Light detection and ranging (LIDAR) systems including high power amplifiers

Abstract

A LIDAR sensor system comprising: 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 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 transmit 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 light detection and ranging (LIDAR) systems, and more particularly to monolithically integrated high power optical amplifiers including passive components and active components for LIDAR systems. BACKGROUND

[0002] LIDAR sensor systems are used for various applications from height finding 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 containing photonic components. There have been past attempts to include more photonic components and optical functionality of a LIDAR system onto a single PIC. SUMMARY

[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 including passive components and active components for LIDAR sensor systems.

[0004] According to an aspect of the subject matter described in this disclosure, a LIDAR sensor system includes a laser configured to output a light beam, a modulator coupled to receive the light beam output from the seed laser and to 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 to generate an amplified light beam, the amplifier including an active layer for amplification and a particular structure configured to dissipate heat, and a transceiver chip coupled to the photonic integrated circuit, the transceiver chip configured to transmit the amplified light beam and to receive a reflected light beam from a target.

[0005] According to another aspect of the subject matter described in this disclosure, a photonic integrated circuit includes a first optical amplifier coupled to receive an input light beam and to generate an amplified light beam, the first amplifier having an active layer for amplification and a particular 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 implementations can each optionally include one or more of the following features. For example, features can include that the active layer is a delta or a multi-quantum well structure, e.g., the delta or multi-quantum well structure is one of a delta quantum well or a group of delta dot layers. Features can also include, for example, that the photonic integrated circuit includes a first heat spreading structure to reduce heat from a lower side of the photonic integrated circuit and a second heat spreading structure to reduce heat from an upper side of the photonic integrated circuit. In another example, features can include that the particular structure includes one or more alternating indium phosphide (InP) layers, or the 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 aluminum indium gallium arsenide (InGaAlAs) or other quaternary or ternary alloy layers with improved heat spreading and high wall plug efficiency. In one example, the 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 optically coupled to an optical waveguide, e.g., a fiber connector. In some features, the photonic integrated circuit includes one or more passive components monolithically integrated with an optical amplifier, or the one or more passive components include a semiconductor optical amplifier (SOA) coupled to a coupler through a U-turn bend that is monolithically integrated to provide optical input and output on the same side of the photonic integrated circuit. For example, the particular SOA includes an alternating or periodic or superlattice structure with improved heat spreading and high wall plug efficiency. Features can include, for example, that the photonic integrated circuit includes and monolithically integrates a second optical amplifier that provides a particular gain, and an output of the second amplifier is coupled to an input of the first amplifier.

[0007] Those skilled in the art will appreciate that the summary is illustrative only and is not intended to be limiting in any way. Any of the features described herein can be used alone, or in combination with any other feature or features. Only the claims defined the written description and the appended claims as actually drafted and presented can be construed as limiting the subject matter of this disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0008] Implementations are illustrated by way of example, and not limitation, in the figures of the accompanying drawings in which like references indicate similar elements, and wherein:

[0009] FIG. 1A is a block diagram illustrating an example of a system environment for an autonomous vehicle in accordance with some implementations.

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

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

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

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

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

[0015] FIG. 4A to FIG. 4C is a high-level plan view of an example 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 a photonic integrated circuit for a LIDAR sensor system for an autonomous vehicle.

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

[0017] FIG. 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 implementations of the structures and methods illustrated herein can 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 improved heat dissipation, and a transceiver chip coupled to the photonic integrated circuit, the transceiver chip configured to transmit 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 to be easily integrated with other components of the LIDAR sensor system. In some implementations, 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 improved 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 can include multiple optical amplifiers and passive components including U-shaped turns, such that the photonic integrated circuit provides both high power and high gain, and has high wall-plug efficiency resulting from improved heat dissipation. Because of this photonic integrated circuit, the LIDAR sensor system overcomes the disadvantages of the prior art described above, because the photonic integrated circuit has high optical power, high gain, and high wall-plug efficiency. Moreover, 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 the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various aspect of different example implementations. It can be noted, however, that in various instances, well-known or conventional details can be omitted, or can be replaced with well-known or conventional equivalents, in order to not obscure the various aspects of the example implementations described herein. Reference will now be made to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like elements. Embodiments of the present disclosure will be described with respect to various implementations. It should be understood that the implementations can be combined, other elements can be added, or some elements can be removed without departing from the scope of the disclosure.

[0021] Furthermore, relative terms such as "lower" or "bottom" or "back" or "rear" and "upper" or "top" or "front" or "forward" can be used herein to describe an element's relationship to another element as the device is oriented in the figures. It will be understood that relative terms are intended to encompass 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 turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. The exemplary term "lower" can therefore encompass both an orientation of "lower" and "upper," depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as "below" or "beneath" other elements would then be oriented "above" the other elements. The exemplary terms "below" or "beneath" can therefore encompass both an orientation of above and below.

[0022] Referring to the drawings, wherein like reference numerals refer to like elements throughout the several views, FIG. 1A An example of a system environment 100A of an autonomous vehicle 111 A in which various techniques disclosed herein can be implemented is shown. For example, the vehicle 111 A can include a powertrain system 102 including a prime mover 104 powered by an energy source 106 and capable of providing power to a drivetrain 108, and a control system 110 including a directional control 112, a powertrain control 114, and a braking control 116. The vehicle 111 A can be implemented as any number of different types of vehicles including vehicles capable of transporting people and / or cargo and capable of traveling over land, and it will be appreciated that the above-described components 102-116 can 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 can include one or more electric motors and / or internal combustion engines (etc.). The energy source 106 can 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 the wheels and / or tires and a transmission and / or any other mechanical drive components suitable for converting the output of the prime mover 104 into vehicle motion, one or more brakes configured to controllably stop or slow the vehicle 111 A, and steering components suitable for controlling the trajectory of the vehicle 111 A (e.g., rack and pinion steering linkage enabling one or more wheels of the vehicle 111 A to pivot about a generally vertical axis to change the angle of the plane of rotation of the wheel relative to the longitudinal axis of the vehicle). In some embodiments, a combination of powertrain and energy source can be used (e.g., in the case of an electric / oil hybrid vehicle), and in other embodiments, multiple electric motors (e.g., dedicated to individual wheels or axles) can be used as the prime mover 104. In the case of a hydrogen fuel cell embodiment, the prime mover 104 can include one or more electric motors, and the energy source 106 can include a fuel cell system powered by hydrogen fuel.

[0024] The direction control 112 can include one or more actuators and / or sensors for controlling and receiving feedback from the direction or steering components to enable the vehicle 111 A to follow a desired trajectory. The powertrain control 114 can be configured to control the output of the powertrain 102, e.g., to control the output power of the prime mover 104, to control the gear of a transmission in the drivetrain 108, etc., thereby controlling the speed and / or direction of the vehicle 111 A. The brake control 116 can 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 the vehicle 111 A.

[0025] Other vehicle types, including but not limited to all-terrain or tracked vehicles, and construction equipment, can utilize different powertrains, drivetrains, energy sources, direction controls, powertrain controls, and brake controls. Moreover, in some embodiments, some components can be combined, e.g., where the direction control of the vehicle is handled primarily by varying the output of one or more prime movers. Thus, the embodiments disclosed herein are not limited to the particular application of the technology described herein in autonomous wheeled land vehicles.

[0026] In the illustrated implementation, various levels of autonomous control, including full or semi-autonomous control of the vehicle 111 A, can be implemented in a vehicle control system 120, which can 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 the memory 124. The processors can include, for example, a graphics processing unit (“GPU”) and / or a central processing unit (“CPU”).

[0027] The sensors 130 can include various sensors suitable for collecting information from the vehicle’s surroundings for use in controlling the operation of the vehicle 111 A. For example, the sensors 130 can include one or more detection and ranging sensors (e.g., RADAR sensors 134, LIDAR sensors 136, or both), a 3D positioning sensor 138, e.g., 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 can be used to determine the vehicle’s position on Earth using satellite signals. The sensors 130 can optionally include a camera 140 and / or an IMU (inertial measurement unit) 142. The camera 140 can be a monoscopic or stereoscopic camera and can record still and / or video images. The IMU 142 can include multiple gyroscopes and accelerometers that are capable of detecting linear and rotational motion of the vehicle 111 A in three directions. One or more encoders 144, such as wheel encoders, can be used to monitor the rotation of one or more wheels of the vehicle 111 A. In some implementations, the LIDAR sensors 136 can include structures for silicon photonic devices for coherent LIDAR systems, as described in detail below.

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

[0029] Will understand, FIG. 1A The assembly of components for the vehicle control system 120 illustrated in the diagram is merely an example. In some embodiments, individual sensors may be omitted. Additionally or alternatively, in some embodiments, FIG. 1A Multiple sensors of the same type illustrated in the diagram can be used for redundancy and / or to cover different areas around the vehicle. In addition to the sensors described above, other types of additional sensors may be used 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. Furthermore, although subsystems 152 to 158 are illustrated 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 to 158 may be implemented using program code instructions 126 residing in one or more memories 124 and executed by one or more processors 122, and in some instances, these subsystems 152 to 158 may be implemented using the same processor and / or memory. Subsystems may be implemented, at least in part, using various special-purpose 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 may utilize circuit systems, processors, sensors, and / or other components. Furthermore, various components in the vehicle control system 120 may be networked in various ways.

[0030] In some embodiments, vehicle 111A may further include an auxiliary vehicle control system (not shown), which can serve as a redundancy or backup control system for vehicle 111A. In some embodiments, the auxiliary vehicle control system can fully operate the autonomous vehicle 111A in the event of an adverse event detected in the primary vehicle control system 120, while in other embodiments, the auxiliary vehicle control system may have only limited functionality, such as 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] Typically, different architectures can be used to implement this. FIG. 1A The various components illustrated in the diagram represent 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 main memory 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 stored in a mass storage device or on another computer controller. FIG. 1A One or more processors 122 or completely independent processors illustrated herein can be used to implement additional functions in the vehicle 1A beyond the purpose of autonomous control, such as controlling the entertainment system, operating doors, lights, convenience features, etc.

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

[0033] In addition, 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. Alternatively, 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] Further, the vehicle 111 A can include one or more network interfaces (e.g., network interface 162) adapted to communicate with one or more networks 176 to allow for information communication with other computers and electronic devices, including for example, central services, such as cloud services, from which the vehicle 111 A receives information including trained machine learning models and other data for use in its autonomous control. The one or more networks 176 may, for example, be communication networks, and include wide area networks (“WANs”) such as the Internet, one or more local area networks (“LANs”), such as Wi-Fi LANs, mesh networks, etc., and one or more bus subsystems. The one or more networks 176 can optionally utilize one or more standard communications technologies, protocols, and / or inter-process communication techniques. In some embodiments, data collected by the one or more sensors 130 can be uploaded to the computing system 172 via the network 176 for additional processing. In the illustrated embodiment, the vehicle 111 A can communicate with the computing system 172 via the network 176 and signal line 178. In some embodiments, the computing system 172 is a cloud-based computing device. Additionally, with reference to FIG. 2 Processing of autonomous vehicle data by the computing system 172 according to many embodiments is described.

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

[0036] Generally, the routines executed to implement the various implementations described herein, whether implemented as part of an operating system or a specific application, component, program, object, module, or sequence of instructions, or even a subset thereof, will be referred to herein as "program code." The program code typically comprises one or more instructions that are resident at various times in various memory and storage devices and that, when read and executed by one or more processors, perform the steps or elements of the steps described herein that are required to execute embodiments of the present disclosure. Moreover, while the embodiments have been described and are shown in the context of fully functioning computers and systems, those skilled in the art will appreciate that the various embodiments described herein are capable of being distributed in the form of program products in a variety of forms, and that the embodiments are capable of being implemented on and used with a variety of other devices. Furthermore, to the extent that the terms "comprises," "comprising," "includes," "including," or the like are used in the detailed description and / or claims, such terms are intended to be inclusive in a manner that does not preclude the presence of other elements and / or the possibility of additional elements.

[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 disks, magnetic tape, and optical disks (e.g., CD-ROMs, DVDs, etc.), among others.

[0038] In addition, the various program code described herein can be identified based on the application within which the programs codes are implemented in, for example, a particular application program that can make use of program codes or a particular business method or process. However, as those skilled in the art will appreciate, any particular program nomenclature that is used to identify the program code herein is not meant to limit the scope of the present disclosure, but is merely meant to

[0039] FIG. 1A The example environment illustrated in FIG. 1 is 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., FIG. 1A the vehicle control system 120 in FIG. 1, FIG. 2lidar system 201, etc.) in some implementations, a lidar system can use frequency modulation to encode optical signals and use optics to scatter the encoded optical signals into free space. By detecting the frequency difference between the encoded optical signals and the return signals reflected back from objects, a frequency-modulated (FM) lidar system can determine the location of the objects and / or precisely measure the velocity of the objects 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”). A lidar system can use phase modulation (PM) to encode optical signals and use optics to scatter the encoded optical signals into free space.

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

[0042] Regardless of the reflectivity of the object, FM lidar systems are able to detect (e.g., classify, discriminate, discover, etc.) objects at greater distances (e.g., 2x) than traditional lidar systems. For example, FM lidar systems can detect low reflectivity objects 300 meters away, as well as high reflectivity objects 400 meters away.

[0043] To achieve this improvement in detection capability, FM lidar systems can use sensors (e.g., sensor 130 in FIG. 1) that are capable of detecting the frequency difference between the encoded optical signals and the return signals reflected back from objects. For example, a sensor can use a photonic integrated circuit (PIC) to detect the frequency difference between the encoded optical signals and the return signals reflected back from objects. FIG. 1A ​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 FM or PM lidar systems within the infrared wavelengths, the FM or PM lidar systems can broadcast stronger pulses or beams of light while meeting eye safety standards. Conventional lidar systems are typically not single-photon sensitive and / or only operate within the near infrared wavelengths, requiring them to limit their light output (and range detection capabilities) for eye safety reasons.

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

[0045] Another advantage of FM lidar systems is that they can instantaneously provide accurate velocities for each data point. In some embodiments, velocity measurements are done 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 velocities encountered in road situations with speeds less than 100 meters per second (m / s), this shift at a wavelength of 1550 nanometers (nm) amounts to less than 130 megahertz (MHz) of frequency shift. This frequency shift is small, making it difficult to detect directly in the optical domain. However, by using coherent detection in FMCW, PMCW, or FMQW lidar systems, 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 autonomous vehicle control systems to process incoming data more quickly.

[0046] Instantaneous velocity calculations also make it easier for FM lidar systems to identify distant or sparse data points as objects and / or track how these objects are moving over time. For example, a FM lidar sensor (e.g., sensor 130 in FIG. 1) can only receive a few returns (e.g., hits) off an object 300 meters away, but if those returns give a velocity value of interest (e.g., moving towards the vehicle at >70 mph), then the FM lidar system and / or autonomous vehicle control system can determine a corresponding weight of probability associated with the object. FIG. 1A 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 FM or PM lidar systems within the infrared wavelengths, the FM or PM lidar systems can broadcast stronger pulses or beams of light while meeting eye safety standards. Conventional lidar systems are typically not single-photon sensitive and / or only operate within the near infrared wavelengths, requiring them to limit their light output (and range detection capabilities) for eye safety reasons.

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

[0045] Another advantage of FM lidar systems is that they can instantaneously provide accurate velocities for each data point. In some embodiments, velocity measurements are done 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 velocities encountered in road situations with speeds less than 100 meters per second (m / s), this shift at a wavelength of 1550 nanometers (nm) amounts to less than 130 megahertz (MHz) of frequency shift. This frequency shift is small, making it difficult to detect directly in the optical domain. However, by using coherent detection in FMCW, PMCW, or FMQW lidar systems, 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 autonomous vehicle control systems to process incoming data more quickly.

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

[0047] Faster recognition and / or tracking of FM lidar systems gives autonomous vehicle control systems more time to maneuver the vehicle. Better understanding of how fast an object is moving also allows autonomous vehicle control systems to plan better reactions.

[0048] Another advantage of FM lidar systems is that they have less static compared to traditional lidar systems. That is, traditional lidar systems that are designed to be sensitive to light often perform poorly in bright sunlight. These systems are also susceptible to cross-talk (e.g., when a sensor is confused by the light pulses or beams of each other) and self-interference (e.g., when a sensor is confused by its own previous light pulses or beams). To overcome these shortcomings, vehicles that use traditional lidar systems often require additional hardware, complex software, and / or more computing power to manage this “noise.”

[0049] In contrast, FM lidar systems are not susceptible to these types of problems because each sensor is specifically designed to only respond to its own light characteristics (e.g., beam, wave, pulse). If the returning light does not match the timing, frequency, and / or wavelength of the originally emitted light, then the FM sensor can filter (e.g., remove, ignore, etc.) that data point. Thus, FM lidar systems produce (e.g., generate, derive, etc.) more accurate data with fewer hardware or software requirements, resulting in safer and smoother driving.

[0050] Finally, FM lidar systems are more easily scalable than traditional lidar systems. As more and more self-driving vehicles (e.g., cars, commercial trucks, etc.) appear on the road, vehicles powered by FM lidar systems can not have to deal with the interference problems that come with sensor cross-talk. Additionally, FM lidar systems use less peak power of light than traditional lidar sensors. Thus, some or all of the optical components of FM lidar can be produced on a single chip, which creates its own benefits as discussed herein.

[0051] FIG. 1BThis 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 cargo 182B. In some embodiments, the commercial truck 180B may include a vehicle configured for long-haul freight transport, regional freight transport, intermodal freight transport (i.e., where a road-based vehicle is used as one of a variety of transport modes to move cargo), and / or any other road-based freight transport application. The commercial truck 180B may be a flatbed truck, a refrigerated truck (e.g., a frozen truck), a ventilated van (e.g., a dry van), a mobile truck, etc. Cargo 182B may be goods and / or products. The commercial truck 180B may include trailers for carrying cargo 182B, such as flatbed trailers, low-floor trailers, ladder trailers, retractable flatbed trailers, side trailers, etc.

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

[0053] Commercial truck 180B may include lidar system 184B (e.g., FM lidar system, FIG. 1A The vehicle control system 120 in FIG. 2 The lidar system 201 (etc.) is used to determine the distance to object 111B and / or measure the velocity of object 111B. Although FIG. 1B A lidar system 184B is shown mounted on the front of a commercial truck 180B, but the number of lidar systems and the mounting areas of the lidar systems on the commercial truck are not limited to a specific number or specific area. The commercial truck 180B may include any number of lidar systems 184B (or components thereof, such as sensors, modulators, coherent signal generators, etc.) mounted in any area of ​​the commercial truck 180B (e.g., front, rear, side, top, bottom, under, and / or ground) to facilitate the detection of objects in any free space relative to the commercial truck 180B.

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

[0055] FIG. 1C This 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 included in environment 100B (e.g., commercial truck 180B, cargo 182B, lidar system 184B, etc.).

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

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

[0058] The environment 100D includes an object 111D (shown in FIG. 1D as another vehicle) that is within a distance range of more than 150 meters from the commercial truck 180B. As shown, the lidar system 184B in the environment 100D can be configured to detect an object (e.g., another vehicle, a bicycle, a tree, a street sign, a pothole, etc.) at a distance (e.g., 300 meters) from the 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 distance required for such vehicles. FM lidar systems (e.g., FMCW and / or FMQW systems) or PM lidar systems are well suited for commercial truck applications due to the advantages described above. Thus, a commercial truck equipped with such a system can have enhanced capabilities to safely move both people and cargo across 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 a FM or PM lidar system can be used in 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 completely operated by the FM or lidar system alone or in conjunction with other vehicle systems.

[0060] In lidar systems that use CW modulation, the modulator continuously modulates the laser. For example, if the modulation period is 10 seconds, then the input signal is modulated for the entire 10 seconds. In contrast, in lidar systems that use quasi-CW modulation, the modulator modulates the laser to have both active and non-active portions. For example, for a 10 second period, the modulator modulates the laser for only 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 is able to reduce the power consumption for that 2 seconds, as the modulator does not have to provide a continuous signal.

[0061] In frequency-modulated continuous-wave (FMCW) lidar for automotive applications, it can 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 always on (e.g., enabled, powered on, transmitted, etc.). In some implementations, the quasi-CW modulation can have a duty cycle equal to or greater than 1% and up to 50%. If energy in the off state (e.g., disabled, powered off, etc.) can be consumed during the actual measurement time, then there can be an improvement in 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] FIG. 2 is a block diagram illustrating an example environment for a lidar sensor system for an autonomous vehicle, according to some embodiments. The environment 200 includes a lidar sensor system 201 that includes 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 implementations, the semiconductor substrate and / or semiconductor package can include the Tx path and the Rx. In some implementations, 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 implementations, the first semiconductor substrate and / or first semiconductor package can include the Tx path and the second semiconductor substrate and / or second semiconductor package can include the Rx path. In some arrangements, the Rx input / output ports and / or Tx input / output ports can occur (or be formed / positioned / placed) along one or more edges of the 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] Environment 200 includes one or more optics 210 (e.g., oscillating scanners, unidirectional scanners, Risley prisms, circulator optics, and / or beam collimators, etc.) coupled to lidar system 201. In some embodiments, one or more optics 210 may be coupled to a Tx path via one or more Tx input / output ports. In some embodiments, one or more optics 210 may be coupled to an Rx path via one or more Rx input / output ports.

[0067] Environment 200 includes a vehicle control system 120 coupled to lidar system 201 (e.g., FIG. 1A (Vehicle control system 120 in the example). In some embodiments, 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, modulator 204A, modulator 204B, amplifier 206, and one or more transmitters 216. The Rx path may include one or more receivers 222, mixer 208, detector 212, transimpedance amplifier (TIA) 214, and one or more analog-to-digital converters (ADCs). Although FIG. 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 multiple functions of the combined lidar system to support vehicle operation.

[0069] Laser source 202 can be configured to generate an optical signal (or beam) derived from (or associated with) 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] Laser source 202 can be configured to provide an optical signal to modulator 204A, modulator 204A being configured to provide an optical signal based on a first radio frequency (RF) signal (in... FIG. 2The modulator 204A can be configured to modulate a phase and / or a frequency of the optical signal based on a first RF signal (shown in FIG. 2 as “RF1”) and using continuous wave (CW) modulation or quasi-CW modulation to generate a modulated optical signal. The modulator 204A can be configured to send the modulated optical signal to the amplifier 206. The amplifier 206 can be configured to amplify the modulated optical signal to generate an amplified optical signal to the optical device 210 via one or more transmitters 216. The one or more transmitters 216 can include one or more optical waveguides or antennas.

[0071] The optical device 210 can be configured to direct the amplified optical signal it receives from the Tx path into the environment within a given field of view toward the object 218, can 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 can include one or more optical waveguides or antennas. In some arrangements, the transmitter 216 and the receiver 222 can constitute one or more transceivers (not shown in FIG. 2). In some arrangements, the one or more transceivers can include a monostatic transceiver or a bistatic transceiver. FIG. 2

[0072] The laser source 202 can be configured to provide the LO signal to the modulator 204B, which is configured to modulate a phase and / or a frequency of the LO signal based on a second RF signal (shown in FIG. 2 as “RF2”) and using continuous wave (CW) modulation or quasi-CW modulation to generate a modulated LO signal and send the modulated LO signal to the mixer 208 of the Rx path. FIG. 3

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

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

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

[0076] ​​In some implementations, the TIA 214 can have a peak noise equivalent power (NEP) of less than 5 picoWatts per square root Hertz (i.e., 5 x 10-12 Watts per square root Hertz). In some implementations, the TIA 214 can have a gain between 4 kiloOhms and 25 kiloOhms.

[0077] In some implementations, the detector 212 and / or the TIA 214 can have a 3 decibel bandwidth between 80 kiloHertz (kHz) and 450 megaHertz (MHz).

[0078] The vehicle control system 120 can be configured to determine a distance to the object 218 and / or measure a 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 implementations, the modulator 204A and / or the modulator 204B can have a bandwidth between 400 megaHertz (MHz) and 1000 (MHz).

[0080] In some implementations, modulator 204A can be configured to transmit the first modulated optical signal and the second modulated optical signal to amplifier 206. Amplifier 206 can be configured to amplify the first modulated optical signal and the second modulated optical signal to generate an amplified optical signal to optical device 210 via transmitter 216. Optical device 210 can be configured to direct the first modulated optical signal and the second modulated optical signal it receives from the Tx path into the environment within a given field of view toward object 218, can 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 can 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. Mixer 208 can 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 transmit the first down-converted signal to detector 212. Similarly, mixer 208 can 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 transmit the second down-converted signal to detector 212. Detector 212 can be configured to generate first and second electrical signals based on the first and second down-converted signals, respectively. Vehicle control system 120 can be configured to determine a distance to object 218 and / or measure a velocity of object 218 based on the first and second electrical signals received via TIA 214 and ADC 220.

[0081] According to some implementations, a LIDAR system includes a seed laser, a modulator, an amplifier, and a transceiver chip. The modular LIDAR system allows components to be discrete optical components and integrated circuit PICS that are optically coupled through micro-lenses. This provides for higher yield of components, ease of configurability, assembly for different variations of each component, and variations of PIC architecture, e.g., optical components can be arranged in an optical circuit to implement different ways of optical functionality.

[0082] A seed laser is provided to generate an optical beam. In some embodiments, the seed laser can be an optical 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 light or optical beam from the seed laser can be optically coupled to input to 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 in that it can be constructed 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 beam splitter. In some embodiments, the modulator performs in-phase and quadrature modulation to generate the modulated optical beam. In some embodiments, the modulator performs phase modulation to generate the modulated optical beam. The beam splitter is coupled to and provides the output of the modulator. In some embodiments, the beam splitter is a single beam splitter that is passively integrated with the modulator of the modulator. In some embodiments, the beam splitter is a plurality of beam splitters. The modulator is modular in that 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 submount and the coupled transceiver chip is mounted on a second submount for alignment of the height of the seed laser assembly and the height of 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 integrated U-turns 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 of 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, e.g., specifically 4 or 5, and is configured to amplify the optical beam by stimulated emission. The amplifier can be optically coupled to the modulator by a microlens. Similarly, the amplifier is optically coupled to provide the amplified signal to the transceiver chip by a microlens.

[0086] In some embodiments, a silicon photonic (SiPho) transceiver chip includes at least one of a silicon photonic circuit, a programmable logic controller (PLC), or a III-V semiconductor circuit. The SiPho transceiver chip uses an amplifier to process coupled light. The SiPho transceiver chip includes a plurality of coherent pixels that process the output of the optical amplifier and emit light out of the surface of the SiPho transceiver chip, including 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 to a voltage that is then coupled out of the integrated chip package.

[0087] Reference will now be made to FIG. 3 FIG. 1 shows an example of a horizontal integration 100 of a photonic integrated circuit (PIC) 108 for a LIDAR long-range sensor system for autonomous vehicles, according to some embodiments. FIG. 3 A cross-section of the PIC 108 mounted to a SiPho carrier or chip 102 is shown. The example of the horizontal integration 100 couples the SiPho carrier or chip 102 with the PIC 108. As shown, the SiPho carrier 102 defines one or more pedestals on which the PIC 108 is coupled. The PIC 108 is coupled to the pedestals of the SiPho carrier 102 by connectors 106. The alignment of the structure of the SiPho carrier 102 with the PIC 108 provides robust alignment due to the optical mode of the PIC 108. For example, the optical mode can have dimensions that can typically range from ~1.0 um to ~3.0-10.0 um. On the same side as the pedestals (top side in FIG. 1), the SiPho carrier 102 has a metal layer 104 that provides heat sinking and backside metal patterning to assist pick and place. A portion of the SiPho carrier 102 is also coupled by a layer 110. Similarly, one side of the PIC 108 is covered with a metal layer 104 for heat sinking and backside metal patterning to assist pick and place. In some embodiments, the PIC 108 can include a second metal layer (not shown) on the side opposite the metal 106 to increase heat sinking. FIG. 3 FIG. 4A to FIG. 4C Reference will now be made to 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.

[0088] FIG. 4A to FIG. 4C FIG. 4A to FIG. 4C ​​​A high-level plan view of an example implementation of a semiconductor optical amplifier for a LIDAR sensor system for an autonomous vehicle is shown. In some implementations, the PIC 308 includes a monolithically integrated point-like transducer that optically couples the photonic integrated circuit to a connector with low-loss hybrid integration. In some implementations, 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 from the group of U-turns, total internal reflectors, mirrors, couplers, and beam splitters. As will be described below with reference to FIG. 4A to FIG. 4C More particularly described, the PIC 308 monolithically integrates two or more optical amplifiers, an array of U-turns, and passive components such that the photonic integrated circuit can be optionally optically coupled from a single side. These and other features will be apparent from the following description FIG. 4A to FIG. 4C of the PIC 308a, 308b, and 308c can be combined in other ways in addition to those specifically set forth herein. FIG. 4A

[0089] FIG. 4A An implementation of a first example PIC 308a is shown. In this implementation, the 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 FIG. 4A Four SOAs 402a-402d, four U-turns 404a-404d, and four passive connectors 406a-406d are shown, it should be understood that any number of SOAs, U-turns, and connectors can be monolithically integrated into the PIC 308a, and the use of four amplifiers is merely by way of example. FIG. 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 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 illustrated is that the SOAs 402a-402d have straight facets. It should be understood that an anti-reflection coating can be used to achieve 20 dB or less back reflection into the straight waveguide. It should be understood that FIG. 4A The symmetrical waveguide layout for the SOAs 402a-402d shown in FIG. 4A provides uniformity of power in the amplifier array due to uniform thermal / temperature distribution and uniform coupling efficiency in the case of bends. In one example, the PIC 308a and its components can have values that approximate those in Table 1.

[0090] ​

[0091] Table 1

[0092] FIG. 4B The PIC 308a also illustrates an arrangement of SOAs 402a-402d, U-turns 404a-404d, and passive connectors 406a-406d, with SOAs 402a-402d positioned near the center of the PIC 308a. Two U-turns 404a and 404b are coupled to connectors 406a and 406b on one side of the SOA 402a-402d array; while the other two U-turns 404c and 404d are coupled to connectors 406c and 406d on the other side of the SOA 402a-402d array. In some embodiments, the input optical power of each SOA 402a-402d is approximately 50mW, and the output power of each SOA 402a-402d is approximately 550mW.

[0093] FIG. 4B An embodiment of the second example PIC 308b is shown. Again, this second example PIC 308b includes a plurality of SOAs 402a-402d, a plurality of U-bends 404a-404d, and a plurality of passive connectors 406a-406d. The number of SOAs 402a-402d is four, with a corresponding number of U-bends 404a-404d and passive connectors 406a-406d. However, alternative embodiments of the PIC 308b can have any number of SOAs 402, U-bends 404, and passive connectors 406. The example PIC 308b and its components can also have values ​​approximating those described above in Table 1. FIG. 4A The layout and FIG. 4B The layout differs. More specifically, SOA 402a-402d is positioned on one side of PIC 308b, while passive connectors 406a-406d extend parallel to SOA 402a-402d and on one side of SOA 402a-402d. U-turns 404 couple the corresponding SOA 402 and passive connectors 406. U-turn 404a is longer than the other U-turns 404b-404d, and the length of each U-turn 404b-404d is slightly reduced compared to the others. FIG. 4B The illustration shows another configuration for integration (e.g., monolithic integration), where the inputs and outputs are both located on one side of the PIC 308a (e.g., FIG. 4B On the top of the PIC 308b, where the input faces the first end of the PIC 308b (e.g., at the top). FIG. 4B (to the left) group, while the outputs 406d-406a face the second end of the PIC 308b (e.g., FIG. 4A (On the right side). Similar toFIG. 4C In this embodiment, the input optical power for each SOA 402a-402d is approximately 50mW, and the output power for each SOA 402a-402d is approximately 550mW.

[0094] FIG. 4C A third example implementation of the PIC 308c is shown. In this implementation, the PIC 308c includes multiple power SOAs 402a-402d, multiple U-turns 404a-404d, a gain amplifier 408, and a beam splitter 410. Although FIG. 4C Four power SOAs 402a-402d and four U-turns 404a-404d are shown, but it should be understood that any number of power SOAs and U-turns can be monolithically integrated into the PIC 308c, and four power SOAs are used only as an example. Similarly, although in FIG. 4C Only a single gain amplifier 408 and a single beam splitter 410 are shown in the illustration, but in other embodiments, various combinations of gain amplifier 408 and beam splitter 410 can be monolithically integrated into the PIC 308c. As illustrated, the input signal is input to gain amplifier 408. In some embodiments, gain amplifier 408 is an SOA providing approximately 10 dB of gain, and the input to the SOA is 50 mW. In some embodiments, multiple gain amplifiers 408 may be present. The output of gain amplifier 408 is input to beam splitter 410. In this example, beam splitter 410 is a 1-to-4 beam splitter. It should be understood that beam splitter 410 or multiple beam splitters have multiple outputs corresponding to the number of power SOAs 402a-402d integrated into the PIC 308c. For example, in various configurations, beam splitter 410 may 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 power amplifier 402. In some implementations, the gain amplifier 408 outputs a signal with approximately 27 dBm. This signal is split into four signals with approximately 19 dBm by a beam splitter 410. 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 approximately 8 dB. Each power SOA 402a-402d amplifies its received signal and outputs a 550 mW signal. For example, each power SOA 402a-402d can provide approximately 8 dB of gain. This results in the PIC 308c being able to output four amplified signals, each approximately 550 mW (+27 dB). FIG. 4AThe embodiment shown is particularly advantageous because the PIC 308c offers exceptionally high gain and / or exceptionally high power amplification. For example, typical optical gain or amplification can be in the range of +2 to +25 dB. FIG. 5A As can be seen from the floor plan, with FIG. 5A and 4B In contrast to the vertical configuration, each of the power SOAs 402a-402d is slightly angled. In some embodiments, the power SOAs 402a-402d and the gain amplifier 408 have a large active waveguide spacing of 500 μm (along the surface) to reduce thermal crosstalk between SOAs. It should be understood that although SOAs 402a-402d are depicted as SOAs without any taper, in alternative embodiments, one or more SOAs may be tapered semiconductor optical amplifiers (TSOAs).

[0095] FIG. 5B A cross-sectional view of an example implementation of SOA 402 for an autonomous vehicle is shown. SOA 402 includes components from... FIG. 5A The layers below the bottom to the top include 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 the opposite direction to the n-type layer 504a. For example, a metal layer is formed, and 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 below the silicon-doped layer 502a. (See reference...) FIG. 5B One or more metal layers can be coupled to layer 502b in the opposite direction to 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 layer 502b. In other embodiments, a metal layer may not be formed below layer 502b. It should be noted that the above refers to... FIG. 6 And below for FIG. 5B and FIG. 6The described configuration is particularly advantageous because backside (bottom of the chip) metallization can be applied even if no current flows 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 assists in making electrical connections with the carrier / submount. Accordingly, 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 electrical circuit.

[0096] In some embodiments, the silicon-doped layer 502a can be an n+-InP layer, for example, as FIG. 5A and FIG. 5B Specifically shown is silicon or sulfur-doped indium phosphide. In some embodiments, other types of n-doped layers can be used.

[0097] 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.

[0098] A guiding layer 506a is formed on the n-doped layer 504a. In some embodiments, the guiding layer 506a has a particular structure configured for heat dissipation. In some embodiments, the particular structure configured for heat dissipation includes an alternating or periodic or superlattice structure. For example, the guiding layer 506a can be 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 can be in the range of 300-500 nm. In some embodiments, the guiding layer 506a can be indium gallium arsenide phosphide (InGaAsP) or aluminum indium gallium 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 silicon photonic waveguides.

[0099] A 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 in the range of 100-150 nm.

[0100] In some embodiments, the first confinement layer 510a and the second confinement layer 514a are separate confinement heterostructures (SCHs). In some embodiments, the first confinement layer 510a and the second confinement layer 514a can 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 a slab of the active layer 512.

[0101] The active layer 512a is formed on the first confinement layer 510a and between the second confinement layers 514b. In some embodiments, the active layer 512a is strained to generate a power of >50 mW, e.g., in a range of 50 mW to 800 mW. In some embodiments, the active layer 512a is a strained quantum mechanical structure. More specifically, the active layer 512a can be a strained multi-quantum well (MQW) or a strained quantum dot. For example, the active layer 512a can have 2 to 8 wells. In some embodiments, the active layer 512 can have 2-4 MQW structures with a lower confinement factor of optical modes, where the active MQW is about 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 a p-doped indium phosphide 518b. For example, as shown, a metal layer 520a is formed on top of and around the sides of the ridge layer 518a. In this example, one or more insulating regions 517a, 517b can 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 certain portions (e.g., the top) of the ridge layer 518a are coupled to the metal layer 520a. FIG. 5A

[0104] FIG. 5B An embodiment of an SOA 402 for a LIDAR sensor system for an autonomous vehicle is shown that is similar to FIG. 6 the SOA 402 described above, but the example specific materials for each of the layers 502b-520b described above have been provided for each of the layers 502a-520a, as shown. For example, the ridge layer 518a is formed of a p-doped indium phosphide 518b. A metal layer 520b is formed on top of and around the sides of the P-InP ridge layer 518b, as shown. FIG. 6 ​The depicted. In this example, one or more insulating regions 517a, 517b can 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 certain portions (e.g., tops) of the ridge layer 518b are coupled to the metal layer 520b.

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

[0106] Reference is now made to FIG. 5A , which describes an example implementation of a PIC including a SOA array 600 for a LIDAR sensor system for an autonomous vehicle, the SOA array 600 including a first SOA 402a and a second SOA 402b. It is provided FIG. 6 to illustrate how the same structures and processes described above with reference to FIG. 5A and 5B can be used to form the SOA array 600. It is further provided FIG. 5B to illustrate how the SOAs 402a, 402b can have the same layers, different layers, additional layers, or fewer layers as the implementations described above with reference to FIG. 6 and FIG. 6 . Additionally, it is provided FIG. 5A to illustrate how a portion of the PIC can be registered for hybrid integration with an alignment fiducial 604 and a recessed cap to further simplify the integration process. As FIG. 5B shown, the first SOA 402a is formed from the layers 502b-518b and the layer 602; and the second SOA 402b is formed from the layers 502b-518b and the layer 602. In this implementation, the first SOA 402a and the second SOA 402b share the n-doped InP 502b. The n + -doped 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 adjacent to the first SOA 402a and the second SOA 402b, respectively. The n + -doped 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 adjacent to the first SOA 402a and the second SOA 402b, respectively. The n +- 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 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 recessed cladding for vertical alignment of 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 a LIDAR sensor system. As noted 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, an n-InP layer 504b, and a p-doped layer, a p-InP layer 518b, between the n-doped layer and the p-doped layer. + - the Q1.3 layer 602 over a portion of the InP 502b proximate to its bottom or base. The Q1.3 layer 602 is positioned between the n-doped layer and the p-doped layer. + - between the InP layer 502b and the n-type layer, the n-InP layer 504b.

[0107] Similarly to FIG. 6 and FIG. 5A , in FIG. 6 , one or more metal layers can be formed below the layer 502b. Further, similarly to FIG. 5A and 5B , in ​ , an insulating region can be formed to cover certain portions of the p-InP ridge layer 518b and certain portions of the current spreading layer 516b of the first SOA 402a and the second SOA 402b, but to expose certain portions of the p-InP layer 518b. Further, similarly to the metal layers 520a, 520b in ​ and 5B , one or more metal layers can be formed to cover the p-InP ridge layer 518b, the insulating region, and the current spreading layer 516b, such that the metal layers can be coupled to only certain portions (e.g., the top portions) of the p-InP ridge layer 518b.

[0108] The foregoing detailed description of the disclosure has been presented for the 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 teaching. The described embodiments were chosen in order to best illustrate the principles of the disclosure and its practical application to thereby enable others skilled in the art to best utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated. The scope of the disclosure is intended to be defined by the claims appended hereto.

[0109] While some embodiments of the present disclosure have been described in detail, and by way of examples, it is to be understood that various changes, modifications, and substitutions can be made by one skilled in the art without departing from the spirit and scope of the present disclosure as defined by the appended claims. For example, it will be readily apparent to one of ordinary skill in the art that the numerous features, functions, processes and materials described herein can be varied, while maintaining within the scope of the present disclosure. Moreover, the scope of the present disclosure is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods or steps.

Claims

1. A light detection and ranging LIDAR system, comprising: A laser, configured to output a 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 structural configuration within the optical amplifier includes (i) an active layer and (ii) a guiding layer coupled to the active layer and including a specific structure of alternating indium phosphide and ternary or quaternary alloy materials configured for heat dissipation. as well as A transceiver chip coupled to the photonic integrated circuit, the transceiver chip being configured to emit the amplified light beam and receive the reflected light beam from the target.

2. The LIDAR system according to claim 1, wherein, The active layer is a deflected volume quantum mechanical structure or a multi-quantum mechanical structure.

3. The LIDAR system according to claim 2, wherein, The offset volume quantum mechanical structure is one of the groups of offset multi-quantum wells or offset quantum dot layers.

4. The LIDAR system according to claim 1, wherein, 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.

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

6. The LIDAR system according to claim 1, wherein, The specific structure includes alternating or periodic or superlattice structures, which include one or more alternating layers of indium phosphide and indium gallium arsenide phosphide (InGaAsP) or indium gallium aluminum arsenide (InGaAlAs) or other quaternary or ternary alloys to improve heat dissipation, thereby producing high wall socket efficiency.

7. The LIDAR 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 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 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 system according to claim 9, wherein, The semiconductor optical amplifier (SOA) is coupled to the coupler via a U-shaped bend, and the semiconductor optical amplifier is monolithically integrated to provide input on the same side of the photonic integrated circuit.

11. The LIDAR system according to claim 1, wherein, The photonic integrated circuit includes and monolithically integrates a second amplifier, the second amplifier providing a specific gain, and the output of the second amplifier being coupled to the input of the optical amplifier.

12. A photonic integrated circuit, comprising: A first amplifier, coupled to receive an input beam and generate an amplified beam, wherein a structural configuration within the first amplifier includes an active layer and a guiding layer coupled to the active layer, the guiding layer including a specific structure of alternating indium phosphide and ternary or quaternary alloy materials configured to improve heat dissipation; as well as One or more passive components, said one or more passive components being monolithically integrated with the first amplifier as part of the photonic integrated circuit.

13. The photonic integrated circuit according to claim 12, wherein, The active layer is an offset body or a multi-quantum well structure.

14. The photonic integrated circuit according to claim 13, wherein, The offset body or multiple quantum well structure is one of the groups of offset body quantum well, multiple quantum well, or offset quantum dot layer.

15. The photonic integrated circuit according to claim 12, wherein, The specific structure is integrated with a silicon photonic waveguide and has an optical mode converter.

16. The photonic integrated circuit of claim 12, comprising a monolithically integrated spot size converter, wherein the photonic integrated circuit is optically coupled to an optical waveguide.

17. The photonic integrated circuit according to claim 12, wherein, The semiconductor optical amplifier (SOA) is coupled to the coupler via a U-shaped bend.

18. The photonic integrated circuit of claim 12, further comprising a second amplifier providing a specific gain, the output of the second amplifier being coupled to the input of the first amplifier.

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