Circuit and method for multiphase control of pump diodes in fiber lasers

Abstract

A light detection and ranging (LiDAR) system is disclosed in which multiple pump lasers are operated in a multi-phase manner at a single pump stage. In some embodiments, the multiple pump lasers are operated by a controller that generates current pulses through the multiple pump lasers. The current pulses that power at least two of the pump lasers have different phases. In some embodiments, the phase difference is such that there is no timing overlap in the current pulses passing through the pump laser. In some embodiments, the phase difference between consecutive current pulses is greater than the pulse width, so that the sum of the duty cycles of all current pulses is less than one. In some embodiments, the junction temperature of the pump laser is monitored, and the temperature information from the monitoring is used to dynamically select which pump laser will be utilized at a given time. Further details of these and other embodiments are disclosed herein.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application Serial No. 18 / 242,456, filed on September 5, 2023, which claims priority to U.S. Provisional Patent Application Serial No. 63 / 404,098, filed on September 6, 2022. The entire contents of these applications are incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to a laser source, and more particularly to an electronic device for facilitating multi-phase control of multiple laser pumps used in a light detection and ranging (LiDAR) system. Background Art

[0004] Light detection and ranging (LiDAR) systems use light pulses to create images or point clouds of the external environment. Some typical LiDAR systems include a light source, a light emitter, a light steering system, and a light detector. The light source generates a light beam, which is guided in a specific direction by the light steering system when emitted from the LiDAR system. When the emitted light beam is scattered by the target, a portion of the scattered light returns to the LiDAR system as a return light pulse. The light detector detects the return light pulse. Using the difference between the time when the return light pulse is detected and the time of the corresponding light pulse in the emitted light beam, the LiDAR system can use the speed of light to determine the distance to the target. The light steering system can guide the light beam along different paths to allow the LiDAR system to scan the surrounding environment and generate images or point clouds. The LiDAR system can also use technologies other than time of flight and scanning to measure the surrounding environment. Summary of the invention

[0005] LiDARs operating at 1550nm use fiber lasers in a master oscillator power amplifier (MOPA) configuration as the laser source. Current challenges with this type of fiber laser include low wall plug efficiency (WPE) and low pump diode reliability. One way to improve reliability is to add redundancy. For example, in a fiber laser, adding redundancy can be achieved by adding multiple pump diodes.

[0006] In an embodiment of the present invention, a plurality of pump lasers are operated in a multi-phase manner under a single pumping stage. In some embodiments, the plurality of pump lasers are operated by a controller that generates current pulses through the plurality of pump lasers. The current pulses that power at least two of the pump lasers have different phases. In some embodiments, the phase difference is such that there is no timing overlap in the current pulses passing through the pump laser. In some embodiments, the phase difference between consecutive current pulses is greater than the pulse width, so that the sum of the duty cycles of all current pulses is less than one.

[0007] In other embodiments, the junction temperature of each of a plurality of pump laser diodes is monitored, and which pump lasers are currently used is selected based on the monitoring results.

[0008] These and other embodiments are further illustrated and described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present application may be best understood by referring to the drawings described below in conjunction with the drawings, in which like components may be represented by like reference numerals.

[0010] Figure 1 One or more exemplary LiDAR systems disposed or included in a motor vehicle are illustrated.

[0011] Figure 2 is a block diagram illustrating the interaction between an exemplary LiDAR system and a number of other systems including a vehicle perception and planning system.

[0012] Figure 3 is a block diagram illustrating an exemplary LiDAR system.

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

[0014] FIG. 5A to FIG. 5C An exemplary LiDAR system that uses pulse signals to measure the distance to objects disposed in a field of view (FOV) is illustrated.

[0015] Figure 6 is a block diagram illustrating an exemplary apparatus for implementing the systems, apparatus, and methods in various embodiments.

[0016] Figure 7 is a block diagram illustrating a fiber-based laser source including multiphase pump diodes and associated control circuitry according to one embodiment.

[0017] Figure 8 is an exemplary control circuit according to one embodiment.

[0018] Fig. 9 is another exemplary control circuit according to one embodiment.

[0019] Fig.10 is another exemplary control circuit according to one embodiment.

[0020] Fig.11 An exemplary timing diagram representing a sequence of laser pump control signals is illustrated.

[0021] Fig.12A comparison between a higher laser pump peak current and a lower laser pump peak current is illustrated.

[0022] Fig.13 A method according to one embodiment is illustrated.

[0023] Fig.14 Another method according to one embodiment is illustrated. DETAILED DESCRIPTION

[0024] In order to provide a more thorough understanding of the present invention, the following description sets forth many specific details, such as specific configurations, parameters, embodiments, etc. However, it should be appreciated that such description is not intended to limit the scope of the present invention, but is intended to provide a better description of exemplary embodiments.

[0025] Throughout the specification and claims, unless the context clearly dictates otherwise, the following terms have the meanings explicitly associated herein:

[0026] As used herein, the phrase "in one embodiment" does not necessarily refer to the same embodiment, even though it may. Thus, as described below, the various embodiments of the present invention can be easily combined without departing from the scope or spirit of the present disclosure.

[0027] As used herein, the term "or" is an inclusive "or" operator, and is equivalent to the terms "and / or" unless the context clearly dictates otherwise.

[0028] The term "based on" is not exclusive and allows for being based on additional factors not described unless the context clearly indicates otherwise.

[0029] As used herein, unless the context indicates otherwise, the term "coupled to" is intended to include direct coupling (where two elements coupled to each other are in contact with each other) and indirect coupling (where at least one additional element is located between the two elements). Therefore, the terms "coupled to" and "coupled with..." are used synonymously. In the context of a networked environment where two or more components or devices are able to exchange data, the terms "coupled to" and "coupled with..." are also used to mean "communicatively coupled with...", possibly via one or more intermediate devices.

[0030] Although the following description uses the terms "first", "second", etc. to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the various described examples, a first transistor may be referred to as a second transistor, and similarly, a second transistor may be referred to as a first transistor. Both the first transistor and the second transistor may be transistors, and in some cases, may be separate different transistors.

[0031] In addition, throughout the specification, the meanings of “a,” “an,” and “the” include plural forms, and the meaning of “in” may include “in” and “on.”

[0032] Although some of the various embodiments provided herein constitute a single combination of inventive elements, it should be understood that the inventive subject matter is considered to include all possible combinations of disclosed elements. Thus, if one embodiment includes elements A, B, and C, and another embodiment includes elements B and D, the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly discussed herein. In addition, the transitional term "comprising" means having parts or components, or those parts or components. As used herein, the transitional term "comprising" is inclusive or open-ended, and does not exclude additional, unlisted elements or method steps.

[0033] Throughout the following disclosure, references may be made to servers, services, interfaces, engines, modules, clients, peers, portals, platforms, or other systems formed by computing devices. It should be understood that the use of such terms is considered to represent one or more computing devices having at least one processor (e.g., ASIC, FPGA, PLD, DSP, x86, ARM, RISC-V, ColdFire, GPU, multi-core processor, etc.) that is configured to run software instructions stored on a computer-readable, tangible, non-transitory medium (e.g., hard drive, solid-state drive, RAM, flash, ROM, etc.). For example, a server may include one or more computers that operate as a web server, database server, or other type of computer server in a manner that performs the described roles, responsibilities, or functions. It should also be understood that the disclosed computer-based algorithms, processes, methods, or other types of instruction sets may be embodied as a computer program product that includes a non-transitory, tangible computer-readable medium storing instructions that cause the processor to execute the disclosed steps. Various servers, systems, databases or interfaces may use standardized protocols or algorithms to exchange information, which may be based on HTTP, HTTPS, AES, public-private key exchange, web service API, known financial transaction protocols or other electronic information exchange methods. Data exchange can be carried out over packet switching networks, circuit switching networks, the Internet, LAN, WAN, VPN or other types of networks.

[0034] 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," "operable to," or "programmed to" is defined as one or more processors or cores of the computing element being programmed by a set of software instructions stored in the memory of the computing element to perform the set of functions on target data or data objects stored in the memory.

[0035] It should be noted that any language for computers should be understood to include any suitable combination of computing devices or network platforms (including servers, interfaces, systems, databases, agents, peers, engines, controllers, modules, or other types of computing devices that operate alone or together). It should be understood that computing devices include processors configured to run software instructions stored on tangible non-temporary computer-readable storage media (e.g., hard drives, FPGAs, PLAs, solid-state drives, RAM, flash, ROM, etc.). Software instructions configure or program computing devices to provide roles, responsibilities, or other functions, as discussed below with respect to the disclosed apparatus. In addition, the disclosed technology can be embodied as a computer program product, which includes a non-temporary computer-readable medium storing software instructions, which enables the processor to run the disclosed steps associated with the implementation of computer-based algorithms, processes, methods, or other instructions. In some embodiments, various servers, systems, databases, or interfaces use standardized protocols or algorithms that may be based on HTTP, HTTPS, AES, public-private key exchange, web service APIs, known financial transaction protocols, or other electronic information exchange methods to exchange data. Data exchange between devices may be performed over a packet switching network, the Internet, a LAN, a WAN, a VPN or other types of packet switching networks, circuit switching networks, cell switching networks or other types of networks.

[0036] Embodiments of the present invention include circuit concepts and control methods to improve the overall efficiency and reliability of the pump laser section of a fiber laser.

[0037] MOPA fiber lasers are composed of seed lasers, pump lasers, pump / seed combiners, and double-clad gain fibers as main components. In addition to these components, there are also passive components used to form a complete fiber laser. Among these components, the reliability of the pump laser diode is of greatest concern. In addition to better diode design and manufacturing processes, the use of redundant laser diodes is another way to address this issue at the system level.

[0038] How the drive circuits are constructed and how these circuits are operated also play an important role in improving system reliability.

[0039] Embodiments of the present invention are described below.

[0040] Figure 1 One or more exemplary LiDAR systems 110 and 120A-120H are illustrated as being arranged or included in a motor vehicle 100. The vehicle 100 may be a car, a sport utility vehicle (SUV), a truck, a train, a van, a bicycle, a motorcycle, a tricycle, a bus, a motor scooter, a tram, a ship, a boat, an underwater vehicle, an airplane, a helicopter, an unmanned aerial vehicle (UAV), a spacecraft, etc. The motor vehicle 100 may be a vehicle with any level of automation. For example, the motor vehicle 100 may be a partially automated vehicle, a highly automated vehicle, a fully automated vehicle, or an unmanned vehicle. A partially automated vehicle may perform some driving functions without human driver intervention. For example, a partially automated vehicle may perform blind spot monitoring, lane keeping and / or lane change operations, automatic emergency braking, smart cruise control, and / or traffic following, etc. Certain operations of a partially automated vehicle may be limited to specific applications or driving scenarios (e.g., limited to highway driving). A highly automated vehicle may generally perform all operations of a partially automated vehicle, but with fewer restrictions. Highly automated vehicles can also detect their own limits when operating the vehicle and request the driver to take over control of the vehicle when necessary. Fully automated vehicles can perform all vehicle operations without driver intervention, but can also detect their own limits and request the driver to take over when necessary. Driverless vehicles can operate autonomously without any driver intervention.

[0041] In a typical configuration, the motor vehicle 100 includes one or more LiDAR systems 110 and 120A-120F. Each of the LiDAR systems 110 and 120A-120F can be a scanning-based LiDAR system and / or a non-scanning LiDAR system (e.g., flash LiDAR). A scanning-based LiDAR system scans one or more light beams in one or more directions (e.g., horizontal and vertical directions) to detect objects in a field of view (FOV). A non-scanning-based LiDAR system emits a laser to illuminate the FOV without scanning. For example, a flash LiDAR is a type of non-scanning-based LiDAR system. A flash LiDAR can emit a laser to illuminate the FOV simultaneously using a single light pulse or light beams.

[0042] LiDAR systems are often the primary sensor for at least partially automated vehicles. Figure 1As shown, the motor vehicle 100 may include a single LiDAR system 110 (e.g., without LiDAR systems 120A-120F) disposed at the highest position of the vehicle (e.g., on top of the vehicle). Placing the LiDAR system 110 on top of the vehicle facilitates 360-degree scanning around the vehicle 100. In some other embodiments, the motor vehicle 100 may include multiple LiDAR systems, including two or more systems 110 and / or 120A-120F. Figure 1 As shown, in one embodiment, multiple LiDAR systems 110 and / or 120A-120F are attached to the vehicle 100 at different locations of the vehicle. For example, LiDAR system 120A is attached to the vehicle 100 at the right front corner; LiDAR system 120B is attached to the vehicle 100 at the front center of the vehicle 100; LiDAR system 120C is attached to the vehicle 100 at the left front corner of the vehicle 100; LiDAR system 120D is attached to the vehicle 100 at the right side mirror; LiDAR system 120E is attached to the vehicle 100 at the left side mirror; and / or LiDAR system 120F is attached to the vehicle 100 at the rear center of the vehicle 100. In some embodiments, LiDAR systems 110 and 120A-120F are independent LiDAR systems with their own laser sources, control electronics, transmitters, receivers, and / or steering mechanisms. In other embodiments, some of the LiDAR systems 110 and 120A-120F may share one or more components, thereby forming a distributed sensor system. In one embodiment, optical fiber is used to deliver laser light from a centralized laser source to all of the LiDAR systems. It should be understood that one or more LiDAR systems may be distributed and attached to a vehicle in any desired manner, and Figure 1 Only one embodiment is illustrated. As another example, LiDAR systems 120D and 120E can be attached to the B-pillars of vehicle 100 instead of rearview mirrors. As another example, LiDAR system 120B can be attached to the windshield of vehicle 100 instead of the front bumper.

[0043] Figure 2 2 is a block diagram 200 illustrating the interaction between an onboard LiDAR system 210 and a plurality of other systems including a vehicle perception and planning system 220. The LiDAR system 210 may be mounted on or integrated into a vehicle. The LiDAR system 210 includes a sensor that scans laser light into the surrounding environment to measure the distance, angle, and / or velocity of objects. Based on the scattered light returned to the LiDAR system 210, it may generate sensor data (e.g., image data or 3D point cloud data) representing the perceived external environment.

[0044] The LiDAR system 210 may include one or more of a short-range LiDAR sensor, a mid-range LiDAR sensor, and a long-range LiDAR sensor. The short-range LiDAR sensor measures targets located at a distance of up to about 20 meters to 40 meters from the LiDAR sensor. The short-range LiDAR sensor can be used, for example, to monitor nearby moving targets (e.g., pedestrians crossing the street in a school area), parking assistance applications, etc. The mid-range LiDAR sensor measures targets located at a distance of up to about 100 meters to 150 meters from the LiDAR sensor. The mid-range LiDAR sensor can be used, for example, to monitor road intersections, assist in merging into or leaving a highway, etc. The long-range LiDAR sensor measures targets located at a distance of up to about 150 meters to 300 meters. Long-range LiDAR sensors are typically used when the vehicle is traveling at high speeds (e.g., on a highway) so that the vehicle's control system may only have a few seconds (e.g., 6 seconds to 8 seconds) to respond to any situation detected by the LiDAR sensor. As Figure 2 As shown, in one embodiment, LiDAR sensor data can be provided to vehicle perception and planning system 220 via communication path 213 for further processing and control of vehicle operation. Communication path 213 can be any wired or wireless communication link capable of transmitting data.

[0045] Still reference Figure 2 In some embodiments, other onboard sensors 230 are used to provide additional sensor data alone or together with the LiDAR system 210. Other onboard sensors 230 may include, for example, one or more cameras 232, one or more radars 234, one or more ultrasonic sensors 236, and / or other sensors 238. Camera 232 can capture images and / or videos of the external environment of the vehicle. Camera 232 can capture, for example, high-definition (HD) videos with millions of pixels per frame. The camera produces monochrome or color images and videos. Color information may be crucial in interpreting data for some situations (e.g., interpreting images of traffic lights). Color information may not be available from other sensors (such as LiDAR or radar sensors). Camera 232 may include one or more of a narrow focal length camera, a wider focal length camera, a side camera, an infrared camera, a fisheye camera, etc. The image and / or video data generated by camera 232 may also be provided to the vehicle perception and planning system 220 via a communication path 233 for further processing and control of vehicle operation. Communication path 233 may be any wired or wireless communication link that can transmit data.

[0046] Other on-board sensors 230 may also include radar sensors 234. Radar sensors 234 use radio waves to determine the distance, angle, and speed of a target. Radar sensors 234 generate electromagnetic waves in the radio or microwave spectrum. The electromagnetic waves reflect off the target, and some of the reflected waves return to the radar sensor, thereby providing information about the location and speed of the target. Radar sensors 234 may include one or more of short-range radars, medium-range radars, and long-range radars. Short-range radars measure objects about 0.1-30 meters from the radar. Short-range radars are useful in detecting objects near vehicles (such as other vehicles, buildings, walls, pedestrians, cyclists, etc.). Short-range radars can be used to detect blind spots, assist in changing lanes, provide rear-end collision alerts, assist in parking, provide emergency braking, etc. Medium-range radars measure objects about 30-80 meters from the radar. Long-range radars measure objects located at about 80-200 meters. Medium-range and / or long-range radars can be used, for example, for traffic tracking, adaptive cruise control, and / or highway automatic braking. Sensor data generated by radar sensor 234 may also be provided to vehicle perception and planning system 220 via communication path 233 for further processing and control of vehicle operation.

[0047] Other on-board sensors 230 may also include ultrasonic sensors 236. Ultrasonic sensors 236 use sound waves or pulses to measure objects located outside the vehicle. Sound waves generated by ultrasonic sensors 236 are emitted to the surrounding environment. At least some of the emitted waves are reflected by the object and returned to the ultrasonic sensor 236. Based on the return signal, the distance of the object can be calculated. Ultrasonic sensors 236 can be used, for example, to check blind spots, identify parking spots, provide lane change assistance for vehicles traveling on the road, etc. The sensor data generated by ultrasonic sensors 236 can also be provided to the vehicle perception and planning system 220 via the communication path 233 for further processing and control of vehicle operation.

[0048] In some embodiments, one or more other sensors 238 may be attached to the vehicle and may also generate sensor data. Other sensors 238 may include, for example, a global positioning system (GPS), an inertial measurement unit (IMU), etc. The sensor data generated by other sensors 238 may also be provided to the vehicle perception and planning system 220 via the communication path 233 for further processing and control of vehicle operation. It should be understood that the communication path 233 may include one or more communication links to transmit data between the various sensors 230 and the vehicle perception and planning system 220.

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

[0050] Still reference Figure 2 In some embodiments, sensors on other vehicles 250 are used to provide additional sensor data alone or in conjunction with the LiDAR system 210. For example, two or more nearby vehicles may have their own LiDAR sensors, cameras, radar sensors, ultrasonic sensors, etc. Nearby vehicles can communicate and share sensor data with each other. Communication between vehicles is also known as V2V (vehicle-to-vehicle) communication. For example, Figure 2 As shown, sensor data generated by other vehicles 250 can be transmitted to vehicle perception and planning system 220 and / or onboard LiDAR system 210 via communication path 253 and / or communication path 251, respectively. Communication paths 253 and 251 can be any wired or wireless communication links capable of transmitting data.

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

[0052] In some embodiments, the smart infrastructure system 240 is used to provide sensor data independently or together with the LiDAR system 210. Certain infrastructures may be configured to communicate with vehicles to convey information, and vice versa. Communication between vehicles and infrastructure is generally referred to as V2I (vehicle to infrastructure) communication. For example, the smart infrastructure system 240 may include a smart traffic light that can communicate its status to the approaching vehicle with a message such as "turn yellow in 5 seconds". The smart infrastructure system 240 may also include its own LiDAR system installed near the intersection so that it can convey traffic monitoring information to the vehicle. For example, a vehicle turning left at an intersection may not have sufficient sensing capabilities because some of its own sensors may be blocked by vehicles traveling on the road in the opposite direction. In such cases, the sensors of the smart infrastructure system 240 can provide useful and sometimes crucial data to the vehicle turning left. The data may include, for example, traffic conditions, information on the target in the direction the vehicle is turning, traffic light status, and prediction results. These sensor data generated by the smart infrastructure system 240 can be provided to the vehicle perception and planning system 220 and / or the vehicle LiDAR system 210 via communication paths 243 and / or 241. Communication paths 243 and / or 241 can include any wired or wireless communication links capable of transmitting data. For example, sensor data from the smart infrastructure system 240 can be transmitted to the LiDAR system 210 and correlated or fused with sensor data generated by the LiDAR system 210, thereby at least partially offloading the sensor fusion process performed by the vehicle perception and planning system 220. The above-mentioned V2V and V2I communications are examples of vehicle-to-X (V2X) communications, where "X" represents any other device, system, sensor, infrastructure, etc. that can share data with the vehicle.

[0053] Still reference Figure 2, via various communication paths, the vehicle perception and planning system 220 receives sensor data from one or more of the LiDAR system 210, other onboard sensors 230, other vehicles 250, and / or the smart infrastructure system 240. In some embodiments, different types of sensor data are related and / or fused by the sensor fusion subsystem 222. For example, the sensor fusion subsystem 222 can generate a 360-degree model using multiple images or videos captured by multiple cameras set at different locations of the vehicle. The sensor fusion subsystem 222 obtains sensor data from different types of sensors and uses the combined data to more accurately perceive the environment. For example, the onboard camera 232 may not capture a clear image because it is directly facing the sun or a light source (e.g., the headlights of another vehicle at night). The LiDAR system 210 may not be affected too much, and therefore the sensor fusion subsystem 222 can combine the sensor data provided by the camera 232 and the LiDAR system 210, and use the sensor data provided by the LiDAR system 210 to compensate for the unclear image captured by the camera 232. As another example, in rainy or foggy weather, radar sensor 234 may work better than camera 232 or LiDAR system 210. Accordingly, sensor fusion subsystem 222 may use sensor data provided by radar sensor 234 to compensate for sensor data provided by camera 232 or LiDAR system 210.

[0054] In other examples, sensor data generated by other onboard sensors 230 may have a lower resolution (e.g., radar sensor data) and, therefore, may need to be correlated and confirmed by the LiDAR system 210, which typically has a higher resolution. For example, the radar sensor 234 may detect a sewer cover (also known as a manhole cover) as an object that the vehicle is approaching. Due to the low-resolution nature of the radar sensor 234, the vehicle perception and planning system 220 may not be able to determine whether the target is an obstacle that the vehicle needs to avoid. Therefore, the high-resolution sensor data generated by the LiDAR system 210 can be used to correlate and confirm that the target is a sewer cover and will not cause harm to the vehicle.

[0055] The vehicle perception and planning system 220 also includes a target classifier 223. The target classifier 223 can use the raw sensor data and / or the related / fused data provided by the sensor fusion subsystem 222 to detect and classify the target and estimate the position of the target. In some embodiments, the target classifier 233 can use machine learning-based techniques to detect and classify the target. Examples of machine learning-based techniques include using algorithms such as region-based convolutional neural networks (R-CNN), fast R-CNN, faster R-CNN, histogram of oriented gradients (HOG), region-based fully convolutional networks (R-FCN), single-shot detectors (SSD), spatial pyramid pooling (SPP-net) and / or "You Only Look Once" (Yolo).

[0056] The vehicle perception and planning system 220 also includes a road detection subsystem 224. The road detection subsystem 224 locates the road and identifies objects and / or markings on the road. For example, based on the raw or fused sensor data provided by the radar sensor 234, the camera 232, and / or the LiDAR system 210, the road detection subsystem 224 can build a 3D model of the road based on machine learning techniques (e.g., a pattern recognition algorithm for identifying lanes). Using the 3D model of the road, the road detection subsystem 224 can identify objects (e.g., obstacles or debris on the road) and / or markings (e.g., lane lines, turn signs, crosswalk signs, etc.) on the road.

[0057] The vehicle perception and planning system 220 also includes a positioning and vehicle attitude subsystem 225. Based on the original or fused sensor data, the positioning and vehicle attitude subsystem 225 can determine the position of the vehicle and the attitude of the vehicle. For example, using sensor data from the LiDAR system 210, the camera 232 and / or GPS data, the positioning and vehicle attitude subsystem 225 can determine the precise position of the vehicle on the road and the six degrees of freedom of the vehicle (e.g., whether the vehicle is moving forward or backward, up or down, left or right). In some embodiments, a high-definition (HD) map is used for vehicle positioning. The HD map can provide a very detailed three-dimensional computer map to accurately locate the position of the vehicle. For example, the positioning and vehicle attitude subsystem 225 can use the HD map to accurately determine the current position of the vehicle (e.g., which lane of the road the vehicle is currently located on, how close it is to the curb or sidewalk) and predict the future position of the vehicle.

[0058] The vehicle perception and planning system 220 also includes an obstacle predictor 226. The objects identified by the object classifier 223 can be stationary (e.g., light poles, road signs) or dynamic (e.g., moving pedestrians, bicycles, another car). For moving objects, predicting their movement paths or future positions is important for avoiding collisions. The obstacle predictor 226 can predict obstacle trajectories and / or warn the driver or the vehicle planning subsystem 228 of potential collisions. For example, if the probability that the trajectory of the obstacle intersects the current movement path of the vehicle is high, the obstacle predictor 226 can generate such a warning. The obstacle predictor 226 can use various techniques to make such predictions. These techniques include, for example, constant speed or acceleration models, constant turning rate and speed / acceleration models, models based on Kalman filters and extended Kalman filters, models based on recursive neural networks (RNNs), models based on long short-term memory (LSTM) neural networks, encoder-decoder RNN models, etc.

[0059] Still reference Figure 2 In some embodiments, the vehicle perception and planning system 220 also includes a vehicle planning subsystem 228. The vehicle planning subsystem 228 may include a route planner, a driving behavior planner, and a motion planner. The route planner may plan the route of the vehicle based on the vehicle's current position data, target position data, traffic information, etc. The driving behavior planner adjusts the timing and planned movement based on the way other targets may move, using the obstacle prediction results provided by the obstacle predictor 226. The motion planner determines the specific operations that the vehicle needs to follow. The planning results are then communicated to the vehicle control system 280 via the vehicle interface 270. Communication can be performed through communication paths 227 and 271, which include any wired or wireless communication links that can transmit data.

[0060] The vehicle control system 280 controls the vehicle's steering mechanism, throttle, brakes, etc. to operate the vehicle according to the planned route and movement. The vehicle perception and planning system 220 may also include a user interface 260, which provides the user (e.g., driver) with access to the vehicle control system 280, for example to override or take over control of the vehicle when necessary. The user interface 260 can communicate with the vehicle perception and planning system 220, for example to obtain and display raw or fused sensor data, identified targets, the position / attitude of the vehicle, etc. These displayed data can help the user better operate the vehicle. The user interface 260 can communicate with the vehicle perception and planning system 220 and / or the vehicle control system 280 via communication paths 221 and 261, respectively, which include any wired or wireless communication links that can transmit data. It should be understood that Figure 2 The various systems, sensors, communication links and interfaces in the can be configured in any desired manner and are not limited to Figure 2 Configuration shown.

[0061] Figure 3 is a block diagram illustrating an exemplary LiDAR system 300. The LiDAR system 300 may be used to implement Figure 1 and Figure 2 The LiDAR system 110, 120A-120H and / or 210 shown. In one embodiment, the LiDAR system 300 includes a laser source 310, a transmitter 320, an optical receiver and light detector 330, a steering system 340, and a control circuit 350. These components are coupled together using communication paths 312, 314, 322, 332, 343, 352, and 362. These communication paths include communication links (wired or wireless, bidirectional or unidirectional) between various LiDAR system components, but do not need to be physical components themselves. Although the communication paths can be implemented by one or more wires, buses, or optical fibers, the communication paths can also be wireless channels or free space optical paths so that there is no physical communication medium. For example, in one embodiment of the LiDAR system 300, the communication path 314 between the laser source 310 and the transmitter 320 can be implemented using one or more optical fibers. Communication paths 332 and 352 can represent optical paths implemented using free space optical components and / or optical fibers. Furthermore, the communication paths 312, 322, 342, and 362 may be implemented using one or more wires carrying electrical signals. The communication paths may also include one or more of the above types of communication media (e.g., they may include optical fibers and free space optical components, or include one or more optical fibers and one or more wires).

[0062] In some embodiments, the LiDAR system 300 may be a coherent LiDAR system. One example is a frequency modulated continuous wave (FMCW) LiDAR. Coherent LiDAR detects objects by mixing the return light from the object with the light from a coherent laser emitter. Thus, Figure 3 As shown, if the LiDAR system 300 is a coherent LiDAR, it can include a route 372 that provides a portion of the transmitted light from the transmitter 320 to the optical receiver and light detector 330. Route 372 may include one or more optical devices (e.g., optical fibers, lenses, mirrors, etc.) for providing light from the transmitter 320 to the optical receiver and light detector 330. The transmitted light provided by the transmitter 320 may be modulated light and may be divided into two parts. One part is emitted to the FOV, while the second part is sent to the optical receiver and light detector of the LiDAR system. The second part is also referred to as light kept locally (LO) in the LiDAR system. The transmitted light is scattered or reflected by various objects in the FOV, and at least a portion of it forms return light. The return light is then detected and recombined by interference with the second part of the transmitted light that remains local. Coherent LiDAR provides a mechanism for optically sensing the range of objects and their relative speed along the line of sight (LOS).

[0063] The LiDAR system 300 may also include Figure 3 Other components not shown in the diagram may include a power bus, power supplies, LED indicators, switches, etc. Additionally, there may be other communication connections between components, such as a direct connection between the light source 310 and the optical receiver and light detector 330 to provide a reference signal so that the time from the emission of a light pulse to the detection until the return light pulse can be accurately measured.

[0064] The laser source 310 outputs laser light for illuminating a target in the field of view (FOV). The laser source 310 may be, for example, a semiconductor-based laser (e.g., a diode laser) and / or an optical fiber-based laser. The semiconductor-based laser may be, for example, an edge-emitting laser (EEL), a vertical cavity surface-emitting laser (VCSEL), etc. An optical fiber-based laser is a laser in which the activated gain medium is an optical fiber doped with rare earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium, and / or holmium. In some embodiments, the optical fiber laser is based on a double-clad optical fiber, in which the gain medium forms the core of an optical fiber surrounded by two layers of cladding. The double-clad optical fiber allows a high-power beam to be pumped to the core, thereby enabling the laser source to become a high-power optical fiber laser source.

[0065] In some embodiments, the laser source 310 includes a master oscillator (also called a seed laser) and a power amplifier (MOPA). The power amplifier amplifies the output power of the seed laser. The power amplifier can be a fiber amplifier, a bulk amplifier, or a semiconductor optical amplifier. The seed laser can be a diode laser (e.g., a Fabry-Perot cavity laser, a distributed feedback laser), a solid-state bulk laser, or an external cavity tunable diode laser. In some embodiments, the laser source 310 can be an optically pumped microchip laser. A microchip laser is a non-adjustable monolithic solid-state laser in which the laser crystal is in direct contact with the end mirror of the laser resonator. A laser diode is usually pumped to the microchip laser (directly or using an optical fiber) to obtain the desired output power. Microchip lasers can be based on neodymium-doped yttrium aluminum garnet (Y3Al5O 12 ) laser crystal (ie, Nd:YAG), or neodymium-doped vanadate (ie, ND:YVO4) laser crystal.

[0066] Figure 4 4 is a block diagram illustrating an exemplary fiber-based laser source 400 having a seed laser and one or more pumps (eg, laser diodes) for pumping a desired output power. Figure 3 An example of a laser source 310 is shown. In some embodiments, the fiber-based laser source 400 includes a seed laser 402 to generate initial optical pulses of one or more wavelengths (e.g., 1550 nm), which are provided to a wavelength division multiplexer (WDM) 404 via an optical fiber 403. The fiber-based laser source 400 also includes a pump 406 for providing laser power (e.g., a different wavelength, such as 980 nm) to the WDM 404 via an optical fiber 405. The WDM 404 multiplexes the optical pulses provided by the seed laser 402 and the laser power provided by the pump 406 onto a single optical fiber 407. The output of the WDM 404 can then be provided to one or more preamplifiers 408 via the optical fiber 407. The preamplifier 408 can be an optical amplifier (e.g., having a gain of about 20-30 dB) that amplifies the optical signal. In some embodiments, the preamplifier 408 is a low noise amplifier. The preamplifier 408 outputs to the combiner 410 via an optical fiber 409. Combiner 410 combines the output laser of preamplifier 408 with the laser power provided by pump 412 via optical fiber 411. Combiner 410 can combine optical signals having the same wavelength or different wavelengths. An example of a combiner is WDM. Combiner 410 provides the pulses to boost amplifier 414, which generates output optical pulses via optical fiber 415. Boost amplifier 414 provides further amplification of the optical signal. The output optical pulses can then be transmitted to transmitter 320 and / or steering mechanism 340 (such as Figure 3 It should be understood that Figure 4An exemplary configuration of a fiber-based laser source 400 is shown. The laser source 400 may have a Figure 4 One or more components shown in and / or Figure 4 Many other configurations of different combinations of other components not shown (e.g., other components such as power supplies, lenses, filters, splitters, combiners, etc.).

[0067] In some variations, the fiber-based laser source 400 can be controlled (e.g., by control circuitry 350) to generate pulses of varying amplitudes based on the fiber gain profile of the optical fiber used in the fiber-based laser source 400. The communication path 312 couples the fiber-based laser source 400 to the control circuitry 350 (e.g., Figure 3 350) so that the components of the fiber-based laser source 400 can be controlled by the control circuit 350 or otherwise communicate with the control circuit. Alternatively, the fiber-based laser source 400 can include its own dedicated controller. Rather than the control circuit system 350 directly communicating with the components of the fiber-based laser source 400, the dedicated controller of the fiber-based laser source 400 communicates with the control circuit system 350 and controls and / or communicates with the components of the fiber-based light source 400. The fiber-based light source 400 may also include other components not shown, such as one or more power connectors, a power supply, and / or a power cord.

[0068] refer to Figure 3, typical operating wavelengths of the laser source 310 include, for example, about 850 nm, about 905 nm, about 940 nm, about 1064 nm, and about 1550 nm. The upper limit of the maximum available laser power is set by the U.S. Food and Drug Administration (FDA) regulations. The optical power limit of the 1550 nm wavelength is much higher than the optical power limits of the other wavelengths mentioned above. In addition, at 1550 nm, the optical power loss in the optical fiber is very low. These characteristics of the 1550 nm wavelength make it more conducive to long-distance LiDAR applications. The amount of optical power output from the laser source 310 can be characterized by its peak power, average power, and pulse energy. Peak power is the ratio of pulse energy to pulse width (e.g., full width at half maximum or FWHM). Therefore, for a fixed amount of pulse energy, a smaller pulse width can provide a larger peak power. The pulse width can be in the range of nanoseconds or picoseconds. The average power is the product of the pulse energy and the pulse repetition rate (PRR). As described in more detail below, PRR represents the frequency of the pulsed laser. PRR generally corresponds to the maximum range that the LiDAR system can measure. The laser source 310 can be configured to generate pulses at a high PRR to meet the desired number of data points in the point cloud generated by the LiDAR system. The laser source 310 can also be configured to generate pulses at a 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 key indicator for evaluating laser efficiency. For example, Figure 1 As shown, multiple LiDAR systems can be attached to a vehicle, which can be an electric vehicle or a vehicle with limited fuel or battery power. Therefore, high WPE and intelligent ways of using laser power are often important considerations when selecting and configuring laser sources 310 and / or designing laser delivery systems for vehicle-mounted LiDAR applications.

[0069] It should be understood that the above description provides non-limiting examples of laser source 310. Laser 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) configured to generate one or more optical signals at various wavelengths. In some embodiments, light source 310 includes an amplifier (e.g., a preamplifier and / or a boost amplifier), which may be a doped fiber amplifier, a solid-state body amplifier, and / or a semiconductor optical amplifier. The amplifiers are configured to receive and amplify the optical signal with a desired gain.

[0070] Return to reference Figure 3, the LiDAR system 300 also includes a transmitter 320. The laser source 310 provides laser light (e.g., in the form of a laser beam) to the transmitter 320. The laser light provided by the laser source 310 can be an amplified laser light having a predetermined or controlled wavelength, pulse repetition rate, and / or power level. The transmitter 320 receives the laser light from the laser source 310 and emits the laser light to the steering mechanism 340 at a low divergence. In some embodiments, the transmitter 320 may include, for example, optical components (e.g., lenses, optical fibers, mirrors, etc.) for emitting a laser beam into a field of view (FOV) directly or via the steering mechanism 340. Although Figure 3 The transmitter 320 and the steering mechanism 340 are illustrated as separate components, but in some embodiments, they may be combined or integrated into a system. The steering mechanism 340 will be described in more detail below.

[0071] The laser beams provided by the laser source 310 may diverge as they travel to the emitter 320. Therefore, the emitter 320 typically includes a collimating lens that is configured to collect the diverging laser beams and produce a more parallel beam with reduced or minimal divergence. The collimated beam can then be further directed through various optical devices, such as mirrors and lenses. The collimating lens can be, for example, a single plano-convex lens or a lens array. The collimating lens can be configured to achieve any desired characteristics, such as beam diameter, divergence, numerical aperture, focal length, etc. The beam spread ratio or beam quality factor (also referred to as M 2 Factor) is used to measure the laser beam quality. In many LiDAR applications, it is important to have good laser beam quality in the generated transmitted laser beam. 2 The factor represents the degree to which the beam deviates from an ideal Gaussian beam. Therefore, M 2 The factor reflects how well a collimated laser beam can be focused on a small spot, or how well a divergent laser beam can be collimated. Thus, the laser source 310 and / or the emitter 320 can be configured to meet, for example, scanning resolution requirements while maintaining a desired M 2 factor.

[0072] One or more of the light beams provided by the transmitter 320 are scanned to the FOV by the steering mechanism 340. The steering mechanism 340 scans the light beams in multiple dimensions (e.g., in the horizontal dimension and the vertical dimension) so that the LiDAR system 300 can map the environment by generating a 3D point cloud. The steering mechanism 340 will be described in more detail below. The laser light scanned to the FOV can be scattered or reflected by the target in the FOV. At least a portion of the scattered or reflected light is returned to the LiDAR system 300. Figure 3An optical receiver and light detector 330 configured to receive the return light is further illustrated. The optical receiver and light detector 330 include an optical receiver configured to collect the return light from the FOV. The optical receiver may include optics (e.g., lenses, optical fibers, mirrors, etc.) for receiving, redirecting, focusing, amplifying, and / or filtering the return light from the FOV. For example, the optical receiver typically includes a collection lens (e.g., a single plano-convex lens or a lens group) to collect the return light and / or focus the collected return light onto the light detector.

[0073] The photodetector detects the return light focused by the optical receiver and generates a current and / or voltage signal proportional to the incident intensity of the return light. Based on such current and / or voltage signals, the depth information of the object in the FOV can be derived. An exemplary method for deriving the depth information is based on direct TOF (time of flight), which is described in more detail below. The photodetector can be characterized by its detection sensitivity, quantum efficiency, detector bandwidth, linearity, signal-to-noise ratio (SNR), overload resistance, interference resistance, etc. Based on the application, the photodetector can be constructed or customized to have any desired characteristics. For example, the optical receiver and the photodetector 330 can be configured so that the photodetector has a large dynamic range and good linearity. The linearity of the photodetector represents the ability of the detector to maintain a linear relationship between the input optical signal power and the output of the detector. A detector with good linearity can maintain a linear relationship within a large dynamic input optical signal range.

[0074] In order to achieve the desired detector characteristics, the structure of the photodetector and / or the material system of the detector can be constructed or customized. Various detector structures can be used for the photodetector. For example, the photodetector structure can be a PIN-based structure having an undoped intrinsic semiconductor region (i.e., an "I" region) between the p-type semiconductor and the n-type semiconductor regions. Other photodetector structures include, for example, APD (avalanche photodiode)-based structures, PMT (photomultiplier tube)-based structures, SiPM (silicon photomultiplier tube)-based structures, SPAD (single photon avalanche diode)-based structures and / or quantum wires. For the material system used in the photodetector, Si, InGaAs and / or Si / Ge-based materials can be used. It should be understood that many other detector structures and / or material systems can be used in the optical receiver and the photodetector 330.

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

[0076] Figure 3 The LiDAR system 300 is further illustrated to include a steering mechanism 340. As described above, the steering mechanism 340 guides the light beam from the transmitter 320 to scan the FOV in multiple dimensions. The steering mechanism is called a grating mechanism or a scanning mechanism. Scanning the light beam in multiple directions (e.g., in the horizontal direction and the vertical direction) helps the LiDAR system to draw the environment by generating an image or a 3D point cloud. The steering mechanism can be based on mechanical scanning and / or solid-state scanning. Mechanical scanning uses a rotating mirror to steer the laser beam or physically rotates the LiDAR transmitter and receiver (collectively referred to as a transceiver) to scan the laser beam. Solid-state scanning guides the laser beam to various positions through the FOV without mechanically moving any macroscopic components, such as a transceiver. The solid-state scanning mechanism includes, for example, steering based on an optical phased array and steering based on a flash LiDAR. In some embodiments, because the solid-state scanning mechanism does not physically move the macroscopic components, the steering performed by the solid-state scanning mechanism can be referred to as effective steering. A LiDAR system using solid-state scanning may also be referred to as a non-mechanical scanning or simply a non-scanning LiDAR system (a flash LiDAR system is an exemplary non-scanning LiDAR system).

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

[0078] As another example, to implement the steering mechanism 340, a one-dimensional mechanical scanner can be used with an array or a large number of single-point transceivers. Specifically, the transceiver array can be mounted on a rotating platform to achieve a 360-degree horizontal field of view. Alternatively, a static transceiver array can be combined with a one-dimensional mechanical scanner. The one-dimensional mechanical scanner includes a polygon mirror, an oscillating mirror, a rotating prism, and a rotating tilt mirror to obtain a forward horizontal field of view. A steering mechanism using a mechanical scanner can provide robustness and reliability in mass production for automotive applications.

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

[0080] Some implementations of the steering mechanism 340 include one or more optical redirecting elements (e.g., mirrors or lenses) that redirect (e.g., by rotating, vibrating, or directing) the return light signal along the receive path to direct the return light signal to the optical receiver and light detector 330. The optical redirecting elements that direct the light signal along the transmit path and the receive path can be the same component (e.g., shared), separate components (e.g., dedicated), and / or a combination of shared and separate components. This means that in some cases, the transmit path and the receive path are distinct, although they can partially overlap (or in some cases, substantially overlap).

[0081] Still reference Figure 3 , the LiDAR system 300 also includes a control circuit system 350. The control circuit system 350 can be configured and / or programmed to control various parts of the LiDAR system 300 and / or perform signal processing. In a typical system, the control circuit 350 can be constructed and / or programmed to perform one or more control operations, which include, for example, controlling the laser source 310 to obtain the desired laser pulse timing, repetition rate and power; controlling the steering mechanism 340 (e.g., controlling speed, direction and / or other parameters) to scan the FOV and maintain pixel registration / alignment; controlling the optical receiver and light detector 330 (e.g., controlling sensitivity, noise reduction, filtering and / or other parameters) to make it optimal; and monitoring the overall system health / status for functional safety.

[0082] The control circuit system 350 can also be configured and / or programmed to perform signal processing on the raw data generated by the optical receiver and light detector 330 to obtain distance and reflectivity information, and to package and communicate the data with the vehicle perception and planning system 220 (e.g., Figure 2 For example, control circuit system 350 determines the time taken from transmitting a light pulse to receiving a corresponding return light pulse; determines the time when a return light pulse is not received for the transmitted light pulse; determines the direction of the transmitted light pulse / return light pulse (e.g., horizontal and / or vertical information); determines an estimated range in a particular direction; and / or determines any other type of data related to LiDAR system 300.

[0083] The LiDAR system 300 can be set in a vehicle that can operate in many different environments, including hot or cold weather, rough road conditions that may cause strong vibrations, high or low humidity, dusty areas, etc. Therefore, in some embodiments, the optical and / or electronic components of the LiDAR system 300 (e.g., the optical devices in the transmitter 320, the optical receiver and light detector 330, and the steering mechanism 340) are arranged or configured in a manner to maintain long-term mechanical and optical stability. For example, the components in the LiDAR system 300 can be fixed and sealed so that they can operate under all conditions that the vehicle may encounter. As an example, a moisture-proof coating and / or an airtight seal can be applied to the optical components of the transmitter 320, the optical receiver and light detector 330, and the steering mechanism 340 (as well as other components susceptible to moisture). As another example, a housing, a casing, and / or a window can be used in the LiDAR system 300 to provide desired features such as hardness, foreign body protection (IP) rating, self-cleaning ability, chemical resistance, and impact resistance. Additionally, efficient and economical methods for assembling the LiDAR system 300 may be used to meet LiDAR operating requirements while keeping costs low.

[0084] Those skilled in the art should understand that Figure 3 The above description is for illustrative purposes only, and the LiDAR system may include other functional units, blocks, or segments, and may include variations or combinations of the above functional units, blocks, or segments. For example, the LiDAR system 300 may also include Figure 3 Other components not depicted in the drawings may include a power bus, power supplies, LED indicators, switches, etc. Additionally, there may be other connections between components, such as a direct connection between the light source 310 and an optical receiver and light detector 330 so that the light detector 330 can accurately measure the time from when the light source 310 emits a light pulse to when the light detector 330 detects a return light pulse.

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

[0086] As described above, some LiDAR systems use the time of flight (TOF) of an optical signal (e.g., a light pulse) to determine the distance to an object in the optical path. Figure 5A , an exemplary LiDAR system 500 includes a laser light source (e.g., a fiber laser), a steering system (e.g., a system of one or more moving mirrors), and a light detector (e.g., a photon detector having one or more optical devices). The LiDAR system 500 can be implemented using, for example, the LiDAR system 300 described above. The LiDAR system 500 emits light pulses 502 along an optical path 504, as determined by the steering system of the LiDAR system 500. In the depicted embodiment, the light pulses 502 generated by the laser source are short laser pulses. In addition, the signal steering system of the LiDAR system 500 is a pulsed signal steering system. However, it should be understood that the LiDAR system can operate by generating, emitting, and detecting non-pulsed light signals, and derive the range to the target 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 also be understood that any of the techniques described herein for time-of-flight-based systems using pulsed signals can also be applied to LiDAR systems that do not use one or both of these techniques.

[0087] Return to reference Figure 5A(e.g., a time-of-flight LiDAR system using light pulses is illustrated), when light pulse 502 reaches object 506, light pulse 502 is scattered or reflected to generate return light pulse 508. Return light pulse 508 may return to system 500 along optical path 510. The time from when the emitted light pulse 502 leaves LiDAR system 500 to when the return light pulse 508 returns to LiDAR system 500 may be measured (e.g., by a processor or other electronic device within the LiDAR system, such as control circuit system 350). This time of flight, combined with knowledge of the speed of light, may be used to determine the distance / distance from LiDAR system 500 to the portion of object 506 where light pulse 502 was scattered or reflected.

[0088] By directing many light pulses, such as Figure 5B As depicted, LiDAR system 500 scans the external environment (e.g., by directing light pulses 502, 522, 526, 530 along optical paths 504, 524, 528, 532, respectively). Figure 5C As depicted, the LiDAR system 500 receives return light pulses 508, 542, 548 (corresponding to transmitted light pulses 502, 522, 530, respectively). The return light pulses 508, 542, and 548 are generated by scattering or reflecting the transmitted light pulses by one of the targets 506 and 514. The return light pulses 508, 542, and 548 may return to the LiDAR system 500 along optical paths 510, 544, and 546, respectively. Based on the direction of the transmitted light pulses (as determined by the LiDAR system 500) and the calculated distance from the LiDAR system 500 to the portion of the object that scattered or reflected the light pulses (e.g., the portion of objects 506 and 514), the external environment within the detectable range (e.g., the field of view between paths 504 and 532, inclusive) may be accurately mapped or mapped (e.g., by generating a 3D point cloud or image).

[0089] If for a particular emitted light pulse, a corresponding light pulse is not received, it can be determined that there is no target within the detectable range of the LiDAR system 500 (e.g., the target is beyond the maximum scanning distance of the LiDAR system 500). Figure 5B In the example, light pulse 526 may not have a corresponding return light pulse (e.g. Figure 5C 528 within the detectable range of the LiDAR system 500).

[0090] exist Figure 5B, light pulses 502, 522, 526, and 530 may be emitted in any order, serially, in parallel, or based on other timings relative to each other. Additionally, although Figure 5B The emitted light pulses are depicted as being directed in one dimension or plane (e.g., the plane of the paper), but the LiDAR system 500 may also direct the emitted light pulses along other dimensions or planes. For example, the LiDAR system 500 may also direct the emitted light pulses in a direction perpendicular to the plane of the paper. Figure 5B The emitted light pulses are guided in the dimension or plane of the dimension or plane shown, thereby forming a 2-dimensional transmission of the light pulses. This 2-dimensional transmission of the light pulses can be performed point by point, line by line, all at once, or in other ways. A point cloud or image from a 1-dimensional emission of a light pulse (e.g., a single horizontal line) can generate 2-dimensional data (e.g., (1) data from the horizontal emission direction and (2) the range or distance to the target). Similarly, a point cloud or image from a 2-dimensional transmission of a light pulse can generate 3-dimensional data (e.g., (1) data from the horizontal transmission direction, (2) data from the vertical transmission direction, and (3) the range or distance to the object). Typically, a LiDAR system that performs n-dimensional transmission of light pulses generates (n+1)-dimensional data. This is because the LiDAR system can measure the depth of an object or the distance to an object, which provides an additional data dimension. Therefore, a 2D scan performed by a LiDAR system can generate a 3D point cloud for mapping the external environment of the LiDAR system.

[0091] The density of the point cloud refers to the number of measurements (data points) per region performed by the LiDAR system. The point cloud density is related to the LiDAR scan resolution. Typically, at least for regions of interest (ROIs), a greater point cloud density is desired, and therefore a higher resolution is required. The point density in the point cloud or image generated by the LiDAR system is equal to the number of pulses divided by the field of view. In some embodiments, the field of view may be fixed. Therefore, in order to increase the density of points generated by a set of transmitting-receiving optical devices (or transceiver optical devices), the LiDAR system may need to generate pulses more frequently. In other words, a light source with a higher pulse repetition rate (PRR) is required. On the other hand, generating and transmitting pulses more frequently may limit the farthest distance that the LiDAR system can detect. For example, if a return signal from a distant object is received after the system transmits the next pulse, the return signal may be detected in an order different from the order in which the corresponding signal was transmitted, so the return signal cannot be correctly associated with the transmitted signal, which will cause ambiguity.

[0092] For illustration, consider an exemplary LiDAR system that can emit laser pulses at a repetition rate between 500kHz and 1MHz. Based on the time it takes for the pulses to return to the LiDAR system and to avoid the mixing of return pulses from consecutive pulses in conventional LiDAR designs, the farthest distances that the LiDAR system can detect can be 300 meters and 150 meters for 500kHz and 1MHz, respectively. The density of points for a LiDAR system with a 500kHz repetition rate is half the density of points for a LiDAR system with a 1MHz repetition rate. Therefore, this embodiment demonstrates that if the system cannot correctly correlate return signals that arrive out of order, increasing the repetition rate from 500kHz to 1MHz (and thus increasing the density of points of the system) can reduce the detection range of the system. Various techniques are used to mitigate the tradeoff between higher PRR and limited detection range. For example, multiple wavelengths can be used to detect targets in different ranges. Optical and / or signal processing techniques are also used to correlate the emitted optical signal with the return optical signal.

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

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

[0095] The various systems, apparatuses, and methods described herein may be implemented using a computer program product tangibly embodied in an information carrier, such as in a non-transitory machine-readable storage device, for execution by a programmable processor; and the method processes and steps described herein (including Figures 1 to 11One or more steps in the above) can be implemented using one or more computer programs executable by such a processor. A computer program is a set of computer program instructions that can be used directly or indirectly in a computer to perform a specific activity or produce a specific result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0096] Figure 6 A simplified block diagram of an exemplary apparatus that can be used to implement the systems, apparatus, and methods described herein is illustrated. Apparatus 600 includes a processor 610 that is operably coupled to a persistent storage device 620 and a main memory device 630. Processor 610 controls the overall operation of apparatus 600 by executing computer program instructions that define these operations. The computer program instructions may be stored in persistent storage device 620 or other computer-readable medium and loaded into main memory device 630 when execution of the computer program instructions is desired. For example, processor 610 may be used to implement one or more components and systems described herein, such as control circuit system 350 ( Figure 3 As shown), vehicle perception and planning system 220 ( Figure 2 shown) and the vehicle control system 280 ( Figure 2 Therefore, Figure 13 to Figure 14 The method steps of the method steps or any of the method steps explicitly or implicitly described herein can be defined by computer program instructions stored in the main memory device 630 and / or the persistent storage device 620, and controlled by the processor 610 that executes the computer program instructions. For example, the computer program instructions can be implemented as a computer executable code programmed by a person skilled in the art to execute an algorithm defined by any of the method steps described herein. Therefore, by executing the computer program instructions, the processor 610 executes the algorithm defined by the method described herein. The device 600 also includes one or more network interfaces 680 for communicating with other devices via a network. The device 600 may also include one or more input / output devices 690, which enable a user to interact with the device 600 (e.g., a display, keyboard, mouse, speaker, button, etc.).

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

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

[0099] Input / output devices 690 may include peripheral devices such as printers, scanners, display screens, etc. For example, input / output devices 690 may include a display device (such as a cathode ray tube (CRT), plasma or liquid crystal display (LCD) monitor, keyboard) for displaying information to a user, and a pointing device (such as a mouse or trackball) that a user may use to provide input to apparatus 600.

[0100] Any or all of the functionality of the systems and devices discussed herein may be performed by the processor 610, and / or incorporated into a device or system such as the LiDAR system 300. Additionally, the LiDAR system 300 and / or device 600 may utilize one or more neural networks or other deep learning techniques performed by the processor 610 or other systems or devices discussed herein.

[0101] Those skilled in the art will recognize that the actual computer or computer system implementation may have other structures and may also include other components, and Figure 6 is a high-level representation of some of the components of such a computer for purposes of illustration.

[0102] Figure 7 is a block diagram illustrating an exemplary fiber-based laser source 700 according to one embodiment, the laser source having a seed laser and multiple pumps (e.g., laser diodes) that operate at different phases in a single stage for pumping a desired output optical power. Fiber-based laser source 700. In this embodiment, the fiber-based laser source 700 includes a seed laser 702 to generate optical pulses of one or more wavelengths (e.g., 1550 nm) that are provided to a combiner 710 via an optical fiber 703. The laser source 700 also includes pumps 712-1 and 712-2 that provide laser power (e.g., at different wavelengths (such as 980 nm)) to the combiner 710 via respective optical fibers 711 and 713.

[0103] Combiner 710 combines the optical pulses provided by seed laser 702, pump 712-1, and pump 712-2 onto a single optical fiber 704. Combiner 710 can combine optical signals having the same wavelength or different wavelengths. An example of a combiner is a WDM. Combiner 710 provides the pulses to boost amplifier 714, which generates output optical pulses via optical fiber 720. Boost amplifier 714 provides further amplification of the optical signal. The output optical pulses can then be transmitted to transmitter 320 and / or steering mechanism 340 (e.g., Figure 3 shown).

[0104] The laser source 700 also includes a controller 715-1 for controlling the pump laser 712-1 and a controller 715-2 for controlling the pump laser 712-2. Figure 8 As further described in the context of , delay circuit 717 provides a delay (which in one example is configurable) to the pulse control signal so that the output pulses of pump lasers 712 - 1 and 712 - 2 can be offset relative to each other.

[0105] In the illustrated embodiment, the pump laser 712-1 and the controller 715-1 are provided on one chip 730-1. Similarly, the pump laser 712-2 and the controller 715-2 are provided on another chip 730-2. However, those skilled in the art will appreciate that in alternative embodiments, multiple pump lasers and corresponding control circuits may be provided on the same chip.

[0106] As shown, LiDAR system control circuitry 750 is coupled to seed laser 702, boost amplifier 714, controllers 715-1 and 715-2, and delay circuit 717. As will be appreciated by those skilled in the art, delay circuit 717 may be provided as part of LiDAR system control circuitry 750 to shift the phase of the electrical pulses provided to controller 715-1 relative to the electrical pulses provided to controller 715-2. For purposes of illustration, it is Figure 7 In the figure (and in Figures 8 to 10 ) is shown separately from the system control circuit system 750.

[0107] In various embodiments, various relationships between the triggering rate of the seed laser 702 and the control pulses provided by the control circuits 715-1 and 715-2 can be used. In some embodiments, the seed laser triggering rate is different from the pulse rate of the current provided by the control circuits for triggering the pump lasers 712-1 and 712-2. In some embodiments, the seed laser triggering rate is in the range of 5-500 kilohertz (kHz), and the pulse rate of the signal triggering the pump laser is in the range of 250-1500 kHz. In some embodiments, the sum of the duty cycles of the signals triggering the pump lasers is less than one.

[0108] It should be understood that Figure 7 An exemplary configuration of a fiber-based laser source 700 is shown. The laser source 700 may have a Figure 7 One or more components shown in and / or Figure 7 Many other configurations of different combinations of other components not shown (e.g., other components such as power supplies, lenses, filters, splitters, combiners, etc.).

[0109] Figure 8 The diagram shows the control circuit for controlling the pump laser diodes 712-1 and 712-2. Figure 7 Further details of one embodiment of controllers 715-1 and 715-2 are provided below. Figure 8As shown, controller 715-1 includes voltage source 801, regulator transistor 804-1, switch transistor 805-1, bias voltage 802-1, control pulse 803 and temperature sensing circuit 807-1. Controller 715-2 includes regulator transistor 804-2, switch transistor 805-2, bias voltage 802-2 and temperature sensing circuit 807-2. In this embodiment, the transistors shown are NMOS transistors (n-channel metal oxide semiconductor field effect transistors). As will be appreciated by those skilled in the art, other types and arrangements of transistors may be used without departing from the spirit of the illustrated embodiments. In various embodiments, the associated switch and / or regulating transistor is one or more of the following: an insulated gate field effect transistor (FET), a metal oxide semiconductor FET (MOSFET), a metal semiconductor FET (MESFET), a fin field effect transistor (FinFET), a gate-all-around FET (GAAFET) and a bipolar transistor. In various implementations, the transistor may be one or more of a silicon-based transistor, a gallium arsenide (GaAs)-based transistor, a silicon carbide (SiC)-based transistor, or a gallium nitride (GaN)-based transistor.

[0110] As shown, supply voltage 801 is coupled to the respective drains of transistors 804-1 and 804-2. Bias voltages 802-1 and 802-2 are coupled to the respective gates of regulator transistors 804-1 and 804-2 to control the amplitude of the current pulses through the circuit and therefore through the pump laser diodes 712-1 and 712-2. System control circuitry 750 controls the value of the bias voltages provided by 802-1 and 802-2. Laser diode 712-1 is coupled between the source of transistor 804-1 and the drain of transistor 805-1. Similarly, laser diode 712-2 is coupled between the source of transistor 804-2 and the drain of transistor 805-2.

[0111] In operation, the voltage pulses from control pulse 803 turn transistors 805-1 and 805-2 on and off, thereby generating current pulses through laser pump diodes 712-1 and 712-2. Delay circuit 717 delays the voltage pulse at transistor 805-2 relative to the voltage pulse at transistor 8051, and thus the current pulse at pump laser diode 712-2 is phase delayed relative to the current pulse at pump laser diode 712-1.

[0112] In some embodiments, delay circuit 717 is programmable based on a signal received from system control circuitry 750 such that the amount of delay provided by delay circuit 717 can be reconfigured.

[0113] If it will Fig.14As further described in the context of , the temperature sensing circuits 807-1 and 807-2 monitor the respective junction temperatures of the respective pump laser diodes 712-1 and 712-2. The temperature sensing circuits provide temperature-related signals to the system control circuit system 750. As shown in Fig.14 As explained in the context of , in embodiments having several pump lasers at one pump stage, such temperature monitoring circuits can allow the system control circuitry to dynamically adjust which pump lasers are used to minimize heating of any one pump laser and thereby extend the life of the pump lasers.

[0114] Fig. 9 Pictured Figure 8 An alternative embodiment to the embodiment shown. Fig. 9 In an embodiment, controller circuits 915-1 and 915-2 each include transistors in a cascode arrangement.

[0115] Laser pump diode 912-1 is coupled between voltage source 901 and the drain of regulator transistor 904-1. Similarly, laser pump diode 912-2 is coupled between voltage source 901 and the drain of regulator transistor 904-2. Regulator transistor 904-1 and switch transistor 905-1 are coupled in a cascode arrangement, wherein the source of regulator transistor 904-1 is coupled to the drain of switch transistor 905-1. Regulator transistor 904-2 and switch transistor 905-2 are similarly coupled as shown. Control pulse 903 is coupled to the gate of switch transistor 905-1. Delay circuit 917 is coupled between control pulse 903 and the gate of switch transistor 905-2.

[0116] Fig. 9 The operation of the implementation scheme is similar to Figure 8 The voltage pulses from control pulse 903 turn transistors 905-1 and 905-2 on and off, thereby generating current pulses through laser pump diodes 912-1 and 912-2. Delay circuit 917 delays the voltage pulse at transistor 905-2 relative to the voltage pulse at transistor 905-1, and thus the current pulse at pump laser diode 912-2 is phase delayed relative to the current pulse at pump laser diode 912-1.

[0117] Bias voltage 902-1 provides a voltage to the gate of adjustment transistor 904-1, which adjusts the amplitude of current pulses through controller circuit 915-1 (including through pump laser diode 912-1). Similarly, bias voltage 902-2 provides a voltage to the gate of adjustment transistor 904-2, which adjusts the amplitude of current pulses through controller circuit 915-2 (including through pump laser diode 912-2).

[0118] Temperature sensing circuit 907-1 monitors the junction temperature of pump laser diode 912-1 and provides a temperature-related signal to system control circuitry 750. Similarly, temperature sensing circuit 907-2 monitors the junction temperature of pump laser diode 912-2 and provides a temperature-related signal to system control circuitry 750.

[0119] Fig.10 Pictured Figure 8 Another alternative embodiment of the embodiment of . Fig.10 In an embodiment of the present invention, an associated controller uses a current sensing circuit to determine the amplitude of the voltage pulse provided by the control pulse generator.

[0120] Specifically, laser pump diode 1012-1 is coupled between voltage source 1001 and current sensing circuit 1020-1. Similarly, laser pump diode 1012-2 is coupled between voltage source 1001 and current sensing circuit 1020-2. Current sensing circuit 1020-1 is coupled to the drain of switching transistor 1005-1. Similarly, current sensing circuit 1020-2 is coupled to the drain of switching transistor 1005-2. Control pulse 1003 is coupled to the gate of switching transistor 1005-1. Delay circuit 1017 is coupled between pulse 1003 and the gate of switching transistor 1005-2.

[0121] Fig.10 The operation of the embodiment of is as follows: the voltage pulse from the control pulse 1003 turns the transistors 1005-1 and 1005-2 on and off, thereby generating a current pulse through the laser pump diodes 1012-1 and 1012-2. The delay circuit 1017 delays the voltage pulse at the transistor 1005-2 relative to the voltage pulse at the transistor 1005-1, and thus the current pulse at the pump laser diode 1012-2 is phase delayed relative to the current pulse at the pump laser diode 1012-1.

[0122] Current sensing circuit 1020-1 senses the current through control circuit 1015-1 (and therefore through pump laser diode 1012-1) and provides a signal to system control circuitry 750 (eg, Figure 7 The voltage signal is responsive to the current through the control circuit 1015-1 (i.e., related to measurement purposes). The control circuit system 750 uses the voltage output of the current sensing circuit 1020-1 to control the amplitude of the voltage pulse provided by the control pulse 1003 so that the amplitude of the current pulse through the circuit 1015-1 and the pump laser diode 1012-1 is maintained at a desired level.

[0123] Similarly, current sensing circuit 1020-2 senses the current through control circuit 1015-2 (and therefore through pump laser diode 1012-2) and provides a voltage signal in response to the current through control circuit 1015-2 to system control circuit 750. Control circuit system 750 uses the output of current sensing circuit 1020-2 to control the amplitude of the voltage pulse provided by control pulse 1003 so that the amplitude of the current pulse through circuit 10152 and pump laser diode 1012-2 is maintained at a desired level.

[0124] Temperature sensing circuit 1007-1 monitors the junction temperature of pump laser diode 1012-1 and provides a temperature-related signal to system control circuitry 750. Similarly, temperature sensing circuit 1007-2 monitors the junction temperature of pump laser diode 1012-2 and provides a temperature-related signal to system control circuitry 750.

[0125] Those skilled in the art will appreciate that there are various known ways to implement current sensing circuits, such as current sensing circuits 1020-1 and 1020-2. In a typical example, the current sensing circuit includes operational amplifier circuitry coupled to a sense resistor through which the sense current flows.

[0126] Figures 7 to 10 The example in shows two pump lasers and corresponding controllers in a single pump stage of a laser source. In operation, the pump lasers output light pulses in an alternating manner in response to the two controllers providing current pulses in an alternating manner. As will be seen in FIG. Fig.12 As further explained in the context of , this arrangement allows the use of shorter, higher amplitude current pulses applied to the pump laser diode, thereby allowing a higher percentage of each current pulse to be above the threshold current of the pump laser. Thus, a greater percentage of electrical power is converted into optical power, and the efficiency and lifetime of the system are improved.

[0127] However, Figures 7 to 10 The principles of the examples in can be readily applied to embodiments with more pump lasers in a single pump stage (e.g., 3, 4, 5, 6, or more pump lasers in a single pump stage). In addition, although Figure 7 The embodiments of the present disclosure show a single pump stage, but the principles of the embodiments of the present disclosure are applicable to laser sources having multiple pump stages. In such alternatives, one or more pump stages may each have multiple pump lasers that are operated in a multi-phase manner relative to each other (i.e., two or more pump lasers have pulses with different phases).

[0128] Fig.111 is a timing diagram illustrating multiple current pulses of different phases for powering corresponding pump lasers. As shown, a current pulse 1101 is generated to power a first pump laser, and a second current pulse 1102 is generated to power a second pump laser. A total of N different current pulses can be generated to power N different pump lasers.

[0129] As shown, the current pulse has a width (i.e., time length) of tw. Current pulses 1101 and 1102 have a phase difference of tpd. In one embodiment, the phase difference between pulses that power different pumps is equal to or greater than the pulse width. In some embodiments, when several different current pulses are used to power several different pump lasers at the same pumping stage, the pulses can be staggered so that the greater the number of pulses and corresponding pump lasers used at a given pumping stage, the smaller the duty cycle of each pulse.

[0130] Furthermore, in some embodiments, the phase delay between consecutive pulses controlling the continuous pump laser is greater than the pulse width, so that the consecutive pulses controlling the continuous pump laser do not overlap in timing and the sum of the duty cycles of all control pulses is less than one.

[0131] In some embodiments, only two of the plurality of pumps are powered using different phase current pulses. In other embodiments, more than two or all of the plurality of pumps are powered using different phase current pulses.

[0132] In some embodiments, a plurality of pump lasers are provided, and the junction temperature of the pump lasers is monitored during operation. In some embodiments, the number of pump lasers that receive the activation control signal is dynamically determined based on the results of the junction temperature monitoring.

[0133] Fig.121 is a timing diagram comparing a higher peak current of a pulse driving a laser pump with a lower peak current of a pulse driving a laser pump to illustrate certain advantages of embodiments of the present invention. In this example, the laser pump has a threshold current 1203. Currents below the threshold current are not converted into optical power. Only currents at or above the threshold current are converted into optical power. Two pulses 1201 and 1202 are shown for comparison. Pulse 1201 has a narrower width and a higher amplitude than pulse 1202. Therefore, a lower percentage of the total area under pulse 1201 is under threshold current 1203 than in the case of pulse 1202. Therefore, pulse 1201 results in less wasted power (higher efficiency) than pulse 1202. Embodiments of the present invention facilitate the use of pulses with higher amplitudes and narrower widths than the prior art, thereby improving efficiency and potential system life relative to the prior art. By providing multiple pump lasers at a single pump stage, current pulses can be alternated to power multiple pump lasers at a higher amplitude for shorter time periods, thereby avoiding a constant lower amplitude current (or at least avoiding wider low amplitude pulses) which would have a higher percentage of wasted power below the threshold current.

[0134] Fig.13 1 is a flow chart illustrating a method 1300 according to one embodiment of the present invention. Step 1301 provides a first current pulse to a first pump laser. The first pump laser is optically coupled to a first optical combiner (e.g., a wavelength division multiplexer or another optical combiner) of a laser source in a LiDAR system. Step 1302 provides a second current pulse to a second pump laser. The second pump laser is optically coupled to the same optical combiner as the first pump laser. In other words, it is part of the same pump stage. The second current pulse is delayed relative to the first current pulse so that the second current pulse has a different phase. Preferably, the phase difference between the first pulse and the second pulse is sufficient in time so that there is no timing overlap between the first pulse that powers the first pump laser and the second pulse that powers the second pump laser. In one embodiment, the pulse width is less than the phase delay so that the sum of the duty cycles of the two pulses is less than one.

[0135] Fig.14 A method 1400 is illustrated in accordance with one embodiment of the present invention. In some embodiments, three or more pump lasers (e.g., laser diodes) are used at a single pump stage of a laser source system. This allows for some redundancy and the potential for increased system lifetime. In one embodiment, the junction temperature of the pump lasers is monitored during operation of the laser source system (e.g., by a temperature monitoring circuit such as a Figures 8 to 10 ), and if the junction temperature of one of the pump lasers exceeds a predetermined amount, only the other pump lasers of the three or more pump lasers are used.

[0136] Step 1401 provides a plurality of pump lasers at a single pump stage of a laser source system. The plurality of pump lasers includes at least three or more pump lasers, so that at least two pump lasers can be operated in a multi-phase manner even if one of the pumps is not currently being used due to excessive junction temperature.

[0137] Step 1402 monitors the junction temperature of each of the plurality of pump lasers. Step 1403 uses the temperature monitoring results of step 1402 to select two or more of the plurality of pump lasers for powering the laser source system at the current time. If one of the plurality of pump lasers has a junction temperature that is higher than or too close to being higher than a predetermined junction temperature, other pump lasers of the plurality of pump lasers may be selected. Step 1404 powers the selected two or more pump lasers using multiphase current pulses.

[0138] During operation of the laser source system, steps 1402 , 1403 , and 1404 continue (periodically or continuously) so that the pump laser selection can be dynamically updated based on changes in junction temperature monitoring results.

[0139] In one embodiment, circuitry for implementing the processing of method 1400 is provided as part of system control circuitry, such as system control circuitry 750. Those skilled in the art will appreciate that the corresponding logic may be readily implemented in software, hardware, firmware, and / or a combination thereof.

[0140] In various embodiments of the present invention, the pump diode is driven in a pulsed manner rather than a constant current. The pulse current amplitude can be constant. The pulse current amplitude can reach the maximum value allowed for safe operation of the pump diode. For a given amplitude, the average current of the pump diode can be controlled by the pulse width. The average current is determined by the specified fiber laser power. The total number of pump diodes is determined by cost, size and target life.

[0141] In various embodiments of the invention, all pump diodes can be turned on in an alternating manner, for example by using a multiphase drive. The seed laser trigger can be used as a time base for turning on the pump laser. The seed trigger rate can be constant or pulse position keyed (PPK). A certain delay (in some embodiments a programmable delay) can be inserted between the seed trigger and turning on the pump diodes.

[0142] Some advantages of embodiments of the present invention are as follows. First, the design uses universal power devices. It can be cost-effective and have a large selection of components. Second, the pulsed current can improve the driving efficiency compared to the constant drive current because the laser diode has a significant threshold. Third, all pump diodes are turned on alternately. Therefore, it will reduce the power consumption of each device and reduce the junction temperature of each device in operation, which is crucial to extend the service life of each device.

[0143] The foregoing description should be understood to be illustrative and exemplary in all respects, rather than restrictive, and the scope of the invention disclosed herein is not determined by the description, but by the claims as interpreted in full as permitted by patent law. It should be understood that the embodiments shown and described herein are merely illustrations of the principles of the invention, and that various modifications may be made by those skilled in the art without departing from the scope and spirit of the invention. Various other feature combinations may be implemented by those skilled in the art without departing from the scope and spirit of the invention.

Claims

1. An electronic device for facilitating multi-phase control of a plurality of laser pumps used in a laser source, the device comprising: one or more power supplies operable to provide power to the plurality of laser pumps; a plurality of pump controllers electrically coupled to the plurality of laser pumps, respectively, each of the plurality of pump controllers operable to control an operating state of a corresponding laser pump of the plurality of laser pumps; and One or more pump control signal generators, the one or more pump control signal generators are electrically coupled to the plurality of pump controllers, the one or more pump control signal generators are operable to generate a plurality of control signals to switch switches in corresponding pump controllers so that pulse current is provided to at least two of the plurality of laser pumps in an alternating manner. 2 . The apparatus of claim 1 , wherein at least one of the plurality of pump controllers comprises a transistor-based switch electrically coupled to a corresponding laser pump of the plurality of laser pumps.

3. The apparatus of claim 2, wherein the transistor-based switch comprises one or more of an insulated gate field effect transistor (FET), a metal oxide semiconductor FET (MOSFET), a metal semiconductor FET (MESFET), a fin field effect transistor (FinFET), a gate-all-around FET (GAAFET), and a bipolar transistor.

4. The apparatus of any one of claims 2 to 3, wherein the transistor-based switch comprises at least one of a silicon-based transistor, a gallium arsenide (GaA)-based transistor, a silicon carbide (SiC)-based transistor, or a gallium nitride (GaN)-based transistor.

5. The apparatus of any one of claims 2 to 4, wherein the transistor-based switch comprises a first transistor having a first terminal and a second terminal, The first terminal of the first transistor is coupled to one of the one or more pump control signal generators to receive one of the plurality of control signals.

6. The apparatus of claim 5, wherein the second terminal of the first transistor is coupled to the laser pump.

7. The apparatus of claim 6, wherein the second terminal of the first transistor is further coupled to a current sensing circuit, or Wherein the first transistor facilitates current sensing by using an on-resistance of the first transistor.

8. The apparatus of any one of claims 5 to 7, wherein the transistor-based switch further comprises a second transistor having a first terminal, a second terminal and a third terminal, the second transistor being operable to facilitate current regulation, Wherein the first terminal of the second transistor is coupled to a bias power supply.

9. The device according to claim 8, wherein the bias power supply is configured to enable the laser pump to have a plurality of peak currents, a peak current of the plurality of peak currents corresponding to a maximum allowable peak current that will not cause irreversible damage to the laser pump.

10. The apparatus according to any one of claims 8 to 9, wherein: The second terminal of the second transistor is coupled to the laser pump, and The third terminal of the second transistor is coupled to at least one of the one or more power supplies.

11. The apparatus according to any one of claims 8 to 9, wherein: the second terminal of the second transistor being coupled to the second terminal of the first transistor such that the first transistor and the second transistor form a cascode configuration; and The third terminal of the second transistor is coupled to the laser pump.

12. The apparatus of any one of claims 2 to 11, wherein the transistor-based switch comprises a plurality of transistors formed in a cascode configuration.

13. An apparatus according to any one of claims 2 to 12, wherein the transistor-based switch comprises a current switch operable to switch on or off to control the current flowing through the laser pump.

14. The apparatus of any one of claims 2 to 13, wherein the transistor-based switch facilitates switching of current at speeds on the order of nanoseconds or sub-nanoseconds.

15. The apparatus of any one of claims 2 to 14, further comprising a current sensing circuit operable to sense a current of the laser pump.

16. The apparatus of any one of claims 1 to 15, wherein the plurality of laser pumps comprises laser diodes.

17. The apparatus according to any one of claims 1 to 16, wherein the plurality of control signals comprises a plurality of electrical pulses, each of the plurality of electrical pulses switching a switch in a corresponding pump controller so as to provide one or more pulsed currents to the corresponding laser pump.

18. The apparatus according to claim 17, wherein the plurality of control signals do not overlap in timing, so that a pulse current is provided to only one laser pump among the plurality of laser pumps at a time.

19. The apparatus according to any one of claims 17 to 18, wherein the plurality of control signals comprise an electrical pulse sequence arranged according to the temporal positions of the electrical pulses, and wherein corresponding pulse currents are sequentially provided to the plurality of laser pumps according to the electrical pulse sequence.

20. The apparatus of claim 17, wherein at least two of the plurality of pulse control signals overlap in timing.

21. The apparatus of any one of claims 17 to 20, wherein at least one of a trigger rate, a duty cycle, and a pulse duration of the plurality of electrical pulses is determined based on a seed laser trigger rate or a seed laser trigger signal modulation.

22. The apparatus of claim 21, wherein the seed laser triggering rate is a constant triggering rate.

23. The apparatus of any one of claims 21 to 22, wherein the seed laser trigger signal modulation is a pulse position keying (PPK) modulation.

24. The apparatus according to any one of claims 21 to 22, wherein the seed laser trigger signal modulation is a frequency hopping based modulation or a spread spectrum based modulation.

25. The apparatus of any one of claims 21 to 24, wherein the seed laser triggering rate is substantially the same as a rate of pulsed current provided to the laser pump or a rate of the plurality of electrical pulses switching transistors in the pump controller.

26. The apparatus of any one of claims 21 to 24, wherein the seed laser triggering rate is different from a rate of pulsed current provided to the laser pump or a rate of the plurality of electrical pulses switching transistors in the pump controller.

27. The apparatus of claim 26, wherein the seed laser trigger rate has any value in the range of 5k to 500k, and wherein the rate of the pulsed current provided to the laser pump or the rate of the plurality of electrical pulses switching transistors in the pump controller has any value in the range of 250k to 1500k.

28. Apparatus according to any one of claims 17 to 27, wherein the amplitude of the one or more pulsed currents provided to the laser pump is predetermined.

29. The apparatus of any one of claims 17 to 28, wherein an average pulse current supplied to the laser pump is controlled by configuring a duty cycle of the pulse current supplied to the laser pump.

30. Apparatus according to any one of claims 17 to 29, wherein the sum of the duty cycles of the plurality of electrical pulses used to trigger respective pump controllers is less than one.

31. The apparatus according to any one of claims 1 to 30, further comprising: one or more seed lasers; and One or more delay circuits coupled to the one or more seed lasers and the plurality of pump controllers, each of the delay circuits being operable to cause a delay between triggering of a corresponding seed laser and switching of a switch of a corresponding pump controller.

32. The apparatus of claim 31, wherein the one or more delay circuits comprise a physical integrated circuit (IC).

33. An apparatus according to any one of claims 31 to 32, wherein the time delay is implemented using a programmable logic structure.

34. Apparatus according to any one of claims 31 to 33, wherein a phase delay or time delay between triggering of a corresponding seed laser and switching of a switch of a corresponding pump controller is programmable.

35. The apparatus of any one of claims 31 to 34, wherein the one or more seed lasers are operable to generate seed laser pulses; and wherein the plurality of control signals comprises a plurality of electrical pulses for switching transistors in the plurality of the pump controllers.

36. The apparatus of claim 35, wherein the seed laser pulses are phase locked or synchronized with the electrical pulses used to switch transistors in the plurality of pump controllers.

37. The apparatus of claim 35, wherein the seed laser pulses are asynchronous.

38. The apparatus of any one of claims 1 to 37, wherein the one or more pump control signal generators are configured to generate the plurality of control signals such that a pulsed current is provided to only one of the plurality of laser pumps during any single laser emission cycle of the laser source.

39. The apparatus of any one of claims 1 to 38, wherein the one or more pump control signal generators are configured to generate the plurality of control signals such that different ones of the plurality of laser pumps are switched on in at least two different laser emission cycles.

40. The apparatus according to any one of claims 1 to 39, wherein the one or more pump control signal generators are configured to generate the plurality of control signals so that pulse currents provided to different laser pumps among the plurality of laser pumps do not overlap in timing.

41. The apparatus of any one of claims 1 to 40, further comprising a junction temperature monitoring circuit operable to monitor junction temperatures of the plurality of laser pumps.

42. The apparatus of claim 41, wherein the junction temperature monitoring circuit comprises a resistance-based monitoring circuit operable to monitor an on-resistance of at least one of the plurality of pump controllers.

43. The apparatus of any one of claims 41 to 42, wherein system control circuitry coupled to the one or more pump control signal generators is configured to: determining the number of laser pumps to which pulse current should be supplied based on the junction temperature monitoring result; and The plurality of control signals are dynamically adjusted so that pulse currents are provided to the determined number of the plurality of laser pumps in an alternating manner.

44. The apparatus of claim 43, wherein the system control circuitry is configured to determine the number of laser pumps that should be provided with pulsed current by being configured to: comparing the junction temperature monitoring result with a threshold temperature; If the junction temperature monitoring result is greater than the threshold temperature, increasing the number of the laser pumps to which pulse current should be provided; and If the junction temperature monitoring result is not greater than the threshold temperature, the number of the laser pumps to which pulse current should be provided is maintained or reduced.

45. The apparatus of claim 43, wherein the system control circuitry is configured to determine the number of laser pumps that should be provided with pulsed current by being configured to: comparing the junction temperature monitoring result with a threshold temperature; and For the laser pump whose junction temperature monitoring result is greater than the threshold, the laser pump is paused or controlled to have a lower duty cycle.

46. ​​The apparatus of any one of claims 1 to 45, further comprising: one or more current sensing circuits operable to sense the pulsed current; a digital sampling circuit coupled to the one or more current sensing circuits, the digital sampling circuit being operable to sample the sensed pulsed current; and A feedback circuit is coupled to the digital sampling circuit, the feedback circuit being operable to provide one or more adjustment signals to the one or more pump control signal generators to adjust the plurality of control signals.

47. The apparatus according to any one of claims 1 to 46, wherein the sum of the powers of the laser pumps is in the order of several watts, tens of watts, hundreds of watts or several kilowatts.

48. A laser source comprising an electronic device according to any one of claims 1 to 46.

49. The laser source of claim 48, further comprising: one or more seed lasers operable to provide seed laser light; one or more combiners operable to combine seed laser light and pump laser light provided by the one or more laser pumps; and One or more optical amplifiers operable to receive the combined light and amplify the seed laser using the pump laser.

50. A light ranging and detection (LiDAR) system comprising a laser source having an electronic device according to any one of claims 1 to 46.

51. A vehicle comprising a light ranging and detection (LiDAR) system according to claim 50.

52. A method for facilitating multi-phase control of a plurality of laser pumps used in a laser source, the method comprising: providing power to the plurality of laser pumps via one or more power supplies; controlling an operating state of a corresponding laser pump of the plurality of laser pumps by each of a plurality of pump controllers electrically coupled to the plurality of laser pumps; as well as A plurality of control signals are generated by one or more pump control signal generators electrically coupled to the plurality of pump control devices to switch respective transistors of respective pump controllers such that pulse current is provided to at least two of the plurality of laser pumps in an alternating manner.

53. The method of claim 52, further comprising: monitoring the junction temperature of the plurality of laser pumps; determining the number of laser pumps to which pulse current should be supplied based on the junction temperature monitoring result; as well as The plurality of control signals are dynamically adjusted so that pulse currents are provided to the determined number of the plurality of laser pumps in an alternating manner.

54. The method of claim 53, wherein: comparing the junction temperature monitoring result with a threshold temperature; If the junction temperature monitoring result is greater than the threshold temperature, increasing the number of the laser pumps to which pulse current should be provided; and If the junction temperature monitoring result is not greater than the threshold temperature, the number of the laser pumps to which pulse current should be provided is maintained or reduced.

55. The method of claim 53, wherein: comparing the junction temperature monitoring result with a threshold temperature; If the junction temperature monitoring result is greater than the threshold temperature, the laser pump whose junction temperature monitoring result is greater than the threshold is suspended or the laser pump is controlled to have a lower duty cycle.

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