LIDAR sensor system

Abstract

The vehicle light detection and ranging (LIDAR) system includes a transmitter, a receiver, one or more scanning optics, and an optical module. The transmitter is configured to output a transmit beam. The receiver includes a first receive grating coupler and a second receive grating coupler. The optical module is configured to receive the transmit beam and provide the transmit beam to the one or more scanning optics, receive a return beam from reflection of the transmit beam by an object, split the return beam into at least a first component and a second component, and direct the first component to the first receive grating coupler and the second component to the second receive grating coupler.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Patent Application No. 17 / 886,398, filed August 11, 2022. The entire disclosure of U.S. Patent Application No. 17 / 886,398 is incorporated herein by reference. [Background technology]

[0002] Optical sensing of distance using lasers, often called mnemonics, and sometimes called "laser RADAR," (Light Detection and Ranging) LIDAR is used in a variety of applications, including imaging and collision avoidance. LIDAR offers finer-scale range resolution with smaller beam sizes than traditional microwave ranging systems such as RADAR (Radio Detection and Ranging). Summary of the Invention

[0003] At least one aspect relates to a light detection and ranging (LIDAR) system, such as a vehicle LIDAR sensor system. The LIDAR system includes a transmitter configured to output a transmit beam. The LIDAR system includes a receiver. The receiver includes a first receive grating coupler and a second receive grating coupler. The LIDAR system includes one or more scanning optics. The LIDAR system includes a circulator. The circulator is configured to receive the transmit beam, direct the transmit beam to the one or more scanning optics, receive a return beam from reflection of the transmit beam by an object, split the return beam into at least a first component and a second component, and direct the first component to the first receive grating coupler and the second component to the second receive grating coupler.

[0004] At least one aspect relates to an autonomous vehicle control system. The autonomous vehicle control system includes a transmitter, a receiver, one or more scanning optics, a circulator, and one or more processors. The transmitter is configured to output a transmit beam. The receiver includes a first receive grating coupler and a second receive grating coupler. The circulator is configured to receive the transmit beam, direct the transmit beam to the one or more scanning optics, receive a return beam from reflection of the transmit beam by an object, split the return beam into at least a first component and a second component, direct the first component to the first receive grating coupler, and direct the second component to the second receive grating coupler. The one or more processors are configured to determine at least one of a distance to the object or a velocity of the object based on the first component and the second component, and control operation of the autonomous vehicle in response to at least one of the distance or velocity.

[0005] At least one embodiment relates to an autonomous vehicle. The autonomous vehicle includes a LIDAR system including a transmitter, a receiver, one or more scanning optics, and a circulator. The transmitter is configured to output a transmit beam. The receiver includes a first receive grating coupler and a second receive grating coupler. The circulator is configured to receive the transmit beam, direct the transmit beam to the one or more scanning optics, receive a return beam from a reflection of the transmit beam by an object, split the return beam into at least a first component and a second component, and direct the first component to the first receive grating coupler and the second component to the second receive grating coupler. The autonomous vehicle includes a steering system, a braking system, and a vehicle controller. The vehicle controller includes one or more processors configured to determine at least one of a distance to the object or a velocity of the object based on the first component and the second component, and control operation of the autonomous vehicle in response to at least one of the distance or velocity.

[0006] At least one embodiment relates to a LIDAR sensor system. The LIDAR sensor system includes a transmitter, a receiver, and an optical module. The transmitter is configured to output a transmit beam. The receiver includes a first receive grating coupler and a second receive grating coupler. The optical module is configured to receive a return beam from reflection of the transmit beam by an object, provide a first component of the return beam to the first receive grating coupler, and provide a second component of the return beam to the second receive grating coupler.

[0007] In some embodiments, the transmit beam has a polarization, and the optical module is further configured to rotate the polarization of the transmit beam, polarize a first component of the return beam so that the polarization of the first component corresponds to the polarization of the transmit beam, and polarize a second component of the return beam so that the polarization of the second component is orthogonal to the polarization of the transmit beam.

[0008] In some embodiments, the LIDAR sensor system includes one or more scanning optics configured to receive the transmit beam from the optics module and output the transmit beam.

[0009] In some embodiments, the LIDAR sensor system includes a chip fabricated from III-V semiconductor materials and on which the transmitter and receiver are implemented.

[0010] In some embodiments, the transmitter includes at least one transmit grating coupler.

[0011] In some embodiments, the first receive grating coupler is a structure etched into the chip or deposited with material on the chip.

[0012] In some embodiments, the optical module includes a first half-wave plate positioned between the transmitter and the one or more scanning optics, a displacer positioned between the half-wave plate and the one or more scanning optics, and a second half-wave plate positioned between the displacer and the one or more scanning optics.

[0013] In some embodiments, the optical module includes a collimator configured to collimate the transmit beam.

[0014] In some embodiments, the LIDAR sensor system includes a local oscillator signal and at least one mixer configured to output a signal based on at least one of the first component of the return beam or the second component of the return beam.

[0015] In some embodiments, the first receiving grating coupler is separated from the transmitter by a first distance corresponding to a time delay associated with a target distance for detecting the object, and the second receiving grating coupler is separated from the transmitter by a second distance corresponding to the time delay and a displacement of the second component relative to the first component due to the optical module.

[0016] In some embodiments, the first receiving grating coupler receives at least about 50% of the first component of the return beam, and the second receiving grating coupler receives at least about 50% of the second component of the return beam.

[0017] In some embodiments, the optical module includes a displacer fabricated from LiNbO3 and having a thickness between about 0.53 millimeters and about 0.65 millimeters. The displacer may be disposed between the transmitter and one or more scanning optics and configured to displace the second component of the return beam by about 18 to about 22 micrometers.

[0018] In some embodiments, the transmitter is mounted on a chip and configured to output a transmit beam at a predetermined angle from the plane of the chip.

[0019] At least one embodiment relates to an autonomous vehicle control system including a transmitter, a receiver, an optical module, and one or more processors. The transmitter is configured to output a transmit beam. The receiver includes a first receive grating coupler and a second receive grating coupler, and the optical module is configured to receive a return beam from a reflection of the transmit beam by an object and direct a first component of the return beam to the first receive grating coupler and a second component of the return beam to the second receive grating coupler. The one or more processors are configured to determine at least one of a distance to the object or a velocity of the object based on the first and second components and control operation of the autonomous vehicle in response to at least one of the distance or velocity.

[0020] In some embodiments, the autonomous vehicle control system includes a modulator configured to apply at least one of frequency modulation or phase modulation to a beam output by the transmitter as a transmit beam.

[0021] In some embodiments, the transmit beam has a polarization, and the circulator is further configured to rotate the polarization of the transmit beam, polarize a first component of the return beam so that the polarization of the first component corresponds to the polarization of the transmit beam, and polarize a second component of the return beam so that the polarization of the second component is orthogonal to the polarization of the transmit beam.

[0022] In some embodiments, the first receiving grating coupler is spaced a first distance from the transmitter, the first distance corresponding to a time delay associated with a target distance for detecting the object, and the second receiving grating coupler is spaced a second distance from the transmitter, the second distance corresponding to the time delay and a displacement of the second component relative to the first component by the optical module.

[0023] At least one embodiment relates to an autonomous vehicle including a LIDAR sensor system, a steering system, a braking system, and a vehicle controller. The LIDAR sensor system includes a transmit grating coupler configured to output a transmit beam, a first receive grating coupler, a second receive grating coupler, and an optical module configured to receive a return beam from a reflection of the transmit beam by an object and to direct a first component of the return beam to the first receive grating coupler and a second component of the return beam to the second receive grating coupler. The vehicle controller further includes one or more processors configured to determine at least one of a distance to the object or a velocity of the object using the first and second components, and to control operation of at least one of the steering system or the braking system in response to at least one of the distance or the velocity.

[0024] In some embodiments, the LIDAR sensor system includes one or more scanning optics configured to receive the transmit beam from the optics module and output the transmit beam.

[0025] In some embodiments, the LIDAR sensor system includes a chip fabricated from III-V semiconductor materials and on which the transmitter and receiver are implemented.

[0026] Those skilled in the art will appreciate that this summary is for illustrative purposes only and is not intended to be limiting in any way. Any feature described herein may be used with any other feature, and any subset of these features may be used in combination, according to various embodiments. Other aspects, inventive features, and advantages of the apparatus and / or processes described herein, as defined solely by the claims, will become apparent from the detailed description set forth herein and taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0027] Embodiments are illustrated by way of example, and not limitation, in the accompanying figures in which like reference numerals refer to similar elements and in which:

[0028] [Figure 1] FIG. 1 is a block diagram illustrating an example of a system environment for an autonomous vehicle.

[0029] [Figure 2] FIG. 1 is a block diagram illustrating an example system environment for an autonomous commercial truck vehicle.

[0030] [Figure 3] FIG. 1 is a block diagram illustrating an example system environment for an autonomous commercial truck vehicle.

[0031] [Figure 4] FIG. 1 is a block diagram illustrating an example system environment for an autonomous commercial truck vehicle.

[0032] [Figure 5] FIG. 1 is a block diagram illustrating an example of a LIDAR sensor system.

[0033] [Figure 6] FIG. 1 is a block diagram illustrating an example of an optical module of a LIDAR sensor system.

[0034] [Figure 7] FIG. 1 is a block diagram illustrating an example of a LIDAR sensor system.

[0035] [Figure 8] FIG. 2 is a block diagram illustrating an example of optical components of the system.

[0036] [Figure 9] FIG. 9 is a block diagram illustrating an example of a LIDAR sensor system including the optical components of FIG. 8.

[0037] [Figure 10]FIG. 2 is a block diagram illustrating an example of optical components of the system.

[0038] [Figure 11] FIG. 11 is a block diagram illustrating an example of a LIDAR sensor system including the optical components of FIG.

[0039] [Figure 12] FIG. 2 is a block diagram illustrating an example of optical components of the system.

[0040] [Figure 13] FIG. 2 is a block diagram illustrating an example of optical components of the system.

[0041] [Figure 14] FIG. 2 is a block diagram illustrating an example of optical components of the system.

[0042] [Figure 15] FIG. 15 is a block diagram illustrating an example of a LIDAR sensor system including the optical components of FIG.

[0043] [Figure 16] FIG. 2 is a block diagram illustrating an example of optical components of the system.

[0044] [Figure 17] FIG. 1 is a block diagram showing an example of a circulator. DETAILED DESCRIPTION OF THE INVENTION

[0045] A LIDAR sensor system generates and transmits a beam of light, which an object can reflect or scatter as a return beam corresponding to the transmitted beam. The LIDAR sensor system can receive the return beam and process the return beam or its characteristics to determine parameters related to the object, such as range and velocity. The LIDAR sensor system can apply various frequency or phase modulations to the transmitted beam, which can facilitate correlating the return beam with the transmitted beam to determine parameters related to the object.

[0046] The LIDAR sensor system may include a transmitter, a receiver, one or more scanning optics, and a circulator. The transmitter is configured to output a transmit beam. The receiver includes a first receive grating coupler and a second receive grating coupler. The circulator is configured to receive the transmit beam, direct the transmit beam to the one or more scanning optics, receive a return beam from reflection of the transmit beam by an object, split the return beam into at least a first component and a second component, and direct the first component to the first receive grating coupler and the second component to the second receive grating coupler. The one or more scanning optics may include a mirror that scans across a field of view and outputs the transmit beam that is reflected or scattered by the object as a return beam, which can be used to determine range, velocity, and Doppler information about the object, such as for controlling the operation of an autonomous vehicle.

[0047] The systems and methods disclosed herein can implement LIDAR sensor systems in which the circulator design is assembled with the receive grating coupler along the mechanical scan axis rather than the transmit array axis. This arrangement simplifies the optical design. For example, the circulator optics can be tilted to reduce back-reflection. The tilt of the circulator optics can affect the amount of return beam displacement without affecting the return beam direction. Thus, the grating coupler emission can occur at a larger angle than the tilt of the circulator optics, improving process efficiency. For example, this can allow the circulator optics to be mounted parallel to an integrated chip where the transmitter and receiver are located. However, the benefits of the integrated chip described above are not limited to autonomous vehicles. This could be advantageous for any type of vehicle equipped with a LIDAR sensor. 1. System Environment for Autonomous Vehicles

[0048] FIG. 1 is a block diagram illustrating an example of a system environment for an autonomous vehicle according to some embodiments. FIG. 1 illustrates an exemplary autonomous vehicle 100 in which various technologies disclosed herein can be implemented. For example, vehicle 100 may include a prime mover 104 powered by an energy source 106, a powertrain 102 that can power a drivetrain 108, and a control system 110 that includes directional control 112, powertrain control 114, and brake control 116. Vehicle 100 can be implemented in a variety of forms, including vehicles capable of transporting people and / or cargo and operating in a variety of environments. The aforementioned components 102-116 can vary widely based on the type of vehicle in which they are used, such as a passenger car, a van, a truck, and a wheeled land vehicle such as a bus. Prime mover 104 may include one or more electric motors and / or an internal combustion engine (among other things). The energy source may include, for example, a fuel system (e.g., providing gasoline, diesel, hydrogen, etc.), a battery system, solar panels or other renewable energy sources, and / or a fuel cell system. Drivetrain 108 includes wheels and / or tires along with a transmission and / or any other mechanical drive components suitable for converting the power output of prime mover 104 into vehicle motion, one or more brakes configured to controllably stop or slow vehicle 100, and a steering or steering component suitable for controlling the trajectory of vehicle 100 (e.g., a rack and pinion steering linkage that causes one or more wheels of vehicle 100 to pivot about a generally vertical axis, thereby changing the angle of the plane of rotation of the wheel relative to the vehicle's longitudinal axis). In some embodiments, a combination of powertrain and energy source can be used (e.g., in the case of an electric / gas hybrid vehicle), and in some embodiments, multiple electric motors (e.g., dedicated to individual wheels or axles) can be used as prime mover 104.

[0049] Directional control 112 may include one or more actuators and / or sensors for controlling and receiving feedback from directional or steering components to enable vehicle 100 to follow a desired trajectory. Powertrain control 114 is configured to control the speed and / or direction of vehicle 100 by controlling the output of powertrain 102, such as by controlling the output power of prime mover 104 and controlling the gears of a transmission in drivetrain 108. Brake control 116 may be configured to control one or more brakes, such as disc or drum brakes coupled to the wheels of the vehicle, to slow or stop vehicle 100.

[0050] Other vehicle types, including, but not limited to, off-road vehicles, all-terrain or tracked vehicles, construction equipment, etc., may use different powertrains, drivetrains, energy sources, directional control, powertrain control, and brake control. Additionally, in some embodiments, some of the components may be combined, for example, directional control of the vehicle is primarily handled by varying the output of one or more prime movers.

[0051] The various levels of autonomous driving control for vehicle 100 are embodied in vehicle control system 120, which may include one or more processors 122 and one or more memories 124, each configured to execute program code instructions 126 stored in memory 124. The processors may include, for example, graphics processing units (GPU(s)) and / or central processing units (CPU(s)).

[0052] The sensors 130 may include various sensors suitable for collecting information from the vehicle's environment for use in controlling the operation of the vehicle 100. For example, the sensors 130 may include a radar sensor 134, a LIDAR sensor 136, a 3D positioning sensor 138, such as an accelerometer, a gyroscope, a magnetometer, or a satellite navigation system such as GPS (Global Positioning System), GLONASS (Globalnaya Navigazionnaya Sputnikovaya Sistema, or Global Navigation Satellite System), BeiDou Navigation Satellite System (BDS), Galileo, or Compass. The 3D positioning sensor 138 can be used to determine the vehicle's position on Earth using satellite signals. The sensors 130 may include a camera 140 and / or an inertial measurement unit (IMU) 142. The camera 140 may be a monographic or stereographic camera and may record still and / or video images. The IMU 142 may include multiple gyroscopes and accelerometers capable of detecting linear and rotational motion of the vehicle in three directions. One or more encoders 144, such as wheel encoders, may be used to monitor the rotation of one or more wheels of the vehicle 100. Each sensor 130 may output sensor data at a variety of data rates that may differ from the data rates of the other sensors 130.

[0053] The outputs of the sensors 130 may be provided to a series of control subsystems 150, including a position estimation subsystem 152, a planning subsystem 156, a perception subsystem 154, and a control subsystem 158. The position estimation subsystem 152 may perform functions such as precisely determining the position and orientation (also sometimes referred to as “pose”) of the vehicle 100 within its surrounding environment, and generally within some frame of reference. The autonomous vehicle's position can be compared to the positions of additional vehicles in the same environment as part of generating labeled autonomous vehicle data. The perception subsystem 154 may perform functions such as detecting, tracking, determining, and / or identifying objects in the environment surrounding the vehicle 100. Machine learning models, according to some embodiments, may be utilized to track the objects. The planning subsystem 156 may perform functions such as planning a trajectory or path of travel for the vehicle 100 over some time frame given a desired destination, as well as primarily static and moving objects in the environment. Machine learning models, according to some embodiments, may be utilized to plan the vehicle trajectory. The control subsystem 158 may perform functions such as generating appropriate control signals to control various controls within the vehicle control system 120 to implement a planned trajectory for the vehicle 100. Machine learning models may be utilized to generate one or more signals to control the autonomous vehicle to implement a planned trajectory.

[0054] Multiple sensors of the type shown in FIG. 1 can be used for redundancy and / or to cover various areas around the vehicle, and other types of sensors can be used. Various types and / or combinations of control subsystems can be used. Some or all of the functionality of subsystems 152-158 can be embodied in program code instructions 126 resident in one or more memories 124 and executed by one or more processors 122, and in some cases, these subsystems 152-158 can be implemented using the same processor and / or memory. Subsystems can be implemented, at least in part, using various dedicated circuit logic, various processors, various field programmable gate arrays (FPGAs), various application-specific integrated circuits (ASICs), various real-time controllers, etc., and, as previously described, multiple subsystems can use circuits, processors, sensors, and / or other components. Additionally, the various components of vehicle control system 120 can be networked in various manners.

[0055] In some embodiments, vehicle 100 may further include a secondary vehicle control system (not shown) that may be used as a redundant or backup control system for vehicle 100. In some embodiments, the secondary vehicle control system may be capable of fully operating autonomous vehicle 100 in the event of an adverse event occurring in vehicle control system 120, while in other embodiments, the secondary vehicle control system may have only limited functionality, such as shutting down vehicle 100 in response to an adverse event detected by primary vehicle control system 120. In still other embodiments, the secondary vehicle control system may be omitted.

[0056] The various components shown in FIG. 1 can be implemented using many different architectures, including various combinations of software, hardware, circuit logic, sensors, and networks. Each processor can be implemented, for example, as a microprocessor, and each memory can represent a random access memory (RAM) device, including main memory and any secondary levels of memory, such as cache memory, non-volatile or backup memory (e.g., programmable or flash memory), read-only memory, etc. Each memory can also be considered to include memory storage devices physically located elsewhere in vehicle 100, such as any cache memory within the processor, as well as any storage capacity used as virtual memory, such as stored in a mass storage device or other computer controller. One or more of the processors shown in FIG. 1, or entirely separate processors, can be used to implement additional functions within vehicle 100 other than those for autonomous driving control, such as operation of entertainment system control, doors, lighting, convenience functions, etc.

[0057] Also, for additional storage, vehicle 100 may include one or more mass storage devices, such as a removable disk drive, a hard disk drive, a direct access storage device (DASD), an optical drive (e.g., a CD drive, a DVD drive, etc.), a solid state storage drive (SSD), network attached storage, a storage area network, and / or a tape drive, among others.

[0058] Vehicle 100 may also include a user interface 164, such as one or more displays, touchscreens, voice and / or gesture interfaces, buttons and other tactile controls, etc., that allows vehicle 100 to receive a number of inputs from a user or operator and generate outputs for the user or operator. Alternatively, user input may be received via an app or web interface on another computer or electronic device, such as a mobile device.

[0059] Vehicle 100 may also include one or more network interfaces, such as network interface 162, suitable for communication with one or more networks 170 (e.g., local area networks (LANs), wide area networks (WANs), wireless networks, and / or the Internet) to allow communication of information with other computers and electronic devices. The communication of information may include, for example, a central service, such as a cloud service, from which vehicle 100 receives environmental and other data used to control the vehicle's autonomous driving. Data collected by one or more sensors 130 may be uploaded via network 170 to computing system 172 for further processing. In some embodiments, a timestamp may be added to each instance of vehicle data before uploading.

[0060] 1 and the various additional controllers and subsystems disclosed herein generally operate under the control of an operating system, as described in more detail below, and execute or rely on various computer software applications, components, programs, objects, modules, data structures, etc. Furthermore, the various applications, components, programs, objects, modules, etc. may execute on one or more processors of other computers coupled to vehicle 100 via network 170, e.g., in a distributed, cloud-based, or client-server computing environment, such that the processing required to implement the functionality of a computer program is allocated across multiple computers and / or services via the network.

[0061] Generally, the routines executed to implement the various embodiments described herein, whether embodied as part of an operating system, a specific application, component, program, object, module, or sequence of instructions, or any subset thereof, are referred to herein as "program code." Program code may reside in various memories and storage devices at various times and, when read and executed by one or more processors, may comprise one or more instructions that perform the steps necessary to perform the steps or elements embodying various aspects of the present disclosure. Furthermore, while embodiments include, and will be described hereinafter in the context of, fully functional computers and systems, it will be understood that the various embodiments described herein can be distributed as program products in various forms, and that the embodiments can be embodied independently of the particular type of computer-readable medium used to actually effect such distribution.

[0062] Examples of computer-readable media include tangible, non-transitory media such as volatile and non-volatile memory devices, floppy and other removable disks, solid-state drives (SSDs), hard disk drives, magnetic tape, and optical disks (e.g., CD-ROMs, DVDs, etc.), among others.

[0063] Additionally, various program code described below may be identified based on the application for which it is embodied in a particular embodiment. However, any particular program nomenclature below is used merely for convenience, and thus the present disclosure should not be limited to use with only any particular application identified and / or implied by such nomenclature. Furthermore, the manner in which computer programs may be organized into routines, procedures, methods, modules, objects, etc. is generally endless, and it should be understood that the present disclosure is not limited to the specific structure and allocation of program functionality described herein, given the various ways in which program functionality may be allocated among the various software layers residing within a typical computer (e.g., operating system, libraries, APIs, applications, applets, etc.). 2. LIDAR for automotive applications

[0064] The truck may include a LIDAR system (e.g., vehicle control system 120 of FIG. 1 , LIDAR sensor system 500 of FIG. 5 , among others described herein). In some embodiments, the LIDAR sensor system 500 uses frequency modulation to encode an optical signal and can scatter the encoded optical signal into free space using an optical system. By detecting the frequency difference between the encoded optical signal and a return signal reflected from an object, a frequency-modulated (FM) LIDAR sensor system can determine the object's position using the Doppler effect or precisely measure the object's velocity. In some embodiments, the FM LIDAR sensor system can use continuous wave (referred to as "FMCW LIDAR") or quasi-continuous wave (referred to as "FMQW LIDAR"). In some embodiments, the LIDAR sensor system can use phase modulation (PM) to encode an optical signal and can scatter the encoded optical signal into free space using an optical system.

[0065] In some cases, an object (e.g., a pedestrian wearing dark clothing) may have low reflectivity in that only a small amount (e.g., 10% or less) of the light that strikes the object is reflected back to the FM or PM LIDAR system's sensor (e.g., sensor 130 in FIG. 1 ). In other cases, an object (e.g., a shiny road sign) may have high reflectivity (e.g., 10% or more) in that a large amount of the light that strikes the object is reflected back to the FM LIDAR system's sensor.

[0066] Regardless of the object's reflectivity, FM LIDAR systems can detect (e.g., classify, recognize, locate, etc.) objects at greater distances (e.g., twice as far) than conventional LIDAR systems. For example, FM LIDAR systems can detect low-reflectivity objects at distances of over 300 meters and high-reflectivity objects at distances of over 400 meters.

[0067] To achieve this improvement in detection capabilities, FM LIDAR systems can use sensors (e.g., sensor 130 in FIG. 1). In some embodiments, these sensors can be sensitive to single photons, meaning the sensors can detect the smallest possible amount of light. In some applications, FM LIDAR systems can use infrared wavelengths (e.g., 950 nm, 1550 nm, etc.), but are not limited to infrared wavelength ranges (e.g., near-infrared: 800 nm to 1500 nm, mid-infrared: 1500 nm to 5600 nm, and far-infrared: 5600 nm to 1,000,000 nm). By operating an FM or PM LIDAR system at infrared wavelengths, the FM or PM LIDAR system can broadcast stronger light pulses or beams than traditional LIDAR systems.

[0068] Therefore, by detecting objects at greater distances, FM LIDAR systems have more time to react to unexpected obstacles. Indeed, even a few additional milliseconds can improve response time and comfort, especially for large vehicles (e.g., commercial trucks) traveling on highways.

[0069] FM LIDAR systems can instantly provide accurate velocity for each data point. In some embodiments, velocity measurement is achieved using the Doppler effect, which shifts the frequency of light received from an object based on at least one of the radial velocity (e.g., the direction vector between the detected object and the sensor) or the frequency of the laser signal. For example, for speeds occurring in road conditions where speeds are less than 100 m / s, this shift at a 1550 nm wavelength corresponds to a frequency shift of less than 130 MHz. This frequency shift is small and difficult to detect directly in the optical domain. However, by utilizing coherent detection in FMCW, PMCW, or FMQW LIDAR systems, the signal can be converted to the RF domain so that the frequency shift can be calculated using various signal processing techniques. This allows autonomous vehicle control systems to process the received data more quickly.

[0070] Instantaneous velocity calculations also make it easier for an FM LIDAR system to determine distant or sparse data points as objects and / or track how these objects are moving over time. For example, an FM LIDAR sensor (e.g., sensor 130 in FIG. 1) may receive only a few returns (e.g., a collision) for an object 300 m away, but if these returns provide a velocity value of interest (e.g., heading toward the vehicle at a speed greater than 70 mph), the FM LIDAR system and / or autonomous vehicle control system can determine individual weights for the probability associated with the object.

[0071] The faster identification and / or tracking of an FM LIDAR system provides the autonomous vehicle control system with more time to maneuver the vehicle. With a better understanding of how fast an object is moving, the autonomous vehicle control system can better plan a response.

[0072] FM LIDAR systems can be less static than traditional LIDAR systems. That is, traditional LIDAR systems, which are designed to be more sensitive to light, typically do not work properly in bright sunlight. Such systems tend to suffer from crosstalk (e.g., when sensors are confused by each other's light pulses or light beams) and self-interference (e.g., when sensors are confused by previous light pulses or light beams). To overcome this drawback, vehicles using traditional LIDAR systems often require additional hardware, complex software, and / or more computing power to manage this "noise."

[0073] In contrast, FM LIDAR systems do not experience these types of problems because each sensor is specifically designed to respond only to its own unique light characteristics (e.g., light beams, light waves, light pulses). If the returning light does not match the timing, frequency, and / or wavelength of the originally transmitted light, the FM sensor can filter (e.g., remove, ignore, etc.) that data point. This allows FM LIDAR systems to compute (e.g., generate, derive, etc.) more accurate data with fewer hardware or software requirements, resulting in a smoother driving experience.

[0074] FM LIDAR systems are more easily scalable than traditional LIDAR systems. As more autonomous vehicles (e.g., cars, commercial trucks, etc.) appear on the road, vehicles powered by FM LIDAR systems will not have to face interference issues due to sensor crosstalk. FM LIDAR systems also use less optical peak power than traditional LIDAR sensors. This allows some or all of the optical components for FM LIDAR to be fabricated on a single chip, which provides unique advantages as discussed herein. 2.1 Commercial Trucking

[0075] FIG. 2 is a block diagram illustrating an example of a system environment for autonomous commercial trucks, according to some embodiments. The environment 100B includes a commercial truck 102B for carrying cargo 106B. In some embodiments, the commercial truck 102B may include a vehicle configured for long-haul freight transportation, regional freight transportation, intermodal freight transportation (i.e., a road-based vehicle is used as one of several modes of transportation to transport cargo), and / or any other road-based freight transportation application. In some embodiments, the commercial truck 102B may be a flatbed truck, a refrigerated truck (e.g., a reefer truck), a ventilated van (e.g., a dry van), a moving truck, etc. In some embodiments, the cargo 106B may be goods and / or products. In some embodiments, the commercial truck 102B may include a trailer for carrying the cargo 106B, such as a flatbed trailer, a lowboy trailer, a step deck trailer, an extendable flatbed trailer, a side kit trailer, etc.

[0076] The environment 100B includes an object 110B (shown in FIG. 2 as another vehicle) within a distance range of 30 meters or less from the truck.

[0077] The commercial truck 102B may include a LIDAR system 104B (e.g., an FM LIDAR system, the vehicle control system 120 of FIG. 1 , the LIDAR sensor system 500 of FIG. 5 ) for determining the distance to the object 110B and / or measuring the speed of the object 110B. While FIG. 2 shows one LIDAR system 104B mounted on the front of the commercial truck 102B, the number of LIDAR systems and the mounting areas of the LIDAR systems on the commercial truck are not limited to a particular number and area. The commercial truck 102B may include any number of LIDAR systems 104B (or components thereof, such as sensors, modulators, coherent signal generators, etc.) mounted on any area (e.g., the front, back, sides, top, bottom, lower, bottom, and / or bottom) to facilitate detection of objects in any free space for the commercial truck 102B.

[0078] As shown, the LIDAR system 104B in the environment 100B may be configured to detect objects (e.g., other vehicles, bicycles, trees, road signs, potholes, etc.) at a short distance (e.g., 30 meters or less) from the commercial truck 102B.

[0079] 3 is a block diagram illustrating an example of a system environment for autonomous commercial trucks, according to some embodiments. Environment 100C includes the same components included in environment 100B (e.g., commercial truck 102B, cargo 106B, LIDAR system 104B, etc.).

[0080] Environment 100C includes object 110C (shown in FIG. 3 as other vehicle) within a distance range of (i) 30 meters or more and (ii) 150 meters or less from commercial truck 102B. As shown, LIDAR system 104B in environment 100C may be configured to detect objects (e.g., other vehicles, bicycles, trees, road signs, potholes, etc.) within a predetermined distance (e.g., 100 meters) from commercial truck 102B.

[0081] 4 is a block diagram illustrating an example of a system environment for autonomous commercial trucks, according to some embodiments. Environment 100D includes the same components included in environment 100B (e.g., commercial truck 102B, cargo 106B, LIDAR system 104B, etc.).

[0082] Environment 100D includes object 110D (shown as other vehicle in FIG. 4) within a distance range of more than 150 meters from commercial truck 102B. As shown, LIDAR system 104B in environment 100D may be configured to detect objects (e.g., other vehicles, bicycles, trees, road signs, potholes, etc.) within a predetermined distance (e.g., 300 meters) from commercial truck 102B.

[0083] In commercial trucking applications, effective object detection at all ranges is important due to increased weight and correspondingly longer stopping distances required for vehicles. FM LIDAR systems (e.g., FMCW and / or FMQW systems) or PM LIDAR systems are ideally suited for commercial trucking applications due to the advantages discussed above. Ultimately, commercial trucks equipped with such systems can be improved in their ability to safely transport both people and goods over short or long distances. In various embodiments, these FM or PM LIDAR systems can be used in semi-autonomous applications, where a driver is onboard the commercial truck and some functions of the commercial truck are operated autonomously using the FM or PM LIDAR system, or in fully autonomous applications, where the commercial truck is operated entirely by the FM or LIDAR system alone or in combination with other vehicle systems. 3. LIDAR sensor system

[0084] FIG. 5 illustrates an example of a LIDAR sensor system 500. The LIDAR sensor system 500 can be used to determine parameters related to an object, such as distance and velocity, and output the parameters to a remote system. For example, the LIDAR sensor system 500 can output the parameters for use by a vehicle controller (e.g., vehicle controller 598) that can control the operation of the vehicle in response to the received parameters, or a display that can show a representation of the parameters. The LIDAR sensor system 500 can be a coherent detection system. The LIDAR sensor system 500 can be used to embody various features and components of the systems described with reference to FIGS. 1-4. The LIDAR sensor system 500 can include components for various detection approaches to operate as an amplitude modular LIDAR system or a coherent LIDAR system. The LIDAR sensor system 500 can be used to perform time-of-flight distance determination. In some embodiments, various components or combinations of components of LIDAR sensor system 500, such as laser source 504 and modulator 514, may be within the same housing, provided on the same circuit board or other electronic components, or may be otherwise incorporated. In some embodiments, various components or combinations of components of LIDAR system 500 may be provided as separate components, using optical coupling (e.g., optical fiber) in the case of components that generate and / or receive optical signals, such as light beams, or wired or wireless electronic connections in the case of components that generate and receive electrical (e.g., data) signals.

[0085] The LIDAR sensor system 500 may include a laser source 504 that generates and emits a beam 506, such as a carrier light beam. A splitter 508 may split the beam 506 into a beam 510 and a reference beam 512 (e.g., a reference signal). In some embodiments, any suitable optical, electronic, or optoelectronic component may be used to provide the beam 510 and the reference beam 512 from the laser source 504 to other components.

[0086] The modulator 514 may modulate one or more attributes of the input beam 510 to generate the beam 516 (e.g., the target beam). In some embodiments, the modulator 514 may modulate the frequency of the input beam 510 (e.g., an optical frequency corresponding to an optical wavelength, where c = λν, where c is the speed of light, λ is the wavelength, and ν is the frequency). For example, the modulator 514 may linearly modulate the frequency of the input beam 510, such that the frequency of the beam 516 increases or decreases linearly over time. As another example, the modulator 514 may nonlinearly (e.g., exponentially) modulate the frequency of the input beam 510. In some embodiments, the modulator 514 may modulate the phase of the input beam 510 to generate the beam 516. However, the modulation technique is not limited to frequency modulation and phase modulation. Any suitable modulation technique may be used to modulate one or more attributes of the beam. Returning to FIG. 5, modulator 514 can modulate beam 510 following splitting of beam 506 by splitter 508 so that reference beam 512 is unmodulated, or modulator 514 can modulate beam 506 and provide the modulated beam to splitter 508 so that splitter 508 splits it into a target beam and a reference beam.

[0087] The beam 516 used to output the transmitted signal may have most of the energy of the beam 506 output by the laser source 504, and the reference beam 512 may have much less energy but still have enough energy to allow mixing with the return beam 548 (e.g., returned light) scattered from the object. The reference beam 512 may be used as a local oscillator (LO) signal. The reference beam 512 may pass through a reference path and be provided to a mixer 560. An amplifier 520 may amplify the beam 516 to output a beam 522.

[0088] The LIDAR sensor system 500 may include an optical module 524 that can receive the beam 522. The optical module 524 may be a free-space optical system. For example, the optical module 524 may include one or more optical systems (e.g., lenses, mirrors, waveguides, grating couplers, prisms, wave plates) arranged with a spacing (e.g., an air gap) between the one or more optical systems, thereby enabling free-space transmission of light (e.g., not all light is coupled between the optical systems by optical fibers). The optical module 524 may perform functions such as collimating, filtering, and / or polarizing the beam 522 and output the beam 530 to an optical system (e.g., a scanning optical system).

[0089] 6, the optical module 524 may include at least one collimator 604 and at least one circulator 608. For example, the circulator 608 may be located between the collimator 604 and the optical system 532 of FIG. 5. The circulator 608 may receive the collimated beam 612 output by the collimator 604 and output a beam 616 (e.g., the beam 530 shown in FIG. 5) to the optical system 532. In some embodiments, the circulator 608 may be located between the laser source 504 and the collimator 604. At least one of the collimator 604 or the circulator 608 may be a free-space optical system (coupling with each other in free space), e.g., optically coupled via an air gap rather than an optical fiber.

[0090] 5, optics module 524 can receive return beam 548 from optics 532 and provide return beam 548 to mixer 560. Optics 532 can be a scanning optic, such as one or more steering mirrors or polygon reflectors or deflectors that adjust the angle of the received beam relative to the output beam based on the orientation of an outer surface (e.g., facet) of the optics relative to the received beam, or solid-state components (e.g., phased arrays, electro-optic crystals) configured to modify the direction of the received light.

[0091] The optical system 532 can define a field of view 544 that corresponds to the angle scanned (e.g., swept) by the beam 542 (e.g., the transmitted beam). For example, the beam 542 can be scanned in a particular plane, such as an azimuth plane or an elevation plane (e.g., relative to an object to which the LIDAR sensor system 500 is coupled, such as an autonomous vehicle). The optical system 532 can be oriented such that the field of view 544 sweeps the azimuth plane relative to the optical system 532.

[0092] At least one motor 540 may be coupled to the optical system 532 to control at least one of the position or orientation of the optical system 532 relative to the beam 530. For example, if the optical system 532 includes a reflector or deflector, the motor 540 may change the angle or orientation of the beam 542 as it exits the optical system 532 by rotating the optical system 532 so that the surface of the optical system 532 where the beam 530 is received changes angle or orientation relative to the beam 530.

[0093] Beam 542 may be output from optical system 532 and may be reflected or scattered by an object (not shown) and reflected as return beam 548 (e.g., a return signal). Return beam 548 may be received in a receive path, which may include circulator 528, and provided to mixer 560.

[0094] Mixer 560 may be an optical hybrid, such as a 90-degree optical hybrid. Mixer 560 may receive reference beam 512 and return beam 548, mix reference beam 512 and return beam 548, and output signal 564 responsive to reference beam 512 and return beam 548. Signal 564 may include an in-phase (I) component 568 and a quadrature (Q) component 572.

[0095] LIDAR sensor system 500 may include a receiver 576 that receives signal 564 from mixer 560. Receiver 576 may generate signal 580, which may be an electronic (e.g., radio frequency) signal, in response to signal 564. Receiver 576 may include one or more photodetectors that output signal 580 in response to signal 564.

[0096] The LIDAR sensor system 500 may include a processing system 590, which may be implemented using features of the vehicle control system 120 described with reference to FIG. 1 . The processing system 590 may process data received associated with the return beam 548, such as signal 580, to determine parameters related to the object, such as range and velocity. The processing system 590 may include a scanner controller 592 that may provide scan signals to control operation of the optical system 532, such as controlling the motor 540 to rotate the optical system 532 to achieve a target scan pattern, such as a sawtooth scan pattern or a step function scan pattern. The processing system 590 may include a Doppler compensator 594 that may determine the sign and magnitude of a Doppler shift associated with processing the return beam 548 and determine a corrected range based thereon, along with other corrections. The processing system 590 may include a modulator controller 596 that may send one or more electrical signals to drive the modulator 514.

[0097] The processing system 590 may include or be communicatively coupled to a vehicle controller 598 to control the operation of a vehicle in which the LIDAR sensor system 500 is installed (e.g., to provide fully autonomous or semi-autonomous control of the vehicle). For example, the vehicle controller 598 may be implemented by at least one of the LIDAR sensor system 500 or the vehicle's control circuitry. The vehicle controller 598 may control the operation of the vehicle in response to at least one of the distance to an object or the velocity of the object determined by the processing system 590. For example, the vehicle controller 598 may send control signals to at least one of the vehicle's steering system or braking system to control at least one of the vehicle's speed or direction. 3-1. LIDAR sensor system including a grating coupler for multi-directional reception

[0098] Figure 7 shows a block diagram of one embodiment of a LIDAR sensor system 700. The LIDAR sensor system 700 can incorporate features of the LIDAR sensor system 500 and the optical module 524 described with reference to Figures 5 and 6, respectively. The LIDAR sensor system 700 facilitates pitch-catch correction, i.e., accounting for time delays or other offsets that occur on the round-trip path of a transmit beam output from the LIDAR sensor system 700, reflected or scattered by an object, and then returned to the LIDAR sensor system 700 for detection and processing, which can affect characteristics of the LIDAR sensor system 700, such as the signal-to-noise ratio.

[0099] The LIDAR sensor system 700 may include a chip 705 that includes a transmitter 710 and a receiver 712 and can include various components of the LIDAR sensor system 700. For example, the chip 705 may be an integrated optical chip, and various components of the LIDAR sensor system 700 for generating, modulating, and processing optical signals, and performing optical computing may be implemented by the chip 705. The chip 705 may be a semiconductor circuit chip. The chip 705 may be fabricated from at least one III-V semiconductor material. For example, the chip 705 may be fabricated from a silicon material or pure silicon. The chip 705 may be fabricated from gallium nitride. The chip 705 may be fabricated from aluminum nitride. The chip 705 may be fabricated from gallium nitride and pure silicon.

[0100] The LIDAR sensor system 700 includes at least one transmitter 710. The transmitter 710 can receive a beam (e.g., the various beams described with reference to FIGS. 5 and 6) and output a transmit beam 735 having particular characteristics, such as direction, polarization, or various combinations thereof.

[0101] The transmitter 710 may include at least one grating coupler 715 (e.g., a first grating coupler). The grating coupler 715 may be a structure having multiple spaced apart channels, such as parallel channels, which may have various shapes of the same or different sizes. The grating coupler 715 may be a structure formed by etching on the chip 705. The grating coupler 715 may be a structure formed by depositing material on the chip 705.

[0102] The grating coupler 715 may be configured to couple light out of the chip 705 and emit it into free space away from the chip 705. For example, the grating coupler 715 may couple light out of the chip 705 in a two-dimensional pattern, such as a two-dimensional polarization. Thus, the grating coupler 715 may output a transmit beam 735 based on the beam output by the laser source 504.

[0103] The grating coupler 715 can output a transmit beam 735 having a transmit polarization 795. For example, various components upstream or downstream of the grating coupler 715 (e.g., the optical module 524) can be used to control the polarization of the transmit beam 735.

[0104] The LIDAR sensor system 700 may include at least one scanner 740, such as a steering mirror. For example, and referring briefly to FIG. 5, the scanner 740 may be coupled to a motor 540 such that the scanner 740 can rotate relative to the direction in which the transmit beam 735 is pointed at the scanner 740.

[0105] The scanner 740 can scan bidirectionally. For example, the scanner 740 can scan in a first direction 760 and a second direction 765 (e.g., based on axis 534 described with reference to FIG. 5 ). The scanner 740 can receive a transmit beam 735 from the transmitter 710 and direct the transmit beam 735 toward the environment surrounding the LIDAR sensor system 700. As shown in FIG. 7 , an object 702 can be present in the environment. The scanner 740 can receive a return beam 755 from the reflection or scattering of the transmit beam 735 by the object 702. During the time it takes for the transmit beam 735 to reach the object 702 and for the return beam 755 to return from the object 702 to the scanner 740, the scanner 740 can be rotated by a certain angle, as discussed further below. The scanner 740 can provide the return beam 755 to the receiver 712.

[0106] The receiver 712 may include multiple grating couplers. For example, the receiver 712 may include a grating coupler 725 and a grating coupler 730. The grating couplers 725, 730 may be provided or formed in a manner similar to or the same as the grating coupler 715. The grating couplers 715, 725, 730 may be arranged in an array on the chip 705 (e.g., at least two parallel, spaced-apart lines may extend through each grating coupler 715, 725, 730). The grating couplers 715, 725, 730 may be positioned in at least one focal plane of the scanner 740 or in one or more optical components between the grating couplers 715, 725, 730 and the scanner 740.

[0107] The grating couplers 725, 730 may be spaced apart from the grating coupler 715. For example, the grating coupler 725 may be spaced apart from the grating coupler 715 by a first spacing (e.g., a first distance). The first spacing may be associated with a first target distance of the scanner 740 for detecting the object 702. For example, the first target distance may be within a distance range from the scanner 740 at which an expected signal-to-noise ratio for determining at least one of the distance or velocity of the object 702 is greater than a threshold signal-to-noise ratio. The first spacing may be between approximately 12 micrometers (μm) and approximately 16 μm. For example, the grating coupler 725 may be spaced apart from the grating coupler 715 by approximately 14 μm.

[0108] Grating coupler 730 may be spaced apart from grating coupler 715 by a second spacing (e.g., a second distance). The second spacing may be related to a second target distance of scanner 740. The second target distance may be greater than the first target distance. The second spacing may be between about 10 μm and about 20 μm. For example, grating coupler 730 may be spaced apart from grating coupler 715 by a spacing of about 12 micrometers.

[0109] The grating couplers 725, 730 may receive a return beam 755 provided by the scanner 740. The grating couplers 725, 730 may couple light, e.g., the return beam 755, into the tip 705 in free space. As previously mentioned, the scanner 740 may rotate during the time it takes for the transmit beam 735 to travel to the object 702 and return to the receiver 712 as the return beam 755, which results in an angular displacement of the return beam 755 in the direction scanned by the scanner 740. The angular displacement may appear as a translation in the focal plane when the return beam 755 is provided to the receiver 712. This translation may be referred to as focal plane drift. The grating couplers 725, 730 may couple light at the tip 705, and because they are distinct and spatially separated from one another, the grating couplers 725, 730 may provide for two directions of focal plane drift. Furthermore, the translation distance can be optimized for a target time for the transmit beam 735 to travel to the object 702 and the return beam 755 to return from the object 702 to the receiver 712, and therefore for a particular distance to the object 702 (since the velocities of the transmit beam 735 and return beam 755 are known).

[0110] The return beam 755 may have components associated with different polarizations based on how the transmit beam 735 is output and / or passes through a device such as the optical module 524. Thus, the scanner 740 may provide a first component 770 of the return beam 755 that may be associated with a first polarization 780, and the grating coupler 725 may receive the first component 770 of the return beam 755. The scanner 740 may provide a second component 775 of the return beam 755 that is associated with a second polarization 785, and the grating coupler 730 may receive the second component 775.

[0111] The first polarization 780 can be different from the second polarization 785. The transmit polarization 795 can be the same as the first polarization 780. For example, the grating coupler 715 can output the transmit beam 735 with the first polarization 780. The grating couplers 725, 730 can receive the return beam 755 with either the first polarization 780 or the second polarization 785. The second polarization 785 can be orthogonal to the first polarization 780.

[0112] The grating couplers 725, 730 may be configured to receive only a single polarization of beam (e.g., light). The grating couplers 725, 730 can receive light of different polarizations. For example, the grating coupler 725 can receive light of the same polarization as the polarization of the transmit beam 735, and the grating coupler 730 can receive light of a polarization orthogonal to the polarization of the transmit beam 735. The grating couplers 725, 730 can be configured to receive light of the same polarization as each other. For example, the grating couplers 725, 730 can only receive light of the same polarization as orthogonal to the polarization of the transmit beam 735, as shown in FIG. 7.

[0113] Receiver 712 may output at least one signal based on a first component 770 of return beam 755 received by grating coupler 725 and based on a second component 775 of return beam 755 received by grating coupler 730. The at least one signal output by receiver 712 may be used by various systems described herein, such as vehicle control system 120, to determine at least one of a range or a velocity of object 702, for example, to control operation of the autonomous vehicle responsive to at least one of the range or velocity.

[0114] 8 is a block diagram illustrating an example of optical components of a system 800. System 800 can include and / or be used to implement various LIDAR sensor system components described herein, such as transmitter 710 and receiver 712. For example, system 800 can be used to implement a single polarization receiver and a switched local oscillator.

[0115] 8, the system 800 may include a transmit antenna 810, which may be implemented by a grating coupler 715 in the transmitter 710. For example, the transmit antenna 810 may be an optical antenna integrated on the chip 705. The transmit antenna 810 may couple a transmit beam 735 into free space. The transmit antenna 810 may be oriented at an angle corresponding to the polarization of the transmit beam 735 relative to a surface on which the transmit antenna 810 is provided.

[0116] The system 800 may include a local oscillator 815. The local oscillator 815 may output a local oscillator (LO) signal. For example, the local oscillator 815 may actively switch the LO signal between at least two mixers depending on the scanning direction of the scanner 740, as discussed in further detail below. For example, the local oscillator 815 may output a first LO signal and a second LO signal. The LO signal may be similar to or identical to the reference beam 512. For example, the local oscillator 815 may transmit a first LO signal, e.g., reference beam 820. The local oscillator 815 may transmit a second LO signal, e.g., reference beam 830. By the local oscillator 815 switching the LO signal, the amount of power required by the local oscillator 815 may be reduced.

[0117] The system 800 may include a receive antenna 825 of the receiver 712. The receive antenna 825 may be implemented by a grating coupler 725 of the receiver 712. For example, the receive antenna 825 may be an optical antenna integrated on the chip 705. The receive antenna 825 may couple a first component 770 of the return beam 755 from free space to the chip 705. The receive antenna 825 may be oriented at an angle relative to a surface provided such that the receive antenna 825 corresponds to a first polarization 780 of the first component 770 of the return beam 755.

[0118] The receive antenna 825 can receive the return beam 755. For example, the receive antenna 825 can receive a first component 770 of the return beam 755. Thus, the receive antenna 825 can be oriented with the same polarization as the first component 770 of the return beam 755. For example, the receive antenna 825 can have the same polarization as the first polarization 780. The receive antenna 825 can provide the first component 770 of the return beam 755 to other elements of the system 800, as discussed further below.

[0119] The system 800 may include a receive antenna 835 of the receiver 712. The receive antenna 835 may be implemented by the grating coupler 730 of the receiver 712. For example, the receive antenna 835 may be an optical antenna integrated on the chip 705. The receive antenna 835 may couple the second component 775 of the return beam 755 from free space to the chip 705. The receive antenna 835 may be oriented at an angle relative to a surface provided such that the receive antenna 835 corresponds to the second polarization 785 of the second component 775 of the return beam 755.

[0120] The receive antenna 835 can receive the return beam 755. For example, the receive antenna 835 can receive a second component 775 of the return beam 755. Thus, the receive antenna 835 can be oriented with the same polarization as the second component 775 of the return beam 755. For example, the receive antenna 835 can have the same polarization as the second polarization 785. The receive antenna 835 can provide the second component 775 of the return beam 755 to other elements of the system 800, as discussed further below.

[0121] System 800 may include at least one mixer. The mixer may be similar to or identical to mixer 560. For example, system 800 may include mixer 840, which functions similarly to mixer 560. For example, system 800 may include mixer 845, which functions similarly to mixer 560. Mixers 840, 845 may each be a 2x2 optical mixer. Mixers 840, 845 may each be an optical hybrid. For example, mixers 840, 845 may each be a 90-degree optical hybrid. For example, mixers 840, 845 may each be a 2x4 optical hybrid.

[0122] The mixers 840 and 845 can receive signals. For example, the mixer 840 can receive the reference beam 820, e.g., the first LO signal. For example, the mixer 840 can receive the first component 770 of the return beam 755 from the receive antenna 825. For example, the mixer 845 can receive the reference beam 830, e.g., the second LO signal. For example, the mixer 845 can receive the second component 775 of the return beam 755 from the receive antenna 835.

[0123] The mixers 840, 845 may each output a signal. For example, the output signal may be based on a signal received by each mixer 840, 845 from the receive antennas 825, 835. For example, the output signal may be based on a signal received by each mixer 840, 845 from the local oscillator 815. For example, the mixers 840, 845 may output a signal responsive to the return beam 755 and the reference beams 820, 830. For example, the mixers 840, 845 may mix the return beam 755 with the reference beams 820, 830 and output a signal, respectively. The mixer 840 may output a signal 850. The signal 850 may be responsive to and based on the first component 770 of the return beam 755 and the reference beam 820. The mixer 845 may output a signal 855. Signal 855 may be responsive to and based on a second component 775 of return beam 755 and reference beam 830. Mixers 840, 845 may provide signals 850, 855 to grating couplers 725, 730, respectively, which may provide components 770, 775 of return beam 755 to optical detection devices, such as one or more optical detectors, of receiver 712.

[0124] Figure 9 is a block diagram of an embodiment of a LIDAR sensor system 900 including the optical components of Figure 8. The LIDAR sensor system 900 can incorporate features of the LIDAR sensor system 500 and the optical module 524 described with reference to Figures 5 and 6, respectively. The LIDAR sensor system 900 can facilitate pitch-catch compensation that can affect characteristics of the LIDAR sensor system 900, such as the signal-to-noise ratio, including accounting for time delays or other offsets that occur on the round-trip path of a transmit beam output from the LIDAR sensor system 900, reflected or scattered by an object, and then returned to the LIDAR sensor system 900 as a return beam for detection and processing.

[0125] The LIDAR sensor system 900 may include a grating coupler 715 configured to output a transmit beam 735. The LIDAR sensor system 900 may include a scanner 740 configured to receive the transmit beam 735 from the transmitter 710, provide the transmit beam 735 to the environment, and receive a return beam 755, which is a reflection of the transmit beam 735, from the object 702. The LIDAR sensor system 900 may include a grating coupler 725 and a grating coupler 730. The grating coupler 725 may receive a first component 770 of the return beam 755 at a first polarization 780. The grating coupler 730 may receive a second component 775 of the return beam 755 at a second polarization 785.

[0126] The first polarization 780 can be the same as the second polarization 785. The transmit polarization 795 can be different from the first polarization 780 and the second polarization 785. For example, the grating coupler 715 can output the transmit beam 735 with the transmit polarization 795, and the grating couplers 725, 730 can receive components 770, 775 of the return beam 755 with polarizations 780, 785, respectively, that are orthogonal to the transmit polarization 795.

[0127] The LIDAR sensor system 900 may include a displacer 905. The transmit beam 735 can pass unaffected through the displacer 905. The displacer 905 may be a birefringent displacer having two different refractive indices (various features and examples of the displacer 905 are described further below). The displacer 905 can displace the return beam 755. For example, the displacer 905 can displace the return beam 755 by a fixed amount to an opposite polarization from the transmit beam 735. For example, the displacer 905 can displace the return beam 755 of the transmit antenna 810 upon receive, e.g., to the right relative to the direction of the array in operation. The receive antennas 825, 835 are aligned with the polarizations 780, 785 of the components 770, 775 of the return beam 755. The receive antennas 825, 835 are positioned on either side of the displaced return beam 755 to correct for the focal plane drift mentioned above at a particular target distance, for example, the distance from the object 702 to the scanner 740.

[0128] The LIDAR sensor system 900 may include an optical module 524 (e.g., a collimator 604 of the optical module 524). The collimator 604 may be located between the transmitter 710 and the scanner 740. The transmit beam 735 may pass unaffected through the collimator 604. For example, the collimator 604 may be configured to provide the transmit beam 735 to the scanner 740. The collimator 604 may be configured to collimate the transmit beam 735. The collimator 604 may be configured to provide a collimated beam 910 to other components of the LIDAR sensor system 900, as discussed in more detail below. For example, the collimator 604 may be configured to provide the collimated beam 910 to the scanner 740.

[0129] The LIDAR sensor system 900 may include a wave plate 915. The wave plate 915 may be a quarter wave plate. The transmitted beam 735 may pass through the wave plate 915 without effect. The wave plate 915 may induce circular polarization. For example, the wave plate 915 may circularly polarize the components 770, 775 of the return beam 755.

[0130] 10 is a block diagram illustrating an example of optical components of a system 1000. The system 1000 may include or be used to implement various LIDAR sensor system components described herein, such as a transmitter 710 and a receiver 712. For example, the system 1000 may be used to implement a single polarization receiver and a switched local oscillator.

[0131] System 1000 is similar to system 800. However, the polarization of receive antennas 825, 835 is aligned with the polarization of transmit antenna 810. As previously mentioned, transmit antenna 810 may have the same polarization as transmit polarization 795, receive antenna 825 may have the same polarization as first polarization 780, and receive antenna 835 may have the same polarization as second polarization 785. In system 1000, transmit polarization 795 may be the same as polarizations 780, 785, and therefore transmit antenna 810 may have the same polarization as receive antennas 825, 835.

[0132] These receive antennas 825, 835 may be located on either side of the transmit antenna 810. For example, the receive antennas 825, 835 and the transmit antenna 810 may be located along the direction of the focal plane drift described above. The physical proximity of the receive antennas 825, 835 to the transmit antenna 810 is selected to correct for focal plane drift for a particular target distance, e.g., the distance between the object 702 and the scanner 740.

[0133] Figure 11 is a block diagram illustrating an example of a LIDAR sensor system 1100 including the optical components of Figure 10. The LIDAR sensor system 1100 can incorporate features of the LIDAR sensor system 500 and optical module 524 described with reference to Figures 5 and 6, respectively. The LIDAR sensor system 1100 can facilitate pitch-catch correction, i.e., accounting for time delays or other offsets that occur on the round-trip path of a transmitted beam output from the LIDAR sensor system 1100, reflected or scattered by an object, and then returned to the LIDAR sensor system 1100 as a return beam for detection and processing, which can affect characteristics of the LIDAR sensor system 1100, such as the signal-to-noise ratio.

[0134] Because system 1000 is similar to system 800, except that the polarizations of receive antennas 825, 835 are aligned with the polarization of transmit antenna 810, the block diagram shown in FIG. 11 is similar to the block diagram shown in FIG. 9. However, because the polarizations of receive antennas 825, 835 are not opposite to the polarization of transmit antenna 810, displacer 905 may be omitted. For example, in LIDAR sensor system 900, displacer 905 may displace return beam 755, which has an opposite polarization to transmit beam 735, by a certain amount. However, in LIDAR sensor system 1100, if the polarizations 780, 785, 795 are the same, no displacement of return beam 755 is necessary.

[0135] 12 is a block diagram illustrating an example of optical components of a system 1200. System 1200 may include or be used to implement various LIDAR sensor system components described herein, such as transmitter 710 and receiver 712. For example, system 1200 may be used to implement a single polarization receiver and a switched local oscillator.

[0136] System 1200 is similar to system 800. However, mixers 840, 845 communicate with two photodiodes (e.g., grating couplers 725, 730) and two independent balanced photodetectors instead of a single photodetector (e.g., receiver 712). Thus, system 1200 may include receiver 1205, e.g., a second receiver. Receiver 1205 may include grating coupler 730. Receiver 712 may include grating coupler 725. Mixer 840 may provide signal 850 to receiver 712, as in system 800. However, in system 1200, mixer 845 may provide signal 855 to receiver 1205.

[0137] In system 1200, local oscillator 815 may be passively split between mixer 840 and mixer 845. For example, local oscillator 815 may actively switch the LO signal between mixer 840 and mixer 845 depending on the scanning direction of scanner 740. For example, local oscillator 815 may transmit a reference beam 820, e.g., a first LO signal, to mixer 840. For example, local oscillator 815 may transmit a reference beam 830, e.g., a second LO signal, to mixer 845.

[0138] 13 is a block diagram illustrating an example of optical components of a system 1300. The system 1300 may include or be used to implement various LIDAR sensor system components described herein, such as the transmitter 710 and receiver 712. For example, the system 1300 may be used to implement a single polarization receiver and a switched local oscillator.

[0139] System 1300 is similar to system 1000 and may omit displacer 905 during operation. However, similar to system 1200, mixers 840, 845 communicate with two independent balanced photodetectors instead of a single photodetector, e.g., receiver 712, equipped with two photodiodes, e.g., grating couplers 725, 730. Accordingly, system 1300 may include receiver 1205. Receiver 1205 may include grating coupler 730. Receiver 712 may include grating coupler 725. Mixer 840 may provide signal 850 to receiver 712, similar to system 800. However, in system 1300, mixer 845 may provide signal 855 to receiver 1205. Additionally, similar to system 1200, local oscillator 815 may be passively split between mixer 840 and mixer 845.

[0140] 14 is a block diagram illustrating an example of optical components of a system 1400. System 1400 may include or be used to implement various LIDAR sensor system components described herein, such as transmitter 710 and receiver 712. For example, system 1400 may be used to implement a single polarization receiver and a switched local oscillator.

[0141] System 1400 is a combination of system 800 and system 1000. Thus, system 1400 may include two separate local oscillators. For example, system 1400 may include local oscillator 815 and local oscillator 1405, e.g., a second local oscillator. Local oscillator 1405 may function similarly or identically to local oscillator 815. For example, local oscillator 1405 may output an LO signal. For example, local oscillator 1405 may actively switch the LO signal between at least two mixers based on the scanning direction of scanner 740. For example, local oscillator 1405 may output a third LO signal and a fourth LO signal. The LO signals may be similar or identical to reference beam 512. For example, local oscillator 1405 may transmit a third LO signal, e.g., reference beam 1410. For example, the local oscillator 1405 can transmit a fourth LO signal, e.g., reference beam 1420. By switching the LO signal, the amount of power required by the local oscillator 1405 can be reduced.

[0142] The system 1400 may include a receive antenna 1415 and a receive antenna 1425. The receive antennas 1415, 1425 are similar to the receive antennas 825, 835. For example, the receive antennas 1415, 1425 may receive the return beam 755, as discussed in more detail below.

[0143] System 1400 may include mixer 1430 and mixer 1435. Mixers 1430, 1435 may be similar to or identical to mixers 840, 845. Mixers 1430, 1435 may receive signals as discussed in more detail below. Mixer 1430 may output signal 1440 as discussed in more detail below. Mixer 1435 may output signal 1445 as discussed in more detail below.

[0144] Figure 15 is a block diagram illustrating an example of a LIDAR sensor system 1500 including the optical components of Figure 14. The LIDAR sensor system 1500 can incorporate features of the LIDAR sensor system 500 and optical module 524 described with reference to Figures 5 and 6, respectively. The LIDAR sensor system 1500 can facilitate pitch-catch correction, i.e., accounting for time delays or other offsets that occur on the round-trip path of a transmitted beam output from the LIDAR sensor system 1500, reflected or scattered by an object, and then returned to the LIDAR sensor system 1500 as a return beam for detection and processing, which can affect characteristics of the LIDAR sensor system 1500, such as the signal-to-noise ratio.

[0145] The LIDAR sensor system 1500 may include a displacer 905 and a collimator 604, similar to the system 800 shown in FIG. 8 . However, in the system 1400, the LIDAR sensor system 1500 may include a wave plate 915. The wave plate 915 may be a quarter-wave plate. The transmit beam 735 can pass through the wave plate 915 without effect. The wave plate 915 can induce circular polarization. For example, the wave plate 915 can circularly polarize a component of the return beam 755. The LIDAR sensor system 1500 may include a grating coupler 1510 and a grating coupler 1520. The grating couplers 1510, 1520 can receive the return beam 755 provided by the scanner 740. For example, the grating coupler 1510 can receive the third component 1505 of the return beam 755 provided by the scanner 740. For example, the grating coupler 1520 can receive a fourth component 1525 of the return beam 755 provided by the scanner 740. The third component 1505 of the return beam 755 can be in a third polarization 1515. The fourth component 1525 of the return beam 755 can be in a fourth polarization 1530.

[0146] The LIDAR sensor system 1500 may include a grating coupler 1510 and a grating coupler 1520. The grating couplers 1510, 1520 may receive a return beam 755 provided by the scanner 740. For example, the grating coupler 1510 may receive a third component 1505 of the return beam 755 provided by the scanner 740. For example, the grating coupler 1520 may receive a fourth component 1525 of the return beam 755 provided by the scanner 740. The third component 1505 of the return beam 755 may be in a third polarization 1515. The fourth component 1525 of the return beam 755 may be in a fourth polarization 1530.

[0147] As previously described, the LIDAR sensor system 1500 may include a receive antenna 1415 and a receive antenna 1425 of the receiver 1205. The receive antenna 1415 may be implemented by a grating coupler 1510 of the receiver 712. For example, the receive antenna 1415 may be an optical antenna integrated on the chip 705. The receive antenna 1415 may couple the third component 1505 of the return beam 755 from free space to the chip 705. The receive antenna 1415 may be oriented at an angle relative to a surface provided such that the receive antenna 1415 corresponds to the third polarization 1515 of the third component 1505 of the return beam 755. The receive antenna 1425 may be implemented by a grating coupler 1520 of the receiver 712. For example, the receive antenna 1425 may be an optical antenna integrated on the chip 705. The receive antenna 1425 may couple the fourth component 1525 of the return beam 755 from free space to the chip 705. The receive antenna 1425 may be oriented at an angle relative to the surface on which the receive antenna 1425 is provided corresponding to a fourth polarization 1530 of the fourth component 1525 of the return beam 755 .

[0148] The receive antenna 1415 can receive the return beam 755. For example, the receive antenna 1415 can receive the third component 1505 of the return beam 755. Thus, the receive antenna 1415 can be oriented with the same polarization as the third component 1505 of the return beam 755. For example, the receive antenna 1415 can have the same polarization as the third polarization 1515. The receive antenna 1415 can provide the third component 1505 of the return beam 755 to the mixer 1430.

[0149] The receive antenna 1425 may receive the return beam 755. For example, the receive antenna 1425 may receive a fourth component 1525 of the return beam 755. Thus, the receive antenna 1425 may be oriented with the same polarization as the fourth component 1525 of the return beam 755. For example, the receive antenna 1425 may have the same polarization as the fourth polarization 1530. The receive antenna 1425 may provide the fourth component 1525 of the return beam 755 to the mixer 1435.

[0150] As described above, the mixers 1430 and 1435 can receive signals. For example, the mixer 1430 can receive the reference beam 1410, e.g., the third LO signal. For example, the mixer 1430 can receive the third component 1505 of the return beam 755 from the receive antenna 1415. For example, the mixer 1435 can receive the reference beam 1420, e.g., the fourth LO signal. For example, the mixer 1435 can receive the fourth component 1525 of the return beam 755 from the receive antenna 1425.

[0151] As described above, the mixers 1430, 1435 can output signals. For example, the output signals can be based on signals received by each mixer 1430, 1435 from the receive antennas 1415, 1425, respectively. For example, the output signals can be based on signals received by each mixer 1430, 1435 from the local oscillator 1405, respectively. For example, the mixers 1430, 1435 can output signals responsive to the return beam 755 and the reference beams 1410, 1420. For example, the mixers 1430, 1435 can mix the return beam 755 with the reference beams 1410, 1420 and output signals, respectively.

[0152] The mixer 1430 may output a signal 1440. The signal 1440 may be responsive to and based on the return beam 755 and the third component 1505 of the reference beam 1410. The mixer 1435 may output a signal 1445. The signal 1445 may be responsive to and based on the return beam 755 and the fourth component 1525 of the reference beam 1420. The mixers 1430 and 1435 may provide the signals 1440 and 1445 to two photodiodes, e.g., grating couplers 1510 and 1520, respectively. The two photodiodes may have two physically separated optical inputs, so that the mixers 1430 and 1435 may provide the signals 1440 and 1445 to a single photodetector. For example, the mixers 1430 and 1435 may provide the signals 1440 and 1445 to the receiver 1205.

[0153] 16 is a block diagram illustrating an example of optical components of a system 1600. System 1600 may include or be used to implement various LIDAR sensor system components described herein, such as transmitter 710 and receiver 712. For example, system 1600 may be used to implement a single polarization receiver and a switched local oscillator.

[0154] System 1600 is similar to system 1400. However, similar to system 1200, mixers 1430 and 1435 communicate with two independent balanced photodetectors instead of a single photodetector, e.g., receiver 1205. Thus, system 1600 may include receiver 1605, e.g., the third receiver, and receiver 1610, e.g., the fourth receiver. Receiver 1605 may include grating coupler 1510. Receiver 1610 may include grating coupler 1520. Also, receiver 712 may include grating coupler 725, and receiver 1205 may include grating coupler 730. Mixer 840 may provide signal 850 to receiver 712. Mixer 845 may provide signal 855 to receiver 1205. Mixer 1430 may provide signal 1440 to receiver 1605. The mixer 1435 may provide a signal 1445 to the receiver 1610 . 3-2. LIDAR sensor system including circulator

[0155] As previously mentioned, the LIDAR sensor system 500 can use various optical components to generate and encode information and output light that is reflected or scattered by objects in the environment surrounding the LIDAR sensor system 500. This can include, for example, implementations in which light is provided from a laser source, modulated in frequency and / or phase using on-chip components, and then directed from the chip to scanning optics into the environment by collimation and / or circulator optics, and can include transmitting at least some of the light through free space between components of the LIDAR sensor system 500. Systems and methods according to the present disclosure can implement such various components to provide free-space optical transmission, maintaining or improving the signal-to-noise ratio and reducing the overall size of the circulator.

[0156] 17 shows a block diagram of a circulator 1700 that can be implemented in various LIDAR sensor systems, such as the various LIDAR sensor systems 500 and optical modules 524 described herein. The circulator 1700 can be implemented by a chip 705. The chip 705 can include a transmitter 710 and a grating coupler 715. The transmitter 710 can output a transmit beam 735. The transmit beam 735 can be associated with a polarization. For example, the transmit beam 735 can be associated with a transmit polarization 795. The transmitter 710 can be disposed on the chip 705. For example, the transmitter 710 can be on the chip 705 and can output the transmit beam 735 from the plane of the chip 705.

[0157] The chip 705 may include a receiver 712. The receiver 712 may include a grating coupler 725. The grating coupler 725 may be separated from the transmitter 710 by a distance 1720. The distance 1720 between the grating coupler 725 and the transmitter 710 may be between about 8 micrometers and about 20 micrometers. The distance 1720 between the grating coupler 725 and the transmitter 710 may be between about 12 micrometers and about 16 micrometers. For example, the distance 1720 may be 14 micrometers. The distance 1720 may correspond to a time delay associated with a first target range for detecting the object 702, as described above. For example, the grating coupler 725 is positioned such that the grating coupler 725 is aligned with the time-delayed movement of the first component 770 of the return beam 755. The receiver 712 may include a grating coupler 730. The grating coupler 730 may be separated from the transmitter 710 by a distance 1725. The spacing 1725 between the grating coupler 730 and the transmitter 710 can be between about 30 micrometers and about 50 micrometers. The spacing 1725 between the grating coupler 730 and the transmitter 710 can be between about 32 micrometers and about 36 micrometers. For example, the spacing 1725 can be 34 micrometers.

[0158] Circulator 1700 may include optical system 532, such as one or more scanning optical systems. Optical system 532 may have a scan axis (e.g., axis 534 described with reference to FIG. 5) about which optical system 532 rotates. Grating coupler 725 and grating coupler 730 may reside along the scan axis.

[0159] Circulator 1700 may be similar to or identical to circulator 528. Circulator 1700 includes a wave plate 1730. Wave plate 1730 may be fabricated from a birefringent material, such as quartz or plastic, which may have different refractive indices for various polarizations of light along at least one particular axis passing through the material. Wave plate 1730 may be located between transmitter 710 and optical system 532. Wave plate 1730 may be a half-wave plate. For example, if wave plate 1730 is a half-wave plate, wave plate 1730 may shift or rotate the polarization direction of linearly polarized light. Compared to the operation of wave plate 915, wave plate 1730 may rotate transmit polarization 795. For example, wave plate 1730 may rotate transmit polarization 795 by 45 degrees.

[0160] Circulator 1700 includes a displacer 905. Displacer 905 may be located between wave plate 1730 and optical system 532. Displacer 905 may be fabricated from a variety of materials, such as birefringent materials including, but not limited to, YVO4, that are optically configured to control the path of light passing through displacer 905 based on the polarization of the light. The thickness of displacer 905 may be selected based on the target displacement and the type of material used for displacer 905.

[0161] For example, the displacer 905 can be made of LiNbO3. The displacer 905 can have a thickness of approximately 0.5 millimeters to 0.7 millimeters. For example, the displacer 905 can have a thickness of 0.6 millimeters. The displacer 905 can displace the return beam 755. For example, as the return beam 755 provided by the object 702 contacts the displacer 905, one of two different refractive indices of the displacer 905 can displace a portion of the return beam 755, e.g., the second component 775.

[0162] The displacer 905 can displace the second component 775 of the return beam 755. For example, the displacer 905 can displace the second component 775 of the return beam 755 so that the second component 775 is between about 32 micrometers and about 36 micrometers from the rotated transmit beam 1715. For example, the displacer 905 can displace the second component 775 of the return beam 755 so that the second component 775 is 34 micrometers from the rotated transmit beam 1715. For example, the displacer 905 can displace the second component 775 of the return beam 755 between about 18 micrometers and about 22 micrometers. For example, the displacer 905 can displace the second component 775 of the return beam 755 by 20 micrometers. For example, the displacer 905 can displace the second component 775 of the return beam 755 by 20 micrometers, such that the second component 775 is 20 micrometers from the first component 770 of the return beam 755. Thus, the spacing 1725 between the grating coupler 730 and the transmitter 710 can be positioned such that the grating coupler 730 receives the second component of the return beam 755 because the second component 775 of the return beam 755 is displaced by approximately 18 and 22 micrometers. For example, the spacing 1725 between the grating coupler 730 and the transmitter 710 corresponds to the displacement of the second component 775 relative to the first component 770 due to the time delay and the circulator 1700.

[0163] Circulator 1700 may include waveplate 1735. Waveplate 1735 may be located between displacer 905 and optical system 532. Waveplate 1735 may be used to handle changes in the polarization of transmitted beam 1715 rotated from a target polarization.

[0164] The circulator 1700 can direct the transmit beam 735 to the optical system 532. For example, the circulator 1700 can direct the transmit beam 735 to the optical system 532 in a direction parallel to the plane of the chip 705. For example, the optical system 532 can be tilted, e.g., by greater than about 8 degrees, with respect to the plane of the chip 705 to reduce back-reflection for light passing through free space around the circulator 1700, and the grating coupler 715 can be tilted, e.g., by at least about 12 degrees, to position the optical system 532 parallel to the chip 705. Positioning the optical system 532 parallel to the plane of the chip 705, e.g., chip 706, can simplify mounting. For example, parallel mechanical mounting of the optical system 532 to the chip 705 can facilitate manufacturing, e.g., by directly coupling (e.g., bonding) the optical system 532 and / or the circulator 1700 to the chip 705.

[0165] Circulator 1700 can receive transmit beam 735 and provide transmit beam 735 to optical system 532. For example, transmit beam 735 can pass through wave plate 1730 and displacer 905 to contact optical system 532. Circulator 1700 can receive return beam 755 from reflection of transmit beam 735 by object 702. For example, return beam 755 can contact displacer 905. Circulator 1700 can split return beam 755 into at least first component 770 and second component 775. For example, circulator 1700 can split return beam 755 into at least first component 770 and second component 775 via displacer 905, as described above. Circulator 1700 can provide first component 770 to grating coupler 725 and second component 775 to grating coupler 730. For example, first component 770 and second component 775 may pass through grating coupler 725 and grating coupler 730, respectively, via waveplate 1730.

[0166] Circulator 1700 can rotate transmit beam 735 and provide rotated transmit beam 1715 to optics 532. For example, transmit beam 735 can contact wave plate 1730, which can rotate transmit beam 735. Wave plate 1730 can provide rotated transmit beam 1715 to displacer 905. Rotated transmit beam 1715 can pass through displacer 905 unaffected and contact optics 532.

[0167] The circulator 1700 can polarize the first component 770 of the return beam 755. For example, the return beam 755 may return from the object 702 unpolarized. The return beam 755 can contact a displacer 905. The displacer 905 can rotate, e.g., polarize, the first component 770 of the return beam 755 so that the polarization associated with the first component 770 corresponds to the polarization of the rotated transmit beam 1715. The first component 770 of the return beam 755 can contact a wave plate 1730. The wave plate 1730 can rotate (e.g., polarize) the first component 770 of the return beam 755 to provide the first component 770 with a first polarization 780. The wave plate 1730 can rotate, e.g., polarize, the first component 770 of the return beam 755 so that the first polarization 780 associated with the first component 770 corresponds to the transmit polarization 795 associated with the transmit beam 735. For example, waveplate 1730 can rotate first component 770 of return beam 755 by 45 degrees.

[0168] The circulator 1700 can polarize the second component 775 of the return beam 755. For example, the return beam 755 can return from the object 702 unpolarized. The return beam 755 can contact a displacer 905. The displacer 905 can displace the second component 775 of the return beam 755 as described above. The displacer 905 can rotate, e.g., polarize, the second component 775 of the return beam 755 so that the polarization associated with the second component 775 is orthogonal to the polarization of the rotated transmitted beam 1715. The second component 775 of the return beam 755 can contact a wave plate 1730. The wave plate 1730 can rotate, e.g., polarize, the second component 775 of the return beam 755 to provide the second component 775 with a second polarization 785. Waveplate 1730 can rotate, e.g., polarize, second component 775 of return beam 755 so that second polarization 785 associated with second component 775 is orthogonal to transmit polarization 795 associated with transmit beam 735. For example, waveplate 1730 can rotate second component 775 of return beam 755 by 45 degrees. Because the polarization of second component 775 is orthogonal to first component 770 before second component 775 and first component 770 contact waveplate 1730, waveplate 1730 can rotate first polarization 780 and second polarization 785 by 45 degrees each in the same direction such that they are orthogonal to each other.

[0169] Circulator 1700 can provide a first component 770 of return beam 755 having a first polarization 780 to grating coupler 725. Circulator 1700 can provide a second component 775 of return beam 755 having a second polarization 785 to grating coupler 730. As described above, grating coupler 725 and grating coupler 730 can be rotated to accommodate first polarization 780 and second polarization 785, respectively, e.g., rotated to effectively align with components 770 and 775. Grating coupler 725 can receive at least a first threshold amount (e.g., greater than or equal to about 30%; between about 30% and about 90%; between about 50% and about 80%) of first component 770 of return beam 755. For example, the first threshold amount can correspond to the amount necessary for grating coupler 725 to output a signal, e.g., signal 850. The grating coupler 730 can receive at least a second threshold amount (e.g., greater than or equal to about 30%; between about 30% and about 90%; between about 50% and about 80%) of the second component 775 of the return beam 755. For example, the second threshold amount can correspond to the amount necessary for the grating coupler 730 to output a signal, e.g., signal 855.

[0170] Although some exemplary embodiments have been described above, it should be apparent that the foregoing embodiments are presented by way of example, and not by way of limitation. In particular, while many of the examples presented herein include specific combinations of method operations or system elements, these operations and elements can be combined in different ways to achieve the same purpose. Operations, elements, and features described with respect to one embodiment are not intended to exclude similar functionality in other embodiments.

[0171] The phraseology and terminology used herein are for purposes of description and should not be considered limiting. As used herein, the use of "including," "comprising," "having," "related to," "featuring," "characterized by," and variations thereof are intended to exclusively include the subsequently listed items, equivalents thereof, and additional items, as well as alternative embodiments of the subsequently listed items. In one embodiment, the systems and methods described herein consist of one, a combination of each of more than one, or all of the described elements, operations, or components.

[0172] Any reference herein to system and method embodiments or elements or operations in the singular may also include embodiments including a plurality of those elements, and any reference herein to any embodiment or element or operation in the plural may also include embodiments including only a single element. The singular or plural references are not intended to limit the presently disclosed systems or methods, their components, operations, or elements to singular or plural configurations. Any reference to any operation or element that is based on any information, operation, or element may include embodiments in which the operation or element is based at least in part on any information, operation, or element.

[0173] The embodiments disclosed herein may be combined with any other embodiment or embodiment, and terms such as "one embodiment," "some embodiments," and "one embodiment" are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or embodiment. As used herein, these terms do not necessarily all refer to the same embodiment. Any embodiment may be combined with any other embodiment, inclusively or exclusively, in any manner consistent with aspects and embodiments disclosed herein.

[0174] Where a reference sign is associated with a technical feature in a drawing, the detailed description, or any claim, the reference sign is included to enhance the understanding of the drawing, the detailed description, and the claim, and therefore the presence or absence of the reference sign does not have any limiting effect on the scope of any claim element.

[0175] The systems and methods described herein may be embodied in other specific forms without departing from their characteristics. Descriptions of additional relative parallel, perpendicular, vertical, or other positioning or orientation include variations within + / - 10% or + / - 10 degrees of purely vertical, parallel, or orthogonal positioning. References to "approximately," "about," "substantially," or other terms of degree include variations of + / - 10% from a given measurement, unit, or range, unless expressly indicated otherwise. Coupled elements may be electrically, mechanically, or physically coupled to one another directly or using intervening elements. Accordingly, the scope of the systems and methods described herein is represented by the appended claims, rather than the foregoing description, and includes modifications that fall within the meaning and scope of the doctrine of equivalents of the claims.

[0176] The term "coupled" and variations thereof include the direct or indirect joining of two members to one another. Such joining may be fixed (e.g., permanent or fixed) or movable (e.g., removable or separable). This joining may be achieved with two members directly joined to one another, two members joined to one another using another intervening member and any additional intermediate member joined to one another, or two members joined to one another using an intervening member integrally formed with one of the two members as a single, unified unit. When "coupled" or variations thereof are modified by additional terms (e.g., "directly coupled"), the general definition of "coupled" provided above is modified to the plain linguistic meaning of the additional terms (e.g., "directly coupled" means the joining of two members without a separate intervening member) and is defined in a narrower sense than the general definition of "coupled" provided above. Such joining may be mechanical, electrical, or fluid.

[0177] References to "or" can be construed as including one, more than one, or all of the described terms. References to "at least one of 'A' or 'B'" can include 'A' alone, 'B' alone, and both 'A' and 'B'. Such references used with "comprises" or other open-ended terms can include additional items.

[0178] Modifications of the described elements and operations, such as changes in the size, dimensions, structure, shape and proportions of various elements, parameter values, mounting arrangements, use of materials, color, and orientation, may occur without substantially departing from the teachings and advantages of the subject matter disclosed herein. For example, elements shown as integrally formed may be composed of multiple parts or elements, the positions of elements may be reversed or changed, and the characteristics or number of individual elements or positions may be varied or changed. Other substitutions, modifications, changes, and omissions in the design, operating conditions, and arrangements of the disclosed elements and operations may also be made without departing from the scope of the present disclosure.

[0179] References herein to the location of elements (e.g., "top," "bottom," "above," "below") are used merely to describe the orientation of the various elements in the drawings. It should be noted that the orientation of the various elements may vary in other exemplary embodiments, and such variations are encompassed by the present disclosure.

Claims

1. 1. A light detection and ranging (LIDAR) sensor system for a vehicle, the LIDAR sensor system comprising: a transmitter configured to output a transmit beam; Receiver - The receiver comprises: a first receiving grating coupler; a second receiving grating coupler; and one or more scanning optics; a circulator; The circulator is receiving the transmit beam and providing the transmit beam to the one or more scanning optics; receiving a return beam from reflection of the transmitted beam by an object; splitting the return beam into at least a first component and a second component; A LIDAR sensor system configured to provide the first component to the first receiving grating coupler and the second component to the second receiving grating coupler.

2. the transmit beam has a polarization; The circulator further comprises: rotating the polarization of the transmit beam and providing the rotated transmit beam to the one or more scanning optics; polarizing the first component of the return beam such that the polarization of the first component corresponds to the polarization of the transmitted beam; polarizing the second component of the return beam such that the polarization of the second component is orthogonal to the polarization of the transmitted beam; 2. The LIDAR sensor system of claim 1, configured to rotate the polarization of the first and second components of the return beam by 45 degrees, respectively, to provide a rotated first component to the first receiving grating coupler and a rotated second component to the second receiving grating coupler.

3. The circulator is a half-wave plate disposed between the transmitter and the one or more scanning optics; 10. The LIDAR sensor system of claim 1, further comprising a displacer disposed between the half-wave plate and the one or more scanning optics.

4. The circulator is a first half-wave plate disposed between the transmitter and the one or more scanning optics; a displacer disposed between the half-wave plate and the one or more scanning optics; 10. The LIDAR sensor system of claim 1, further comprising: a second half-wave plate disposed between the displacer and the one or more scanning optics.

5. the first receive grating coupler is spaced from the transmitter by about 8 micrometers to about 20 micrometers; 10. The LIDAR sensor system of claim 1, wherein the second receive grating coupler is spaced from the transmitter by about 30 micrometers to about 50 micrometers.

6. the first receiving grating coupler is spaced from the transmitter by a first distance corresponding to a time delay associated with a target range for detecting the object; 10. The LIDAR sensor system of claim 1, wherein the second receiving grating coupler is spaced from the transmitter by a second distance corresponding to the time delay and the displacement of the second component relative to the first component by the circulator.

7. the one or more scanning optics having a scan axis about which the one or more scanning optics rotate; The LIDAR sensor system of claim 1 , wherein the first receiving grating coupler and the second receiving grating coupler are located along the scan axis.

8. the first receiving grating coupler receives at least about 50% of the first component of the return beam; 10. The LIDAR sensor system of claim 1, wherein the second receiving grating coupler receives at least about 50% of the second component of the return beam.

9. 10. The LIDAR sensor system of claim 1, wherein the circulator includes a displacer configured to displace the second component of the return beam relative to the first component of the return beam, the displacer being fabricated from a birefringent material.

10. The circulator is LiNbO ３ and a displacer having a thickness of between about 0.53 millimeters and about 0.65 millimeters; 10. The LIDAR sensor system of claim 1, wherein the displacer is disposed between the transmitter and the one or more scanning optics and configured to displace the second component of the return beam by about 18 to about 22 micrometers.

11. 10. The LIDAR sensor system of claim 1, wherein the transmitter is on a chip and configured to output the transmit beam at a predetermined angle relative to a plane of the chip.

12. 12. The LIDAR sensor system of claim 11, wherein the circulator is configured to direct the transmit beam toward the one or more scanning optics in a direction parallel to the plane.

13. 1. An autonomous vehicle control system, comprising: a transmitter configured to output a transmit beam; a receiver including a first receive grating coupler and a second receive grating coupler; A scanner and Circulator - The circulator comprises: receiving the transmit beam and directing the transmit beam toward the scanner; receiving a return beam from reflection of the transmitted beam by an object; splitting the return beam into at least a first component and a second component; configured to direct the first component to the first receive grating coupler and the second component to the second receive grating coupler; one or more processors; The one or more processors: determining at least one of a distance of the object or a velocity of the object based on the first component and the second component; An autonomous vehicle control system configured to control operation of the autonomous vehicle in response to at least one of the distance or the velocity.

14. 14. The autonomous vehicle control system of claim 13, further comprising a modulator configured to apply at least one of frequency modulation or phase modulation to a beam output by the transmitter as the transmit beam.

15. the transmit beam has a polarization; The circulator further comprises: rotating the polarization of the transmit beam and providing the rotated transmit beam to the one or more scanners; polarizing the first component of the return beam such that the polarization of the first component corresponds to the polarization of the transmitted beam; polarizing the second component of the return beam such that the polarization of the second component is orthogonal to the polarization of the transmitted beam; 14. The autonomous vehicle control system of claim 13, configured to rotate the polarization of the first and second components of the return beam by 45 degrees, respectively, thereby providing a rotated first component to the first receiving grating coupler and a rotated second component to the second receiving grating coupler.

16. the first receiving grating coupler is spaced a first distance from the transmitter, the first distance corresponding to a time delay associated with a target range for detecting the object; 14. The autonomous vehicle control system of claim 13, wherein the second receiving grating coupler is spaced a second distance from the transmitter, the second distance corresponding to the time delay and the displacement of the second component relative to the first component due to the circulator.

17. the first receiving grating coupler receives at least about 50% of the first component of the return beam; The autonomous vehicle control system of claim 13 , wherein the second receive grating coupler receives at least about 50% of the second component of the return beam.

18. 1. An autonomous vehicle, the autonomous vehicle comprising: LIDAR sensor system - The LIDAR sensor system comprises: a transmit grating coupler configured to output a transmit beam; a first receiving grating coupler; a second receiving grating coupler; A scanner and a circulator; The circulator is receiving the transmit beam and providing the transmit beam to the scanner; receiving a return beam from reflection of the transmitted beam by an object; splitting the return beam into at least a first component and a second component; configured to direct the first component to the first receive grating coupler and the second component to the second receive grating coupler; A steering system, The brake system and one or more processors; The vehicle controller determining at least one of a distance of the object or a velocity of the object using the first component and the second component; An autonomous vehicle configured to control operation of at least one of the steering system and the braking system in response to at least one of the distance or the velocity.

19. the transmit beam has a polarization; The circulator further comprises: rotating the polarization of the transmit beam and providing the rotated transmit beam to the one or more scanners; polarizing the first component of the return beam such that the polarization of the first component corresponds to the polarization of the transmitted beam; polarizing the second component of the return beam such that the polarization of the second component is orthogonal to the polarization of the transmitted beam; 20. The autonomous vehicle of claim 18, configured to rotate the polarization of the first and second components of the return beam by 45 degrees, respectively, thereby providing a rotated first component to the first receiving grating coupler and a rotated second component to the second receiving grating coupler.

20. the first receiving grating coupler receives at least about 50% of the first component of the return beam; 20. The autonomous vehicle of claim 18, wherein the second receive grating coupler receives at least about 50% of the second component of the return beam.

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