Optical detection and ranging system including a high power amplifier

Abstract

The LIDAR system includes an optical integrated circuit including a laser configured to output a beam, a modulator configured to receive the beam and modulate the beam to produce a modulated beam, an amplifier configured to receive the modulated beam from the modulator and produce an amplified beam, the amplifier having an active layer configured to dissipate heat and an alternating lattice or periodic lattice or superlattice structure, and a transceiver chip coupled to the optical integrated circuit and configured to emit the amplified beam and receive the beam reflected from the target.

Description

[Technical Field]

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

[0002] LIDAR sensor systems are used for a variety of applications, ranging from altitude measurement to imaging to collision avoidance. LIDAR sensor systems can be designed and implemented using one or more photonic integrated circuits (PICs), or integrated optical circuits, which are chips that contain photonic components. In the past, there have been attempts to combine more of the photonic components and optical functions of a LIDAR system into a single PIC. Summary of the Invention

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

[0004] According to one aspect of the subject matter described in this disclosure, a LIDAR system includes an optical integrated circuit having a laser configured to output a beam, a modulator coupled to receive the beam output from the seed laser and modulate the beam to produce a modulated beam, an optical amplifier coupled to receive the modulated beam from the modulator and produce an amplified beam, the amplifier having an active layer for amplification and a specific structure configured to dissipate heat, and a transceiver chip coupled to the optical integrated circuit and configured to emit the amplified beam and receive the beam reflected from a target.

[0005] According to another aspect of the subject matter described in this disclosure, an optical integrated circuit includes a first optical amplifier coupled to receive an input beam and generate an amplified beam, 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 optical integrated circuit.

[0006] These and other embodiments may each optionally include one or more of the following features. For example, the feature may include the active layer being an offset bulk or multiple quantum well structure, e.g., the offset bulk or multiple quantum well structure being one of the group consisting of an offset quantum well or an offset quantum dot layer. For example, the feature may also include the optical integrated circuit including a first heat dissipation structure that reduces heat from below the optical integrated circuit and a second heat dissipation structure that reduces heat from above the optical integrated circuit. In other examples, the feature may include the feature that the particular structure includes one or more alternating indium phosphide (InP) layers, or the particular structure includes an alternating, 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 with improved heat dissipation and high wall-plug efficiency. In one example, the particular structure is integrated with a silicon photonics waveguide and has an optical mode size. In other features, the optical integrated circuit includes a monolithically integrated spot-size converter, where the optical integrated circuit is optically coupled to an optical waveguide, e.g., an optical fiber connector. In some features, the optical integrated circuit includes one or more passive components monolithically integrated with the optical amplifier, or the one or more passive components include a semiconductor optical amplifier (SOA) coupled in a U-turn to a monolithically integrated coupler to provide optical input and output to the same side of the optical integrated circuit. For example, the particular SOA includes an alternating, periodic, or superlattice structure with improved heat dissipation and high wall-plug efficiency. For example, features may include a feature in which the optical integrated circuit includes and monolithically integrates a second optical amplifier providing a specific gain, the output of the second amplifier being coupled to the input of the first amplifier.

[0007] Those skilled in the art will appreciate that this summary is illustrative only and is not intended to be limiting in any way. Any of the features described herein may be used with other features, and any subset of such features may be used in combination, according to various embodiments. Other aspects, inventive features, and advantages of the apparatus and / or processes described herein, as defined solely by the claims, will become apparent from the detailed description disclosed herein in conjunction with the accompanying drawings. Additionally, the language used in this disclosure has been chosen primarily for readability and descriptive purposes, and not to limit the scope of the subject matter disclosed herein. [Brief explanation of the drawings]

[0008] Some embodiments in the accompanying drawings are provided by way of example, and not by way of limitation, and like reference numerals refer to similar elements.

[0009] [Figure 1a] 1 is a block diagram illustrating an example of an autonomous vehicle system environment in accordance with some embodiments.

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

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

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

[0013] [Figure 2] FIG. 1 is a block diagram illustrating an example of a LIDAR sensor system for an autonomous vehicle, according to some embodiments.

[0014] [Figure 3] 1 is a cross-sectional view of a high-level block diagram illustrating an example of horizontal integration of semiconductor optical amplifiers for LIDAR systems for autonomous vehicles in accordance with some embodiments.

[0015] [Figure 4a] Or [Figure 4c] FIG. 1 is a high-level plan view of an exemplary embodiment of a semiconductor optical amplifier integrated with U-turns and other passive components to provide optical input and output on the same side of an optical integrated circuit for a LIDAR system for an autonomous vehicle.

[0016] [Figure 5a] and [Figure 5b] 1 is a cross-sectional view of an embodiment of a portion of a semiconductor optical amplifier (SOA) for a LIDAR system for an autonomous vehicle.

[0017] [Figure 6] FIG. 1 is a cross-sectional view of a second exemplary embodiment of a semiconductor optical amplifier (SOA) for a LIDAR system for an autonomous vehicle.

[0018] It should be understood that alternative embodiments of the structures and methods illustrated herein may be used without departing from the principles described herein. DETAILED DESCRIPTION OF THE INVENTION

[0019] According to certain aspects, a LIDAR system includes a laser configured to output a beam, a modulator configured to receive the beam from the laser and modulate the beam to produce a modulated beam, an optical integrated circuit having an optical amplifier coupled to receive the modulated beam from the modulator and produce an amplified beam, the optical amplifier including an active layer and an alternating, periodic, or superlattice structure for improved heat dissipation, and a transceiver chip coupled to the optical integrated circuit and configured to emit the amplified beam and receive a beam reflected from a target. The LIDAR system is advantageous because it includes an optical integrated circuit configured for easy horizontal integration with other components of the LIDAR system. In some embodiments, the optical integrated circuit includes a first amplifier coupled to receive an input beam and produce an amplified beam, the first amplifier having an active layer for high output power and an alternating, periodic, or superlattice structure for improved heat dissipation, and one or more passive components monolithically integrated with the first amplifier as part of the optical integrated circuit. Because optical integrated circuits can include passive components, including multiple optical amplifiers and U-turns, they provide both high output power and high gain, and provide high wall-plug efficiency through improved heat dissipation. Such optical integrated circuits enable LIDAR systems to overcome the aforementioned drawbacks of the prior art by providing high optical power, high gain, and high wall-plug efficiency. Optical integrated circuits also include inputs and outputs along one side or facet of the chip for easy optical coupling.

[0020] In the following description, for purposes of explanation, numerous specific details are presented in order to provide a thorough understanding of the various aspects of various exemplary embodiments. It should be noted that certain exemplary embodiments may be practiced in various cases without all of the specific details and / or by variations, substitutions, 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 numbers are used in the drawings and the description to refer to the same or like parts.

[0021] Additionally, relative terms such as "bottom" or "lower" or "back" or "below" and "top" or "upper" or "front" or "top" may be used herein to describe the relationship of one element to other elements, as depicted in the figures. It will be understood that the relative terms are intended to include other orientations of the device in addition to the orientation depicted in the figures. For example, if a device in one of the figures were turned over, an element described as being "below" the other elements would then be "above" the other elements. Thus, the exemplary term "lower" can encompass both an orientation of "lower" and "upper," depending on the particular orientation of the figure. Similarly, if a device in one of the figures were turned over, an element described as being "below" or "bottom" the other elements would then be "above" the other elements. Thus, the exemplary terms "lower" or "lower" can encompass both an orientation of up and down.

[0022] Referring to the drawings, in which like numbers indicate like parts in some figures, FIG. 1a illustrates one embodiment of a system environment 100A for an autonomous vehicle 111A in which various techniques disclosed herein may be implemented. For example, the vehicle 111A may include a powertrain 102 including a prime mover 104 driven by an energy source 106 and capable of powering a drivetrain 108, and a control system 110 including a direction control 112, a powertrain control 114, and a brake control 116. It should be appreciated that the vehicle 111A may be implemented as any number of different types of vehicles, including vehicles capable of transporting people and / or cargo and traveling on land, and that the components 102-116 described above may vary significantly 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, and buses. In such embodiments, the prime mover 104 may include (among other things) one or more electric motors and / or an internal combustion engine. 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 may include wheels and / or tires along with a transmission and / or any other mechanical drive components suitable for converting the power output of the prime mover 104 into vehicle motion, one or more brakes configured to controllably stop or slow the vehicle 111A, and a steering or steering component suitable for controlling the trajectory of the vehicle 111A (e.g., a rack and pinion steering linkage allowing the wheels to pivot about a generally vertical axis to change the angle of the plane of rotation of the wheels relative to the vehicle's longitudinal axis). In some embodiments, a combination of powertrain and energy source can be used (e.g., in the case of electric / gas hybrid vehicles), and in other embodiments, multiple electric motors (e.g., dedicated to individual wheels or axles) can be used as prime mover 104. In the case of a hydrogen fuel cell implementation, prime mover 104 can include one or more electric motors, and energy source 106 can include a fuel cell system powered by hydrogen fuel.

[0024] Directional control 112 may include one or more actuators and / or sensors for controlling and receiving feedback from directional or steering components to enable vehicle 111A to follow a desired trajectory. Powertrain controls 114 may be configured to control the speed and / or direction of vehicle 111A by controlling the output of powertrain 102, such as by controlling the output power of prime mover 104 and controlling the gears of a transmission in drivetrain 108. Brake controls 116 may be configured to control one or more brakes (e.g., disc or drum brakes coupled to the wheels of the vehicle) to slow or stop vehicle 111A.

[0025] Other vehicle types, including, but not limited to, all-terrain or tracked vehicles, construction equipment, and the like, may utilize different powertrains, drivetrains, energy sources, directional controls, powertrain controls, and brake controls. Also, in some embodiments, some of the components may be combined, for example, where vehicle directional control is primarily handled by varying the power output of one or more prime movers. Accordingly, the embodiments described herein are not limited to the specific application of the technology described herein in autonomous wheeled land vehicles.

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

[0027] The sensors 130 may include various sensors suitable for collecting information from the vehicle's surrounding environment for use in controlling the operation of the vehicle 111A. For example, the sensors 130 may include one or more detection and ranging sensors (e.g., a RADAR sensor 134 and / or a LIDAR sensor 136), a 3D positioning sensor 138, and a satellite navigation system such as the Global Positioning System (GPS), Globalnaya Navigazionnaya Sputnikovaya Sistema (GLONASS), or Global Navigation Satellite System (GLONASS), the BeiDou Navigation Satellite System (BDS), Galileo, or Compass. The 3D positioning sensor 138 can be used to determine the vehicle's position on Earth using satellite signals. The sensors 130 may optionally include a camera 140 and / or an inertial measurement device (IMU) 142. The camera 140 may be a monographic or stereographic camera and may record still and / or video images. The IMU 142 may include multiple gyroscopes and accelerometers capable of detecting linear and rotational motion of the vehicle 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 the vehicle 111A. In some embodiments, the LIDAR sensor 136 may include a silicon photonics device structure for a coherent LIDAR system, as described in more detail below.

[0028] The outputs of the sensors 130 may be provided to a set of control subsystems 150, including a position estimation subsystem 152, a perception subsystem 154, a planning subsystem 156, and a control subsystem 158. The position estimation subsystem 152 may primarily perform functions such as precisely determining the position and orientation (also sometimes referred to as “pose” or “pose estimation”) of the vehicle 111A within the surrounding environment and generally within some reference frame. The perception subsystem 154 may primarily perform functions such as detecting, tracking, and / or identifying objects within the vehicle 111A's environment. Machine learning models, according to some embodiments, may be utilized to track the objects. The planning subsystem 156 may primarily perform functions such as planning a movement trajectory or path for the vehicle 111A over some time frame given a desired destination as well as static and moving objects within the environment. Machine learning models, according to some embodiments, may be utilized to plan the vehicle trajectory. The control subsystem 158 may primarily perform functions such as generating appropriate control signals to control various controls within the vehicle control system 120 to implement the planned trajectory of the vehicle 111A. Similarly, a machine learning model can be utilized to generate one or more signals for controlling the autonomous vehicle 111A to implement a planned trajectory.

[0029] It will be understood that the collection of components for vehicle control system 120 shown in FIG. 1a is merely an example. In some embodiments, individual sensors may be omitted. Additionally or alternatively, in some embodiments, multiple sensors of the same type shown in FIG. 1a may be used for redundancy and / or to cover different areas around the vehicle. Also, other types of additional sensors may be present beyond those described above to provide actual sensor data related to the operation and environment of the wheeled land vehicle. Similarly, different types and / or combinations of control subsystems may be used in other implementations. Also, while subsystems 152-158 are shown as separate from processor 122 and memory 124, it should be understood that in some embodiments, some or all of the functionality of subsystems 152-158 may be implemented as program code instructions 126 resident in one or more memories 124 and executed by one or more processors 122, and that these subsystems 152-158 may, in some cases, be implemented using the same processor and / or memory. The subsystems may be implemented, at least in part, using various dedicated circuit logic, various processors, various field programmable gate arrays (“FPGAs”), various application specific integrated circuits (“ASICs”), various real-time controllers, etc., and as previously mentioned, multiple subsystems may utilize circuits, processors, sensors, and / or other components. Additionally, the various components of vehicle control system 120 may be networked in various ways.

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

[0031] In general, the various components shown in FIG. 1a can be implemented using many different architectures, including various combinations of software, hardware, circuit logic, sensors, and networks. Each processor can be implemented, for example, as a microprocessor, and each memory can include not only random access memory (RAM) devices constituting main storage, but also any secondary levels of memory, such as cache memory, non-volatile or backup memory (e.g., programmable or flash memory), read-only memory, etc. Each memory can also be considered to include memory storage devices physically located elsewhere in the vehicle 111A, such as any cache memory within the processor, as well as any storage capacity used as virtual memory, such as stored in a mass storage device or other computer controller. One or more of the processors 122 shown in FIG. 1a, or entirely separate processors, can be used to implement additional functions within the vehicle 111A other than those for autonomous control, such as controlling the entertainment system, operating doors, lighting, convenience functions, etc.

[0032] Also, for additional storage devices, vehicle 111A may include one or more mass storage devices, such as, among others, a removable disk drive, a hard disk drive, a direct access storage device (DASD), an optical drive (e.g., a CD drive, a DVD drive, etc.), a solid state storage drive (SSD), network attached storage, a storage area network, and / or a tape drive.

[0033] Vehicle 100 may also include a user interface 118, such as one or more displays, touchscreens, voice and / or gesture interfaces, buttons and other tactile controls, etc., that enables vehicle 111A to receive a number of inputs from and generate outputs for a user or operator. Alternatively, user input may be received through another computer or electronic device, such as an app or web interface on a mobile device.

[0034] Vehicle 111A may also include one or more network interfaces, such as network interface 162, suitable for communication with one or more networks 176 to enable communication with other computers and electronic devices, including, for example, a central service, such as a cloud service, through which vehicle 111A receives information including trained machine learning models and other data for use in its autonomous control. One or more networks 176 may be, for example, a communications network and may include a wide area network (“WAN”) such as the Internet, one or more local area networks (“LAN”) such as a Wi-Fi LAN or a mesh network, and one or more bus subsystems. One or more networks 176 may optionally utilize one or more standard communications technologies, protocols, and / or inter-process communications technologies. In some embodiments, data collected by one or more sensors 130 may be uploaded via network 176 to computing system 172 for further 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. Further processing of autonomous vehicle data by computing system 172 according to many embodiments is described with reference to FIG. 2.

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

[0036] In general, the routines executed to implement the various embodiments described herein are referred to herein as "program code," whether implemented as part of an operating system or a specific application, component, program, object, module, or sequence of instructions, or a subset thereof. Program code typically resides at different times in various memory and storage devices and comprises one or more instructions that, when read and executed by one or more processors, perform the steps necessary to perform the steps or elements embodying various aspects of the present disclosure. Also, while the embodiments are described in the context of fully functional computers and systems, it should be understood that the various embodiments described herein are capable of being distributed as program products in various forms, and that the embodiments may be implemented independently of the particular type of computer-readable medium used to actually accomplish such distribution.

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

[0038] Additionally, various program code described below may be identified based on the application for which it is implemented in a particular embodiment. However, any particular program nomenclature below is used merely for convenience, and thus the present disclosure should not be limited to use with only any particular application identified and / or implied by such nomenclature. Furthermore, given the generally infinite number of ways in which computer programs can be organized into routines, procedures, methods, modules, objects, etc., and the various ways in which program functionality may be allocated among the various software layers (e.g., operating system, libraries, APIs, applications, applets, etc.) resident within a typical computer, it should be understood that the present disclosure is not limited to the specific structure and allocation of program functionality described herein.

[0039] The exemplary environment illustrated in Figure 1a is not intended to limit the embodiments disclosed herein, and in fact, other alternative hardware and / or software environments may be used without departing from the scope of the embodiments disclosed herein.

[0040] The truck may include a LIDAR system (e.g., vehicle control system 120 in FIG. 1a, LIDAR sensor system 201 in FIG. 2, etc.). In some embodiments, the LIDAR system may encode an optical signal using frequency modulation and scatter the encoded optical signal into free space using an optical system. By detecting the frequency difference between the encoded optical signal and a return signal reflected from an object, a frequency modulation (FM) LIDAR system can determine the object's location or precisely measure the object's velocity using the Doppler effect. FM LIDAR systems can 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 encode an optical signal using phase modulation (PM) and scatter the encoded optical signal into free space using an optical system.

[0041] FM or phase-modulated (PM) LIDAR systems may offer significant advantages over conventional LIDAR systems for automotive and / or commercial truck applications. First, in some cases, an object (e.g., a pedestrian wearing dark clothing) may have low reflectivity, in that it reflects only a small amount (e.g., 10% or less) of the incident light incident on the object back to the FM or PM LIDAR system's sensor (e.g., sensor 130 in FIG. 1a). In other cases, an object (e.g., a shiny road sign) may have high reflectivity (e.g., 10% or more), in that it reflects a large amount of the incident light incident on the object back to the FM LIDAR system's sensor.

[0042] Regardless of the object's reflectivity, FM LIDAR systems can detect (e.g., classify, recognize, locate, etc.) objects at greater distances (e.g., twice as far) than conventional LIDAR systems. For example, FM LIDAR systems can detect low-reflectivity objects at distances of over 300 meters and high-reflectivity objects at distances of over 400 meters.

[0043] To achieve this improved detection capability, FM LIDAR systems can use sensors (e.g., sensor 130 in FIG. 1a). In some embodiments, these sensors can be sensitive to single photons, meaning they can detect the smallest amount of light possible. In some applications, FM LIDAR systems can use infrared wavelengths (e.g., 950 nm, 1550 nm, etc.), but are not limited to infrared wavelength ranges (e.g., near-infrared: 800 nm to 1500 nm, mid-infrared: 1500 nm to 5600 nm, and far-infrared: 5600 nm to 1,000,000 nm). By operating an FM or PM LIDAR system at infrared wavelengths, the FM or PM LIDAR system can broadcast stronger light pulses or beams while still meeting eye safety standards. Conventional LIDAR systems are often not sensitive to single photons and / or operate only at near-infrared wavelengths, which means that their light output (and distance detection capabilities) must be limited for eye safety reasons.

[0044] Therefore, by detecting objects at greater distances, FM LIDAR systems have more time to react to unexpected obstacles. In fact, even a few extra milliseconds can improve stability and convenience, especially for large vehicles (e.g., commercial trucks) traveling at high speeds on highways.

[0045] Another advantage of FM LIDAR systems is that they provide accurate speed information instantly for each data point. In some embodiments, speed measurements are made using the Doppler effect, which shifts the frequency of 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 speeds occurring in road conditions where speeds are less than 100 m / s, this shift at a 1550 nm wavelength corresponds to a frequency shift of less than 130 MHz. This frequency shift is small enough to be difficult to detect directly in the optical domain. However, by utilizing coherent detection in FMCW, PMCW, or FMQW LIDAR systems, the signal can be converted to the RF domain so that the frequency shift can be calculated using various signal processing techniques. This allows autonomous vehicle control systems to process the data received more quickly.

[0046] The instantaneous velocity calculation also makes it easier for the FM LIDAR system to determine remote or rare data points as objects and / or track how these objects are moving over time. For example, an FM LIDAR sensor (e.g., sensor 130 in FIG. 1 a) may receive only a few return signals (e.g., optical reception signals (Hits)) from an object 300 m away, but if the return signals provide a velocity value of interest (e.g., a vehicle closing speed of 70 mph or greater), the FM LIDAR system and / or autonomous vehicle control system can determine individual weights for the probability associated with the object.

[0047] The FM LIDAR system's quick identification and / or tracking gives the autonomous vehicle control system more time to activate the vehicle, and a better understanding of how fast an object is moving allows the autonomous vehicle control system to better plan a response.

[0048] Another advantage of FM LIDAR systems is that they have less static noise than traditional LIDAR systems. That is, traditional LIDAR systems are designed for increased light sensitivity and typically perform poorly in bright sunlight. These systems tend to be challenged by crosstalk (e.g., when sensors are confused by each other's light pulses or light beams) and self-interference (e.g., when a sensor is confused by its own previous light pulse or light beam). To overcome this drawback, vehicles using traditional LIDAR systems often require additional hardware, complex software, and / or more computing power to manage this "noise."

[0049] FM LIDAR systems, on the other hand, do not experience these types of problems because each sensor is specifically designed to respond only to its own unique light characteristics (e.g., light beams, light waves, light pulses). If the returning light does not match the timing, frequency, and / or wavelength of the originally transmitted light, the FM sensor can filter (e.g., remove, ignore, etc.) that data point. This allows FM LIDAR systems to compute (e.g., generate, derive, etc.) more accurate data with fewer hardware or software requirements, resulting in safer, smoother driving.

[0050] Finally, FM LIDAR systems are more easily scalable than traditional LIDAR systems. With more autonomous vehicles (e.g., cars, commercial trucks, etc.) on the road, vehicles powered by FM LIDAR systems will not have to face interference issues due to sensor crosstalk. FM LIDAR systems also use less optical peak power than traditional LIDAR sensors. This allows some or all of the optical components for FM LIDAR to be fabricated on a single chip, which provides unique advantages as discussed herein.

[0051] FIG. 1b is a block diagram illustrating an example of a system environment for an autonomous commercial truck fleet, according to some embodiments. The environment 100B includes a commercial truck 180B for carrying 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., transportation in which a road-based vehicle is used as one of multiple transportation modes to transport 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 reefer truck), a ventilated van (e.g., a dry van), a moving truck, etc. The cargo 182B may be merchandise and / or agricultural 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, an extendable flatbed trailer, a side kit trailer, etc.

[0052] The environment 100B includes an object 111B (shown as another vehicle in FIG. 1b) within a distance range of 30 meters or less from the truck.

[0053] The commercial truck 180B may include a LIDAR system 184B (e.g., an FM LIDAR system, the vehicle control system 120 of FIG. 1a, the LIDAR system 201 of FIG. 2, etc.) for determining the distance to the object 111B and / or measuring the speed of the object 111B. Although FIG. 1b shows one LIDAR system 184B mounted on the front of the commercial truck 180B, the number of LIDAR systems and the areas in which the LIDAR systems are mounted on the commercial truck are not limited to a particular number and area. The commercial truck 180B may include any number of LIDAR systems 184B (or components such as sensors, modulators, coherent signal generators, etc.) mounted on any area of ​​the commercial truck 180B (e.g., the front, back, sides, top, bottom, lower, bottom, and / or bottom) to facilitate detection of objects in any free space relative to the commercial truck 180B.

[0054] As shown, LIDAR system 184B in environment 100B may be configured to detect objects (e.g., other vehicles, bicycles, trees, road signs, potholes, etc.) at a short distance (e.g., 30 meters or less) from commercial truck 180B.

[0055] 1c is a block diagram illustrating an example 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 other vehicles in FIG. 1c) within a distance range of (i) 30 meters or more and (ii) 150 meters or less from commercial truck 180B. As shown, LIDAR system 184B in environment 100C may be configured to detect objects (e.g., other vehicles, bicycles, trees, road signs, potholes, etc.) within a predetermined distance (e.g., 100 meters) from commercial truck 180B.

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

[0058] Environment 100D includes object 111D (shown as another vehicle in FIG. 1d) within a distance range of 150 meters or more from commercial truck 180B. As shown, LIDAR system 184B in environment 100D may be configured to detect objects (e.g., other vehicles, bicycles, trees, road signs, potholes, etc.) within a predetermined distance (e.g., 300 meters) from commercial truck 180B.

[0059] In commercial truck applications, the increased weight and correspondingly longer stopping distances required of the vehicle make it important to effectively detect objects at all distances. FM LIDAR systems (e.g., FMCW and / or FMQW systems) or PM LIDAR systems are ideally suited for commercial truck applications due to the advantages discussed above. Thus, commercial trucks equipped with these systems may have an improved ability to safely transport both people and goods over short or long distances, thereby improving the safety of not only the commercial truck but also surrounding vehicles. In various embodiments, these FM or PM LIDAR systems can be used in semi-autonomous driving applications, where a driver is on board the commercial truck and some functions of the commercial truck operate autonomously using the FM or PM LIDAR system, or in fully autonomous driving applications, where the commercial truck operates fully autonomously using 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 light. For example, if the modulation period is 10 seconds, the input signal is modulated for the entire 10 seconds. Alternatively, in a LIDAR system using quasi-CW modulation, the modulator modulates the laser light to have both active and inactive portions. For example, in a 10-second period, the modulator modulates the laser light only for 8 seconds (also called the "active portion") and does not modulate the laser light for 2 seconds (also called the "inactive portion"). This allows the LIDAR system to reduce power consumption for 2 seconds because the modulator does not need to provide a continuous signal.

[0061] In the case of frequency-modulated continuous wave (FMCW) LIDAR for vehicle applications, FMCW measurement and signal processing methods are used, but it may be advantageous to operate the LIDAR system using quasi-CW modulation, rather than the optical signal always being on (e.g., activated, powered, transmitting, etc.). In some embodiments, the quasi-CW modulation may have a duty cycle that is greater than or equal to 1% and less than or equal to 50%. If the energy in the off state (e.g., inactivated, powered down, etc.) is consumed during the actual measurement time, this may improve the signal-to-noise ratio (SNR) and / or reduce the signal processing requirements to consistently integrate all the energy over a longer period of time.

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

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

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

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

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

[0067] The environment 200 includes a vehicle control system (e.g., vehicle control system 120 of FIG. 1a) coupled to a LIDAR system 201. In some embodiments, the vehicle control system 120 may 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). While Figure 2 shows only a select number of components and one input / output channel, the environment 200 may include any number of components and / or input / output channels (in any combination) interconnected in any arrangement to facilitate the combination of various functions of the LIDAR system to support vehicle operation.

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

[0070] The laser source 202 may be configured to provide an optical signal to the modulator 204A, which is configured to generate a modulated optical signal by modulating the phase and / or frequency of the optical signal using continuous wave (CW) modulation or quasi-CW modulation based on a first radio frequency (RF) signal (denoted as "RF1" in FIG. 2). The modulator 204A may be configured to transmit the modulated optical signal to the amplifier 206. The amplifier 206 may be configured to amplify the modulated optical signal to generate an amplified optical signal to the optical system 210 via one or more transmitters 216. The one or more transmitters 216 may include one or more optical waveguides or antennas.

[0071] The optical system 210 may be configured to direct the amplified optical signal received from the Tx path toward an object 218 in an environment within a given field of view, receive a return signal reflected back from the object 218, and provide the return signal to the mixer 208 of the Rx path via one or more receivers 222. The one or more receivers 222 may include one or more optical waveguides or antennas. In some arrangements, the transmitter 216 and the receiver 222 may form one or more transceivers (not shown in FIG. 2). In some arrangements, the one or more transceivers may include monostatic transceivers or bistatic transceivers.

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

[0073] The 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 the detector 212. In some arrangements, the mixer 208 may be configured to send the modulated LO signal to the detector 212.

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

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

[0076] In some embodiments, the TIA 214 may have a Peak Noise-Equivalent Power (NEP) of less than 5 picowatts per square root hertz (i.e., 5×10 Watts per square root hertz). In some embodiments, the TIA 214 may have a gain between 4 kilohms and 25 kilohms.

[0077] In some embodiments, the detector 212 and / or the TIA 214 may have a 3 decibel bandwidth between 80 kilohertz (kHz) and 450 megahertz (MHz).

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

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

[0080] In some embodiments, modulator 204A may be configured to transmit the first modulated optical signal and the second modulated optical signal to amplifier 206. Amplifier 206 may be configured to amplify the first and second modulated optical signals to generate amplified optical signals for optical system 210 via transmitter 216. Optical system 210 may be configured to direct the first and second modulated optical signals received from the Tx path toward an object 218 in an environment within a given field of view, receive corresponding first and second return signals reflected back from object 218, and provide the first and second return signals 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 transmit the first and second modulated LO signals to mixer 208 of the Rx path. The mixer 208 may be configured to pair (e.g., connect, link, identify, etc.) the first return optical signal and the first modulated LO signal, 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 transmit the first down-converted signal to the detector 212. Similarly, the mixer 208 may be configured to pair the second return optical signal with the second modulated LO signal, mix the second return optical signal with the second modulated LO signal to generate a second down-converted signal, and transmit the second down-converted signal to the detector 212. The detector 212 may be configured to generate first and second electrical signals based on the first and second down-converted signals, respectively. The vehicle control system 120 may be configured to determine a distance to the object 218 and / or measure a velocity of the object 218 based on the first and second electrical signals received via the TIA 214 and the ADC 220.

[0081] In some embodiments, the LIDAR system includes a seed laser, a modulator, an amplifier, and a transceiver chip. Modular LIDAR systems allow components to be individual optical components and integrated circuits (PICs) optically coupled by microlenses. This provides variations on the PIC architecture, such as high component yield, ease of configuration, assembly for different variations of each component, and various ways in which optical components can be arranged within an optical circuit to achieve 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, a distributed feedback (DFB) or distributed Bragg reflector (DBR) laser diode or an external cavity laser source. The seed laser's light or beam can be optically coupled for input to the 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 in that it can be configured as a single integrated circuit.

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

[0084] In some embodiments, the seed laser and modulator may be integrated to form a seed laser assembly, in which the seed laser assembly is mounted on a first submount and the coupled transceiver chip is mounted on a second submount to align the height of the seed laser assembly with the height of the transceiver chip 302, thereby optimizing 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 a III-V semiconductor-based integrated photonic device in which all components are formed of III-V materials and fabricated / monolithically integrated on a single substrate formed of III-V materials. Furthermore, in some embodiments, each SOA array chip can include one or more, e.g., four or five, channels and is configured to amplify a beam by stimulated emission of light. The amplifier can be optically coupled to a modulator via a microlens. Similarly, the amplifier is optically coupled by the microlens to provide the amplified signal to a transceiver chip.

[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 processes the coupled light using an amplifier. The SiPho transceiver chip includes multiple coherent pixels that process the output of the optical amplifier and emit light from the surface of the SiPho transceiver chip through an optical window in the integrated chip packaging. The SiPho transceiver chip processes the collected light reflected from the target and couples the detected photocurrent to a transimpedance amplifier. The transimpedance amplifier converts the photocurrent to an electrical voltage, which is then coupled externally to the integrated chip packaging.

[0087] Referring to FIG. 3, an example of horizontal integration 300 of a photonic integrated circuit (PIC) 308 for a LIDAR system for an autonomous vehicle is shown, according to some embodiments. FIG. 3 shows a cross section of a PIC 308 mounted on a SiPho carrier or chip 302. The example horizontal integration 300 couples the SiPho carrier or chip 302 with the PIC 308. As shown in FIG. 3, the SiPho carrier 302 defines one or more pedestals that couple to the PIC 308. The PIC 308 is coupled to these pedestals of the SiPho carrier 302 by connectors 306. The structural alignment of the PIC 308 to the SiPho carrier 302 provides robust alignment for the optical mode of the PIC 308. For example, the optical mode may have a size that is typically in the range of ∼1.0 μm to ∼3.0-10.0 μm. On the same side as the pedestal (the top side in FIG. 3), SiPho carrier 302 includes metal layer 304 that provides backside metal patterning to support heat dissipation and pick-and-place. Portions of SiPho carrier 302 are also bonded by layer 310. Similarly, PIC 308 has one side covered with metal layer 304 for backside metal patterning to support heat dissipation and pick-and-place. In some embodiments, PIC 308 may include a second metal layer (not shown) on the opposite side of metal 306 for improved heat dissipation.

[0088] Various embodiments of exemplary PICs 308a, 308b, and 308c are now described with reference to FIGS. 4a-4c. The PIC 308 advantageously includes both passive and active optical components monolithically integrated. FIGS. 4a-4c illustrate high-level planar views of exemplary embodiments of a semiconductor optical amplifier for a LIDAR system for an autonomous vehicle. In some embodiments, the PIC 308 includes a monolithically integrated spot-size converter that optically couples the optical integrated circuit to a connector through low-loss hybrid integration. In some embodiments, the PIC 308 includes one or more passive components monolithically integrated with the optical amplifier as part of the PIC 308. For example, the one or more passive components are one or more of the following: a U-turn, a total internal reflection reflector, mirrors, a coupler, and a splitter. As described in more detail below with reference to FIGS. 4a-4c, the PIC 308 monolithically integrates two or more optical amplifiers, a U-turn, and an array of passive components such that the optical integrated circuit can be optically coupled on a single side. These and other features will become apparent from the following description of Figures 4a-4c. Also, certain features of different embodiments of exemplary PICs 308a, 308b, and 308c may be combined in other ways in addition to those specifically shown in Figures 4a-4c.

[0089] FIG. 4a illustrates a first example embodiment of a PIC 308a. In this embodiment, the PIC 308a includes multiple output SOAs 402a-402d, multiple U-turns 404a-404d, and multiple passive connectors 406a-406d. While FIG. 4a illustrates 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 the PIC 308a, and four amplifiers is used merely for illustrative purposes. FIG. 4a also illustrates how the multiple SOAs 402a-402d and multiple passive connectors 406a-406d each receive and transmit optical signals from a single side of the PIC 308a. This is particularly advantageous for horizontal integration of the PIC 308 with other components, as it allows for easy optical alignment of the four SOAs 402a-402d. FIG. 4a also shows that SOAs 402a-402d have straight facets. It should be understood that anti-reflection coatings can be used to achieve back-reflection to straight waveguides at -20 dB or less. It should be understood that the symmetrical waveguide layout of SOAs 402a-402d shown in FIG. 4a provides power uniformity within the amplifier array due to uniform heat / temperature distribution and uniform coupling efficiency during bowing. In one example, PIC 308a and its components may have values ​​approximating those in Table 1.

[0090] [Table 1]

[0091] 4a also shows the arrangement of SOAs 402a-402d, U-turns 404a-404d, and passive connectors 406a-406d, where the SOAs 402a-402d are located near the center of the PIC 308, and two U-turns 404a and 404b are coupled to connectors 406a and 406b on one side of the array of SOAs 402a-402d, while 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 to each SOA 402a-402d is about 50 mW, and the output power of each SOA 402a-402d is about 550 mW.

[0092] FIG. 4b illustrates a second exemplary embodiment of a PIC 308b. In other words, the 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, along with a corresponding number of U-turns 404a-404d and passive connectors 406a-406d. However, alternative embodiments of the PIC 308b may have any number of SOAs 402, U-turns 404, and passive connectors 406. The exemplary PIC 308b and its components may also have values ​​similar to those described in Table 1 above. FIG. 4b illustrates some differences in layout from the layout of FIG. 4a. More specifically, the SOAs 402a-402d are disposed on one side of the PIC 308b, while the passive connectors 406a-406d are disposed parallel to the sides of the SOAs 402a-402d. A U-turn 404 couples each SOA 402 to the passive connector 406. The U-turn 404a is longer than the other U-turns 404b-404d, and each of the U-turns 404b-404d is slightly shorter in length than the others. Figure 4b illustrates an alternative configuration for integration, e.g., monolithic integration, in which the inputs and outputs are both provided on one side of the PIC 308a (e.g., the top end of Figure 4b), the inputs are grouped toward a first end of the PIC 308b (e.g., the left side of Figure 4b), and the outputs 406a-406d are toward a second end of the PIC 308b (e.g., the right side of Figure 4b). Similar to the embodiment of FIG. 4a, in this embodiment the input optical power to each SOA 402a-402d is about 50 mW, and the output power of each SOA 402a-402d is about 550 mW.

[0093] FIG. 4c illustrates a third exemplary embodiment of a PIC 308c. In this embodiment, the PIC 308c includes multiple output SOAs 402a-402d, multiple U-turns 404a-404d, a gain amplifier 408, and a splitter 410. While FIG. 4c illustrates four output SOAs 402a-402d and four U-turns 404a-404d, it should be understood that any number of output SOAs and U-turns may be monolithically integrated into the PIC 308c, and four output SOAs are used merely for illustrative purposes. Similarly, while FIG. 4c illustrates only a single gain amplifier 408 and a single splitter 410, in other embodiments, various combinations of gain amplifiers 408 and splitters 410 may be monolithically integrated into the PIC 308c. As illustrated, an input signal is input to the gain amplifier 408. In some embodiments, the gain amplifier 408 is an SOA providing approximately 10 dB of gain, and the input to the SOA is 50 mW. In some embodiments, there may be multiple gain amplifiers 408. The output of the gain amplifier 408 is input to a splitter 410. In this example, the splitter 410 is a 1:4 splitter. It should be understood that the splitter 410 or splitters have multiple outputs corresponding to the number of output SOAs 402a-402d integrated into the PIC 308c. For example, the splitter 410 may be 1:2, 1:4, 1:8, 1:16, etc., in various configurations where the number of outputs of one or more splitters matches the number of inputs to the output amplifier 402. In some embodiments, the gain amplifier 408 outputs a signal of approximately 27 dBm. This signal is split by the splitter 410 into four signals of approximately 19 dBm each. The signals are input to each output SOA 402a-402d via a corresponding U-turn 404a-404d. The loss through the splitter 410 and the U-turns 404a-404d may be approximately 8 dB. Each output SOA 402a-402d amplifies the received signal and outputs a 550 mW signal. For example, each output SOA 402a-402d may provide approximately 8 dB of gain. This allows the PIC 308c to output four amplified signals, each approximately 550 mW (+27 dB).This embodiment, shown in FIG. 4c, is particularly advantageous because PIC 308c provides both particularly high gain and / or particularly high power amplification. For example, typical optical gain or amplification may range from +2 to +25 dB. As can be seen from the plan view in FIG. 4c, each of output SOAs 402a-402d is slightly tilted, as opposed to the vertical configuration of FIGS. 4a and 4b. In some embodiments, output SOAs 402a-402d and gain amplifier 408 have a large active waveguide spacing (along the cross section) of 500 μm, thereby reducing thermal crosstalk between the SOAs. While SOAs 402a-402d are shown as untapered SOAs, it should be understood that in alternative embodiments, one or more SOAs may be tapered semiconductor optical amplifiers (TSOAs).

[0094] FIG. 5a shows a cross-sectional view of an exemplary embodiment of an SOA 402 for a LIDAR system for an autonomous vehicle. The SOA 402 includes the following layers from bottom to top in FIG. 5a: a silicon or sulfur-doped layer 502, an n-doped layer 504, a guide 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 the opposite direction from the n-type layer 504a. For example, after the metal layer is formed, 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 below the silicon-doped layer 502a. Referring to Figure 5b, one or more metal layers may be coupled to layer 502b in the opposite direction to layer 504b. For example, a metal layer may be formed, +An InP layer 502b is formed on the metal layer, and an n-doped indium phosphide layer 504b is formed on layer 502b. In other embodiments, a metal layer need not be formed under layer 502b. It should be noted that the configuration described above with reference to FIG. 5a and below with reference to FIGS. 5b and 6 is particularly advantageous because backside metallization (on the bottom of the chip) can be applied even when current does not flow to the bottom. The backside metallization supports soldering to a carrier / submount (also known as die-attach) and is also used to improve thermal conductivity. In many embodiments, current can flow to the bottom of the chip, in which case the backside metallization also supports electrical connection to the carrier / submount. Therefore, the present disclosure includes embodiments with and without backside (bottom) metallization. In the absence of backside metallization, current flows to the top of the chip, where another (additional) metal layer (not shown) is present to complete the circuit.

[0095] In some embodiments, the silicon-doped layer 502a is made of n-doped indium phosphide, such as silicon or sulfur-doped indium phosphide, as specifically shown in FIGS. 5b and 6. + -InP layers. In some embodiments, other types of n-doped layers can be used.

[0096] An 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.

[0097] 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, periodic, or superlattice structure. For example, the guiding layer 506a may be composed of alternating indium phosphide (InP) and ternary or quaternary layers 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 may be in the range of 300 to 500 nm. In some embodiments, the guiding layer 506a may 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 may provide a large optical mode size for integration with silicon photonics waveguides.

[0098] 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 may have a thickness in the range of 100 to 150 nm.

[0099] In some embodiments, the first confinement layer 510a and the second confinement layer 514a are confinement heterostructures (SCH). In some embodiments, the first confinement layer 510a and the second confinement layer 514a may have a thickness in the range of 20 nm to 100 nm, for example, 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.

[0100] The active layer 512a is formed on the first confinement layer 510a and is located between the second confinement layer 514b. In some embodiments, the active layer 512a is offset to generate an output power greater than 50 mW, for example, an output power 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 can be an offset multiple quantum well (MQW) or an offset quantum dot. For example, the active layer 512a can have two to eight quantum wells. In some embodiments, the active layer 512a can have a two to four MQW structure with a low optical mode confinement factor, for example, on the order of 1-2%.

[0101] A current spreading layer 516a is formed on the second confinement layer 514a. In some embodiments, the current spreading layer 516a is a layer of p-doped indium phosphide 516b.

[0102] A 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 shown in FIG. 5a, a metal layer 520a is formed on the top and sides of the ridge layer 518a. In this example, one or more insulating regions 517a, 517b may be formed to cover a specific portion (e.g., a side portion) of the ridge layer 518a and a specific portion (e.g., a top portion) of the current spreading layer 516a, thereby coupling only the specific portion (e.g., the top portion) of the ridge layer 518a to the metal layer 520a.

[0103] FIG. 5b illustrates an embodiment of an SOA 402 for a LIDAR system for an autonomous vehicle similar to FIG. 5a , but with exemplary specific materials for each of the aforementioned layers 502b–520b provided for each of the layers 502a–520a, as shown. For example, the ridge layer 518a is formed of p-doped indium phosphide 518b. A metal layer 520b is formed on the top and sides of the P-InP ridge layer 518b, as shown in FIG. 5b. In this example, one or more insulating regions 517a, 517b are formed to cover specific portions (e.g., side portions) of the ridge layer 518b and specific portions (e.g., top portions) of the current-spreading P-InP layer 516b, thereby coupling only specific portions (e.g., top portions) of the ridge layer 518b to the metal layer 520b.

[0104] Although the SOA 402 is described above with particular 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 nitride (GaN), or indium antimonide (InSb).

[0105] Next, an exemplary embodiment of a PIC for a LIDAR system for an autonomous vehicle will be described with reference to FIG. 6 , which includes an SOA array 600 including a first SOA 402a and a second SOA 402b. FIG. 6 is provided to illustrate how the array 600 of SOAs can be formed using the same structure and process as described above with reference to FIGS. 5a and 5b. FIG. 6 is also provided to illustrate how the SOAs 402a, 402b can have the same layers, different layers, additional layers, or fewer layers than the embodiment described above with reference to FIGS. 5a and 5b. FIG. 6 is also provided to illustrate how a portion of the PIC can include an alignment reference point 604 for hybrid integration and recess cladding to further simplify the integration process. As shown in FIG. 6 , the first SOA 402a is formed from layers 502b-518b and layer 602, and the second SOA 402b is formed from layers 502b-518b and layer 602. In this embodiment, the first SOA 402a and the second SOA 402b are n-doped layers. + -InP layer 502b is shared. + The InP layer 502b forms the bottom of the first SOA 402a and the second SOA 402b and defines a pair of trenches 606a and 606b adjacent to the first SOA 402a and the second SOA 402b, respectively. + A portion of the InP layer 502b defines a pedestal 608. On one side of the pedestal 608, a Q1.3 layer 602 is formed. The Q1.3 layer 602 is a recessed cladding layer into which alignment fiducials 604 can be etched. In some embodiments, the alignment fiducials are created using the Q1.3 layer 602 as an etch stop to define recessed cladding for vertical alignment of optical modes for hybrid integration. This is particularly advantageous because these alignment fiducials allow the SOA array 600 to be easily horizontally integrated with other photonics components of a LIDAR system. As previously mentioned, the first SOA 402a and the second SOA 402b in this embodiment are n-doped layers, with each of the first SOA 402a and the second SOA 402b being an n-doped layer near the bottom or base. +The difference is that the InP layer 502b also includes a Q1.3 layer 602 on a portion of the InP layer 502b. + The insulating layer 502 is located between the InP layer 502b and the n-type InP layer 504b.

[0106] 5a and 5b, in FIG. 6, one or more metal layers may be formed under layer 502b. Also, as in FIG. 5a and 5b, in FIG. 6, an insulating region may be formed to cover a specific portion of P-InP ridge layer 518b and a specific portion of current spreading layer 516b of first SOA 402a and second SOA 402b, but to expose a specific portion of P-InP layer 518b. Also, as in FIG. 5a and 5b, one or more metal layers may be formed to cover P-InP ridge layer 518b, the insulating region, and current spreading layer 516b, so as to be coupled only to a specific portion (e.g., an upper portion) of P-InP ridge layer 518b.

[0107] The foregoing detailed description of the present disclosure has been presented for purposes of illustration and description. It is not intended to be complete 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 selected to best explain the principles of the present disclosure and its practical application, and thus to enable those skilled in the art to best utilize the present disclosure through various modifications suited to the particular uses contemplated in the various embodiments. It is intended that the scope of the present disclosure be defined by the claims appended hereto.

[0108] Although some embodiments of the present disclosure and its advantages have been described in detail, it should be understood that various modifications, substitutions, and alterations are possible 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 be retained and modified within the scope of the present disclosure. Furthermore, the scope of the present disclosure is not intended to be limited to the particular implementations of the processes, machines, manufacture, compositions of matter, means, methods, and steps described herein. As those skilled in the art will readily understand from the description of the present disclosure, currently existing or future developed processes, machines, manufacture, compositions of matter, means, methods, and steps can perform substantially the same function or achieve substantially the same result as the implementations described herein in accordance with the present disclosure. Therefore, it is intended that the appended claims include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

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

2. 10. The LIDAR system of claim 1, wherein the active layer is an Offset Bulk Quantum Mechanical Structure or a Multiple Quantum Mechanical Structure.

3. 3. The LIDAR system of claim 2, wherein the offset bulk quantum mechanical structure is one of the group of an offset multiple quantum well or an offset quantum dot layer.

4. 10. The LIDAR system of claim 1, wherein the optical integrated circuit includes a first heat dissipation structure configured to reduce heat from a top side of the optical integrated circuit and a second heat dissipation structure configured to reduce heat from the top side of the optical integrated circuit.

5. 10. The LIDAR system of claim 1, wherein the particular structure includes one or more alternating indium phosphide (InP) layers.

6. 10. The LIDAR system of claim 1, wherein the particular structure comprises 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 for high wall-plug efficiency with improved heat dissipation.

7. 10. The LIDAR system of claim 1, wherein the specific structure is integrated with a silicon photonics waveguide, and the specific structure includes an optical mode converter.

8. 10. The LIDAR system of claim 1, wherein the integrated optical circuit includes a monolithically integrated spot-size converter, the integrated optical circuit optically coupled to an optical waveguide connector.

9. 10. The LIDAR system of claim 1, wherein the optical integrated circuit includes one or more passive components monolithically integrated with the optical amplifier.

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

11. The LIDAR system of claim 1 , wherein the particular structure comprises an alternating, periodic, or superlattice structure.

12. 10. The LIDAR system of claim 1, wherein the optical integrated circuit includes a second amplifier providing a specific gain and is monolithically integrated, the output of the second amplifier being coupled to the input of the optical amplifier.

13. An optical integrated circuit, comprising: a first amplifier coupled to receive the input beam and generate an amplified beam, the first amplifier having an active layer and a specific structure configured for improved heat dissipation; an optical integrated circuit including the first amplifier and one or more passive components monolithically integrated as part of the optical integrated circuit;

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

15. 15. The optical integrated circuit of claim 14, wherein the offset bulk or multiple quantum well structure is one of the group of an offset bulk quantum well, a multiple quantum well, or an offset quantum dot layer.

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