Light detection and ranging (LIDAR) system including high power amplifier

Abstract

A LIDAR sensor system includes: a laser configured to output a light beam; a modulator configured to receive the light beam and modulate the light beam to generate a modulated light beam; a photonic integrated circuit having an amplifier coupled to receive the modulated light beam from the modulator and to generate an amplified light beam, the amplifier having an active layer and an alternating or periodic or superlattice structure configured to dissipate heat; and a transceiver chip coupled to the photonic integrated circuit, the transceiver chip configured to emit the amplified light beam and receive a reflected light beam from a target.

Description

Technical Field

[0001] The present disclosure relates to high-power amplifiers (e.g., optical amplifiers) for optical detection and ranging (LIDAR) systems, and more particularly to monolithically integrated high-power optical amplifiers for LIDAR systems that include passive and active components. Background Art

[0002] LIDAR sensor systems are used for a variety of applications from altimetry to imaging to collision avoidance. The design and implementation of LIDAR sensor systems can use one or more photonic integrated circuits (PICs) or integrated optical circuits, which are chips that contain photonic components. In the past, attempts have been made to include more photonic components and optical functions of LIDAR systems onto a single PIC. Summary of the Invention

[0003] Embodiments of the present disclosure relate to high-power optical amplifiers for LIDAR sensor systems for vehicles, and more particularly to monolithically integrated high-power optical amplifiers for LIDAR sensor systems that include passive and active components.

[0004] In accordance with one aspect of the subject matter described in the present invention, a LIDAR sensor system includes: a laser configured to output a beam of light; a modulator coupled to receive the beam of light output from a seed laser and modulate the beam of light to generate a modulated beam of light; a photonic integrated circuit having an optical amplifier coupled to receive the modulated beam of light from the modulator and generate an amplified beam of light, the amplifier including an active layer for amplification and a specific structure configured to dissipate heat; and a transceiver chip coupled to the photonic integrated circuit, the transceiver chip being configured to transmit the amplified beam of light and receive a reflected beam of light from a target.

[0005] In accordance with another aspect of the subject matter described in the present disclosure, a photonic integrated circuit includes: a first optical amplifier coupled to receive an input beam of light and generate an amplified beam of light, the first amplifier having an active layer for amplification and a specific structure configured to dissipate heat; and one or more passive components monolithically integrated with the first optical amplifier as part of the photonic integrated circuit.

[0006] These and other embodiments may each optionally include one or more of the following features. For example, the features may include: the active layer is an offset body or multiple quantum well structure, for example, the offset body or multiple quantum well structure is one of a group of offset quantum wells or offset dot layers. For example, the features may further include: the photonic integrated circuit includes a first heat dissipation structure for reducing heat from the lower side of the photonic integrated circuit and a second heat dissipation structure for reducing heat from the upper side of the photonic integrated circuit. In another example, the features may include: a particular structure includes one or more alternating indium phosphide (InP) layers, or a particular structure includes an alternating or periodic or superlattice structure that includes one or more alternating indium phosphide and indium gallium arsenide phosphide (InGaAsP) or indium gallium aluminum arsenide (InGaAlAs) or other quaternary or ternary alloy layers with improved heat dissipation and high wall plug efficiency. In one example, a particular structure is integrated with a silicon photonic waveguide and has an optical mode size. In another feature, the photonic integrated circuit includes a monolithically integrated spot size converter, where the photonic integrated circuit is optionally optically coupled to an optical waveguide, such as an optical fiber connector. In some features, the photonic integrated circuit includes one or more passive components monolithically integrated with an optical amplifier, or one or more passive components include a semiconductor optical amplifier (SOA) coupled to a coupler through a U-turn and monolithically integrated to provide optical input and output on the same side of the photonic integrated circuit. For example, a particular SOA includes an alternating or periodic or superlattice structure with improved heat dissipation and high wall plug efficiency. For example, the features may include: the photonic integrated circuit includes and monolithically integrates a second optical amplifier that provides a specific gain, and the output of the second amplifier is coupled to the input of the first amplifier.

[0007] Those skilled in the art will understand that the summary is illustrative only and is not intended to be limiting in any way. Any feature described herein can be used with any other feature, and any subset of these features can be used in combination according to various embodiments. Other aspects, inventive features, and advantages of the devices and / or processes described herein, which are limited only by the claims, will become apparent in the detailed description set forth herein and in connection with the accompanying drawings. In addition, the language used in this disclosure has been selected primarily for readability and guidance purposes and does not limit the scope of the subject matter disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like reference numerals refer to similar elements and in which:

[0009] Figure 1A is a block diagram illustrating an example of a system environment for an autonomous vehicle according to some embodiments.

[0010] Figure 1B is a block diagram illustrating an example of a system environment for an autonomous commercial truck vehicle according to some embodiments.

[0011] Figure 1C is a block diagram illustrating an example of a system environment for an autonomous commercial truck vehicle according to some embodiments.

[0012] Figure 1D is a block diagram illustrating an example of a system environment for an autonomous commercial truck vehicle according to some embodiments.

[0013] Figure 2 is a block diagram illustrating an example of a LIDAR sensor system for an autonomous vehicle according to some embodiments.

[0014] Figure 3 is a cross-sectional view of a high-level block diagram illustrating an example of horizontal integration of semiconductor optical amplifiers in a LIDAR sensor system for an autonomous vehicle according to some embodiments.

[0015] Figures 4A to 4C is a high-level plan view of an example embodiment of a semiconductor optical amplifier that integrates a U-turn and other passive components to provide optical input and output on the same side of a photonic integrated circuit for a LIDAR sensor system for an autonomous vehicle.

[0016] Figure 5A and Figure 5B are cross-sectional views of some embodiments of a semiconductor optical amplifier (SOA) for a LIDAR sensor system for an autonomous vehicle.

[0017] Figure 6 is a cross-sectional view of a second example embodiment of a semiconductor optical amplifier (SOA) for a LIDAR sensor system for an autonomous vehicle.

[0018] It should be understood that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein. Detailed Description

[0019] According to certain aspects, a LIDAR sensor system for a vehicle includes: a laser configured to output a light beam; a modulator configured to receive the light beam from the laser and modulate the light beam to generate a modulated light beam; a photonic integrated circuit having an amplifier coupled to receive the modulated light beam from the modulator and generate an amplified light beam, the optical amplifier including an active layer and an alternating or periodic or superlattice structure for improving heat dissipation; and a transceiver chip coupled to the photonic integrated circuit, the transceiver chip being configured to emit the amplified light beam and receive a reflected light beam from a target. The LIDAR sensor system is advantageous because it includes a photonic integrated circuit that is configured for easy horizontal integration with other components of the LIDAR sensor system. In some embodiments, the photonic integrated circuit includes: a first amplifier coupled to receive an input light beam and generate an amplified light beam, the first amplifier having an active layer for high power and an alternating, periodic or superlattice structure for improving heat dissipation; and one or more passive components monolithically integrated with the first amplifier as part of the photonic integrated circuit. The photonic integrated circuit may include multiple optical amplifiers and passive components including U-turns such that the photonic integrated circuit provides both high power and high gain and has a high wall plug efficiency due to improved heat dissipation. Due to such a photonic integrated circuit, the LIDAR sensor system overcomes the disadvantages of the above prior art because the photonic integrated circuit has high optical power, high gain and high wall plug efficiency. In addition, for easy optical coupling, the photonic integrated circuit has inputs and outputs along one side or facet of the chip.

[0020] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various aspects of different example embodiments. Note that in various instances, any particular example embodiment may be practiced without all specific details and / or with variations, permutations, and combinations of the various features and elements described herein. Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used in the drawings and the description to refer to the same or like parts.

[0021] In addition, relative terms such as "lower" or "bottom" or "rear" or "below" and "upper" or "top" or "front" or "above" may be used herein to describe the relationship of one element to another element, as shown in the figures. It should be understood that the relative terms are intended to cover different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in one of the figures is flipped, an element described as on the "lower" side of other elements will be oriented on the "upper" side of the other elements. Thus, depending on the specific orientation of the figure, the exemplary term "lower" can cover the orientations of both "lower" and "upper". Similarly, if the device in one of the figures is flipped, an element described as "below" or "beneath" other elements will be oriented "above" the other elements. Thus, the exemplary terms "below" or "beneath" can cover the orientations of both above and below.

[0022] Referring to the accompanying drawings, in which like reference numerals refer to like parts throughout the several views, Figure 1A an example of a system environment 100A of an autonomous vehicle 111A in which various techniques disclosed herein may be implemented is shown. For example, vehicle 111A may include: a powertrain 102 that includes a prime mover 104 powered by an energy source 106 and capable of providing power to a driveline 108; and a control system 110 that includes a steering control 112, a powertrain control 114, and a braking control 116. Vehicle 111A may be implemented as any number of different types of vehicles, including vehicles capable of transporting people and / or goods and capable of traveling over land, and it should be understood that the above components 102 to 116 may vary widely depending on the type of vehicle in which they are utilized.

[0023] For simplicity, the embodiments discussed below focus on wheeled land vehicles such as cars, vans, trucks, buses, etc. In such embodiments, the prime mover 104 may include one or more electric motors and / or internal combustion engines (etc.). The energy source 106 may include, for example, a fuel system (e.g., providing gasoline, diesel, hydrogen, etc.), a battery system, solar panels or other renewable energy sources and / or a fuel cell system. The drivetrain 108 includes wheels and / or tires and a transmission and / or any other mechanical drive components adapted to convert the output of the prime mover 104 into vehicle motion, and one or more brakes configured to controllably stop or slow down the vehicle 111A, and a direction or steering component suitable for controlling the trajectory of the vehicle 111A (e.g., a rack and pinion steering linkage enables one or more wheels of the vehicle 111A to pivot about a generally vertical axis to change the angle of the rotational plane of the wheels relative to the longitudinal axis of the vehicle). In some embodiments, a combination of power systems and energy sources may be used (e.g., in the case of an electric / gasoline hybrid vehicle), and in other embodiments, multiple electric motors (e.g., dedicated to individual wheels or axles) may be used as the prime mover 104. In the case of a hydrogen fuel cell embodiment, the prime mover 104 may include one or more electric motors, and the energy source 106 may include a fuel cell system powered by hydrogen fuel.

[0024] The direction control 112 may include one or more actuators and / or sensors for controlling and receiving feedback from the direction or steering component to enable the vehicle 111A to follow a desired trajectory. The power system control 114 may be configured to control the output of the power system 102, e.g., control the output power of the prime mover 104, control the gear position of the transmission in the drivetrain 108, etc., thereby controlling the speed and / or direction of the vehicle 111A. The brake control 116 may be configured to control one or more brakes that slow down or stop the vehicle 111A, e.g., a disc brake or a drum brake coupled to the wheels of the vehicle.

[0025] Other vehicle types including but not limited to all-terrain or tracked vehicles, and construction equipment may utilize different power systems, drivetrains, energy sources, direction controls, power system controls, and brake controls. Additionally, in some embodiments, some components may be combined, e.g., where the direction control of the vehicle is mainly handled by changing the output of one or more prime movers. Thus, the embodiments disclosed herein are not limited to the specific application of the techniques described herein to autonomous wheeled land vehicles.

[0026] In the illustrated embodiment, various levels of autonomous control, including full or semi-autonomous control of vehicle 111A, may be implemented in vehicle control system 120, which may include one or more processors 122 and one or more memories 124, where each processor 122 is configured to execute program code instructions 126 stored in memory 124. The processor may include, for example, a graphics processing unit (“GPU”) and / or a central processing unit (“CPU”).

[0027] Sensors 130 may include various sensors suitable for collecting information from the vehicle's surrounding environment for use in controlling the operation of vehicle 111A. For example, sensors 130 may include one or more detection and ranging sensors (e.g., RADAR sensor 134, LIDAR sensor 136, or both), a 3D positioning sensor 138, such as a satellite navigation system, such as GPS (Global Positioning System), GLONASS (Global Naya Navigazionnaya Sputnikovaya Sistema or Global Navigation Satellite System), BeiDou Navigation Satellite System (BDS), Galileo, Compass, etc. The 3D positioning sensor 138 may be used to determine the vehicle's position on the earth using satellite signals. Sensors 130 may optionally include camera 140 and / or IMU (Inertial Measurement Unit) 142. Camera 140 may be a single-image or stereo camera and may record static and / or video images. IMU 142 may include multiple gyroscopes and accelerometers capable of detecting the linear and rotational motion of vehicle 111A in three directions. One or more encoders 144, such as wheel encoders, may be used to monitor the rotation of one or more wheels of vehicle 111A. In some embodiments, LIDAR sensor 136 may include a structure of silicon photonics devices for a coherent LIDAR system, as described in detail below.

[0028] The output of sensor 130 can be provided to a set of control subsystems 150, including a localization subsystem 152, a perception subsystem 154, a planning subsystem 156, and a control subsystem 158. The localization subsystem 152 is primarily responsible for precisely determining the position and orientation (sometimes referred to as “pose” or “pose estimation”) of vehicle 111A within its surrounding environment and typically within a certain reference frame. The perception subsystem 154 is primarily responsible for detecting, tracking, and / or identifying objects within the environment surrounding vehicle 111A. Machine learning models according to some embodiments can be used in tracking objects. The planning subsystem 156 is primarily responsible for planning the trajectory or path of the movement of vehicle 111A within a certain time range given a desired destination and static and moving objects within the environment. Machine learning models according to some embodiments can be used in planning the vehicle trajectory. The control subsystem 158 is primarily responsible for generating appropriate control signals to control the various controls in the vehicle control system 120 in order to achieve the planned trajectory of vehicle 111A. Similarly, machine learning models can be utilized to generate one or more signals to control the autonomous vehicle 111A to achieve the planned trajectory.

[0029] It will be understood that Figure 1A the set of components for the vehicle control system 120 illustrated therein is merely an example. In some embodiments, individual sensors may be omitted. Additionally or alternatively, in some embodiments, Figure 1A multiple sensors of the same type illustrated therein can be used for redundancy and / or to cover different areas around the vehicle. Further, in addition to the sensors described above, there may be other types of additional sensors to provide actual sensor data related to the operation and environment of the wheeled land vehicle. Similarly, in other embodiments, different types and / or combinations of control subsystems may be used. Additionally, although subsystems 152 through 158 are illustrated as separate from the processor 122 and the memory 124, it should be understood that in some embodiments, some or all of the functions of subsystems 152 through 158 can be implemented with program code instructions 126 residing in one or more memories 124 and executed by one or more processors 122, and these subsystems 152 through 158 can use the same processor and / or memory in some instances. The subsystems can be implemented at least in part using various dedicated circuit logics, various processors, various field programmable gate arrays (“FPGAs”), various application specific integrated circuits (“ASICs”), various real-time controllers, etc., and as described above, multiple subsystems can utilize circuitry, processors, sensors, and / or other components. Additionally, the various components in the vehicle control system 120 can be networked in various ways.

[0030] In some embodiments, vehicle 111A may further include an auxiliary vehicle control system (not shown), which may serve as a redundant or backup control system for vehicle 111A. In some embodiments, the auxiliary vehicle control system may be capable of fully operating autonomous vehicle 111A in the event of an adverse event in vehicle control system 120, while in other embodiments, the auxiliary vehicle control system may have only limited functionality, e.g., performing a controlled stop of vehicle 111A in response to an adverse event detected in the primary vehicle control system 120. In still other embodiments, the auxiliary vehicle control system may be omitted.

[0031] Generally, different architectures can be used to implement Figure 1A the various components illustrated in, and these architectures include various combinations of software, hardware, circuit logic, sensors, networks, etc. For example, each processor can be implemented as a microprocessor, and each memory can represent a random access memory (“RAM”) device, including a main storage device and any supplementary levels of memory, such as cache memory, non-volatile or backup memory (e.g., programmable or flash memory), read-only memory, etc. Additionally, each memory can be considered to include memory storage devices physically located elsewhere in vehicle 111A, such as any cache memory in the processor, and any storage capacity used as virtual memory, such as that stored on a mass storage device or another computer controller. Figure 1A One or more of the processors 122 illustrated in or a completely separate processor can be used to implement additional functions in vehicle 1A other than for autonomous control purposes, such as controlling an entertainment system, operating doors, lights, convenience features, etc.

[0032] Additionally, for additional storage, vehicle 111A may include one or more mass storage devices, e.g., removable disk drives, hard disk drives, direct access storage devices (“DASD”), optical disk drives (e.g., CD drives, DVD drives, etc.), solid state storage drives (“SSD”), network attached storage, storage area network, and / or tape drives, etc.

[0033] Furthermore, vehicle 100 may include a user interface 118 for enabling vehicle 111A to receive multiple inputs from a user or operator and generate outputs for the user or operator, such as one or more displays, touchscreens, voice and / or gesture interfaces, buttons, and other tactile controls, etc. Otherwise, user input may be received via another computer or electronic device (e.g., via an application on a mobile device or via a web interface).

[0034] In addition, vehicle 111A may include one or more network interfaces (e.g., network interface 162) adapted to communicate with one or more networks 176 to permit information communication with other computers and electronic devices, including, for example, central services such as cloud services, from which vehicle 111A receives information including a trained machine learning model and other data for its autonomous control. One or more networks 176 may be, for example, communication networks and include a wide area network (“WAN”) such as the Internet, one or more local area networks (“LAN”) such as Wi-Fi LAN, mesh networks, etc., and one or more bus subsystems. One or more networks 176 may optionally utilize one or more standard communication technologies, protocols, and / or inter-process communication technologies. In some embodiments, data collected by one or more sensors 130 may be uploaded via network 176 to computing system 172 for additional processing. In the illustrated embodiment, vehicle 111A may communicate with computing system 172 via network 176 and signal line 178. In some embodiments, computing system 172 is a cloud-based computing device. Additionally, reference Figure 2 describes the processing of autonomous vehicle data by computing system 172 according to a number of embodiments.

[0035] Figure 1A Each of the illustrated processors and the various additional controllers and subsystems disclosed herein typically operate under the control of an operating system and execute or otherwise rely on various computer software applications, components, programs, objects, modules, data structures, etc., as described in more detail below. Additionally, the various applications, components, programs, objects, modules, etc. may also be executed, for example, on one or more processors in another computer (e.g., computing system 172) of vehicle 100 coupled via network 176 in a distributed, cloud-based, or client-server computing environment, where the processing required to implement the functionality of the computer program may be distributed across multiple computers and / or services via the network.

[0036] Typically, the routines executed to implement the various embodiments described herein, whether implemented as part of an operating system or as a particular application, component, program, object, module, or sequence of instructions, or even a subset thereof, will be referred to herein as "program code". Program code typically includes one or more instructions that reside at various times in various memories and storage devices and, when read and executed by one or more processors, perform the steps required to execute the steps or elements embodying the various aspects of the present disclosure. Additionally, while the embodiments have been and will hereinafter be described in the context of fully operational computers and systems, it should be understood that the various embodiments described herein can be distributed in a variety of forms as a program product, and that the embodiments can be implemented regardless of the particular type of computer-readable medium used to actually effectuate the distribution.

[0037] Examples of computer-readable media include tangible, non-transitory media such as volatile and non-volatile memory devices, floppy disks and other removable disks, solid state drives, hard disk drives, magnetic tape, and optical discs (e.g., CD-ROM, DVD, etc.).

[0038] Additionally, the various program codes described hereinafter can be identified based on the application in which the program code is implemented in its particular embodiment. However, it should be understood that any particular program nomenclature hereinafter is used for convenience only, and thus the present disclosure should not be limited to use only in any particular application identified and / or implied by such nomenclature. Further, a given computer program can be organized in any of a typically innumerable number of ways into routines, procedures, methods, modules, objects, etc., and in various ways in which the program functionality can be distributed among the various software layers (e.g., operating system, libraries, APIs, applications, applets, etc.) that typically reside within a typical computer, it should be understood that the present disclosure is not limited to the particular organization and distribution of program functionality described herein.

[0039] Figure 1A The example environments illustrated herein are not intended to limit the embodiments disclosed herein. Indeed, other alternative hardware and / or software environments can be used without departing from the scope of the embodiments disclosed herein.

[0040] The truck can include a lidar system (e.g., Figure 1A the vehicle control system 120 in Figure 2such as the lidar system 201). In some embodiments, the lidar system may use frequency modulation to encode an optical signal and use optical devices to scatter the encoded optical signal into free space. By detecting the frequency difference between the encoded optical signal and the return signal reflected from an object, a frequency modulated (FM) lidar system can determine the position of the object and / or accurately measure the speed of the object using the Doppler effect. The FM lidar system may use continuous wave (referred to as "FMCW lidar" or "coherent FMCW lidar") or quasi-continuous wave (referred to as "FMQW lidar"). The lidar system may use phase modulation (PM) to encode an optical signal and use optical devices to scatter the encoded optical signal into free space.

[0041] For automotive and / or commercial truck applications, FM or phase modulation (PM) lidar systems can offer significant advantages over traditional lidar systems. First, in some instances, an object (e.g., a pedestrian wearing dark clothing) may have a low reflectivity as it only reflects a small amount (e.g., 10% or less) of the light hitting the object back to the sensor (e.g., Figure 1A the sensor 130 in). In other instances, an object (e.g., a shiny road sign) may have a high reflectivity (e.g., greater than 10%) as it reflects a large amount of the light hitting the object back to the sensor of the FM lidar system.

[0042] Regardless of the reflectivity of the object, the FM lidar system is able to detect (e.g., classify, distinguish, discover, etc.) objects at greater distances (e.g., 2 times) than traditional lidar systems. For example, the FM lidar system can detect low-reflectivity objects beyond 300 meters and high-reflectivity objects beyond 400 meters.

[0043] To achieve this improvement in detection capabilities, the FM lidar system can use sensors (e.g., Figure 1AThe sensors in (e.g., sensor 130). In some embodiments, these sensors can be single-photon sensitive, meaning they can detect the smallest possible amount of light. While FM lidar systems can use infrared wavelengths (e.g., 950 nm, 1550 nm, etc.) in some applications, they are not limited to the infrared wavelength range (e.g., near infrared: 800 nm to 1500 nm; mid-infrared: 1500 nm to 5600 nm; and far-infrared: 5600 nm to 1,000,000 nm). By operating an FM or PM lidar system within the infrared wavelength, the FM or PM lidar system can broadcast stronger light pulses or beams while meeting eye safety standards. Traditional lidar systems are generally not single-photon sensitive and / or operate only within the near-infrared wavelength, thus requiring them to limit their light output (and distance detection capabilities) for eye safety reasons.

[0044] Therefore, by detecting objects at greater distances, an FM lidar system can have more time to react to unexpected obstacles. In fact, even a few milliseconds of additional time can improve safety and comfort, especially for heavy vehicles (e.g., commercial truck vehicles) driving at highway speeds.

[0045] Another advantage of an FM lidar system is that it can provide accurate velocity for each data point instantaneously. In some embodiments, velocity measurements are done using the Doppler effect, which shifts the frequency of the light received from an object based on at least one of the velocity in the radial direction (e.g., the direction vector between the detected object and the sensor) or the frequency of the laser signal. For example, for velocities encountered in road situations where the velocity is less than 100 meters per second (m / s), this shift at a wavelength of 1550 nanometers (nm) amounts to a frequency shift of less than 130 megahertz (MHz). This frequency shift is very small, making it difficult to directly detect in the optical domain. However, by using coherent detection in an FMCW, PMCW, or FMQW lidar system, the signal can be converted to the RF domain so that various signal processing techniques can be used to calculate the frequency shift. This enables the autonomous vehicle control system to process incoming data faster.

[0046] Instantaneous velocity calculation also makes it easier for an FM lidar system to identify distant or sparse data points as objects and / or track how these objects are moving over time. For example, an FM lidar sensor (e.g., Figure 1A sensor 130 in) may only receive a few returns (e.g., hits) from an object 300 meters away, but if these returns give a velocity value of interest (e.g., moving towards the vehicle at a speed > 70 mph), the FM lidar system and / or the autonomous vehicle control system can determine the corresponding weights of the probabilities associated with the object.

[0047] The faster recognition and / or tracking of the FM lidar system gives the autonomous vehicle control system more time to maneuver the vehicle. A better understanding of how fast an object is moving also allows the autonomous vehicle control system to plan a better response.

[0048] Another advantage of the FM lidar system is that it has less static interference compared to traditional lidar systems. That is, traditional lidar systems designed to be light-sensitive typically do not perform well in bright sunlight. These systems are also prone to crosstalk (e.g., when sensors are confused by each other's light pulses or beams) and self-interference (e.g., when a sensor is confused by its own previous light pulses or beams). To overcome these drawbacks, vehicles using traditional lidar systems typically require additional hardware, complex software, and / or more computing power to manage this "noise".

[0049] In contrast, the FM lidar system does not suffer from these types of problems because each sensor is specifically designed to respond only to its own light characteristics (e.g., beam, light wave, light pulse). If the returned light does not match the timing, frequency, and / or wavelength of the originally emitted light, the FM sensor can filter (e.g., remove, ignore, etc.) that data point. Thus, the FM lidar system produces (e.g., generates, exports, etc.) more accurate data with fewer hardware or software requirements, enabling safer and smoother driving.

[0050] Finally, the FM lidar system is easier to scale than traditional lidar systems. As more and more self-driving vehicles (e.g., cars, commercial trucks, etc.) appear on the road, vehicles driven by the FM lidar system may not have to face the interference problems caused by sensor crosstalk. In addition, the FM lidar system uses less optical peak power than traditional lidar sensors. Therefore, some or all of the optical components of the FM lidar can be produced on a single chip, which has its own benefits as discussed herein.

[0051] Figure 1BFIG. is a block diagram illustrating an example of a system environment for an autonomous commercial truck vehicle according to some embodiments. Environment 100B includes a commercial truck 180B for hauling a cargo 182B. In some embodiments, the commercial truck 180B may include a vehicle configured for long-haul freight transportation, regional freight transportation, intermodal freight transportation (i.e., where a road-based vehicle is used as one of multiple modes of transportation to move cargo), and / or any other road-based freight transportation application. The commercial truck 180B may be a flatbed truck, a refrigerated truck (e.g., a freezer truck), a ventilated van (e.g., a dry van), a moving truck, etc. The cargo 182B may be merchandise and / or products. The commercial truck 180B may include a trailer for carrying the cargo 182B, such as a flatbed trailer, a lowboy trailer, a step deck trailer, a telescopic flatbed trailer, a side-hanging trailer, etc.

[0052] Environment 100B includes an object 111B (shown as another vehicle in Figure 1B ), which is within a distance range of equal to or less than 30 meters from the truck.

[0053] The commercial truck 180B may include a lidar system 184B (e.g., an FM lidar system, Figure 1A the vehicle control system 120 in Figure 2 the lidar system 201 in Figure 1B etc.), for determining the distance to the object 111B and / or measuring the speed of the object 111B. Although Figure 1B one lidar system 184B is shown mounted in front of the commercial truck 180B, the number of lidar systems and the mounting area of the lidar systems on the commercial truck are not limited to a specific number or a specific area. The commercial truck 180B may include any number of lidar systems 184B (or its components, such as sensors, modulators, coherent signal generators, etc.), which are mounted on any area (e.g., front, rear, side, top, bottom, underneath, and / or below) of the commercial truck 180B to facilitate the detection of objects in any free space relative to the commercial truck 180B.

[0054] As shown, the lidar system 184B in the environment 100B may be configured to detect objects (e.g., another vehicle, a bicycle, a tree, a street sign, a pothole, etc.) at a short distance (e.g., 30 meters or less) from the commercial truck 180B.

[0055] Figure 1C FIG. is a block diagram illustrating an example of a system environment for an autonomous commercial truck vehicle according to some embodiments. Environment 100C includes the same components (e.g., commercial truck 180B, cargo 182B, lidar system 184B, etc.) included in environment 100B.

[0056] Environment 100C includes object 111C (shown as another vehicle in Figure 1C ), which is within a distance range from commercial truck 180B that is (i) greater than 30 meters and (ii) equal to or less than 150 meters. As shown, the lidar system 184B in environment 100C can be configured to detect an object (e.g., another vehicle, bicycle, tree, street sign, pothole, etc.) at a distance (e.g., 100 meters) from commercial truck 180B.

[0057] Figure 1D is a block diagram illustrating an example of a system environment for an autonomous commercial truck vehicle according to some embodiments. Environment 100D includes the same components as included in environment 100B (e.g., commercial truck 180B, cargo 182B, lidar system 184B, etc.).

[0058] Environment 100D includes object 111D (shown as another vehicle in Figure 1D ), which is within a distance range from commercial truck 180B that is greater than 150 meters. As shown, the lidar system 184B in environment 100D can be configured to detect an object (e.g., another vehicle, bicycle, tree, street sign, pothole, etc.) at a distance (e.g., 300 meters) from commercial truck 180B.

[0059] In commercial truck applications, it is important to effectively detect objects at all ranges due to the increased weight and correspondingly longer stopping distances required for such vehicles. Due to the above advantages, FM lidar systems (e.g., FMCW and / or FMQW systems) or PM lidar systems are well-suited for commercial truck applications. Thus, a commercial truck equipped with such a system can have enhanced capabilities to safely move both people and cargo over short or long distances, thereby improving not only the safety of the commercial truck but also the safety of surrounding vehicles. In various embodiments, such an FM or PM lidar system can be used in the following: semi-autonomous applications, where the commercial truck has a driver and some functions of the commercial truck are autonomously operated using the FM or PM lidar system; or fully autonomous applications, where the commercial truck is operated entirely by the FM or lidar system alone or in combination with other vehicle systems.

[0060] In a lidar system using CW modulation, the modulator continuously modulates the laser. For example, if the modulation period is 10 seconds, the input signal is modulated throughout the 10 seconds. In contrast, in a lidar system using quasi-CW modulation, the modulator modulates the laser to have both an active portion and a non-active portion. For example, for a 10-second period, the modulator modulates the laser only for 8 seconds (sometimes referred to as the "active portion") but not for 2 seconds (sometimes referred to as the "non-active portion"). By doing so, the lidar system can reduce power consumption for that 2 seconds because the modulator does not have to provide a continuous signal.

[0061] In frequency-modulated continuous-wave (FMCW) lidar for automotive applications, it may be beneficial to operate the lidar system using quasi-CW modulation, where FMCW measurement and signal processing methods are used, but the optical signal is not on all the time (e.g., enabled, powered on, transmitting, etc.). In some embodiments, the quasi-CW modulation can have a duty cycle equal to or greater than 1% and up to 50%. If energy can be consumed during the off state (e.g., disabled, powered off, etc.) during the actual measurement time, then there can be an improvement in the signal-to-noise ratio (SNR) and / or a reduction in signal processing requirements to coherently integrate all the energy over a longer time scale.

[0062] Figure 2 is a block diagram showing an example environment of a lidar sensor system for an autonomous vehicle according to some embodiments. Environment 200 includes a lidar sensor system 201, and the lidar sensor system 201 includes a transmit (Tx) path and a receive (Rx) path. The Tx path includes one or more Tx input / output ports ( Figure 2 not shown in the figure), and the Rx path includes one or more Rx input / output ports ( Figure 2 not shown in the figure).

[0063] In some embodiments, the semiconductor substrate and / or semiconductor package can include the Tx path and the Rx. In some embodiments, the semiconductor substrate and / or semiconductor package can include at least one of a silicon photonics circuit, a programmable logic controller (PLC), or a III-V semiconductor circuit.

[0064] In some embodiments, the first semiconductor substrate and / or the first semiconductor package can include the Tx path, and the second semiconductor substrate and / or the second semiconductor package can include the Rx path. In some arrangements, the Rx input / output ports and / or the Tx input / output ports can occur (or be formed / set / located / placed) along one or more edges of one or more semiconductor substrates and / or semiconductor packages.

[0065] Environment 200 includes one or more transmitters 216 and one or more receivers 222 .

[0066] The environment 200 includes one or more optical devices 210 (e.g., an oscillating scanner, a one-way scanner, a Risley prism, a circulator optical device, and / or a beam collimator, etc.) coupled to the lidar system 201. In some embodiments, the one or more optical devices 210 can be coupled to the Tx path via one or more Tx input / output ports. In some embodiments, the one or more optical devices 210 can be coupled to the Rx path via one or more Rx input / output ports.

[0067] Environment 200 includes a vehicle control system 120 (eg, Figure 1A In some implementations, the vehicle control system 120 can be coupled to the Rx path via one or more Rx input / output ports.

[0068] The Tx path may include a laser source 202, a modulator 204A, a modulator 204B, an amplifier 206, and one or more transmitters 216. The Rx path may include one or more receivers 222, a mixer 208, a detector 212, a transimpedance amplifier (TIA) 214, and one or more analog-to-digital converters (ADCs). Figure 2 Only a selected number of components and only one input / output channel are shown; however, environment 200 may include any number of components and / or input / output channels (in any combination) interconnected in any arrangement to facilitate combining multiple functions of a lidar system to support operation of a vehicle.

[0069] The laser source 202 can be configured to generate an optical signal (or light beam) derived from (or associated with) a local oscillator (LO) signal. In some embodiments, the optical signal can have an operating wavelength equal to or substantially equal to 1550 nanometers. In some embodiments, the optical signal can have an operating wavelength between 1400 nanometers and 1440 nanometers.

[0070] The laser source 202 may be configured to provide an optical signal to a modulator 204A, which is configured to generate an optical signal based on a first radio frequency (RF) signal (in Figure 2shown as “RF1” in ) and modulates the phase and / or frequency of the optical signal using continuous wave (CW) modulation or quasi-CW modulation to generate a modulated optical signal. Modulator 204A may be configured to send the modulated optical signal to amplifier 206. Amplifier 206 may be configured to amplify the modulated optical signal to generate an amplified optical signal to optical device 210 via one or more transmitters 216. One or more transmitters 216 may include one or more optical waveguides or antennas.

[0071] Optical device 210 may be configured to direct the amplified optical signal it receives from the Tx path towards object 218 into the environment within a given field of view, may receive a return signal reflected back from object 218, and provide the return signal to mixer 208 in the Rx path via one or more receivers 222. One or more receivers 222 may include one or more optical waveguides or antennas. In some arrangements, transmitters 216 and receivers 222 may constitute one or more transceivers ( Figure 2 not shown in ). In some arrangements, one or more transceivers may include monostatic transceivers or bistatic transceivers.

[0072] Laser source 202 may be configured to provide an LO signal to modulator 204B, which is configured to modulate the phase and / or frequency of the LO signal based on a second RF signal (shown as “RF2” in Figure 2 ) and use continuous wave (CW) modulation or quasi-CW modulation to generate a modulated LO signal and send the modulated LO signal to mixer 208 in the Rx path.

[0073] Mixer 208 may be configured to mix (e.g., combine, multiply, etc.) the modulated LO signal with the return signal to generate a down-converted signal and send the down-converted signal to detector 212. In some arrangements, mixer 208 may be configured to send the modulated LO signal to detector 212.

[0074] Detector 212 may be configured to generate an electrical signal based on the down-converted signal and send the electrical signal to TIA 214. In some arrangements, detector 212 may be configured to generate an electrical signal based on the down-converted signal and the modulated signal.

[0075] TIA 214 may be configured to amplify the electrical signal and send the amplified electrical signal to vehicle control system 120 via one or more ADCs 220.

[0076] In some embodiments, the TIA 214 can have a peak noise equivalent power (NEP) of less than 5 pW / √Hz (i.e., 5 x 10-12 W / √Hz). In some embodiments, the TIA 214 can have a gain between 4 kΩ and 25 kΩ.

[0077] In some embodiments, the detector 212 and / or the TIA 214 can have a 3 dB bandwidth between 80 kHz and 450 MHz.

[0078] The vehicle control system 120 can be configured to determine the distance to the object 218 and / or measure the speed of the object 218 based on one or more electrical signals it receives from the TIA via one or more ADCs 220.

[0079] In some embodiments, the modulator 204A and / or the modulator 204B can have a bandwidth between 400 MHz and 1000 MHz.

[0080] In some embodiments, modulator 204A may be configured to send a first modulated optical signal and a second modulated optical signal to amplifier 206. Amplifier 206 may be configured to amplify the first modulated optical signal and the second modulated optical signal to generate an amplified optical signal via transmitter 216 to optics 210. Optics 210 may be configured to direct the first modulated optical signal and the second modulated optical signal it receives from the Tx path towards object 218 into an environment within a given field of view, may receive corresponding first return signal and second return signal reflected back from object 218, and provide the first return signal and the second return signal to mixer 208 of the Rx path via receiver 222. Modulator 204B may be configured to generate (1) a first modulated LO signal associated with the first modulated optical signal and (2) a second modulated LO signal associated with the second modulated optical signal, and send the first modulated LO signal and the second modulated LO signal to mixer 208 of the Rx path. Mixer 208 may be configured to pair (e.g., associate, link, identify, etc.) the first return optical signal with the first modulated LO signal, and mix (e.g., combine, multiply, etc.) the first return optical signal with the first modulated LO signal to generate a first down-converted signal, and send the first down-converted signal to detector 212. Similarly, mixer 208 may be configured to pair the second return optical signal with the second modulated LO signal, and mix the second return optical signal with the second modulated LO signal to generate a second down-converted signal, and send the second down-converted signal to detector 212. Detector 212 may be configured to generate a first electrical signal and a second electrical signal respectively based on the first and second down-converted signals. Vehicle control system 120 may be configured to determine the distance to object 218 and / or measure the speed of object 218 based on the first electrical signal and the second electrical signal received via TIA 214 and ADC 220.

[0081] According to some embodiments, a LIDAR system includes a seed laser, a modulator, an amplifier, and a transceiver chip. A modular LIDAR system allows the components to be discrete optical components and integrated circuit PICs optically coupled by microlenses. This provides higher yields of components, ease of configurability, assembly for different variations of each component, and variations in the PIC architecture. For example, the optical components may be arranged in an optical circuit in different ways to achieve different optical functions.

[0082] A seed laser is provided to generate a light beam. In some embodiments, the seed laser can be a light source, examples of which include but are not limited to distributed feedback (DFB) or distributed Bragg reflector (DBR) laser diodes or external cavity laser sources. The light or light beam from the seed laser can be optically coupled to be input into a modulator. In one example, the seed laser includes a DFB diode laser source and a microlens assembly that couples the DFB diode laser source to the modulator. The seed laser can be modular as it can be constructed as a single integrated circuit.

[0083] The modulator receives the light beam generated by the seed laser and generates a modulated optical signal. In some embodiments, the modulator includes a modulator and a beam splitter. In some embodiments, the modulator performs in-phase and quadrature modulation to generate a modulated light beam. In some embodiments, the modulator performs phase modulation to generate a modulated light beam. The beam splitter is coupled to the output of the modulator and provides the output of the modulator. In some embodiments, the beam splitter is a single beam splitter that is a passive component integrated with the modulator of the modulator. In some embodiments, the beam splitter is a plurality of beam splitters. The modulator is modular as it can be constructed as a single integrated circuit.

[0084] In some embodiments, the seed laser and the modulator can be integrated to form a seed laser assembly. In some embodiments, the seed laser assembly is mounted on a first sub-base, and the coupled transceiver chip is mounted on a second sub-base for aligning the heights of the seed laser assembly and the transceiver chip 302 to optimize the optical coupling between the seed laser assembly and the transceiver chip.

[0085] The optical amplifier is one or more semiconductor optical amplifiers (SOAs). In some embodiments, the optical amplifier is one or more tapered semiconductor optical amplifiers (TSOAs). In some embodiments, the optical amplifier is one or more SOA array chips. Each SOA array chip includes an integrated U-turn and other passive components for optical amplification. In some embodiments, the SOA array chip can be an integrated photonic device based on III-V semiconductors, where all its components are made of III-V materials and are fabricated / monolithically integrated on a single substrate made of III-V materials. Further, in some embodiments, each SOA array chip can include one or more channels, for example specifically 4 or 5, and is configured to amplify a light beam by stimulated emission. The amplifier can be optically coupled to the modulator through a microlens. Similarly, the amplifier is optically coupled to provide an amplified signal to the transceiver chip through a microlens.

[0086] In some embodiments, a silicon photonics (SiPho) transceiver chip includes at least one of a silicon photonics circuit, a programmable logic controller (PLC), or a III-V semiconductor circuit. The SiPho transceiver chip uses an amplifier to process the coupled light. The SiPho transceiver chip includes a plurality of coherent pixels that process the output of the optical amplifier and emit light from the surface of the SiPho transceiver chip, which includes via an optical window of an integrated chip package. The SiPho transceiver chip processes light collected from reflections from a target and couples the detected photocurrent to a transimpedance amplifier. The transimpedance amplifier converts the photocurrent into a voltage, which is then coupled out of the integrated chip package.

[0087] Now refer to Figure 3 , an example of a horizontal integration 300 of a photonic integrated circuit (PIC) 308 of a LIDAR transceiver system for an autonomous vehicle according to some embodiments. Figure 3 A cross-section of the PIC 308 mounted to the SiPho carrier or chip 302 is shown. The example of the horizontal integration 300 couples the SiPho carrier or chip 302 with the PIC 308. As Figure 3 shown, the SiPho carrier 302 defines one or more bases to which the PIC 308 is coupled. The PIC 308 is coupled to these bases of the SiPho carrier 302 through connectors 306. Due to the optical mode of the PIC 308, the structural alignment of the PIC 308 with the SiPho carrier 302 provides robust alignment. For example, the optical mode may have dimensions that typically can range from ~1.0um to ~3.0 - 10.0um. On the same side as the base (the top side in Figure 3 ), the SiPho carrier 302 has a metal layer 304 that provides heat dissipation and backside metal patterning to assist in pick-and-place. A portion of the SiPho carrier 302 is also coupled through layer 310. Similarly, one side of the PIC 308 is covered with a metal layer 304 for heat dissipation and backside metal patterning to assist in pick-and-place. In some embodiments, the PIC 308 may include a second metal layer (not shown) on the side opposite the metal 306 to increase heat dissipation.

[0088] Now refer to Figures 4A to 4C , various embodiments of example PICs 308a, 308b, and 308c will be described. The PIC 308 is advantageous because it includes monolithically integrated passive and active optical components. Figures 4A to 4CShows a high-level plan view of an example implementation of a semiconductor optical amplifier for a LIDAR sensor system for autonomous vehicles. In some implementations, PIC 308 includes a monolithic integrated spot converter that optically couples a photonic integrated circuit to a connector with low-loss hybrid integration. In some implementations, PIC 308 includes one or more passive components monolithically integrated with the optical amplifier as part of PIC 308. For example, one or more of the passive components are one or more from a combination of U-turns, total internal reflectors, mirrors, couplers, and beam splitters. As will be described in more detail below with reference to Figures 4A to 4C PIC 308 monolithically integrates an array of two or more optical amplifiers, U-turns, and passive components such that the photonic integrated circuit can optionally be optically coupled from a single side. These and other features will become apparent from the following Figures 4A to 4C description. Additionally, specific features of different implementations of example PICs 308a, 308b, and 308c can be combined in other ways in addition to those specifically set forth in Figures 4A to 4C .

[0089] Figure 4A Shows an implementation of a first example PIC 308a. In this implementation, PIC 308a includes a plurality of power SOAs 402a - 402d, a plurality of U-turns 404a - 404d, and a plurality of passive connectors 406a - 406d. While Figure 4A shows four SOAs 402a - 402d, four U-turns 404a - 404d, and four passive connectors 406a - 406d, it should be understood that any number of SOAs, U-turns, and connectors can be monolithically integrated into PIC 308a, and only four amplifiers are used as an example. Figure 4A Also illustrated is how the plurality of SOAs 402a - 402d and the plurality of passive connectors 406a - 406d receive and transmit optical signals respectively from a single side of PIC 308a. This is particularly advantageous for the horizontal integration of PIC 308 with other components as it allows for easy optical alignment of the four SOAs 402a - 402d. Figure 4A Also illustrated is that the SOAs 402a - 402d have straight faces. It should be understood that an anti-reflection coating can be used to achieve 20 dB or less of back reflection into a straight waveguide. It should be understood that Figure 4A the symmetric waveguide layout shown for SOAs 402a - 402d provides uniformity of power in the amplifier array due to a uniform thermal / temperature distribution and uniform coupling efficiency in the case of bending. In one example, PIC 308a and its components can have values approximating those in Table 1.

[0090]

[0091] Table 1

[0092] Figure 4A The PIC 308a also shows the arrangement of SOAs 402a - 402d, U-turns 404a - 404d, and passive connectors 406a - 406d, where the SOAs 402a - 402d are near the middle of the PIC 308, and two of the U-turns 404a and 404b are coupled to connectors 406a and 406b on one side of the array of SOAs 402a - 402d; and the other two U-turns 404c and 404d are coupled to connectors 406c and 406d on the other side of the array of SOAs 402a - 402d. In some embodiments, the input optical power of each SOA 402a - 402d is about 50 mW, and the output power of each SOA 402a - 402d is about 550 mW.

[0093] Figure 4B An embodiment of a second exemplary PIC 308b is shown. Again, this second exemplary PIC 308b includes multiple SOAs 402a - 402d, multiple U-turns 404a - 404d, and multiple passive connectors 406a - 406d. The number of SOAs 402a - 402d is four, with a corresponding number of U-turns 404a - 404d and passive connectors 406a - 406d. However, alternative embodiments of the PIC 308b can have any number of SOAs 402, U-turns 404, and passive connectors 406. The exemplary PIC 308b and its components can also have values approximating those described above in Table 1. Figure 4B shows the difference in the layout from Figure 4A the layout of. More specifically, the SOAs 402a - 402d are positioned on one side of the PIC 308b, and the passive connectors 406a - 406d extend parallel to and on one side of the SOAs 402a - 402d. The U-turns 404 couple the corresponding SOAs 402 and passive connectors 406. The U-turn 404a is longer than the other U-turns 404b - 404d, and the length of each of the U-turns 404b - 404d is slightly reduced compared to the other. Figure 4B illustrates another configuration for integration (e.g., monolithic integration), where both the input and output are provided on one side (e.g., Figure 4B the top in Figure 4B ), of the PIC 308b, where the inputs are grouped towards the first end (e.g., Figure 4B the left side inFigure 4A In an embodiment, the input optical power for each of the SOAs 402a - 402d is about 50 mW, and the output power for each of the SOAs 402a - 402d is about 550 mW.

[0094] Figure 4C An embodiment of a third example PIC 308c is shown. In this embodiment, PIC 308c includes a plurality of power SOAs 402a - 402d, a plurality of U - turns 404a - 404d, a gain amplifier 408, and a beam splitter 410. Although Figure 4C four power SOAs 402a - 402d and four U - turns 404a - 404d are shown, it should be understood that any number of power SOAs and U - turns can be monolithically integrated into PIC 308c, and four power SOAs are used only as an example. Similarly, although only a single gain amplifier 408 and a single beam splitter 410 are shown in Figure 4C , in other embodiments, various combinations of the gain amplifier 408 and the beam splitter 410 can be monolithically integrated into PIC 308c. As illustrated, the input signal is input to the gain amplifier 408. In some embodiments, the gain amplifier 408 is an SOA that provides a gain of approximately 10 dB, and the input to the SOA is 50 mW. In some embodiments, there can be multiple gain amplifiers 408. The output of the gain amplifier 408 is input to the beam splitter 410. In this example, the beam splitter 410 is a 1 - to - 4 beam splitter. It should be understood that the beam splitter 410 or multiple beam splitters have a plurality of outputs corresponding to the number of power SOAs 402a - 402d integrated into PIC 308c. For example, in various configurations, the beam splitter 410 can be 1 - to - 2, 1 - to - 4, 1 - to - 8, 1 - to - 16, etc., where the number of outputs from one or more beam splitters matches the number of inputs to the power amplifier 402. In some embodiments, the gain amplifier 408 outputs a signal having about 27 dBm. This signal is split by the beam splitter 410 into four signals having about 19 dBm each. Each signal is input to a corresponding power SOA 402a - 402d via a corresponding U - turn 404a - 404d. The losses on the beam splitter 410 and the U - turns 404a - 404d can be about 8 dB. Each power SOA 402a - 402d amplifies the signal it receives and outputs a signal of 550 mW. For example, each power SOA 402a - 402d can provide a gain of about 8 dB. This results in PIC 308c being able to output four amplified signals each having about 550 mW (+27 dB). Figure 4CThe embodiment shown is particularly advantageous because the PIC 308c provides particularly high gain and / or particularly high power amplification. For example, typical optical gain or amplification can be in the range of +2 to +25 dB. From Figure 4C As can be seen from the plan view of Figure 4A and 4B In contrast to the vertical configuration of

[0095] Figure 5A FIG. shows a cross-sectional view of an exemplary embodiment of the SOA 402 of a LIDAR sensor system for an autonomous vehicle. The SOA 402 includes the following layers from Figure 5A the bottom to the top, including a silicon or sulfur doped layer 502, an n-doped layer 504, a guiding layer 506, a spacer layer 508, a first confinement layer 510, an active layer 512, a second confinement layer 514, a current spreading layer 516, a ridge layer 518, and a metal layer 520. In some embodiments, one or more metal layers (not shown) may be coupled to the n-doped layer 502a in a direction opposite to the n-type layer 504a. For example, a metal layer is formed, then a silicon doped layer 502a is formed on the metal layer, and an N-doped layer is formed on the silicon doped layer 502a. In other embodiments, a metal layer may not be formed under the silicon doped layer 502a. Referring to Figure 5B , one or more metal layers may be coupled to the layer 502b in a direction opposite to the layer 504b. For example, a metal layer is formed, an n+-InP layer 502b is formed on the metal layer, and an n-doped indium phosphide layer 504b is formed on the layer 502b. In other embodiments, a metal layer may not be formed under the layer 502b. It should be noted that the above is for Figure 5A and the following is for Figure 5B and Figure 6The described configuration is particularly advantageous because the backside (bottom of the chip) metallization can be applied even when current does not flow to the bottom. The backside metallization is also used to assist in soldering (also known as die attach) to the carrier / submount and to improve thermal conductivity. In many embodiments, current can flow to the bottom of the chip, in which case the backside metallization also aids in electrical connection to the carrier / submount. Thus, the present disclosure includes embodiments with and without backside (bottom) metallization. In the absence of backside metallization, current then flows to the top of the chip, where other (additional) metal layers (not shown) are present to complete the circuit.

[0096] In some embodiments, the silicon-doped layer 502a can be an n+-InP layer, e.g., such as Figure 5B and Figure 6 specifically shown silicon- or sulfur-doped indium phosphide. In some embodiments, other types of n-doped layers can be used.

[0097] The n-doped layer 504a is formed on the silicon-doped layer 502a. In some embodiments, the n-doped layer 504a is an n-doped indium phosphide layer.

[0098] The guiding layer 506a is formed on the n-doped layer 504a. In some embodiments, the guiding layer 506a has a specific structure configured for heat dissipation. In some embodiments, the specific structure configured for heat dissipation includes an alternating or periodic or superlattice structure. For example, the guiding layer 506a can be an alternating indium phosphide (InP) and ternary or quaternary layer 506b for high wall plug efficiency for heat dissipation. This is particularly advantageous for improving heat dissipation. In some embodiments, the thickness of the guiding layer 506a can be in the range of 300 - 500 nm. In some embodiments, the guiding layer 506a can be indium gallium arsenide phosphide (InGaAsP) or indium gallium aluminum arsenide (InGaAlAs) or other quaternary or ternary alloys or other types of III-V semiconductor materials. The guiding layer 506a can provide a large optical mode size for integration with a silicon photonic waveguide.

[0099] The spacer layer 508a is formed on the guiding layer 506a. In some embodiments, the spacer layer 508a is an n-type indium phosphide spacer. In some embodiments, the spacer layer 508a can have a thickness ranging from 100 - 150 nm.

[0100] In some embodiments, the first confinement layer 510a and the second confinement layer 514a are separate separate confinement heterostructures (SCHs). In some embodiments, the first confinement layer 510a and the second confinement layer 514a may have a thickness ranging from 20 nm to ~100 nm, e.g., about 25 nm. In some embodiments, the first confinement layer 510a and the second confinement layer 514a are part of the active layer 512 slab.

[0101] The active layer 512a is formed on the first confinement layer 510a and is located between the second confinement layers 514b. In some embodiments, the active layer 512a is offset to generate power greater than 50 mW, e.g., in the range of 50 mW to 800 mW. In some embodiments, the active layer 512a is an offset quantum mechanical structure. More specifically, the active layer 512a may be an offset multiple quantum well (MQW) or an offset quantum dot. For example, the active layer 512a may have 2 to 8 wells. In some embodiments, the active layer 512 may have 2 - 4 MQW structures with a lower confinement factor for the optical mode, where the active MQW is on the order of a few percent, e.g., ~1 - 2%.

[0102] The current spreading layer 516a is formed on the second confinement layer 514a. In some embodiments, the current spreading layer 516a is a p-doped indium phosphide layer 516b.

[0103] The ridge layer 518a is formed on the current spreading layer 516a. In some embodiments, the ridge layer 518a forms a waveguide. In some embodiments, the ridge layer 518a is formed of p-doped indium phosphide 518b. For example, as Figure 5A shown, a metal layer 520a is formed over the top and sides of the ridge layer 518a. In this example, one or more insulating regions 517a, 517b may be formed to cover certain portions (e.g., the sides) of the ridge layer 518a and certain portions (e.g., the top) of the current spreading layer 516a such that only a certain portion (e.g., the top) of the ridge layer 518a is coupled to the metal layer 520a.

[0104] Figure 5B An embodiment of the SOA 402 for a LIDAR sensor system for an autonomous vehicle similar to Figure 5A is shown, but example specific materials for each layer 502a - 520a as described above for each layer 502b - 520b have been provided, as shown. For example, the ridge layer 518a is formed of p-doped indium phosphide 518b. A metal layer 520b is formed over the top and sides of the P-InP ridge layer 518b, as Figure 5BDepicted in. In this example, one or more insulating regions 517a, 517b may be formed to cover certain portions (e.g., sides) of the ridge layer 518b and certain portions (e.g., tops) of the current spreading p-InP layer 516b such that only a certain portion (e.g., the top) of the ridge layer 518b is coupled to the metal layer 520b.

[0105] Although the SOA 402 has been described above with specific materials, it should be understood that the SOA 402 may be composed of other materials, including but not limited to indium phosphide (InP), gallium arsenide (GaAs), indium arsenide (InAs), gallium and nitrides (GaN), or indium antimonide (InSb).

[0106] Now referring to Figure 6 , an example embodiment of a PIC including an SOA array 600 for a LIDAR sensor system for an autonomous vehicle is described. The SOA array 600 includes a first SOA 402a and a second SOA 402b. Provided Figure 6 to illustrate how the same structures and processes described above with reference to Figure 5A and 5B can form the SOA array 600. Also provided Figure 6 to illustrate how the SOA 402a, 402b can have the same layers, different layers, additional layers, or fewer layers as the embodiments described above with reference to Figure 5A and Figure 5B . Additionally, provided Figure 6 to illustrate how a portion of the PIC can include alignment fiducials 604 and recess coatings for hybrid integration to further simplify the integration process. As Figure 6 shown, the first SOA 402a is formed by layers 502b to 518b and layer 602; and the second SOA 402b is formed by layers 502b to 518b and layer 602. In this embodiment, the first SOA 402a and the second SOA 402b share an n-doped layer, an n + -InP 502b. The n + -InP layer 502b forms the bottom of both the first SOA 402a and the second SOA 402b and defines a pair of trenches 606a and 606b, each trench being adjacent to the first SOA 402a and the second SOA 402b, respectively. The n between the pair of trenches 606a and 606b +-A portion of the -InP layer 502b defines a pedestal 608. The Q1.3 layer 602 is formed on one side of the pedestal 608. The Q1.3 layer 602 is a recess cladding layer in which alignment fiducials 604 can be etched. In some embodiments, the alignment fiducials are created by using the Q1.3 layer 602 as an etch stop layer to define a recess cladding for vertical alignment of the optical modes for hybrid integration. This is particularly advantageous because these alignment fiducials provide for easy horizontal integration of the SOA array 600 with other photonic components of the LIDAR sensor system. As described above, the first SOA 402a and the second SOA 402b in this embodiment differ in that each of the first SOA 402a and the second SOA 402b further includes an n-doped layer, n + -The Q1.3 layer 602 above a portion of the -InP 502b near its bottom or base. The Q1.3 layer 602 is positioned between the n + -InP layer 502b and the n-type layer, the n-InP layer 504b.

[0107] Similar to Figure 5A and Figure 5B , in Figure 6 , one or more metal layers can be formed below the layer 502b. Additionally, similar to Figure 5A and 5B , in Figure 6 , insulating regions can be formed to cover certain portions of the P-InP ridge layer 518b and the current spreading layer 516b of the first SOA 402a and the second SOA 402b, but expose certain portions of the P-InP layer 518b. Additionally, similar to Figure 5A and 5B the metal layers 520a, 520b in, one or more metal layers can be formed to cover the P-InP ridge layer 518b, the insulating regions, and the current spreading layer 516b such that the metal layers can be coupled to only certain portions (e.g., the top) of the P-InP ridge layer 518b.

[0108] The foregoing detailed description of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. The described embodiments were chosen in order to best explain the principles of the disclosure and its practical application, thereby enabling others skilled in the art to best utilize the disclosure in various embodiments and with various modifications suited to the particular use contemplated. The scope of the disclosure is intended to be defined by the appended claims.

[0109] Although some embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the present disclosure as defined by the appended claims. For example, those skilled in the art will readily understand that many of the features, functions, processes, and materials described herein can vary while remaining within the scope of the present disclosure. Additionally, the scope of the present disclosure is not intended to be limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, devices, methods, and steps described in the specification. As will be readily understood by those of ordinary skill in the art from the description of the present disclosure, processes, machines, manufactures, compositions of matter, devices, methods, or steps that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized according to the present disclosure, using currently existing or later developed ones. Accordingly, the appended claims are intended to cover such processes, machines, manufactures, compositions of matter, means, methods, or steps within their scope.

Claims

1. A light detection and ranging (LIDAR) sensor system for a vehicle, comprising: A laser configured to output a light beam; A modulator configured to receive the light beam from the laser and modulate the light beam to generate a modulated light beam; A photonic integrated circuit having an optical amplifier coupled to receive the modulated light beam from the modulator and generate an amplified light beam, wherein the optical amplifier includes (i) an active layer, and (ii) a specific structure configured to dissipate heat; And A transceiver chip coupled to the photonic integrated circuit, the transceiver chip being configured to emit the amplified light beam and receive a reflected light beam from a target.

2. The LIDAR sensor system according to claim 1, wherein The active layer is an offset bulk quantum mechanics structure or a multi-quantum mechanics structure.

3. The LIDAR sensor system according to claim 2, wherein, The offset bulk quantum mechanics structure is one from the group of offset multiple quantum wells or offset quantum dot layers.

4. The LIDAR sensor system according to claim 1, wherein, The photonic integrated circuit includes a first heat dissipation structure for reducing heat from the upper side of the photonic integrated circuit and a second heat dissipation structure for reducing heat from the upper side of the photonic integrated circuit.

5. The LIDAR sensor system according to claim 1, wherein, The specific structure includes one or more alternating indium phosphide (InP) layers.

6. The LIDAR sensor system according to claim 1, wherein, The specific structure includes an alternating or periodic or superlattice structure including one or more alternating indium phosphide and indium gallium arsenide phosphide (InGaAsP) or indium gallium aluminum arsenide (InGaAlAs) or other quaternary or ternary alloy layers to improve heat dissipation, thereby resulting in a high wall-plug efficiency.

7. The LIDAR sensor system according to claim 1, wherein, The specific structure is integrated with a silicon photonic waveguide and has an optical mode converter.

8. The LIDAR sensor system according to claim 1, wherein, The photonic integrated circuit includes a monolithically integrated spot size converter, wherein the photonic integrated circuit is optically coupled to an optical waveguide connector.

9. The LIDAR sensor system according to claim 1, wherein, The photonic integrated circuit includes one or more passive components monolithically integrated with the optical amplifier.

10. The LIDAR sensor system according to claim 9, wherein, The one or more passive components include a semiconductor optical amplifier (SOA) coupled to a coupler by a U-turn and monolithically integrated to provide an input on the same side of the photonic integrated circuit.

11. The LIDAR sensor system according to claim 1, wherein, The specific structure includes an alternating or periodic or superlattice structure.

12. The LIDAR sensor system according to claim 1, wherein, The photonic integrated circuit includes and monolithically integrates a second amplifier that provides a specific gain, and an output of the second amplifier is coupled to an input of the optical amplifier.

13. A photonic integrated circuit, comprising: A first amplifier coupled to receive an input light beam and generate an amplified light beam, the first amplifier having an active layer and a specific structure configured to improve heat dissipation; And One or more passive components monolithically integrated with the first amplifier as part of the photonic integrated circuit.

14. The photonic integrated circuit according to claim 13, wherein, The active layer is an offset bulk or multiple quantum well structure.

15. The photonic integrated circuit according to claim 14, wherein, The offset bulk or multiple quantum well structure is one from the group of offset bulk quantum wells, multiple quantum wells, or offset quantum dot layers.

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