Semiconductor laser grouping

Abstract

A system for light ranging and detection (LiDAR) is described. The system comprises a semiconductor laser (SL) device array comprising a plurality of SL devices mounted on a substrate. A charging capacitor array comprising a plurality of charging capacitors is mounted on the substrate proximate to the SL device array, where each SL device of the SL device array is coupled to a different charging capacitor of the charging capacitor array. A charging bus element comprising a plurality of charging buses is proximate to the charging capacitor array, where each adjacent charging capacitor of the charging capacitor array is coupled to a different charging bus of the charging bus element.

Description

SEMICONDUCTOR LASER GROUPING

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 541,740, filed September 29, 2023, entitled “EEL GROUPING,” the content of which is hereby incorporated by reference in its entirety for all purposes.FIELD OF THE TECHNOLOGY

[0002] This disclosure relates generally to LiDAR system light sources and, more particularly, to a LiDAR system semiconductor laser (SL) device array.BACKGROUND

[0003] Light detection and ranging (LiDAR) systems use light pulses to create an image or point cloud of the external environment. A LiDAR system may be a scanning or non-scanning system. Some typical scanning LiDAR systems include a light source, a light transmitter, a light steering system, and a light detector. The light source generates a light beam that is directed by the light steering system in particular directions when being transmitted from the LiDAR system. When a transmitted light beam is scattered or reflected by an object, a portion of the scattered or reflected light returns to the LiDAR system to form a return light pulse. The light detector detects the return light pulse. Using the difference between the time that the return light pulse is detected and the time that a corresponding light pulse in the light beam is transmitted, the LiDAR system can determine the distance to the object based on the speed of light. This technique of determining the distance is referred to as the time-of-flight (ToF) technique. The light steering system can direct light beams along different paths to allow the LiDAR system to scan the surrounding environment and produce images or point clouds. A typical non-scanning LiDAR system illuminates an entire field-of-view (FOV) rather than scanning across or through the FOV. An example of the non-scanning LiDAR system is a flash LiDAR, which can also use the ToF technique to measure the distance to an object. LiDAR systems can also use techniques other than time-of-flight and scanning to measure the surrounding environment.SUMMARY

[0004] Semiconductor laser sources may comprise various structures, including edge-emitting laser (EEL), vertical -cavity surface-emitting laser (VCSEL), and light-emitting diode (LED) structures. EEL device arrays (which emit light from an edge of the array structure) and VCSEL device arrays (which emit light vertically from an array structure) are a common laser sources in LiDAR applications. One difficulty in using semiconductor laser device arrays is grouping the array with the charging capacitors used to power the individual semiconductor laser devices. Because the charging capacitors are usually much larger than the semiconductor laser devices, the capacitors are typically wire bonded to adjacent laser elements. For example, adjacent semiconductor laser device channels (e.g., EEL devices #1 and #2 in an EEL device array arranged in series) are typically wire bonded to a same charging capacitor #1 because they are close together, and because the use of relatively longer wires can increase inductance and reduce the performance of a semiconductor laser pulse. Also, in a practical LiDAR system, it may be undesirable to fire adjacent channels simultaneously because of the increased risk of crosstalk inside the LiDAR. It may be desirable to fire non-adjacent semiconductor laser devices (e.g., EELs #1 and #5) simultaneously, but that would require the non-adjacent semiconductor laser devices to be wire bonded to the same capacitor, e.g., the aforementioned charging capacitor #1. However, such a configuration may require wires that cross over other wires between semiconductor lasers and capacitors, which may require an increase in wire length and carry an increased risk of short circuits. The embodiments herein propose a new method to solve this grouping issue.

[0005] A silicon capacitor is a kind of capacitor made on silicon wafers. The capacitance density of a silicon capacitor is high relative to size, so silicon capacitors can be smaller than other types of capacitors with comparable performance. In the embodiments herein, silicon capacitors may be used as charging capacitors for a semiconductor laser device array. For example, a 1x16 EEL device array having 16 EEL devices may be configured with an adjacent 1x16 silicon capacitor array. Each semiconductor laser device may be coupled to a silicon capacitor element, e.g., by wire bonding. Therefore, each semiconductor laser transmission pulse emission may be controlled by one silicon capacitor. For example, a first EEL device, EEL device #1, emits atransmission pulse when corresponding a silicon capacitor, silicon capacitor #1, discharges to EEL device #1.

[0006] In one innovation of the embodiments herein, a charging bus is configured next to the silicon charging capacitor array. Each silicon charging capacitor can be coupled (e.g., wire bonded) to the charging bus. For example, the 1x16 silicon charging capacitor array may be coupled to four charging buses, noted as bus #1, 2, 3, and 4. Charging capacitors #1, 5, 9, and 13 may be in one group and connected to bus #1. Therefore, charging capacitors #1, 5, 9, and 13 will be charged together and may discharge together to semiconductor laser devices #1, 5, 9, and 13. In this way, semiconductor laser devices #1, 5, 9, and 13 are firing together but they are not next to each other. This is important in some LiDAR systems to reduce crosstalk between channels. Also, the wire length between each element may be very short, which benefits the laser performance because of less inductance. Additionally, transmission control circuitry, coupled to the semiconductor laser device array and the charging capacitor array, may be operative to select a first semiconductor laser grouping comprising any one of the plurality of semiconductor laser devices; and cause, within a firing cycle, the first semiconductor laser grouping to emit first transmission pulses.

[0007] In some embodiments, the semiconductor laser device array, silicon capacitor array, and charging bus are mounted on a substrate (e.g., a ceramic layer). In some embodiments, the charging bus may be co-located with the silicon capacitor array, e.g., mounted over the silicon capacitor array rather than to the substrate, which can further reduce the discharging circuit length. In some embodiments, the charging bus may comprise one or more metal bars or metal etchings on the surface of the substrate.

[0008] The embodiments also include a method of manufacturing a LiDAR system in accordance with the various embodiments herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present application can be best understood by reference to the embodiments described below taken in conjunction with the accompanying drawing figures, in which like parts may be referred to by like numerals.

[0010] FIG. 1 illustrates one or more example LiDAR systems disposed or included in a motor vehicle.

[0011] FIG. 2 is a block diagram illustrating interactions between an example LiDAR system and multiple other systems including a vehicle perception and planning system.

[0012] FIG. 3 is a block diagram illustrating an example LiDAR system.

[0013] FIG. 4 is a block diagram illustrating an example fiber-based laser source.

[0014] FIGs. 5A-5C illustrate an example LiDAR system using pulse signals to measure distances to objects disposed in a field-of-view (FOV).

[0015] FIG. 6 is a block diagram illustrating an example apparatus used to implement systems, apparatus, and methods in various embodiments.

[0016] FIG. 7A is a block diagram illustrating an example Edge Emitting Laser (EEL) device in accordance with an embodiment.

[0017] FIG. 7B is a block diagram illustrating an example vertical -cavity surface-emitting laser (VCSEL) device in accordance with an embodiment.

[0018] FIG. 7C is a block diagram illustrating an example light-emitting diode (LED) Laser device in accordance with an embodiment.

[0019] FIG. 8 illustrates an example LiDAR system comprising an EEL device array within a housing.

[0020] FIG. 9 is a block diagram illustrating an example of a conventional EEL device array.

[0021] FIG. 10 illustrates a perspective view of a LiDAR system comprising an EEL device array, silicon capacitors, and a charging bus element in accordance with an embodiment.

[0022] FIG. 11 is a block diagram illustrating a LiDAR system comprising an EEL device array, silicon capacitors, and a charging bus element in accordance with an embodiment.

[0023] FIG. 12 is a flow diagram illustrating example operations for transmission control circuitry of an EEL device array in accordance with an embodiment.

[0024] FIG. 13 A is a block diagram illustrating an EEL device array having a parallel charging bus in accordance with an embodiment.

[0025] FIG. 13B is a block diagram illustrating an EEL device array having a stacked charging bus in accordance with an embodiment.

[0026] FIG. 14 is a flow diagram illustrating a process for manufacturing a LiDAR system in accordance with an embodiment.DETAILED DESCRIPTION

[0027] To provide a more thorough understanding of various embodiments of the present invention, the following description sets forth numerous specific details, such as specific configurations, parameters, examples, and the like. It should be recognized, however, that such description is not intended as a limitation on the scope of the present invention but is intended to provide a better description of the exemplary embodiments.

[0028] Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise:

[0029] The phrase “in one embodiment” as used herein does not necessarily refer to the same embodiment, though it may. Thus, as described below, various embodiments of the disclosure may be readily combined, without departing from the scope or spirit of the invention.

[0030] As used herein, the term “or” is an inclusive “or” operator and is equivalent to the term “and / or,” unless the context clearly dictates otherwise.

[0031] The term “based on” is not exclusive and allows for being based on additional factors not described unless the context clearly dictates otherwise.

[0032] As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously. Within the context of a networked environment where two or more components or devices are able to exchange data, the terms “coupled to” and “coupled with” are also used to mean “communicatively coupled with”, possibly via one or more intermediary devices. The components or devices can be optical, mechanical, and / or electrical devices.

[0033] Although the following description uses terms “first,” “second,” etc. to describe various elements, these elements should not be limited by the terms. These terms are only used to distinguish one element from another. For example, a first semiconductor laser device could be termed a second semiconductor laser and, similarly, a second semiconductor laser device could be termed a first semiconductor laser device, without departing from the scope of the various described examples. The first semiconductor laser device and the second semiconductor laser device can both be semiconductor laser devices and, in some cases, can be separate and different semiconductor laser devices.

[0034] In addition, throughout the specification, the meaning of “a”, “an”, and “the” includes plural references, and the meaning of “in” includes “in” and “on”.

[0035] Although some of the various embodiments presented herein constitute a single combination of inventive elements, it should be appreciated that the inventive subject matter is considered to include all possible combinations of the disclosed elements. As such, if one embodiment comprises elements A, B, and C, and another embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly discussed herein. Further, the transitional term “comprising” means to have as parts or members, or to be those parts or members. As used herein, the transitional term “comprising” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.

[0036] As used in the description herein and throughout the claims that follow, when a system, engine, server, device, module, or other computing element is described as being configured to perform or execute functions on data in a memory, the meaning of “configured to” or “programmed to” is defined as one or more processors or cores of the computing element being programmed by a set of software instructions stored in the memory of the computing element to execute the set of functions on target data or data objects stored in the memory.

[0037] It should be noted that any language directed to a computer should be read to include any suitable combination of computing devices or network platforms, including servers, interfaces, systems, databases, agents, peers, engines, controllers, modules, or other types of computing devices operating individually or collectively. One should appreciate the computing devices comprise a processor configured to execute software instructions stored on a tangible, non-transitory computer readable storage medium (e.g., hard drive, FPGA, PLA, solid state drive, RAM, flash, ROM, or any other volatile or non-volatile storage devices). The software instructions configure or program the computing device to provide the roles, responsibilities, or other functionality as discussed below with respect to the disclosed apparatus. Further, the disclosed technologies can be embodied as a computer program product that includes a non- transitory computer readable medium storing the software instructions that causes a processor to execute the disclosed steps associated with implementations of computer-based algorithms, processes, methods, or other instructions. In some embodiments, the various servers, systems, databases, or interfaces exchange data using standardized protocols or algorithms, possibly based on HTTP, HTTPS, AES, public-private key exchanges, web service APIs, known financial transaction protocols, or other electronic information exchanging methods. Data exchanges among devices can be conducted over a packet-switched network, the Internet, LAN, WAN, VPN, or other type of packet switched network; a circuit switched network; cell switched network; or other type of network.

[0038] In one embodiment, a system for light ranging and detection (LiDAR) comprises an semiconductor laser (SL) device array comprising a plurality of SL devices mounted on a substrate. A charging capacitor array comprising a plurality of charging capacitors is mounted on the substrate proximate to the SL device array, where each SL device of the SL device array is coupled to a different charging capacitor of the charging capacitor array. A charging bus element comprising a plurality of charging buses is proximate to the charging capacitor array, where each adjacent charging capacitor of the charging capacitor array is coupled to a different charging bus of the charging bus element. Further embodiments of present invention are described below.

[0039] FIG. 1 illustrates one or more example LiDAR systems 110 and 120A-120I disposed or included in a motor vehicle 100. Vehicle 100 can be a car, a sport utility vehicle (SUV), a truck, a train, a wagon, a bicycle, a motorcycle, a tricycle, a bus, a mobility scooter, a tram, a ship, a boat, an underwater vehicle, an airplane, a helicopter, an unmanned aviation vehicle (UAV), a spacecraft, etc. Motor vehicle 100 can be a vehicle having any automated level. For example, motor vehicle 100 can be a partially automated vehicle, a highly automated vehicle, a fully automated vehicle, or a driverless vehicle. A partially automated vehicle can perform some driving functions without a human driver’s intervention. For example, a partially automatedvehicle can perform blind-spot monitoring, lane keeping and / or lane changing operations, automated emergency braking, smart cruising and / or traffic following, or the like. Certain operations of a partially automated vehicle may be limited to specific applications or driving scenarios (e.g., limited to only freeway driving). A highly automated vehicle can generally perform all operations of a partially automated vehicle but with less limitations. A highly automated vehicle can also detect its own limits in operating the vehicle and ask the driver to take over the control of the vehicle when necessary. A fully automated vehicle can perform all vehicle operations without a driver’s intervention but can also detect its own limits and ask the driver to take over when necessary. A driverless vehicle can operate on its own without any driver intervention.

[0040] In typical configurations, motor vehicle 100 comprises one or more LiDAR systems 110 and 120A-120I. Each of LiDAR systems 110 and 120A-120I can be a scanning-based LiDAR system and / or a non-scanning LiDAR system (e.g., a flash LiDAR). A scanning-based LiDAR system scans one or more light beams in one or more directions (e.g., horizontal and vertical directions) to detect objects in a field-of-view (FOV). A non-scanning based LiDAR system transmits laser light to illuminate an FOV without scanning. For example, a flash LiDAR is a type of non-scanning based LiDAR system. A flash LiDAR can transmit laser light to simultaneously illuminate an FOV using a single light pulse or light shot.

[0041] A LiDAR system is a frequently used sensor of a vehicle that is at least partially automated. In one embodiment, as shown in FIG. 1, motor vehicle 100 may include a single LiDAR system 110 (e.g., without LiDAR systems 120A-120I) disposed at the highest position of the vehicle (e.g., at the vehicle roof). Disposing LiDAR system 110 at the vehicle roof facilitates a 360-degree scanning around vehicle 100. In some other embodiments, motor vehicle 100 can include multiple LiDAR systems, including two or more of systems 110 and / or 120A-120I. As shown in FIG. 1, in one embodiment, multiple LiDAR systems 110 and / or 120A-120I are attached to vehicle 100 at different locations of the vehicle. For example, LiDAR system 120A is attached to vehicle 100 at the front right comer; LiDAR system 120B is attached to vehicle 100 at the front center position; LiDAR system 120C is attached to vehicle 100 at the front left corner; LiDAR system 120D is attached to vehicle 100 at the right-side rear view mirror; LiDAR system 120E is attached to vehicle 100 at the left-side rear view mirror; LiDAR system 120F is attached to vehicle 100 at the back center position; LiDAR system 120G is attached to vehicle100 at the back right corner; LiDAR system 120H is attached to vehicle 100 at the back left corner; and / or LiDAR system 1201 is attached to vehicle 100 at the center towards the backend (e.g., back end of the vehicle roof). It is understood that one or more LiDAR systems can be distributed and attached to a vehicle in any desired manner and FIG. 1 only illustrates one embodiment. As another example, LiDAR systems 120D and 120E may be attached to the B- pillars of vehicle 100 instead of the rear-view mirrors. As another example, LiDAR system 120B may be attached to the windshield of vehicle 100 instead of the front bumper.

[0042] In some embodiments, LiDAR systems 110 and 120A-120I are independent LiDAR systems having their own respective laser sources, control electronics, transmitters, receivers, and / or steering mechanisms. In other embodiments, some of LiDAR systems 110 and 120A- 1201 can share one or more components, thereby forming a distributed sensor system. In one example, optical fibers are used to deliver laser light from a centralized laser source to all LiDAR systems. For instance, system 110 (or another system that is centrally positioned or positioned anywhere inside the vehicle 100) includes a light source, a transmitter, and a light detector, but has no steering mechanisms. System 110 may distribute transmission light to each of systems 120A-120I. The transmission light may be distributed via optical fibers. Optical connectors can be used to couple the optical fibers to each of system 110 and 120A-120I. In some examples, one or more of systems 120A-120I include steering mechanisms but no light sources, transmitters, or light detectors. A steering mechanism may include one or more moveable mirrors such as one or more polygon mirrors, one or more single plane mirrors, one or more multi-plane mirrors, or the like. Embodiments of the light source, transmitter, steering mechanism, and light detector are described in more detail below. Via the steering mechanisms, one or more of systems 120A-I20I scan light into one or more respective FOVs and receive corresponding return light. The return light is formed by scattering or reflecting the transmission light by one or more objects in the FOVs. Systems 120A-120I may also include collection lens and / or other optics to focus and / or direct the return light into optical fibers, which deliver the received return light to system 110. System 110 includes one or more light detectors for detecting the received return light. In some examples, system 110 is disposed inside a vehicle such that it is in a temperature-controlled environment, while one or more systems 120A-120I may be at least partially exposed to the external environment.

[0043] FIG. 2 is a block diagram 200 illustrating interactions between vehicle onboard LiDAR system(s) 210 and multiple other systems including a vehicle perception and planning system 220. LiDAR system(s) 210 can be mounted on or integrated to a vehicle. LiDAR system(s) 210 include sensor(s) that scan laser light to the surrounding environment to measure the distance, angle, and / or velocity of objects. Based on the scattered light that returned to LiDAR system(s) 210, it can generate sensor data (e.g., image data or 3D point cloud data) representing the perceived external environment.

[0044] LiDAR system(s) 210 can include one or more of short-range LiDAR sensors, mediumrange LiDAR sensors, and long-range LiDAR sensors. A short-range LiDAR sensor measures objects located up to about 20-50 meters from the LiDAR sensor. Short-range LiDAR sensors can be used for, e.g., monitoring nearby moving objects (e g., pedestrians crossing street in a school zone), parking assistance applications, or the like. A medium-range LiDAR sensor measures objects located up to about 70-200 meters from the LiDAR sensor. Medium-range LiDAR sensors can be used for, e.g., monitoring road intersections, assistance for merging onto or leaving a freeway, or the like. A long-range LiDAR sensor measures objects located up to about 200 meters and beyond. Long-range LiDAR sensors are typically used when a vehicle is travelling at a high speed (e.g., on a freeway), such that the vehicle’s control systems may only have a few seconds (e.g., 6-8 seconds) to respond to any situations detected by the LiDAR sensor. As shown in FIG. 2, in one embodiment, the LiDAR sensor data can be provided to vehicle perception and planning system 220 via a communication path 213 for further processing and controlling the vehicle operations. Communication path 213 can be any wired or wireless communication links that can transfer data.

[0045] With reference still to FIG. 2, in some embodiments, other vehicle onboard sensor(s) 230 are configured to provide additional sensor data separately or together with LiDAR system(s) 210. Other vehicle onboard sensors 230 may include, for example, one or more camera(s) 232, one or more radar(s) 234, one or more ultrasonic sensor(s) 236, and / or other sensor(s) 238. Camera(s) 232 can take images and / or videos of the external environment of a vehicle. Camera(s) 232 can take, for example, high-definition (HD) videos having millions of pixels in each frame. A camera includes image sensors that facilitate producing monochrome or color images and videos. Color information may be important in interpreting data for some situations (e g., interpreting images of traffic lights). Color information may not be available from othersensors such as LiDAR or radar sensors. Camera(s) 232 can include one or more of narrowfocus cameras, wider-focus cameras, side-facing cameras, infrared cameras, fisheye cameras, or the like. The image and / or video data generated by camera(s) 232 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations. Communication path 233 can be any wired or wireless communication links that can transfer data. Camera(s) 232 can be mounted on, or integrated to, a vehicle at any location (e.g., rear-view mirrors, pillars, front grille, and / or back bumpers, etc.).

[0046] Other vehicle onboard sensos(s) 230 can also include radar sensor(s) 234. Radar sensor(s) 234 use radio waves to determine the range, angle, and velocity of objects. Radar sensor(s) 234 produce electromagnetic waves in the radio or microwave spectrum. The electromagnetic waves reflect off an object and some of the reflected waves return to the radar sensor, thereby providing information about the object’s position and velocity. Radar sensor(s) 234 can include one or more of short-range radar(s), medium-range radar(s), and long-range radar(s). A short-range radar measures objects located at about 0.1-30 meters from the radar. A short-range radar is useful in detecting objects located near the vehicle, such as other vehicles, buildings, walls, pedestrians, bicyclists, etc. A short-range radar can be used to detect a blind spot, assist in lane changing, provide rear-end collision warning, assist in parking, provide emergency braking, or the like. A medium-range radar measures objects located at about 30-80 meters from the radar. A long-range radar measures objects located at about 80-200 meters. Medium- and / or long-range radars can be useful in, for example, traffic following, adaptive cruise control, and / or highway automatic braking. Sensor data generated by radar sensor(s) 234 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations. Radar sensor(s) 234 can be mounted on, or integrated to, a vehicle at any location (e.g., rear-view mirrors, pillars, front grille, and / or back bumpers, etc.).

[0047] Other vehicle onboard sensor(s) 230 can also include ultrasonic sensor(s) 236. Ultrasonic sensor(s) 236 use acoustic waves or pulses to measure objects located external to a vehicle. The acoustic waves generated by ultrasonic sensor(s) 236 are transmitted to the surrounding environment. At least some of the transmitted waves are reflected off an object and return to the ultrasonic sensor(s) 236. Based on the return signals, a distance of the object can be calculated. Ultrasonic sensor(s) 236 can be useful in, for example, checking blind spots, identifying parkingspaces, providing lane changing assistance into traffic, or the like. Sensor data generated by ultrasonic sensor(s) 236 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations.Ultrasonic sensor(s) 236 can be mounted on, or integrated to, a vehicle at any location (e.g., rearview mirrors, pillars, front grille, and / or back bumpers, etc.).

[0048] In some embodiments, one or more other sensor(s) 238 may be attached in a vehicle and may also generate sensor data. Other sensor(s) 238 may include, for example, global positioning systems (GPS), inertial measurement units (IMU), or the like. Sensor data generated by other sensor(s) 238 can also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and controlling the vehicle operations. It is understood that communication path 233 may include one or more communication links to transfer data between the various sensor(s) 230 and vehicle perception and planning system 220.

[0049] In some embodiments, as shown in FIG. 2, sensor data from other vehicle onboard sensor(s) 230 can be provided to vehicle onboard LiDAR system(s) 210 via communication path 231. LiDAR system(s) 210 may process the sensor data from other vehicle onboard sensor(s) 230. For example, sensor data from camera(s) 232, radar sensor(s) 234, ultrasonic sensor(s) 236, and / or other sensor(s) 238 may be correlated or fused with sensor data LiDAR system(s) 210, thereby at least partially offloading the sensor fusion process performed by vehicle perception and planning system 220. It is understood that other configurations may also be implemented for transmitting and processing sensor data from the various sensors (e.g., data can be transmitted to a cloud or edge computing service provider for processing and then the processing results can be transmitted back to the vehicle perception and planning system 220 and / or LiDAR system 210).

[0050] With reference still to FIG. 2, in some embodiments, sensors onboard other vehicle(s) 250 are used to provide additional sensor data separately or together with LiDAR system(s) 210. For example, two or more nearby vehicles may have their own respective LiDAR sensor(s), camera(s), radar sensor(s), ultrasonic sensor(s), etc. Nearby vehicles can communicate and share sensor data with one another. Communications between vehicles are also referred to as V2V (vehicle to vehicle) communications. For example, as shown in FIG. 2, sensor data generated by other vehicle(s) 250 can be communicated to vehicle perception and planning system 220 and / or vehicle onboard LiDAR system(s) 210, via communication path 253 and / or communication path251 , respectively. Communication paths 253 and 251 can be any wired or wireless communication links that can transfer data.

[0051] Sharing sensor data facilitates a better perception of the environment external to the vehicles. For instance, a first vehicle may not sense a pedestrian that is behind a second vehicle but is approaching the first vehicle. The second vehicle may share the sensor data related to this pedestrian with the first vehicle such that the first vehicle can have additional reaction time to avoid collision with the pedestrian. In some embodiments, similar to data generated by sensor(s) 230, data generated by sensors onboard other vehicle(s) 250 may be correlated or fused with sensor data generated by LiDAR system(s) 210 (or with other LiDAR systems located in other vehicles), thereby at least partially offloading the sensor fusion process performed by vehicle perception and planning system 220.

[0052] In some embodiments, intelligent infrastructure system(s) 240 are used to provide sensor data separately or together with LiDAR system(s) 210. Certain infrastructures may be configured to communicate with a vehicle to convey information and vice versa.Communications between a vehicle and infrastructures are generally referred to as V2I (vehicle to infrastructure) communications. For example, intelligent infrastructure system(s) 240 may include an intelligent traffic light that can convey its status to an approaching vehicle in a message such as “changing to yellow in 5 seconds.” Intelligent infrastructure system(s) 240 may also include its own LiDAR system mounted near an intersection such that it can convey traffic monitoring information to a vehicle. For example, a left-turning vehicle at an intersection may not have sufficient sensing capabilities because some of its own sensors may be blocked by traffic in the opposite direction. In such a situation, sensors of intelligent infrastructure system(s) 240 can provide useful data to the left-turning vehicle. Such data may include, for example, traffic conditions, information of objects in the direction the vehicle is turning to, traffic light status and predictions, or the like. These sensor data generated by intelligent infrastructure system(s) 240 can be provided to vehicle perception and planning system 220 and / or vehicle onboard LiDAR system(s) 210, via communication paths 243 and / or 241, respectively.Communication paths 243 and / or 241 can include any wired or wireless communication links that can transfer data. For example, sensor data from intelligent infrastructure system(s) 240 may be transmitted to LiDAR system(s) 210 and correlated or fused with sensor data generated by LiDAR system(s) 210, thereby at least partially offloading the sensor fusion processperformed by vehicle perception and planning system 220. V2V and V2I communications described above are examples of vehicle-to-X (V2X) communications, where the “X” represents any other devices, systems, sensors, infrastructure, or the like that can share data with a vehicle.

[0053] With reference still to FIG. 2, via various communication paths, vehicle perception and planning system 220 receives sensor data from one or more of LiDAR system(s) 210, other vehicle onboard sensor(s) 230, other vehicle(s) 250, and / or intelligent infrastructure system(s) 240. In some embodiments, different types of sensor data are correlated and / or integrated by a sensor fusion sub-system 222. For example, sensor fusion sub-system 222 can generate a 360- degree model using multiple images or videos captured by multiple cameras disposed at different positions of the vehicle. Sensor fusion sub-system 222 obtains sensor data from different types of sensors and uses the combined data to perceive the environment more accurately. For example, a vehicle onboard camera 232 may not capture a clear image because it is facing the sun or a light source (e.g., another vehicle’s headlight during nighttime) directly. A LiDAR system 210 may not be affected as much and therefore sensor fusion sub-system 222 can combine sensor data provided by both camera 232 and LiDAR system 210, and use the sensor data provided by LiDAR system 210 to compensate the unclear image captured by camera 232. As another example, in a rainy or foggy weather, a radar sensor 234 may work better than a camera 232 or a LiDAR system 210. Accordingly, sensor fusion sub-system 222 may use sensor data provided by the radar sensor 234 to compensate the sensor data provided by camera 232 or LiDAR system 210.

[0054] In other examples, sensor data generated by other vehicle onboard sensor(s) 230 may have a lower resolution (e.g., radar sensor data) and thus may need to be correlated and confirmed by LiDAR system(s) 210, which usually has a higher resolution. For example, a sewage cover (also referred to as a manhole cover) may be detected by radar sensor 234 as an object towards which a vehicle is approaching. Due to the low-resolution nature of radar sensor 234, vehicle perception and planning system 220 may not be able to determine whether the object is an obstacle that the vehicle needs to avoid. High-resolution sensor data generated by LiDAR system(s) 210 thus can be used to correlated and confirm that the object is a sewage cover and causes no harm to the vehicle.

[0055] Vehicle perception and planning system 220 further comprises an object classifier 223. Using raw sensor data and / or correlated / fused data provided by sensor fusion sub-system 222, object classifier 223 can use any computer vision techniques to detect and classify the objects and estimate the positions of the objects. In some embodiments, object classifier 223 can use machine-learning based techniques to detect and classify objects. Examples of the machinelearning based techniques include utilizing algorithms such as region-based convolutional neural networks (R-CNN), Fast R-CNN, Faster R-CNN, histogram of oriented gradients (HOG), region-based fully convolutional network (R-FCN), single shot detector (SSD), spatial pyramid pooling (SPP-net), and / or You Only Look Once (Yolo).

[0056] Vehicle perception and planning system 220 further comprises a road detection subsystem 224. Road detection sub-system 224 localizes the road and identifies objects and / or markings on the road. For example, based on raw or fused sensor data provided by radar sensor(s) 234, camera(s) 232, and / or LiDAR system(s) 210, road detection sub-system 224 can build a 3D model of the road based on machine-learning techniques (e.g., pattern recognition algorithms for identifying lanes). Using the 3D model of the road, road detection sub-system 224 can identify objects (e.g., obstacles or debris on the road) and / or markings on the road (e.g., lane lines, turning marks, crosswalk marks, or the like).

[0057] Vehicle perception and planning system 220 further comprises a localization and vehicle posture sub-system 225. Based on raw or fused sensor data, localization and vehicle posture sub-system 225 can determine position of the vehicle and the vehicle’s posture. For example, using sensor data from LiDAR system(s) 210, camera(s) 232, and / or GPS data, localization and vehicle posture sub-system 225 can determine an accurate position of the vehicle on the road and the vehicle’s six degrees of freedom (e.g., whether the vehicle is moving forward or backward, up or down, and left or right). In some embodiments, high-definition (HD) maps are used for vehicle localization. HD maps can provide highly detailed, three-dimensional, computerized maps that pinpoint a vehicle’s location. For instance, using the HD maps, localization and vehicle posture sub-system 225 can determine precisely the vehicle’s current position (e.g., which lane of the road the vehicle is currently in, how close it is to a curb or a sidewalk) and predict vehicle’s future positions.

[0058] Vehicle perception and planning system 220 further comprises obstacle predictor 226. Objects identified by object classifier 223 can be stationary (e.g., a light pole, a road sign) or dynamic (e.g., a moving pedestrian, bicycle, another car). For moving objects, predicting their moving path or future positions can be important to avoid collision. Obstacle predictor 226 can predict an obstacle trajectory and / or warn the driver or the vehicle planning sub-system 228 about a potential collision. For example, if there is a high likelihood that the obstacle’s trajectory intersects with the vehicle’s current moving path, obstacle predictor 226 can generate such a warning. Obstacle predictor 226 can use a variety of techniques for making such a prediction. Such techniques include, for example, constant velocity or acceleration models, constant turn rate and velocity / acceleration models, Kalman Filter and Extended Kalman Filter based models, recurrent neural network (RNN) based models, long short-term memory (LSTM) neural network-based models, encoder-decoder RNN models, or the like.

[0059] With reference still to FIG. 2, in some embodiments, vehicle perception and planning system 220 further comprises vehicle planning sub-system 228. Vehicle planning sub-system 228 can include one or more planners such as a route planner, a driving behaviors planner, and a motion planner. The route planner can plan the route of a vehicle based on the vehicle’s current location data, target location data, traffic information, etc. The driving behavior planner adjusts the timing and planned movement based on how other objects might move, using the obstacle prediction results provided by obstacle predictor 226. The motion planner determines the specific operations the vehicle needs to follow. The planning results are then communicated to vehicle control system 280 via vehicle interface 270. The communication can be performed through communication paths 227 and 271, which include any wired or wireless communication links that can transfer data.

[0060] Vehicle control system 280 controls the vehicle’s steering mechanism, throttle, brake, etc., to operate the vehicle according to the planned route and movement. In some examples, vehicle perception and planning system 220 may further comprise a user interface 260, which provides a user (e.g., a driver) access to vehicle control system 280 to, for example, override or take over control of the vehicle when necessary. User interface 260 may also be separate from vehicle perception and planning system 220. User interface 260 can communicate with vehicle perception and planning system 220, for example, to obtain and display raw or fused sensor data, identified objects, vehicle’s location / posture, etc. These displayed data can help a user to betteroperate the vehicle. User interface 260 can communicate with vehicle perception and planning system 220 and / or vehicle control system 280 via communication paths 221 and 261 respectively, which include any wired or wireless communication links that can transfer data. It is understood that the various systems, sensors, communication links, and interfaces in FIG. 2 can be configured in any desired manner and not limited to the configuration shown in FIG. 2.

[0061] FIG. 3 is a block diagram illustrating an example LiDAR system 300. LiDAR system 300 can be used to implement LiDAR systems 110, 120A-120I, and / or 210 shown in FIGs. 1 and 2. In one embodiment, LiDAR system 300 comprises a light source 310, a transmitter 320, an optical receiver and light detector 330, a steering system 340, and a control circuitry 350. These components are coupled together using communications paths 312, 314, 322, 332, 342, 352, and 362. These communications paths include communication links (wired or wireless, bidirectional or unidirectional) among the various LiDAR system components, but need not be physical components themselves. While the communications paths can be implemented by one or more electrical wires, buses, or optical fibers, the communication paths can also be wireless channels or free-space optical paths so that no physical communication medium is present. For example, in one embodiment of LiDAR system 300, communication path 314 between light source 310 and transmitter 320 may be implemented using one or more optical fibers. Communication paths 332 and 352 may represent optical paths implemented using free space optical components and / or optical fibers. And communication paths 312, 322, 342, and 362 may be implemented using one or more electrical wires that carry electrical signals. The communications paths can also include one or more of the above types of communication mediums (e g., they can include an optical fiber and a free-space optical component, or include one or more optical fibers and one or more electrical wires).

[0062] In some embodiments, LiDAR system 300 can be a coherent LiDAR system. One example is a frequency-modulated continuous-wave (FMCW) LiDAR. Coherent LiDARs detect objects by mixing return light from the objects with light from the coherent laser transmitter. Thus, as shown in FIG. 3, if LiDAR system 300 is a coherent LiDAR, it may include a route 372 providing a portion of transmission light from transmitter 320 to optical receiver and light detector 330. Route 372 may include one or more optics (e.g., optical fibers, lens, mirrors, etc.) for providing the light from transmitter 320 to optical receiver and light detector 330. The transmission light provided by transmitter 320 may be modulated light and can be split into twoportions. One portion is transmitted to the FOV, while the second portion is sent to the optical receiver and light detector of the LiDAR system. The second portion is also referred to as the light that is kept local (LO) to the LiDAR system. The transmission light is scattered or reflected by various objects in the FOV and at least a portion of it forms return light. The return light is subsequently detected and interferometrically recombined with the second portion of the transmission light that was kept local. Coherent LiDAR provides a means of optically sensing an object’s range as well as its relative velocity along the line-of-sight (LOS).

[0063] LiDAR system 300 can also include other components not depicted in FIG. 3, such as power buses, power supplies, LED indicators, switches, etc. Additionally, other communication connections among components may be present, such as a direct connection between light source 310 and optical receiver and light detector 330 to provide a reference signal so that the time from when a light pulse is transmitted until a return light pulse is detected can be accurately measured.

[0064] Light source 310 outputs laser light for illuminating objects in a field of view (FOV). The laser light can be infrared light having a wavelength in the range of 700nm to 1mm. Light source 310 can be, for example, a semiconductor-based laser (e.g., a diode laser) and / or a fiberbased laser. A semiconductor-based laser can be, for example, an edge emitting laser (EEL), a vertical cavity surface emitting laser (VCSEL), an external-cavity diode laser, a vertical- extemal-cavity surface-emitting laser, a distributed feedback (DFB) laser, a distributed Bragg reflector (DBR) laser, an interband cascade laser, a quantum cascade laser, a quantum well laser, a double heterostructure laser, or the like. A fiber-based laser is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium and / or holmium. In some embodiments, a fiber laser is based on double-clad fibers, in which the gain medium forms the core of the fiber surrounded by two layers of cladding. The double-clad fiber allows the core to be pumped with a high-power beam, thereby enabling the laser source to be a high power fiber laser source.

[0065] In some embodiments, light source 310 comprises a master oscillator (also referred to as a seed laser) and power amplifier (MOP A). The power amplifier amplifies the output power of the seed laser. The power amplifier can be a fiber amplifier, a bulk amplifier, or a semiconductor optical amplifier. The seed laser can be a diode laser (e.g., a Fabry-Perot cavity laser, a distributed feedback laser), a solid-state bulk laser, or a tunable external-cavity diode laser. Insome embodiments, light source 310 can be an optically pumped microchip laser. Microchip lasers are alignment-free monolithic solid-state lasers where the laser crystal is directly contacted with the end mirrors of the laser resonator. A microchip laser is typically pumped with a laser diode (directly or using a fiber) to obtain the desired output power. A microchip laser can be based on neodymium-doped yttrium aluminum garnet (Y3AI5O12) laser crystals (i.e., Nd:YAG), or neodymium-doped vanadate (i.e., NDiYVCh) laser crystals. In some examples, light source 310 may have multiple amplification stages to achieve a high power gain such that the laser output can have high power, thereby enabling the LiDAR system to have a long scanning range. In some examples, the power amplifier of light source 310 can be controlled such that the power gain can be varied to achieve any desired laser output power.

[0066] FIG. 4 is a block diagram illustrating an example fiber-based laser source 400 having a seed laser and one or more pumps (e.g., laser diodes) for pumping desired output power. Fiberbased laser source 400 is an example of light source 310 depicted in FIG. 3. In some embodiments, fiber-based laser source 400 comprises a seed laser 402 to generate initial light pulses of one or more wavelengths (e.g., infrared wavelengths such as 1550 nm), which are provided to a wavelength-division multiplexor (WDM) 404 via an optical fiber 403. Fiber-based laser source 400 further comprises a pump 406 for providing laser power (e.g., of a different wavelength, such as 980 nm) to WDM 404 via an optical fiber 405. WDM 404 multiplexes the light pulses provided by seed laser 402 and the laser power provided by pump 406 onto a single optical fiber 407. The output of WDM 404 can then be provided to one or more pre-amplifier(s) 408 via optical fiber 407. Pre-amplifier(s) 408 can be optical amplifier(s) that amplify optical signals (e.g., with about 10-30 dB gain). In some embodiments, pre-amplifier(s) 408 are low noise amplifiers. Pre-amplifier(s) 408 output to an optical combiner 410 via an optical fiber 409. Combiner 410 combines the output laser light of pre-amplifier(s) 408 with the laser power provided by pump 412 via an optical fiber 411. Combiner 410 can combine optical signals having the same wavelength or different wavelengths. One example of a combiner is a WDM. Combiner 410 provides combined optical signals to a booster amplifier 414, which produces output light pulses via optical fiber 415. The booster amplifier 414 provides further amplification of the optical signals (e.g., another 20-40dB). The output light pulses can then be transmitted to transmitter 320 and / or steering mechanism 340 (shown in FIG. 3). It is understood that FIG. 4 illustrates one example configuration of fiber-based laser source 400.Laser source 400 can have many other configurations using different combinations of one or more components shown in FIG. 4 and / or other components not shown in FIG. 4 (e.g., other components such as power supplies, lens(es), filters, splitters, combiners, etc.).

[0067] In some variations, fiber-based laser source 400 can be controlled (e.g., by control circuitry 350) to produce pulses of different amplitudes based on the fiber gain profile of the fiber used in fiber-based laser source 400. Communication path 312 couples fiber-based laser source 400 to control circuitry 350 (shown in FIG. 3) so that components of fiber-based laser source 400 can be controlled by or otherwise communicate with control circuitry 350. Alternatively, fiber-based laser source 400 may include its own dedicated controller. Instead of control circuitry 350 communicating directly with components of fiber-based laser source 400, a dedicated controller of fiber-based laser source 400 communicates with control circuitry 350 and controls and / or communicates with the components of fiber-based laser source 400. Fiber-based laser source 400 can also include other components not shown, such as one or more power connectors, power supplies, and / or power lines.

[0068] Referencing FIG. 3, typical operating wavelengths of light source 310 comprise, for example, about 850 nm, about 905 nm, about 940 nm, about 1064 nm, and about 1550 nm. For laser safety, the upper limit of maximum usable laser power is set by the U.S. FDA (U.S. Food and Drug Administration) regulations. The optical power limit at 1550 nm wavelength is much higher than those of the other aforementioned wavelengths. Further, at 1550 nm, the optical power loss in a fiber is low. There characteristics of the 1550 nm wavelength make it more beneficial for long-range LiDAR applications. The amount of optical power output from light source 310 can be characterized by its peak power, average power, pulse energy, and / or the pulse energy density. The peak power is the ratio of pulse energy to the width of the pulse (e.g., full width at half maximum or FWHM). Thus, a smaller pulse width can provide a larger peak power for a fixed amount of pulse energy. A pulse width can be in the range of nanosecond or picosecond. The average power is the product of the energy of the pulse and the pulse repetition rate (PRR). As described in more detail below, the PRR represents the frequency of the pulsed laser light. In general, the smaller the time interval between the pulses, the higher the PRR. The PRR typically corresponds to the maximum range that a LiDAR system can measure. Light source 310 can be configured to produce pulses at high PRR to meet the desired number of data points in a point cloud generated by the LiDAR system. Light source 310 can also be configuredto produce pulses at medium or low PRR to meet the desired maximum detection distance. Wall plug efficiency (WPE) is another factor to evaluate the total power consumption, which may be a useful indicator in evaluating the laser efficiency. For example, as shown in FIG. 1, multiple LiDAR systems may be attached to a vehicle, which may be an electrical -powered vehicle or a vehicle otherwise having limited fuel or battery power supply. Therefore, high WPE and intelligent ways to use laser power are often among the important considerations when selecting and configuring light source 310 and / or designing laser delivery systems for vehicle-mounted LiDAR applications.

[0069] It is understood that the above descriptions provide non-limiting examples of a light source 310. Light source 310 can be configured to include many other types of light sources (e.g., laser diodes, short-cavity fiber lasers, solid-state lasers, and / or tunable external cavity diode lasers) that are configured to generate one or more light signals at various wavelengths. In some examples, light source 310 comprises amplifiers (e.g., pre-amplifiers and / or booster amplifiers), which can be a doped optical fiber amplifier, a solid-state bulk amplifier, and / or a semiconductor optical amplifier. The amplifiers are configured to receive and amplify light signals with desired gains.

[0070] With reference back to FIG. 3, LiDAR system 300 further comprises a transmitter 320. Light source 310 provides laser light (e.g., in the form of a laser beam) to transmitter 320. The laser light provided by light source 310 can be amplified laser light with a predetermined or controlled wavelength, pulse repetition rate, and / or power level. Transmitter 320 receives the laser light from light source 310 and transmits the laser light to steering mechanism 340 with low divergence. In some embodiments, transmitter 320 can include, for example, optical components (e.g., lens, fibers, mirrors, etc.) for transmitting one or more laser beams to a field-of-view (FOV) directly or via steering mechanism 340. While FIG. 3 illustrates transmitter 320 and steering mechanism 340 as separate components, they may be combined or integrated as one system in some embodiments. Steering mechanism 340 is described in more detail below.

[0071] Laser beams provided by light source 310 may diverge as they travel to transmitter 320. Therefore, transmitter 320 often comprises a collimating lens configured to collect the diverging laser beams and produce more parallel optical beams with reduced or minimum divergence. The collimated optical beams can then be further directed through various optics such as mirrors andlens. A collimating lens may be, for example, a single plano-convex lens or a lens group. The collimating lens can be configured to achieve any desired properties such as the beam diameter, divergence, numerical aperture, focal length, or the like. A beam propagation ratio or beam quality factor (also referred to as the M2factor) is used for measurement of laser beam quality. In many LiDAR applications, it is important to have good laser beam quality in the generated transmitting laser beam. The M2factor represents a degree of variation of a beam from an ideal Gaussian beam. Thus, the M2factor reflects how well a collimated laser beam can be focused on a small spot, or how well a divergent laser beam can be collimated. Therefore, light source 310 and / or transmitter 320 can be configured to meet, for example, a scan resolution requirement while maintaining the desired M2factor.

[0072] One or more of the light beams provided by transmitter 320 are scanned by steering mechanism 340 to a FOV. Steering mechanism 340 scans light beams in multiple dimensions (e.g., in both the horizontal and vertical dimension) to facilitate LiDAR system 300 to map the environment by generating a 3D point cloud. A horizontal dimension can be a dimension that is parallel to the horizon or a surface associated with the LiDAR system or a vehicle (e.g., a road surface). A vertical dimension is perpendicular to the horizontal dimension (i.e., the vertical dimension forms a 90-degree angle with the horizontal dimension). Steering mechanism 340 will be described in more detail below. The laser light scanned to an FOV may be scattered or reflected by an object in the FOV. At least a portion of the scattered or reflected light forms return light that returns to LiDAR system 300. FIG. 3 further illustrates an optical receiver and light detector 330 configured to receive the return light. Optical receiver and light detector 330 comprises an optical receiver that is configured to collect the return light from the FOV. The optical receiver can include optics (e.g., lens, fibers, mirrors, etc.) for receiving, redirecting, focusing, amplifying, and / or filtering return light from the FOV. For example, the optical receiver often includes a collection lens (e.g., a single plano-convex lens or a lens group) to collect and / or focus the collected return light onto a light detector.

[0073] A light detector detects the return light focused by the optical receiver and generates current and / or voltage signals proportional to the incident intensity of the return light. Based on such current and / or voltage signals, the depth information of the object in the FOV can be derived. One example method for deriving such depth information is based on the direct TOF (time of flight), which is described in more detail below. A light detector may be characterizedby its detection sensitivity, quantum efficiency, detector bandwidth, linearity, signal to noise ratio (SNR), overload resistance, interference immunity, etc. Based on the applications, the light detector can be configured or customized to have any desired characteristics. For example, optical receiver and light detector 330 can be configured such that the light detector has a large dynamic range while having a good linearity. The light detector linearity indicates the detector’s capability of maintaining linear relationship between input optical signal power and the detector’s output. A detector having good linearity can maintain a linear relationship over a large dynamic input optical signal range.

[0074] To achieve desired detector characteristics, configurations or customizations can be made to the light detector’s structure and / or the detector’s material system. Various detector structures can be used for a light detector. For example, a light detector structure can be a PIN based structure, which has a undoped intrinsic semiconductor region (i.e., an “i” region) between a p- type semiconductor and an n-type semiconductor region. Other light detector structures comprise, for example, an APD (avalanche photodiode) based structure, a PMT (photomultiplier tube) based structure, a SiPM (Silicon photomultiplier) based structure, a SPAD (single-photon avalanche diode) based structure, and / or quantum wires. For material systems used in a light detector, Si, InGaAs, and / or Si / Ge based materials can be used. It is understood that many other detector structures and / or material systems can be used in optical receiver and light detector 330.

[0075] A light detector (e g., an APD based detector) may have an internal gain such that the input signal is amplified when generating an output signal. However, noise may also be amplified due to the light detector’s internal gain. Common types of noise include signal shot noise, dark current shot noise, thermal noise, and amplifier noise. In some embodiments, optical receiver and light detector 330 may include a pre-amplifier that is a low noise amplifier (LNA). In some embodiments, the pre-amplifier may also include a transimpedance amplifier (TIA), which converts a current signal to a voltage signal. For a linear detector system, input equivalent noise or noise equivalent power (NEP) measures how sensitive the light detector is to weak signals. Therefore, they can be used as indicators of the overall system performance. For example, the NEP of a light detector specifies the power of the weakest signal that can be detected and therefore it in turn specifies the maximum range of a LiDAR system. It is understood that various light detector optimization techniques can be used to meet the requirement of LiDAR system 300. Such optimization techniques may include selectingdifferent detector structures, materials, and / or implementing signal processing techniques (e.g., filtering, noise reduction, amplification, or the like). For example, in addition to, or instead of, using direct detection of return signals (e.g., by using ToF), coherent detection can also be used for a light detector. Coherent detection allows for detecting amplitude and phase information of the received light by interfering the received light with a local oscillator. Coherent detection can improve detection sensitivity and noise immunity.

[0076] FIG. 3 further illustrates that LiDAR system 300 comprises steering mechanism 340. As described above, steering mechanism 340 directs light beams from transmitter 320 to scan an FOV in multiple dimensions. A steering mechanism is referred to as a raster mechanism, a scanning mechanism, or simply a light scanner. Scanning light beams in multiple directions (e.g., in both the horizontal and vertical directions) facilitates a LiDAR system to map the environment by generating an image or a 3D point cloud. A steering mechanism can be based on mechanical scanning and / or solid-state scanning. Mechanical scanning uses rotating mirrors to steer the laser beam or physically rotate the LiDAR transmitter and receiver (collectively referred to as transceiver) to scan the laser beam. Solid-state scanning directs the laser beam to various positions through the FOV without mechanically moving any macroscopic components such as the transceiver. Solid-state scanning mechanisms include, for example, optical phased arrays based steering and flash LiDAR based steering. In some embodiments, because solid- state scanning mechanisms do not physically move macroscopic components, the steering performed by a solid-state scanning mechanism may be referred to as effective steering. A LiDAR system using solid-state scanning may also be referred to as a non-mechanical scanning or simply non-scanning LiDAR system (a flash LiDAR system is an example non-scanning LiDAR system).

[0077] Steering mechanism 340 can be used with a transceiver (e.g., transmitter 320 and optical receiver and light detector 330) to scan the FOV for generating an image or a 3D point cloud. As an example, to implement steering mechanism 340, a two-dimensional mechanical scanner can be used with a single-point or several single-point transceivers. A single-point transceiver transmits a single light beam or a small number of light beams (e.g., 2-8 beams) to the steering mechanism. A two-dimensional mechanical steering mechanism comprises, for example, polygon mirror(s), oscillating mirror(s), rotating prism(s), rotating tilt mirror surface(s), singleplane or multi-plane mirror(s), or a combination thereof. In some embodiments, steeringmechanism 340 may include non-mechanical steering mechanism(s) such as solid-state steering mechanism(s). For example, steering mechanism 340 can be based on tuning wavelength of the laser light combined with refraction effect, and / or based on reconfigurable grating / phase array. In some embodiments, steering mechanism 340 can use a single scanning device to achieve two- dimensional scanning or multiple scanning devices combined to realize two-dimensional scanning.

[0078] As another example, to implement steering mechanism 340, a one-dimensional mechanical scanner can be used with an array or a large number of single-point transceivers. Specifically, the transceiver array can be mounted on a rotating platform to achieve 360-degree horizontal field of view. Alternatively, a static transceiver array can be combined with the onedimensional mechanical scanner. A one-dimensional mechanical scanner comprises polygon mirror(s), oscillating mirror(s), rotating prism(s), rotating tilt mirror surface(s), or a combination thereof, for obtaining a forward-looking horizontal field of view. Steering mechanisms using mechanical scanners can provide robustness and reliability in high volume production for automotive applications.

[0079] As another example, to implement steering mechanism 340, a two-dimensional transceiver can be used to generate a scan image or a 3D point cloud directly. In some embodiments, a stitching or micro shift method can be used to improve the resolution of the scan image or the field of view being scanned. For example, using a two-dimensional transceiver, signals generated at one direction (e.g., the horizontal direction) and signals generated at the other direction (e.g., the vertical direction) may be integrated, interleaved, and / or matched to generate a higher or full resolution image or 3D point cloud representing the scanned FOV.

[0080] Some implementations of steering mechanism 340 comprise one or more optical redirection elements (e.g., mirrors or lenses) that steer return light signals (e.g., by rotating, vibrating, or directing) along a receive path to direct the return light signals to optical receiver and light detector 330. The optical redirection elements that direct light signals along the transmitting and receiving paths may be the same components (e.g., shared), separate components (e.g., dedicated), and / or a combination of shared and separate components. This means that in some cases the transmitting and receiving paths are different although they may partially overlap (or in some cases, substantially overlap or completely overlap).

[0081] With reference still to FIG. 3, LiDAR system 300 further comprises control circuitry 350. Control circuitry 350 can be configured and / or programmed to control various parts of the LiDAR system 300 and / or to perform signal processing. In a typical system, control circuitry 350 can be configured and / or programmed to perform one or more control operations including, for example, controlling light source 310 to obtain the desired laser pulse timing, the pulse repetition rate, and power; controlling steering mechanism 340 (e.g., controlling the speed, direction, and / or other parameters) to scan the FOV and maintain pixel registration and / or alignment; controlling optical receiver and light detector 330 (e.g., controlling the sensitivity, noise reduction, filtering, and / or other parameters) such that it is an optimal state; and monitoring overall system health / status for functional safety (e.g., monitoring the laser output power and / or the steering mechanism operating status for safety).

[0082] Control circuitry 350 can also be configured and / or programmed to perform signal processing to the raw data generated by optical receiver and light detector 330 to derive distance and reflectance information, and perform data packaging and communication to vehicle perception and planning system 220 (shown in FIG. 2). For example, control circuitry 350 determines the time it takes from transmitting a light pulse until a corresponding return light pulse is received; determines when a return light pulse is not received for a transmitted light pulse; determines the direction (e.g., horizontal and / or vertical information) for a transmitted / retum light pulse; determines the estimated range in a particular direction; derives the reflectivity of an object in the FOV, and / or determines any other type of data relevant to LiDAR system 300.

[0083] LiDAR system 300 can be disposed in a vehicle, which may operate in many different environments including hot or cold weather, rough road conditions that may cause intense vibration, high or low humidities, dusty areas, etc. Therefore, in some embodiments, optical and / or electronic components of LiDAR system 300 (e.g., optics in transmitter 320, optical receiver and light detector 330, and steering mechanism 340) are disposed and / or configured in such a manner to maintain long term mechanical and optical stability. For example, components in LiDAR system 300 may be secured and sealed such that they can operate under all conditions a vehicle may encounter. As an example, an anti-moisture coating and / or hermetic sealing may be applied to optical components of transmitter 320, optical receiver and light detector 330, and steering mechanism 340 (and other components that are susceptible to moisture). As anotherexample, housing(s), enclosure(s), fairing(s), and / or window can be used in LiDAR system 300 for providing desired characteristics such as hardness, ingress protection (IP) rating, selfcleaning capability, resistance to chemical and resistance to impact, or the like. In addition, efficient and economical methodologies for assembling LiDAR system 300 may be used to meet the LiDAR operating requirements while keeping the cost low.

[0084] It is understood by a person of ordinary skill in the art that FIG. 3 and the above descriptions are for illustrative purposes only, and a LiDAR system can include other functional units, blocks, or segments, and can include variations or combinations of these above functional units, blocks, or segments. For example, LiDAR system 300 can also include other components not depicted in FIG. 3, such as power buses, power supplies, LED indicators, switches, etc. Additionally, other connections among components may be present, such as a direct connection between light source 310 and optical receiver and light detector 330 so that light detector 330 can accurately measure the time from when light source 310 transmits a light pulse until light detector 330 detects a return light pulse.

[0085] These components shown in FIG. 3 are coupled together using communications paths 312, 314, 322, 332, 342, 352, and 362. These communications paths represent communication (bidirectional or unidirectional) among the various LiDAR system components but need not be physical components themselves. While the communications paths can be implemented by one or more electrical wires, buses, or optical fibers, the communication paths can also be wireless channels or open-air optical paths so that no physical communication medium is present. For example, in one example LiDAR system, communication path 314 includes one or more optical fibers; communication path 352 represents an optical path; and communication paths 312, 322, 342, and 362 are all electrical wires that carry electrical signals. The communication paths can also include more than one of the above types of communication mediums (e.g., they can include an optical fiber and an optical path, or one or more optical fibers and one or more electrical wires).

[0086] As described above, some LiDAR systems use the time-of-flight (ToF) of light signals (e g., light pulses) to determine the distance to objects in a light path. For example, with reference to FIG. 5A, an example LiDAR system 500 includes a laser light source (e.g., a fiber laser), a steering mechanism (e.g., a system of one or more moving mirrors), and a light detector(e g., a photodetector with one or more optics). LiDAR system 500 can be implemented using, for example, LiDAR system 300 described above. LiDAR system 500 transmits a light pulse 502 along light path 504 as determined by the steering mechanism of LiDAR system 500. In the depicted example, light pulse 502, which is generated by the laser light source, is a short pulse of laser light. Further, the signal steering mechanism of the LiDAR system 500 is a pulsed-signal steering mechanism. However, it should be appreciated that LiDAR systems can operate by generating, transmitting, and detecting light signals that are not pulsed and derive ranges to an object in the surrounding environment using techniques other than time-of-flight. For example, some LiDAR systems use frequency modulated continuous waves (i.e., “FMCW”). It should be further appreciated that any of the techniques described herein with respect to time-of-flight based systems that use pulsed signals also may be applicable to LiDAR systems that do not use one or both of these techniques.

[0087] Referring back to FIG. 5A (e.g., illustrating a time-of-flight LiDAR system that uses light pulses), when light pulse 502 reaches object 506, light pulse 502 scatters or reflects to form a return light pulse 508. Return light pulse 508 may return to system 500 along light path 510. The time from when transmitted light pulse 502 leaves LiDAR system 500 to when return light pulse 508 arrives back at LiDAR system 500 can be measured (e.g., by a processor or other electronics, such as control circuitry 350, within the LiDAR system). This time-of-flight combined with the knowledge of the speed of light can be used to determine the range / di stance from LiDAR system 500 to the portion of object 506 where light pulse 502 scattered or reflected.

[0088] By directing many light pulses, as depicted in FIG. 5B, LiDAR system 500 scans the external environment (e.g., by directing light pulses 502, 522, 526, 530 along light paths 504, 524, 528, 532, respectively). As depicted in FIG. 5C, LiDAR system 500 receives return light pulses 508, 542, 548 (which correspond to transmitted light pulses 502, 522, 530, respectively). Return light pulses 508, 542, and 548 are formed by scattering or reflecting the transmitted light pulses by one of objects 506 and 514. Return light pulses 508, 542, and 548 may return to LiDAR system 500 along light paths 510, 544, and 546, respectively. Based on the direction of the transmitted light pulses (as determined by LiDAR system 500) as well as the calculated range from LiDAR system 500 to the portion of objects that scatter or reflect the light pulses (e.g., the portions of objects 506 and 514), the external environment within the detectable range (e.g., thefield of view between path 504 and 532, inclusively) can be precisely mapped or plotted (e.g., by generating a 3D point cloud or images).

[0089] If a corresponding light pulse is not received for a particular transmitted light pulse, then LiDAR system 500 may determine that there are no objects within a detectable range of LiDAR system 500 (e.g., an object is beyond the maximum scanning distance of LiDAR system 500). For example, in FIG. 5B, light pulse 526 may not have a corresponding return light pulse (as illustrated in FIG. 5C) because light pulse 526 may not produce a scattering event along its transmission path 528 within the predetermined detection range. LiDAR system 500, or an external system in communication with LiDAR system 500 (e g., a cloud system or service), can interpret the lack of return light pulse as no object being disposed along light path 528 within the detectable range of LiDAR system 500.

[0090] In FIG. 5B, light pulses 502, 522, 526, and 530 can be transmitted in any order, serially, in parallel, or based on other timings with respect to each other. Additionally, while FIG. 5B depicts transmitted light pulses as being directed in one dimension or one plane (e.g., the plane of the paper), LiDAR system 500 can also direct transmitted light pulses along other dimension(s) or plane(s). For example, LiDAR system 500 can also direct transmitted light pulses in a dimension or plane that is perpendicular to the dimension or plane shown in FIG. 5B, thereby forming a 2-dimensional transmission of the light pulses. This 2-dimensional transmission of the light pulses can be point-by-point, line-by-line, all at once, or in some other manner. That is, LiDAR system 500 can be configured to perform a point scan, a line scan, a one-shot without scanning, or a combination thereof. A point cloud or image from a 1-dimensional transmission of light pulses (e.g., a single horizontal line) can generate 2- dimensional data (e.g., (1) data from the horizontal transmission direction and (2) the range or distance to objects). Similarly, a point cloud or image from a 2-dimensional transmission of light pulses can generate 3-dimensional data (e.g., (1) data from the horizontal transmission direction, (2) data from the vertical transmission direction, and (3) the range or distance to objects). In general, a LiDAR system performing an / / -dimensional transmission of light pulses generates ( / / + ! ) dimensional data. This is because the LiDAR system can measure the depth of an object or the range / di stance to the object, which provides the extra dimension of data. Therefore, a 2D scanning by a LiDAR system can generate a 3D point cloud for mapping the external environment of the LiDAR system.

[0091] The density of a point cloud refers to the number of measurements (data points) per area performed by the LiDAR system. A point cloud density relates to the LiDAR scanning resolution. Typically, a larger point cloud density, and therefore a higher resolution, is desired at least for the region of interest (ROI). The density of points in a point cloud or image generated by a LiDAR system is equal to the number of pulses divided by the field of view. In some embodiments, the field of view can be fixed. Therefore, to increase the density of points generated by one set of transmission-receiving optics (or transceiver optics), the LiDAR system may need to generate a pulse more frequently. In other words, a light source in the LiDAR system may have a higher pulse repetition rate (PRR). On the other hand, by generating and transmitting pulses more frequently, the farthest distance that the LiDAR system can detect may be limited. For example, if a return signal from a distant object is received after the system transmits the next pulse, the return signals may be detected in a different order than the order in which the corresponding signals are transmitted, thereby causing ambiguity if the system cannot correctly correlate the return signals with the transmitted signals.

[0092] To illustrate, consider an example LiDAR system that can transmit laser pulses with a pulse repetition rate between 500 kHz and 1 MHz. Based on the time it takes for a pulse to return to the LiDAR system and to avoid mix-up of return pulses from consecutive pulses in a typical LiDAR design, the farthest distance the LiDAR system can detect may be 300 meters and 150 meters for 500 kHz and 1 MHz, respectively. The density of points of a LiDAR system with 500 kHz repetition rate is half of that with 1 MHz. Thus, this example demonstrates that, if the system cannot correctly correlate return signals that arrive out of order, increasing the repetition rate from 500 kHz to 1 MHz (and thus improving the density of points of the system) may reduce the detection range of the system. Various techniques are used to mitigate the tradeoff between higher PRR and limited detection range. For example, multiple wavelengths can be used for detecting objects in different ranges. Optical and / or signal processing techniques (e.g., pulse encoding techniques) are also used to correlate between transmitted and return light signals.

[0093] Various systems, apparatus, and methods described herein may be implemented using digital circuitry, or using one or more computers using well-known computer processors, memory units, storage devices, computer software, and other components. Typically, a computer includes a processor for executing instructions and one or more memories for storing instructions and data. A computer may also include, or be coupled to, one or more mass storagedevices, such as one or more magnetic disks, internal hard disks and removable disks, magnetooptical disks, optical disks, etc.

[0094] Various systems, apparatus, and methods described herein may be implemented using computers operating in a client-server relationship. Typically, in such a system, the client computers are located remotely from the server computers and interact via a network. The client-server relationship may be defined and controlled by computer programs running on the respective client and server computers. Examples of client computers can include desktop computers, workstations, portable computers, cellular smartphones, tablets, or other types of computing devices.

[0095] Various systems, apparatus, and methods described herein may be implemented using a computer program product tangibly embodied in an information carrier, e.g., in a non-transitory machine-readable storage device, for execution by a programmable processor; and the method processes and steps described herein, including one or more of the steps of at least some of the FIGs. 1-5 and 7A-14, may be implemented using one or more computer programs that are executable by such a processor. A computer program is a set of computer program instructions that can be used, directly or indirectly, in a computer to perform a certain activity or bring about a certain result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0096] A high-level block diagram of an example apparatus that may be used to implement systems, apparatus and methods described herein is illustrated in FIG. 6. Apparatus 600 comprises a processor 610 operatively coupled to a persistent storage device 620 and a main memory device 630. Processor 610 controls the overall operation of apparatus 600 by executing computer program instructions that define such operations. The computer program instructions may be stored in persistent storage device 620, or other computer-readable medium, and loaded into main memory device 630 when execution of the computer program instructions is desired. For example, processor 610 may be used to implement one or more components and systems described herein, such as control circuitry 350 (shown in FIG. 3), vehicle perception and planning system 220 (shown in FIG. 2), and vehicle control system 280 (shown in FIG. 2).Thus, the method steps of at least some of FIGs. 1-5 and 7A-14 can be defined by the computer program instructions stored in main memory device 630 and / or persistent storage device 620 and controlled by processor 610 executing the computer program instructions. For example, the computer program instructions can be implemented as computer executable code programmed by one skilled in the art to perform an algorithm defined by the method steps discussed herein in connection with at least some of FIGs. 1-5 and 7A-14. Accordingly, by executing the computer program instructions, the processor 610 executes an algorithm defined by the method steps of the aforementioned figures. Apparatus 600 also includes one or more network interfaces 680 for communicating with other devices via a network. Apparatus 600 may also include one or more input / output devices 690 that enable user interaction with apparatus 600 (e.g., display, keyboard, mouse, speakers, buttons, etc.).

[0097] Processor 610 may include both general and special purpose microprocessors and may be the sole processor or one of multiple processors of apparatus 600. Processor 610 may comprise one or more central processing units (CPUs), and one or more graphics processing units (GPUs), which, for example, may work separately from and / or multi-task with one or more CPUs to accelerate processing, e.g., for various image processing applications described herein.Processor 610, persistent storage device 620, and / or main memory device 630 may include, be supplemented by, or incorporated in, one or more application-specific integrated circuits (ASICs) and / or one or more field programmable gate arrays (FPGAs).

[0098] Persistent storage device 620 and main memory device 630 each comprise a tangible non-transitory computer readable storage medium. Persistent storage device 620, and main memory device 630, may each include high-speed random access memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), double data rate synchronous dynamic random access memory (DDR RAM), or other random access solid state memory devices, and may include non-volatile memory, such as one or more magnetic disk storage devices such as internal hard disks and removable disks, magneto-optical disk storage devices, optical disk storage devices, flash memory devices, semiconductor memory devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), digital versatile disc read-only memory (DVD-ROM) disks, or other non-volatile solid state storage devices.

[0099] Input / output devices 690 may include peripherals, such as a printer, scanner, display screen, etc. For example, input / output devices 690 may include a display device such as a cathode ray tube (CRT), plasma or liquid crystal display (LCD) monitor for displaying information to a user, a keyboard, and a pointing device such as a mouse or a trackball by which the user can provide input to apparatus 600.

[0100] Any or all of the functions of the systems and apparatuses discussed herein may be performed by processor 610, and / or incorporated in, an apparatus or a system such as LiDAR system 300. Further, LiDAR system 300 and / or apparatus 600 may utilize one or more neural networks or other deep-learning techniques performed by processor 610 or other systems or apparatuses discussed herein.

[0101] One skilled in the art will recognize that an implementation of an actual computer or computer system may have other structures and may contain other components as well, and that FIG. 6 is a high-level representation of some of the components of such a computer for illustrative purposes.

[0102] FIGs. 7A-7C are block diagrams illustrating example semiconductor laser (SL) devices in accordance with various embodiments.

[0103] In FIG. 7A, is a block diagram illustrating an example Edge Emitting Laser (EEL) device 700A is shown. An edge-emitting laser, also known as an in-plane laser, is a semiconductor chip-based laser that emits light along the wafer (substrate) surface, where the optical cavity is parallel to the wafer surface. For example, the EEL device 700A may be mounted on a substrate 710A. In an embodiment, the EEL device 700A may comprise epitaxial layers 720A and 725 A, an active region 730, and a top contact 740.

[0104] The Epitaxial layers 720A and 725A are used in edge-emitting lasers (EELs) to create optical waveguides that optimize the overlap of the optical field with the cavity resonance and material gain. The epitaxial layers 720A and 725A may be grown using a variety of techniques, e.g., epitaxial lateral overgrowth (ELO) which is used to grow a Gallium Nitride (GaN) layer on a silicon (Si) substrate, that result in a unique shape that can be cleaved to create laser facets. For example, ELO layers are typically thin and narrow, which allow for a shorter cavity length than other processes for growing epitaxial layers.

[0105] Current flow is vertical through the active region 730A, e g., a p-n junction, and light is emitted from an end of the active region 730A in the form of an emission pattern 735A, which is typically reflected or coupled out at a cleaved edge of the active region 730 A, as shown.

[0106] The top contact 740A on the edge-emitting laser (EEL) device 700A can be made, from a metal, e.g., titanium / aluminum (Ti / Au), deposited on top of the epitaxial layers 720A and 725A. Alternatively, a blanket top contact, e.g., made from Ti / Au, can also be deposited on the back of the substrate 710A.

[0107] FIG. 7B is a block diagram illustrating an example vertical-cavity surface-emitting laser (VCSEL) device 700B in accordance with an embodiment. VCSEL devices differ from EEL sources in that VCSEL laser light pulses are emitted vertically from a VCSEL device array, where the optical cavity is orthogonal to the active region plane. For example, the VCSEL device 700B may be mounted on a substrate 710B. In an embodiment, the VCSEL device 700B may comprise reflector mirrors 720B and 725B, an active region 730B, and a top contact 740B.

[0108] The reflector mirrors 720B and 725B used in VCSEL devices are multilayer structures comprising alternating high and low refractive index dielectric layers that reflect light at a particular wavelength through constructive interference.

[0109] Current flow is vertical through the active region 730B, e.g., a p-n junction, stacked between the reflector mirrors 720B and 725B. Light propagates in the vertical direction, orthogonal to the active region plane and the current is injected from the mirrors 720B and 725B. light is emitted from an end of the active region 730B in the form of an emission pattern 735B. The vertical epitaxial growth of the VCSEL device 700B allows for reduced thickness of the active region 730B (micro-cavity dimensions) that can be orders of magnitude smaller than then active region of an EEL device. In some implementations of a VCSEL device 700B, the reflector mirrors 720B and 725B may be highly reflective to satisfy threshold current conditions due to the reduced thickness of the active region 730B.

[0110] The top contact 740B on the VCSEL device 700B can be made, from a metal, e.g., titanium / aluminum (Ti / Au), deposited on top of (or below) the Bragg reflector mirrors 720B and 725B.[0U1] FIG. 7C is a block diagram illustrating an example light-emitting diode (LED) laser device 700C in accordance with an embodiment. LED laser devices 700C comprise LEDs that emit a concentrated light pulse. In general, LEDs have a diverging light output beam pattern.For example, the LED laser device 700C may be mounted on a substrate 710CB. In an embodiment, the LED laser device 700C may comprise reflector mirrors 720C and 725C, an active region 730C, and a top contact 740C.

[0112] The reflector mirrors 720C and 725C used in LED laser devices at the edges of the active region 730C are operative to provide for sustained reinjection of photons into the active region 730C. Thus, the active region 730C operative to be filled with excited atoms that stimulate emission, effectively duplicating the reinjected photons. As the photons get reinjected and reduplicated, they become a concentrated laser beam that can be outputted in the form of an emission pattern 735C from an edge of the optical cavity that is configured to be only partially reflective.

[0113] The top contact 740C on the LED laser device 700C can be made, from a metal, e g., titanium / aluminum (Ti / Au), deposited on top of (or below) the reflector mirrors 720C and 725C.

[0114] One skilled in the art will appreciate that EEL devices 700A, VCSEL devices 700B, and / or LED laser devices 700C are laser light sources that can be used in LiDAR applications. While some embodiments herein are described in the context of an EEL device array, other semiconductor (SL) laser light sources can be used, including Vertical Cavity Surface Emitting Laser (VCSEL) sources and Light Emitting Diode (LED) sources. The EEL devices differ from these other SL sources in that EEL laser light pulses are emitted from an edge of the EEL array but, with appropriate modification, orthogonally emitting VCSEL and / or LED sources (or other laser sources) may be equally suitable for implementing the various embodiments described herein.

[0115] FIG. 8 illustrates a perspective view of an example LiDAR system 800 comprising an SL device array within a housing 805, as may be employed for a vehicular LiDAR system. In an embodiment, an SL device array 810 may comprise a plurality of SL devices, e.g., VCSEL or EEL devices arranged on a substrate. In FIG. 8, the housing 805 of the LiDAR system 800 encloses SL device array 810, charging capacitors 820, and SL wire bondings 830 shown as connecting the SL devices of the SL device array 810 to the charging capacitors 820. However, one difficulty in employing SL devices in LiDAR applications is grouping, e.g., within the dimensions of a housing and / or a substrate employed to host an SL device array.

[0116] FIG. 9 is a block diagram illustrating an example of a conventional SL array 900, such as may be employed within the housing 800 of FIG. 8. Referring to FIG. 9, SL devices 910A-H areshown as being wire bonded to charging capacitors 920 A-D via wire bondings 930A-H. The wire bonding between the SL devices 910A-H and the charging capacitors 920A-D dictates the SL device grouping methods that can be employed for LiDAR applications. For example, SL devices 910A-H comprise a 1x8 SL device array that receives energy to discharge laser light pulses via the four charging capacitors 920A-D. In typical applications, the relative number of charging capacitors is reduced compared to the number of SL devices due to physical constraints. Particularly, charging capacitors are oftentimes physically larger than SL devices, so LiDAR designers often employ wire bonding only between adjacent SL devices due to the packaging constraints. For example, SL devices 910A-B are connected to charging capacitor 920A via wire bonds 930A-B, respectively, because they are close in proximity with respect to each other. Likewise, SL devices 910C-D are connected to charging capacitor 920B via wire bonds 930C-D, respectively; SL devices 910E-F are connected to charging capacitor 920C via wire bonds 930E-F, respectively; and SL devices 910G-H are connected to charging capacitor 920D via wire bonds 930G-H, respectively. Notably, the relatively longer wires necessary for bonding nonadj acent SL devices will often increase the inductance of the wire bonding and reduce the performance of laser light pulse emissions. Further, it is oftentimes not desirable to fire adjacent channels, e.g., SL devices 910A-B, because to do so may increase crosstalk between the channels inside of the LiDAR system. While a designer may want SL devices 910A and 910E to fire laser simultaneously, this sequence would require SL devices 910A and 910E to be bonded to a common charging capacitor, e.g., charging capacitor 920A. However, as shown in FIG. 9, the proposed wire bonding 9301 connecting charging capacitor 920A to SL device 910E would have to cross over other wires (e.g., at least the wires 930C-D to SL devices 910C- D, respectively, and possibly also the wire 930B to SL device 910B), which would not only increase the length of the wire bonding to SL device 910E but also create an increased risk of scenarios that would result in a short circuit.

[0117] To solve this SL device grouping issue, new systems and methods for a LiDAR system are proposed by the various embodiments herein.

[0118] FIG. 10 illustrates a perspective view of a LiDAR system 1000 comprising an SL device array, silicon capacitors, and a charging bus element in accordance with an embodiment. For example, a LiDAR system 1000 may comprise a substrate 1010 (e.g., a ceramic substrate), an SL device array 1020, a charging capacitor array 1030, a charging bus 1030 comprising pads1045A-D, and transmission control circuitry 1050 comprising, e.g., field-effect transistor (FET) circuitry (e g., GaN FET circuitry) and a FET driver 1060. One skilled in the art will appreciate that a LiDAR system, such as LiDAR system 1000, may include additional elements, e.g., elements adapted to vehicular use cases as described in FIG. 1 or to other use cases or applications.

[0119] In an embodiment, the SL device array 1020 may comprise a plurality of SL devices (e.g., VCSEL, EEL, and / or LED devices) on the substrate 1010. For example, the substrate 1010 may be ceramic substrate or a substrate made from a composite material and the SL device array 1020 may be mounted on and / or etched into the substrate 1010.

[0120] The charging capacitor array 1030 may comprise a plurality of charging capacitors on the substrate 1010 proximate to the SL device array 1020, wherein each SL device of the SL device array 1020 is coupled to a different charging capacitor of the charging capacitor array 1030. In an embodiment, the charging capacitor array 1030 may comprise a plurality of silicon capacitors, e.g., capacitors made on silicon wafers, mounted and / or etched on to the substrate 1010 that are operative to be used as charging capacitors for the SL device array 1020. Silicon capacitors are useful for the embodiments described herein because their capacitance density is relatively high in comparison to conventional capacitors. In addition, silicon capacitors are relatively small in comparison to conventional capacitors.

[0121] A charging bus element 1040 may comprise a plurality of charging buses proximate to the charging capacitor array 1030, where each adjacent charging capacitor of the charging capacitor array 1030 is coupled to a different charging bus of the charging bus element 1040. As shown, the charging bus element 1040 may comprise one or more pads, e.g., pads 1045A-D, operative to provide electrical power to the respective charging buses.

[0122] FIG. 11 is a block diagram illustrating the LiDAR system 1000 of FIG. 10 comprising the SL device array 1020, silicon capacitors 1030A-P, and the charging bus element 1040 in accordance with an embodiment. The LiDAR system 1000 may comprise the SL device array 1020, the plurality of SL devices 1020A-P, the plurality of silicon capacitor elements 1030A-P, and the charging bus element 1040. For example, the plurality of SL devices may comprise 4 SL devices, 8 SL devices, 16 SL devices, or another number of SL devices, e.g., mounted in series on the substrate 1010. Referring to both FIGs. 10-11, the SL device array 1020 comprises 16 SLdevices mounted on the substrate in series, where each SL device 1020A-P is connected to a respective silicon charging capacitor 1030A-P. Therefore, the SL device array 1020 is a 1x16 SL device array. A 1x16 silicon charging capacitor array 1030 may be located immediately adjacent to the 1x16 SL device array 1020, e.g., mounted in series on substrate 1010. For example, the silicon charging capacitors of the silicon charging capacitor array 1030 may be mounted on the substrate 1010 in series and substantially in parallel to the SL devices of the SL device array 1020, where each SL device element 1020A-P may be connected to a respective silicon capacitor element 1030A-P, e.g., by wire bonding. In other words, each SL device of the SL device array may be coupled to a corresponding adjacent silicon charging capacitor of the silicon charging capacitor array. Therefore, each SL device 1020A-P operative to emit laser light pulses is controlled by a respective silicon charging capacitor, e.g., one of silicon charging capacitors 1030A-P. For example, SL device 1020A may be operative to emit a laser light pulse when silicon capacitor 1030A discharges to SL device 1020A.

[0123] The charging bus element 1040 may be located immediately adjacent to the silicon charging capacitor array 1030 on substrate 1010. For example, each silicon charging capacitor may be wire-bonded to one or more charging buses, e.g., charging buses 1040A-D, of the charging bus element 1040. Continuing to refer to both FIGs. 10-11, the charging bus element 1040 may comprise four charging buses, e.g., charging buses 1040A-D, or another number of charging buses, e.g., 2 charging buses, 8 charging buses, 16 charging buses, etc. In an embodiment, each adjacent silicon charging capacitor of the silicon charging capacitor array 1030 may be connected, e.g. wire bonded, to a different charging bus of the charging bus element 1040. For example, silicon charging capacitors 1030A, 1030E, 10301, and 1030M may be in a first group and connected to charging bus 1040A. Therefore, silicon capacitors 1030A, 1030E, 10301, and 1030M are operative to be charged together and discharge together to EEL devices 1020A, 1020E, 10201, and 1020M. In other words, SL devices 1020A, 1020E, 10201, and 1020M may discharge (fire) together even though they are not physically located next to each other. In another example, silicon capacitors 1030B, 1030F, 10301, and 1030N may be in a second group and connected to charging bus 1040B. Therefore, silicon capacitors 1030B, 1030F, 1030J, and 1030N are operative to be charged together and discharge together to SL devices 1020B, 1020F, 1020J, and 1020N. In other words, SL devices 1020B, 1020F, 1020 J, and 1020N may discharge (fire) together even though they are not physically located next toeach other. In another example, silicon capacitors 1030C, 1030G, 1030K, and 10300 may be in a third group and connected to bus 1040C. Therefore, silicon capacitors 1030C, 1030G, 1030K, and 10300 are operative to be charged together and discharge together to EEL devices 1020C, 1020G, 1020K, and 10200. In other words, SL devices 1020C, 1020G, 1020K, and 10200 may discharge (fire) together even though they are not physically located next to each other. In yet another example, silicon capacitors 1030D, 103 OH, 1030L, and 103 OP may be in a fourth group and connected to bus 1040D. Therefore, silicon capacitors 1030D, 1030H, 1030L, and 1030P are operative to be charged together and discharge together to SL devices 1020D, 1020H, 1020L, and 1020P. In other words, SL devices 1020D, 1020H, 1020L, and 1020P may discharge (fire) together even though they are not physically located next to each other. While the preceding examples of SL device, silicon charging capacitor, and charging bus combinations are exemplary for illustrative purposes, one skilled in the art should appreciate that various other combinations to simultaneously discharge non-adjacent SL devices and / or discharge SL devices in consecutive cycles are possible and within the scope of the various embodiments. Particularly, the ability to discharge non-adjacent SL devices may be advantageous in some LiDAR systems, e.g., to reduce crosstalk between channels.

[0124] Referring back to FIG. 10, LiDAR system 1000 may further comprise transmission control circuitry 1050 coupled to the SL device array 1020 and the silicon charging capacitor array 1030. For example, the transmission control circuitry 1050 may comprise a GaN FET 1052 and a FET driver 1054. As shown in FIG. 10, the transmission control circuitry 1050 may be located adjacent to the silicon charging capacitor array 1030 and / or the SL device array 1020 on substrate 1010.

[0125] In an embodiment, the transmission control circuitry 1050 may be operative to select SL groupings comprising any of the plurality of SL devices 1020A-P to collectively discharge during a particular firing cycle due to the arrangement of the charging bus element 1040. Therefore, the configurations described herein allow any one of the SL devices to emit laser transmission pulses in consecutive firing cycles, if desired. Thus, the various embodiments improve the operational capabilities of the LiDAR device 1000 to, e.g., scan overlapping coverage areas in consecutive firing sequences, scan non-overlapping or disparate coverage areas in same and / or consecutive firing sequences, focus on areas of interest in consecutive firing sequences, or any combination thereof. Further, the transmission control circuitry 1050 may beoperative to determine or select an SL grouping comprising any one of the plurality of SL devices 1020A-P based on one or more parameters and / or thresholds.

[0126] FIG. 12 is a flow diagram illustrating example operations 1200 for transmission control circuitry of an SL device array in accordance with an embodiment. At block 1210, the transmission control circuitry 1050 is operative to determine or select a first SL grouping comprising any one of the plurality of SL devices 1020A-P. For example, the transmission control circuitry 1050 may be operative to determine or select the first SL grouping using a machine learning model based on, e.g., previous firing sequences, a preprogrammed pattern, sensor information, or a combination thereof. The first SL grouping may comprise any one of the plurality of SL devices 1020A-P such as, to continue the example of FIGs. 10-11, SL devices 1020A, 1020E, 10201, and 1020M. Referring back to FIG. 12, the transmission control circuitry 1050 may be further operative to cause, within a first firing cycle, the first SL grouping to emit first laser transmission pulses at block 1220. As shown in FIG. 11, silicon charging capacitors 1030A, 1030E, 10301, and 1030M may be in the first SL grouping and connected to bus 1040A. Therefore, silicon charging capacitors 1030A, 1030E, 10301, and 1030M may be operative to be charged together and discharge together to SL devices 1020A, 1020E, 10201, and 1020M when selected by the transmission control circuitry 1050. Again, referring back to FIG. 12, the transmission control circuitry 1050 may be further operative to select a second SL grouping comprising any one of the plurality of SL devices 1020A-P at block 1230. For example, the transmission control circuitry 1050 may be operative to determine or select the second SL grouping using a machine learning model based on, e.g., previous firing sequences, a preprogrammed pattern, sensor information, or a combination thereof. The second SL grouping may comprise any one of the plurality of SL devices 1020A-P such as, to continue the example of FIG. 11, SL devices 1020B, 1020F, 1020J, and 1020N. For example, silicon charging capacitors 1030B, 1030F, 1030J, and 1030N may be in the second SL grouping and connected to bus 1040B. Therefore, silicon charging capacitors 1030B, 1030F, 1030J, and 1030N may be operative to be charged together and discharge together to SL devices 1020B, 1020F, 1020J, and 1020N when selected by the transmission control circuitry 1050. At block 1240, the transmission control circuitry is further operative to cause, within a second firing cycle, the second SL grouping to emit second laser transmission pulses, where the first firing cycle and second firing cycle are consecutive firing cycles. In some embodiments, the second SL groupingmay comprise at least one SL device of the first SL grouping. For example, the transmission control circuitry 1050 may be operative to select SL devices 1020B and 1020F for the first grouping as well as the second grouping. Thus, SL devices 1020B and 1020F will emit laser transmission pulses in consecutive firing cycles. In addition, the transmission control circuitry 1050 may be operative to select, e.g., SL device 1020A for the first grouping and SL device 1020B for the second grouping. Thus, adjacent SL devices 1020A and 1020B will emit laser transmission pulses in consecutive firing cycles.

[0127] FIGs. 13A-13B show example structures for implementing an SL device array in accordance with various embodiments. For example, FIG. 13A is a block diagram 1300A illustrating an SL device array 1310A having a parallel charging bus in accordance with an embodiment. In FIG. 13 A, a side view of a grouping method shows the SL device array 1310, silicon charging capacitor array 1320A, and charging bus 1330A are mounted on the ceramic layer 1340A. For example, the charging bus 1330A may be a metal etching on the surface of (or etched into) the ceramic substrate 1340A, or a metal bar connected to (mounted on) the substrate 1340A. The silicon charging capacitors of the charging capacitor array 1320A may be mounted on the substrate 1340A in series and substantially in parallel to the charging bus element 1330A. Further, the plurality of charging buses, e.g., charging buses 1040A-D shown in FIG. 10, may be arranged in parallel.

[0128] Alternatively, FIG. 13B is a block diagram illustrating an SL device array having a stacked charging bus in accordance with an embodiment. The difference between the LiDAR systems in FIGs. 13A-13B is the location of the charging bus. In FIG. 13B, a side view of a grouping method shows the SL device array 1310B and the charging capacitor array 1320B (e.g., comprising silicon capacitors) are mounted on the ceramic layer, but the charging bus 133OB is mounted on the silicon charging capacitor array 1320B. In other words, the charging capacitor array 1320B comprises the charging bus element 1330B. The grouping configuration of FIG. 13B may be advantageous because it further reduces the length of the respective discharging circuits. Thus, the wire length between each element is relatively short, which may benefit the SL array’s laser performance because of the expected lower amount of inductance.

[0129] FIG. 14 is a flow diagram illustrating a process 1400 for manufacturing a LiDAR system in accordance with an embodiment. At block 1410, the process for manufacturing a LiDARsystem comprises building a semiconductor laser (SL) device array comprising a plurality of SL devices mounted on a substrate. At block 1420, the process for manufacturing a LiDAR system further comprises building a charging capacitor array comprising a plurality of charging capacitors mounted on the substrate proximate to the SL device array, where each SL device of the SL device array is coupled to a different charging capacitor of the charging capacitor array. At block 1430, the process for manufacturing a LiDAR system further comprises building a charging bus element comprising a plurality of charging buses proximate to the charging capacitor array, where each adjacent charging capacitor of the charging capacitor array is coupled to a different charging bus of the charging bus element.

[0130] Additional embodiments are described below.

[0131] (1) A system for light ranging and detection (LiDAR), comprising: a semiconductor laser (SL) device array comprising a plurality of SL devices mounted on a substrate; a charging capacitor array comprising a plurality of charging capacitors mounted on the substrate proximate to the SL device array, wherein each SL device of the SL device array is coupled to a different charging capacitor of the charging capacitor array; and a charging bus element comprising a plurality of charging buses proximate to the charging capacitor array, wherein each adjacent charging capacitor of the charging capacitor array is coupled to a different charging bus of the charging bus element.

[0132] (2) The system of (1), further comprising transmission control circuitry coupled to the SL device array and the charging capacitor array, the transmission control circuitry operative to: select a first SL grouping comprising any one of the plurality of SL devices; and cause, within a first firing cycle, the first SL grouping to emit first transmission pulses.

[0133] (3) The system of (2), wherein the transmission control circuitry is further operative to: select a second SL grouping comprising any one of the plurality of SL devices; and cause, within a second firing cycle, the second SL grouping to emit second transmission pulses, wherein the first firing cycle and second firing cycle are consecutive firing cycles.

[0134] (4) The system of (3), wherein the second SL grouping comprises at least one SL device of the first SL grouping.

[0135] (5) The system of (2), wherein the transmission control circuity comprises a Gallium Nitride (GaN) field-effect transistor (FET) and a FET driver.

[0136] (6) The system of any one of ( 1 )-(5), wherein the plurality of SL devices comprises one of 4 SL devices, 8 SL devices, or 16 SL devices.

[0137] (7) The system of any one of (1 )-(6), wherein the plurality of SL devices of the EEL array is mounted on the substrate in series.

[0138] (8) The system of (7), wherein the charging capacitors of the charging capacitor array are mounted on the substrate in series and substantially in parallel to the SL devices of the SL device array.

[0139] (9) The system of (8), wherein each SL device of the SL device array is coupled to a corresponding adjacent charging capacitor of the charging capacitor array.

[0140] (10) The system of (9), wherein each SL device of the SL device array is wire-bonded to a corresponding adjacent charging capacitor.

[0141] (11) The system of any one of (l)-(10), wherein each adjacent charging capacitor of the charging capacitor array is wire-bonded to a different charging bus of the charging bus element.

[0142] (12) The system of any one of (l)-(l 1), wherein the charging bus element is mounted on the substrate.

[0143] (13) The system of any one of (1 )-(l 2), wherein the charging bus element is etched into the substrate.

[0144] (14) The system of (13), wherein the charging capacitors of the charging capacitor array are mounted on the substrate in series and substantially in parallel to the charging bus element.

[0145] (15) The system of any one of (l)-( 14), wherein the plurality of charging buses is arranged in parallel.

[0146] (16) The system of any one of ( l)-( 15), wherein the charging capacitor array comprises the charging bus element.

[0147] (17) The system of any one of (1 )-(l 6), wherein the charging capacitor array comprises silicon capacitors.

[0148] (18) The system of any one of (l)-( 17), wherein the SL device comprises at least one of the following: an edge-emitting laser (EEL) device, a vertical-cavity surface-emitting laser (VCSEL) device, or a light-emitting diode (LED) laser device.

[0149] (19) A vehicle comprising: a system for light ranging and detection (LiDAR) comprising: a semiconductor laser (SL) device array comprising a plurality of SL devices mounted on a substrate; a charging capacitor array comprising a plurality of charging capacitors mounted on the substrate proximate to the SL device array, wherein each SL device of the SL device array is coupled to a different charging capacitor of the charging capacitor array; and a charging bus element comprising a plurality of charging buses proximate to the charging capacitor array, wherein each adjacent charging capacitor of the charging capacitor array is coupled to a different charging bus of the charging bus element.

[0150] (20) A method of manufacturing a LiDAR system, the method comprising: building a semiconductor laser (SL) device array comprising a plurality of SL devices mounted on a substrate; building a charging capacitor array comprising a plurality of charging capacitors mounted on the substrate proximate to the SL device array, wherein each SL device of the SL device array is coupled to a different charging capacitor of the charging capacitor array; and building a charging bus element comprising a plurality of charging buses proximate to the charging capacitor array, wherein each adjacent charging capacitor of the charging capacitor array is coupled to a different charging bus of the charging bus element.

[0151] The foregoing specification is to be understood as being in every respect illustrative and exemplary, but not restrictive, and the scope of the invention disclosed herein is not to be determined from the specification, but rather from the claims as interpreted according to the full breadth permitted by the patent laws. It is to be understood that the embodiments shown and described herein are only illustrative of the principles of the present invention and that variousmodifications may be implemented by those skilled in the art without departing from the scope and spirit of the invention. Those skilled in the art could implement various other feature combinations without departing from the scope and spirit of the invention.

Claims

CLAIMS1. A system for light ranging and detection (LiDAR), comprising:A semiconductor laser (SL) device array comprising a plurality of SL devices mounted on a substrate; a charging capacitor array comprising a plurality of charging capacitors mounted on the substrate proximate to the SL device array, wherein each SL device of the SL device array is coupled to a different charging capacitor of the charging capacitor array; and a charging bus element comprising a plurality of charging buses proximate to the charging capacitor array, wherein each adjacent charging capacitor of the charging capacitor array is coupled to a different charging bus of the charging bus element.

2. The system of claim 1, further comprising transmission control circuitry coupled to the SL device array and the charging capacitor array, the transmission control circuitry operative to: select a first SL grouping comprising any one of the plurality of SL devices; and cause, within a first firing cycle, the first SL grouping to emit first transmission pulses.

3. The system of claim 2, wherein the transmission control circuitry is further operative to: select a second SL grouping comprising any one of the plurality of SL devices; and cause, within a second firing cycle, the second SL grouping to emit second transmission pulses, wherein the first firing cycle and second firing cycle are consecutive firing cycles.

4. The system of claim 3, wherein the second SL grouping comprises at least one SL device of the first SL grouping.

5. The system of claim 2, wherein the transmission control circuity comprises a Gallium Nitride (GaN) field-effect transistor (FET) and a FET driver.

6. The system of any one of claims 1-5, wherein the plurality of SL devices comprises one of 4 SL devices, 8 SL devices, or 16 SL devices.

7. The system of any one of embodiments 1-6, wherein the plurality of SL devices of the SL device array is mounted on the substrate in series.

8. The system of claim 7, wherein the charging capacitors of the charging capacitor array are mounted on the substrate in series and substantially in parallel to the SL devices of the SL device array.

9. The system of claim 8, wherein each SL device of the SL device array is coupled to a corresponding adjacent charging capacitor of the charging capacitor array.

10. The system of claim 9, wherein each SL device of the SL device array is wire-bonded to a corresponding adjacent charging capacitor.

11. The system of any one of claims 1-10, wherein each adjacent charging capacitor of the charging capacitor array is wire-bonded to a different charging bus of the charging bus element.

12. The system of any one of claims 1-11, wherein the charging bus element is mounted on the substrate.

13. The system of any one of claims 1-12, wherein the charging bus element is etched into the substrate.

14. The system of claim 13, wherein the charging capacitors of the charging capacitor array are mounted on the substrate in series and substantially in parallel to the charging bus element.

15. The system of any one of claims 1-14, wherein the plurality of charging buses is arranged in parallel.

16. The system of any one of claims 1-15, wherein the charging capacitor array comprises the charging bus element.

17. The system of any one of claims 1-16, wherein the charging capacitor array comprises silicon capacitors.

18. The system of any one of claims 1-17, wherein the SL device comprises at least one of the following: an edge-emitting laser (EEL) device, a vertical-cavity surface-emitting laser (VCSEL) device, or a light-emitting diode (LED) laser device.

19. A vehicle comprising: a system for light ranging and detection (LiDAR) comprising: a semiconductor (SL) device array comprising a plurality of SL devices mounted on a substrate; a charging capacitor array comprising a plurality of charging capacitors mounted on the substrate proximate to the SL device array, wherein each SL device of the SL device array is coupled to a different charging capacitor of the charging capacitor array; and a charging bus element comprising a plurality of charging buses proximate to the charging capacitor array, wherein each adjacent charging capacitor of the charging capacitor array is coupled to a different charging bus of the charging bus element.

20. A method of manufacturing a LiDAR system, the method comprising: building a semiconductor laser (SL) device array comprising a plurality of SL devices mounted on a substrate; building a charging capacitor array comprising a plurality of charging capacitors mounted on the substrate proximate to the SL device array, wherein each SL device of the SL device array is coupled to a different charging capacitor of the charging capacitor array; and building a charging bus element comprising a plurality of charging buses proximate to the charging capacitor array, wherein each adjacent charging capacitor of the charging capacitor array is coupled to a different charging bus of the charging bus element.

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