting, shaping, splitting and converging are performed on the one or more transmitted light beams.

13. The system according to any one of claims 1 to 12, wherein the receiver further comprises: Receiver fiber array, wherein the one or more receiver optics are disposed between the beam steering device and the receiver fiber array, and wherein the one or more metasurface-based optical devices include a first receiver metalens; and A detector is optically coupled to the receiver fiber array.

14. The system of claim 13, wherein the first receiver metalens is configured as: The return light formed by scattering or reflecting the one or more transmitted light beams by one or more objects in the field of view is collected.

15. The system of any one of claims 13 to 14, wherein the one or more metasurface-based optical devices further comprise: One or more second receiver metalenses configured to perform one or more of collimation, shifting, shaping, separation, and focusing of the return light.

16. The system according to any one of claims 1 to 15, wherein the receiver further comprises: an optical slit configured to allow a portion of the returning light to pass therethrough; wherein the one or more metasurface-based optical devices further include one or more third metalenses configured to receive the portion of the returned light passing through the optical slit and perform beam homogenization; and A detector is configured to receive the return light after the beam is homogenized.

17. A system according to any one of claims 1 to 16, wherein the one or more steering optical devices include one or more cylindrical structures, each of the cylindrical structures having a surface printed with a subwavelength structure, and the subwavelength structure is configured to redirect the one or more transmitted light beams to the FOV in at least one of the horizontal direction and the vertical direction.

18. A system according to any one of claims 1 to 17, wherein the one or more steering optical devices include a disk-shaped structure having a surface printed with a subwavelength structure, and the subwavelength structure is configured to redirect the one or more transmitted light beams to the FOV in at least one of the horizontal direction and the vertical direction.

19. The system of any one of claims 1 to 18, wherein the transmitter further comprises a vertical cavity surface emitting laser (VCSEL) that transmits the transmitted light beam in a plurality of transmitter channels.

20. The system of claim 19, wherein the VCSEL comprises 30 or more emitter channels such that a scan line of the LiDAR system has an angular resolution of less than 0.5 degrees.

21. The system of any one of claims 1 to 20, wherein the one or more metasurface-based optical devices include a third emitter metalens configured to operate as an emitter lens group to perform coarse and fine collimation of the transmitted light beam.

22. The system of any one of claims 1 to 21, wherein the one or more metasurface-based optical devices include a fourth receiver metalens configured to operate as a receiver lens group to focus the return light; The receiver further comprises: a detector or a multi-element detector array; and An additional spatial or spectral filter structure is arranged in front of the detector element.

23. The system of claim 22, wherein the receiver further comprises a folding mirror having an opening configured to allow the transmitted light beam to pass therethrough to reach the beam steering device.

24. A vehicle comprising a light ranging and detection (LiDAR) system according to any one of claims 1 to 23.

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