LIDAR sensor system including a seed modulation module

Abstract

A vehicle-mounted LIDAR (Light Detection and Ranging) system may include an input optical path, a first optical path, multiple second optical paths, a first optical amplifier, and multiple second optical amplifiers. The input optical path may be configured to receive a beam from a laser source. The first optical path and the multiple second optical paths may each branch off from the input optical path. The first optical amplifier may be coupled to the first optical path and configured to output a local oscillator (LO) signal. The multiple second optical amplifiers may be coupled to the multiple second optical paths, respectively, and one of the multiple second optical amplifiers may be configured to modulate a beam received via the second optical path and selectively turn on to output a modulated optical signal of the beam.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Application No. 17 / 888,364 (now U.S. Patent No. 11,619,716), filed August 15, 2022, the disclosure of which is incorporated herein by reference in its entirety. [Background technology]

[0002] Light detection and ranging (LIDAR) sensor systems are used in a variety of applications, from altitude measurement to imaging and collision avoidance. LIDAR offers finer range resolution with smaller beam sizes than traditional microwave ranging systems such as Radio-Wave Detection and Ranging (RADAR). Optical ranging can be performed using a variety of techniques, including direct ranging based on the round-trip travel time of a light pulse to an object; chirp detection, based on the frequency difference between a transmitted chirped light signal and the return signal scattered from the object; and phase-encoded detection, based on a series of single-frequency phase changes that are distinguishable from natural signals.

[0003] When applying such technology, a LIDAR sensor system may include a modulator configured to receive an optical signal from a laser source and modulate the optical signal before transmitting the optical signal to the environment. The LIDAR sensor system may use time-separated I / Q processing (also known as time-domain multiplexing) to overcome hardware requirements. For example, multiple transmit (TX) channels may be time-multiplexed to share limited hardware resources (e.g., receive (RX) side hardware resources). Therefore, a mechanism is needed to efficiently perform modulation and multiplexing with limited hardware resources. Summary of the Invention

[0004] Embodiments of the present disclosure relate to systems and methods for light detection and ranging (LIDAR) sensor systems, and more particularly, to systems and methods for LIDAR sensor systems that include a seed modulation module.

[0005] In some embodiments of the present disclosure, an apparatus may include an input optical path, a first optical path, a plurality of second optical paths, a first optical amplifier, a plurality of second optical amplifiers, and a control circuit. The input optical path may be configured to receive a beam from a laser source at one end. The first optical path and the plurality of second optical paths may each branch at the other end of the input optical path. The first optical amplifier may be coupled to the first optical path. The plurality of second optical amplifiers may be coupled to the plurality of second optical paths, respectively. The control circuit may be configured to selectively turn on one of the plurality of second optical amplifiers to output a modulated optical signal of the beam. The control circuit may be configured to turn on the first optical amplifier in synchronization with turning on one of the plurality of second optical amplifiers to output a local oscillator (LO) signal.

[0006] In some embodiments of the present disclosure, an autonomous vehicle control system may include one or more processors and one or more computer-readable storage media. The storage medium may store instructions, which, when executed by the one or more processors, cause the one or more processors to generate, based on a beam generated from a laser source, an optical signal that is frequency-shifted by a frequency offset relative to a local oscillator (LO) signal. The one or more processors may be configured to transmit the optical signal into an environment. In response to transmitting the optical signal, the one or more processors may be configured to receive a return optical signal that is reflected back from an object in the environment. The one or more processors may be configured to generate a digital signal based on the received signal. The one or more processors may be configured to digitally mix the digital signal based on the frequency offset to generate a sample signal. The one or more processors may be configured to determine a distance to the object based on the sample signal. The one or more processors may be configured to control operation of the vehicle using the distance to the object.

[0007] In some embodiments of the present disclosure, a LIDAR system may include a device, a laser source configured to generate a beam, multiple transmit (TX) channels, and one or more optical components. The one or more optical components may be configured to receive a first modulated optical signal and a first LO signal associated with the first modulated optical signal from the device. The one or more optical components may be configured to receive a second modulated optical signal and a second LO signal associated with the second modulated optical signal from the device. The one or more optical components may be configured to transmit the first and second modulated optical signals, respectively, on the first and second TX channels of the multiple TX channels into an environment. The one or more optical components may be configured to receive first and second return optical signals reflected back from one or more objects in the environment. The one or more optical components may be configured to pair the first and second return optical signals with the first and second LO signals, respectively.

[0008] In some embodiments of the present disclosure, a method for generating a modulated optical signal in a circuit may include the circuit receiving a beam from a laser source at an input optical path of the circuit. The circuit may include the input optical path, a first optical path and a plurality of second optical paths each branching from the input optical path, a first optical amplifier coupled to the first optical path, and a plurality of second optical amplifiers coupled to each of the plurality of second optical paths. The method may include the circuit receiving a beam from the laser source at the input optical path. The method may include the circuit selectively turning on one of the plurality of second optical amplifiers to output a modulated optical signal of the beam. The method may include the circuit turning on the first optical amplifier synchronously with turning on one of the plurality of second optical amplifiers to output a local oscillator (LO) signal.

[0009] In some embodiments of the present disclosure, a vehicle LIDAR system may include an input optical path configured to receive a beam from a laser source, a first optical path and a plurality of second optical paths each branching from the input optical path, a first optical amplifier coupled to the first optical path and configured to output a local oscillator (LO) signal, and a plurality of second optical amplifiers coupled to each of the plurality of second optical paths, wherein one of the plurality of second optical amplifiers can be selectively turned on to modulate the beam received via the second optical path and output a modulated optical signal of the beam.

[0010] In some embodiments of the present disclosure, an autonomous vehicle may include a vehicle controller including at least one of a LIDAR system, a steering system, or a braking system and one or more processors. The LIDAR system may include an input optical path configured to receive a beam from a laser source, a first optical path and multiple second optical paths each branching from the input optical path, a first optical amplifier coupled to the first optical path and configured to output a local oscillator (LO) signal, and multiple second optical amplifiers coupled to the multiple second optical paths, respectively. One of the multiple second optical amplifiers can be selectively turned on to modulate the beam received via the second optical path and output a modulated optical signal for the beam. The one or more processors may be configured to transmit the modulated optical signal into an environment, receive a return optical signal reflected back from an object in the environment, pair the return optical signal with the LO signal to generate an electrical signal, and operate the LIDAR system to control at least one of the steering system or the braking system using the electrical signal. [Brief explanation of the drawings]

[0011] The patent or application file contains one or more drawings executed in color. Copies of patent application publications with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0012] These and other aspects and features of the present embodiments will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments in conjunction with the accompanying drawings.

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

[0014] [Figure 1b] FIG. 1 is a block diagram illustrating an example of a system environment for an autonomous commercial trucking vehicle, according to some embodiments.

[0015] [Figure 1c] FIG. 1 is a block diagram illustrating an example of a system environment for an autonomous commercial trucking vehicle, according to some embodiments.

[0016] [Figure 1d] FIG. 1 is a block diagram illustrating an example of a system environment for an autonomous commercial trucking vehicle, according to some embodiments.

[0017] [Figure 2] FIG. 1 is a block diagram illustrating an example of a LIDAR system for an autonomous vehicle, according to some embodiments.

[0018] [Figure 3a] FIG. 1 is a block diagram illustrating an example of a LIDAR system according to some embodiments.

[0019] [Figure 3b] 1 is a block diagram illustrating an example of a seed modulation device according to some embodiments.

[0020] [Figure 3c] FIG. 1 is a block diagram illustrating an example of a seed modulation assembly according to some embodiments.

[0021] [Figure 4] FIG. 1 is a block diagram illustrating another example of a LIDAR system according to some embodiments.

[0022] [Figure 5] 1 is a flowchart illustrating an exemplary methodology for generating a modulated optical signal using a seed modulator according to some embodiments.

[0023] [Figure 6] 1 is a flowchart illustrating an exemplary methodology for controlling a LIDAR system using a seed modulation device in accordance with some embodiments.

[0024] [Figure 7] FIG. 1 is a block diagram illustrating an example of a computing system according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0025] According to certain aspects, embodiments of the present disclosure relate to systems and methods for controlling a vehicle using light detection and ranging (LIDAR), and more particularly, to systems and methods for a LIDAR sensor system that includes a seed modulation module.

[0026] According to certain aspects, an apparatus may include an input optical path, a first optical path, a plurality of second optical paths, a first optical amplifier, a plurality of second optical amplifiers, and a control circuit. The input optical path may be configured to receive a beam from a laser source at one end. The first optical path and the plurality of second optical paths may each branch at the other end of the input optical path. The first optical amplifier may be coupled to the first optical path. The plurality of second optical amplifiers may be coupled to the plurality of second optical paths, respectively. The control circuit may be configured to selectively turn on one of the plurality of second optical amplifiers to output a modulated optical signal of the beam. The control circuit may be configured to turn on the first optical amplifier synchronously with turning on one of the plurality of second optical amplifiers to output a local oscillator (LO) signal. 1. System Environment for Autonomous Vehicles

[0027] FIG. 1a is a block diagram illustrating an example system environment for an autonomous vehicle, according to some embodiments.

[0028] 1a, an exemplary autonomous vehicle 110A in which various techniques disclosed herein may be implemented is shown. For example, vehicle 110A may include a powertrain 192 including a prime mover 194 that may be powered by an energy source 196 and provide power to a drivetrain 198, and a control system 180 including directional control 182, powertrain control 184, and brake control 186. Vehicle 110A may be implemented as any number of different types of vehicles, including vehicles capable of transporting people and / or cargo and operating in a variety of environments, and the components 180-198 described above may vary widely based on the type of vehicle in which they are used.

[0029] For simplicity, the embodiments discussed below focus on wheeled land vehicles such as cars, vans, trucks, and buses. In such embodiments, prime mover 194 may include (among other things) one or more electric motors and / or internal combustion engines. Energy sources 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. Drivetrain 198 may include wheels and / or tires along with a transmission and / or any other mechanical drive components for converting the power output of prime mover 194 into vehicle motion, and may include one or more brakes configured to controllably stop or slow vehicle 110A, and directional or steering components suitable for controlling the trajectory of vehicle 110A (e.g., a rack-and-pinion steering linkage that allows one or more wheels of vehicle 110A to pivot about a generally vertical axis to change the angle of the wheel's plane of rotation relative to the vehicle's longitudinal axis). In some embodiments, a combination of powertrains and energy sources can be used (e.g., in the case of electric / gas hybrid vehicles), and in some embodiments, multiple electric motors (e.g., dedicated to individual wheels or axles) can be used as prime movers.

[0030] Directional control 182 may include one or more actuators and / or sensors for controlling and receiving feedback from directional or steering components to enable vehicle 110A to follow a desired trajectory. Powertrain control 184 may be configured to control the speed and / or direction of vehicle 110A by controlling the output of powertrain 102, such as by controlling the output of prime mover 194 and controlling the gears of a transmission in drivetrain 198. Brake control 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 110A.

[0031] Other vehicle types, including, but not limited to, off-road vehicles, all-terrain or tracked vehicles, construction equipment, etc., may use different powertrains, drivetrains, energy sources, directional control, powertrain control, and braking control. Also, in some embodiments, some of the components may be combined; for example, directional control of the vehicle is primarily handled by modifying the 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.

[0032] Various levels of autonomous control for vehicle 110A may be implemented in vehicle control system 120, which may include one or more processors 122 and one or more memories 124, each of which may be 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)).

[0033] The sensors 130 may include various sensors suitable for collecting information from the vehicle's surrounding environment for use in controlling the vehicle's operation. For example, the sensors 130 may include a radar sensor 134, a LIDAR sensor 136, and a 3D positioning sensor 138 (e.g., an accelerometer, a gyroscope, a magnetometer, or one of a satellite navigation system such as GPS (Global Positioning System), GLONASS (Globalnaya Navigazionnaya Sputnikovaya Sistema, or Global Navigation Satellite System), 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 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 in three directions. One or more encoders (not shown), such as wheel encoders, may be used to monitor the rotation of one or more wheels of the vehicle 110A. Each sensor 130 may output sensor data at a variable data rate that may differ from the data rates of the other sensors 130.

[0034] The outputs of the sensors 130 may be provided to a set of control subsystems 150, including a position estimation subsystem 152, a planning subsystem 156, a perception subsystem 154, and a control subsystem 158. The position estimation subsystem 152 may perform functions such as precisely determining the position and orientation (also sometimes referred to as “pose”) of the vehicle 110A within the surrounding environment, and generally within some reference frame. The autonomous vehicle's position may be compared to the positions of additional vehicles within the same environment as part of generating labeled autonomous vehicle data. The perception subsystem 154 may perform functions such as detecting, tracking, determining, and / or identifying objects within the vehicle's 110A environment. Machine learning models may be utilized to track the objects. The planning subsystem 156 may perform functions such as planning the vehicle's trajectory over some time frame given a desired destination, as well as primarily static and moving objects within the environment. Machine learning models may be utilized to plan the vehicle trajectory. Control subsystem 158 may perform functions such as generating appropriate control signals to control various controls within vehicle control system 120 to implement a planned trajectory for vehicle 110A. Machine learning models may be utilized to generate one or more signals to control the autonomous vehicle to implement the planned trajectory.

[0035] It will be understood that the collection of components shown in FIG. 1a for vehicle control system 120 is merely exemplary. In some embodiments, individual sensors may be omitted. Additionally or alternatively, in some embodiments, multiple sensors of the type shown in FIG. 1a may be used redundantly and / or to cover different areas around the vehicle, and other types of sensors may be used. Similarly, different types and / or combinations of control subsystems may be used in other embodiments. 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 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. As previously mentioned, multiple subsystems may use circuits, processors, sensors, and / or other components, and the various components of vehicle control system 120 may be networked in a variety of ways.

[0036] In some embodiments, vehicle 110A may further include a secondary vehicle control system (not shown) that can be used as a redundant or backup control system for vehicle 110A. The secondary vehicle control system may be capable of fully operating autonomous vehicle 110A 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, for example, shutting down vehicle 110A 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.

[0037] 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 vehicle 110A, 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 shown in FIG. 1a, or entirely separate processors, can be used to implement additional functions within vehicle 110A other than those for autonomous control, such as operation of entertainment system control, doors, lighting, convenience functions, etc.

[0038] Also, for additional storage devices, vehicle 110A 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.

[0039] Additionally, vehicle 110A may include a user interface 164, such as one or more displays, touchscreens, voice and / or gesture interfaces, buttons and other tactile controls, etc., that allows vehicle 110A to receive a number of inputs from a user or operator and generate outputs for the user or operator. Alternatively, user input may be received via an app or web interface on another computer or electronic device, such as a mobile device.

[0040] Vehicle 110A may also include one or more network interfaces, e.g., network interface 162, suitable for communicating with one or more networks 170 (e.g., a local area network (LAN), a wide area network (WAN), a wireless network, and / or the Internet, etc.), thereby enabling communication of information with other computers and electronic devices, including, for example, a central service such as a cloud service, so that vehicle 110A may receive environmental and other data usable for autonomous control. Data collected by one or more sensors 130 may be uploaded via network 170 to computing system 172 for further processing. A timestamp may be added to each instance of vehicle data before uploading. Further processing of autonomous vehicle data by computing system 172 according to many embodiments is described in connection with FIG. 2.

[0041] Each processor shown in FIG. 1a, and the various additional controllers and subsystems disclosed herein, generally operates under the control of an operating system, as described in more detail below, and executes or relies on various computer software applications, components, programs, objects, modules, data structures, etc. Additionally, the various applications, components, programs, objects, modules, etc. may execute on one or more processors of other computers coupled to vehicle 110A via network 170, e.g., in a distributed, cloud-based, or client-server computing environment where the processing required to implement the functionality of a computer program is allocated across multiple computers and / or services via the network.

[0042] Generally, the routines executed to implement the various embodiments described herein, whether embodied as part of an operating system, a specific application, component, program, object, module, or sequence of instructions, or any subset thereof, are referred to herein as "program code." Program code comprises one or more instructions that reside at various times in various memory and storage devices and that, when read and executed by one or more processors, perform the steps necessary to perform the steps or elements that embody various aspects of the present disclosure. Also, while the embodiments are described in the context of fully functional computers and systems, it will be understood that the various embodiments described herein can be distributed as program products in various forms, and that the embodiments can be embodied independently of the particular type of computer-readable medium used to actually accomplish such distribution.

[0043] 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.

[0044] Additionally, various program code described below may be identified based on the application for which it is embodied 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 open-ended way in which computer programs may be organized into routines, procedures, methods, modules, objects, etc., and the various ways in which program functions 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 functions described herein.

[0045] The environment illustrated in Figure 1a is not intended to be limiting of 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. 2. FM LIDAR for automotive applications

[0046] The truck may include a LIDAR system (e.g., vehicle control system 120 of FIG. 1a, LIDAR system 201 of FIG. 2, LIDAR system 301 of FIG. 3a, LIDAR system 401 of FIG. 4, 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.

[0047]

[0048]

[0049]

[0050]

[0051]

[0052] FM or phase-modulated (PM) LIDAR systems may offer significant advantages over conventional LIDAR systems for automotive and / or commercial trucking applications. First, in some cases, an object (e.g., a pedestrian wearing dark clothing) may have low reflectivity, in that only a small amount (e.g., 10% or less) of the light striking the object is reflected 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 a large amount of the light striking the object is reflected back to the FM LIDAR system's sensor.

[0053] 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.

[0054] To achieve this improvement in detection capabilities, 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 the sensor 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 requires limiting their light output (and distance sensing capabilities) for eye safety reasons.

[0055] Therefore, by detecting objects at greater distances, FM LIDAR systems have more time to react to unexpected obstacles. Indeed, even a few milliseconds of additional time can improve stability and convenience, especially for large vehicles (e.g., commercial trucks) traveling on highways.

[0056] Another advantage of FM LIDAR systems is that they can instantly provide accurate velocity for each data point. In some embodiments, velocity measurement is achieved using the Doppler effect, which shifts the frequency of light received from an object based on at least one of the radial velocity (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 velocities 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.

[0057] Instantaneous velocity calculations also make it easier for an FM LIDAR system to qualify distant or sparse data points as objects and / or track how these objects are moving over time. For example, an FM LIDAR sensor (e.g., sensor 130 in FIG. 1a) may receive only a few returns (e.g., collisions) for an object 300 m away, but if these returns provide a velocity value of interest (e.g., heading toward the vehicle at a speed greater than 70 mph), the FM LIDAR system and / or autonomous vehicle control system can determine individual weights for the probability associated with the object.

[0058] Faster identification and / or tracking for FM LIDAR systems gives autonomous vehicle control systems more time to steer the vehicle. With a better understanding of how fast an object is moving, autonomous vehicle control systems can better plan their response.

[0059] Another advantage of FM LIDAR systems is that they are less static than traditional LIDAR systems. That is, traditional LIDAR systems, designed to be more sensitive to light, typically perform poorly in bright sunlight. Such systems tend to suffer from 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."

[0060] 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 a smoother driving experience.

[0061] Finally, FM LIDAR systems are more easily scalable than traditional LIDAR systems. As more autonomous vehicles (e.g., cars, commercial trucks, etc.) appear 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 offers unique advantages as discussed herein. 3. Commercial Trucking

[0062] FIG. 1b is a block diagram illustrating an example of a system environment for autonomous commercial trucking vehicles, according to some embodiments. The environment 100B includes a commercial truck 102B for carrying cargo 106B. In some embodiments, the commercial truck 102B may include a vehicle configured for long-haul freight transportation, regional freight transportation, intermodal freight transportation (i.e., 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 102B 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 106B may be merchandise and / or agricultural products. The commercial truck 102B may include a trailer for carrying the cargo 106B, such as a flatbed trailer, a lowboy trailer, a step deck trailer, an extendable flatbed trailer, a side-kick trailer, etc.

[0063] The environment 100B includes an object 110B (shown as another vehicle in FIG. 1b) within a distance range of 30 meters or less from the truck.

[0064] The commercial truck 102B may include a LIDAR system 104B (e.g., the FM LIDAR system of FIG. 1a, the LIDAR system 201 of FIG. 2, the LIDAR system 301 of FIG. 3a, the LIDAR system 401 of FIG. 4, etc.) for determining the distance to the object 110B and / or measuring the velocity of the object 110B. Although FIG. 1b shows one LIDAR system 104B mounted on the front of the commercial truck 102B, the number of LIDAR systems mounted on the commercial truck and the mounting areas of the LIDAR systems are not limited to a particular number and area. The commercial truck 102B may include any number of LIDAR systems 104B (or components thereof, such as sensors, modulators, coherent signal generators, etc.) mounted on any area (e.g., the front, back, sides, top, bottom, lower, bottom, and / or bottom) of the commercial truck 102B to facilitate detection of objects in any free space about the commercial truck 102B.

[0065] As shown, the LIDAR system 104B in the 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 the commercial truck 102B.

[0066] 1c is a block diagram illustrating an example of a system environment for an autonomous commercial trucking vehicle, according to some embodiments. Environment 100C includes the same components included in environment 100B (e.g., commercial truck 102B, cargo 106B, LIDAR system 104B, etc.).

[0067] Environment 100C includes object 110C (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 102B. As shown, LIDAR system 104B 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 102B.

[0068] 1d is a block diagram illustrating an example of a system environment for an autonomous commercial trucking vehicle, according to some embodiments. Environment 100D includes the same components included in environment 100B (e.g., commercial truck 102B, cargo 106B, LIDAR system 104B, etc.).

[0069] Environment 100D includes object 110D (shown as another vehicle in FIG. 1d) within a distance range of 150 meters or more from commercial truck 102B. As shown, LIDAR system 104B 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 102B.

[0070] For commercial trucking applications, effective object detection at all ranges is important due to increased vehicle weight and correspondingly longer stopping distances. FM LIDAR systems (e.g., FMCW and / or FMQW systems) or PM LIDAR systems are ideally suited for commercial trucking 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 the commercial truck as well as surrounding vehicles. In various embodiments, these FM or PM LIDAR systems can be used in semi-autonomous applications, where a driver is on board the commercial truck and some functions of the commercial truck are operated autonomously using the FM or PM LIDAR system, or in fully autonomous applications, where the commercial truck is operated entirely by the FM or LIDAR system alone or in combination with other vehicle systems. 4. Continuous Wave (CW) Modulation and Quasi-Continuous Wave (Quasi-CW) Modulation

[0071] 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 for only 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.

[0072] For frequency-modulated continuous wave (FMCW) LIDAR for vehicle applications, FMCW measurement and signal processing methodologies are used, but it may be advantageous to operate the LIDAR system using quasi-CW modulation, rather than having the optical signal always on (e.g., activated, powered, transmitting, etc.). In some embodiments, the quasi-CW modulation may have a duty cycle of 1% or more up to 50% or less. If the energy in the off state (e.g., inactivated, powered down, etc.) is dissipated during the actual measurement time, the signal-to-noise ratio (SNR) may be improved or less signal processing is required, allowing all energy to be consistently integrated over a longer period of time. 5. LIDAR Systems for Autonomous Vehicles

[0073] 2 is a block diagram illustrating an example environment of a LIDAR system for an autonomous vehicle according to some embodiments. The environment 200 includes a LIDAR 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).

[0074] 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 Circuitry, a Photonic Lightwave Circuit (PLC), or a III-V semiconductor circuit.

[0075] In some embodiments, the first semiconductor substrate and / or first semiconductor package may include a TX path, and the second semiconductor substrate and / or second semiconductor package may include an RX path. In some configurations, the RX input / output ports and / or the TX input / output ports may be present (or formed / located / positioned / placed) along one or more edges of one or more semiconductor substrates and / or semiconductor packages.

[0076] 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.

[0077] The environment 200 includes a vehicle control system (e.g., vehicle control system 120 of FIG. 1) 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.

[0078] The TX path may include a laser source 202, a modulator 204A, a modulator 204B, and an amplifier 206. The RX path may include a mixer 208, a detector 212, and a transimpedance amplifier (TIA) 214. While FIG. 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 the operation of the vehicle.

[0079] 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 1250 nanometers and 1400 nanometers.

[0080] Laser source 202 may be configured to provide an optical signal to modulator 204A, which may be configured to modulate the phase and / or frequency of the optical signal based on a first radio frequency (RF) signal (shown as "RF1" in FIG. 2) to generate a modulated optical signal using continuous wave (CW) modulation or quasi-CW modulation. Modulator 204A may be configured to transmit the modulated optical signal to amplifier 206. Amplifier 206 may be configured to amplify the modulated optical signal to generate an amplified optical signal in optical system 210.

[0081] The optical system 210 may be configured to steer the amplified optical signal received from the TX path toward an object 218 in the 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.

[0082] The laser source 202 may be configured to provide an LO signal to the modulator 204B, which may be configured to modulate 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) to generate a modulated LO signal, and send the modulated LO signal to the mixer 208 in the RX path.

[0083] 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 configurations, the mixer 208 may be configured to send the modulated LO signal to the detector 212.

[0084] The detector 212 may be configured to generate an electrical signal based on the downconverted signal and send the electrical signal to the TIA 214. In some configurations, the detector 212 may be configured to generate an electrical signal based on the downconverted signal and the modulated signal.

[0085] The TIA 214 may be configured to amplify the electrical signal and transmit the amplified electrical signal to the vehicle control system 120 .

[0086] In some embodiments, the TIA 214 provides 5 Picowatts per Square Root Hertz (i.e., 5×10 per Square Root Hertz). -12 In some embodiments, the TIA 214 may have a gain between 4 kiloohms and 25 kiloohms.

[0087] 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).

[0088] Vehicle control system 120 may be configured to determine the distance to object 218 and / or measure the velocity of object 218 based on one or more electrical signals received from the TIA.

[0089] In some embodiments, modulator 204A and / or modulator 204B may have a bandwidth between 400 MHz and 1000 MHz.

[0090] In some embodiments, modulator 204A may be configured to transmit a first modulated optical signal and a 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. Optical system 210 may be configured to steer the first and second modulated optical signals received from the TX path toward an object 218 in the 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. 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 with 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 downconverted signal, and transmit the first downconverted 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 downconverted signal, and transmit the second downconverted signal to the detector 212. The detector 212 may be configured to generate first and second electrical signals based on the first and second downconverted 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. 6. LIDAR system including seed modulation module

[0091] A LIDAR sensor system may include a modulator (e.g., a Mach-Zehnder modulator) configured to receive an optical signal from a laser source and modulate the optical signal before transmitting it to the environment. The LIDAR sensor system may also use temporal multiplexing to overcome hardware requirements. For example, multiple transmit (TX) channels can be time-multiplexed to share limited hardware resources (e.g., analog-to-digital converters (ADCs)). Similarly, multiple local oscillator (LO) channels can be time-multiplexed to share limited hardware resources (e.g., photoreceivers / detectors). In some cases, time multiplexing can be performed by optical or electro-optical switches. Currently, photonic integrated circuits (PICs) are widely used to reduce costs, and PIC modules / devices are needed to efficiently perform modulation and multiplexing.

[0092] To address this issue, in some embodiments, a LIDAR sensor system (e.g., an FMCW or other coherent LIDAR sensor system) may include a seed modulator (or seed modulation module) configured to simultaneously perform modulation and multiplexing. In some embodiments, the seed modulator may include one or more optical amplifiers (e.g., semiconductor optical amplifiers (SOAs), erbium-doped fiber amplifiers (EDFAs), or fiber Raman amplifiers (FRAs)) for time sequencing of the amplifiers, thereby enabling time multiplexing of multiple transmit (TX) optical signals. In some embodiments, the seed modulator may perform amplitude modulation (AM) or phase modulation using one or more SOAs. For example, the seed modulator may generate an optical signal modulated in a range of -20 dBm to 0 dBm relative to the original input optical signal. The seed modulator may forward or reverse bias the SOAs according to a time sequence controlled by a control circuit.

[0093] In some embodiments, the seed modulator may include an input leg (or input optical path), a first leg (or first optical path) branching off from the input optical path at one end of the input optical path, and a second leg (or second optical path) branching off from the input optical path at one end of the input optical path. In some embodiments, the input optical path may be formed / disposed / located between the first optical path and the second optical path. The seed modulator may receive an optical beam (or optical signal) on the input optical path. In some embodiments, the device may receive an optical signal from a laser source on the input optical path. The first optical path may function as a local oscillator (LO) path, and the second optical path may function as a TX path. The device may include multiple TX paths branching off from the second optical path at one end of the second optical path. In some embodiments, the device may include a laser source.

[0094] In some embodiments, the seed modulation device may include an input port coupled to the input optical path and configured to receive an optical signal from a laser source, and the device may include an LO output port coupled / connected to the other end of the first optical path, and a plurality of TX output ports coupled / connected to the other ends of the plurality of TX paths, respectively.

[0095] In some embodiments, the seed modulation device may include one or more first optical amplifiers coupled to the first optical path. The one or more first optical amplifiers may include an SOA. In some embodiments, the device may include a plurality of first phase modulators coupled to the first optical path. The plurality of first phase modulators may include electro-optic modulators or liquid crystal modulators. The one or more first optical amplifiers may be formed / disposed / located between the plurality of first phase modulators and the LO output port.

[0096] In some embodiments, the seed modulation device may include a plurality of second optical amplifiers coupled to the plurality of TX paths, respectively. Each of the plurality of second optical amplifiers may be an SOA. In some embodiments, the device may include a plurality of second phase modulators coupled to the second optical paths. The plurality of second phase modulators may include electro-optic modulators or liquid crystal modulators. Each of the plurality of second optical amplifiers may be formed / disposed / located between a corresponding one of the plurality of second phase modulators and the TX output port.

[0097] In some embodiments, the seed modulation device may include a control circuit configured to generate control signals for turning on or off each of the one or more first optical amplifiers and the plurality of second optical amplifiers based on the electrical signal. In some embodiments, the control circuit is not included in the device but is included in the LIDAR sensor system. The electrical signal may include one or more electromagnetic signals, e.g., one or more radio frequency (RF) signals. The control signals indicate a time sequence for turning on or off each optical amplifier, thereby time-multiplexing the outputs of the optical amplifiers. For example, the device may time-multiplex the output signals of the plurality of second optical amplifiers according to the time sequence and activate / deactivate the output signals of the one or more first optical amplifiers in synchronization with the time sequence of the plurality of second optical amplifiers. That is, the seed modulation device may control the plurality of second optical amplifiers (e.g., SOAs) to time-multiplex the TX channels by turning on or off the plurality of TX paths. In some embodiments, the device may output the signals of the plurality of second optical amplifiers according to multiple separate time sequences that are independent of each other.

[0098] In some embodiments, the seed modulator can turn each of the multiple second optical amplifiers on or off with high fidelity (e.g., a 20-25 dB suppression ratio). In some embodiments, the seed modulator can turn each SOA on or off by forward or reverse biasing the SOA. The device can forward bias the SOA to generate photon emissions, thereby allowing the input optical signal to pass through the SOA. Alternatively, the device can reverse bias the SOA to suppress optical gain, thereby turning off the input optical signal. For example, if all of the multiple second optical amplifiers (e.g., SOAs) are forward biased, when an input optical path receives a 20 milliwatt (mW) optical beam, the optical beam can be split into two 10 mW optical beams for the first and second optical paths and further split into multiple optical beams of 2-5 mW each for multiple TX paths. On the other hand, if none of the multiple second optical amplifiers (e.g., SOAs) are biased (forward biased or reverse biased), a 1 mW optical beam can flow through each of the multiple TX paths. When one of the SOAs is forward biased, that SOA may output a 2-5 mW optical beam through the corresponding TX path, but when reverse biased, that SOA may output substantially no optical beam.

[0099] In some embodiments, the seed modulation device can turn on the first optical amplifier in synchronization with turning on one of the multiple TX paths. In some embodiments, the device can turn on the first optical path in synchronization with turning on any of the multiple TX paths. The device can turn on the first optical path by turning on the first SOA.

[0100] In some embodiments, the seed modulation device may include multiple LO paths branched from the first optical path at one end. The device may include multiple third optical amplifiers coupled to the multiple LO paths, respectively. Each of the multiple third optical amplifiers may be an SOA. The device may time-multiplex output signals of the multiple third optical amplifiers according to a time sequence. That is, the device may control the multiple third optical amplifiers (e.g., SOAs) to time-multiplex the LO channels by turning on or off the multiple LO paths. In some embodiments, the device may output signals of the multiple third optical amplifiers according to multiple separate time sequences that are independent of each other.

[0101] In some embodiments, the seed modulation device may perform amplitude modulation (AM) or phase modulation (PM) using one or more SOAs. For example, the device may perform AM or PM of an input optical signal to generate a modulated TX signal using multiple SOAs coupled to multiple second optical paths. Similarly, the device may perform AM or PM of an input optical signal to generate a modulated LO signal using one or more SOAs coupled to the first optical path. In some embodiments, the device may perform AM or PM of an input optical signal by changing or varying the drive current of each of multiple SOAs. The device may perform AM or PM of an input optical signal by changing or varying the amplitude of the drive current of the SOA. In some embodiments, the device may simultaneously perform AM and PM of an input optical signal by changing or varying the amplitude of the drive current of the SOA. In some embodiments, the device may perform PM of an input optical signal by changing or varying the drive current of an SOA to change the effective length of the active region of the SOA. The device may perform AM or PM of an input optical signal intertwined with multiplexing of modulated optical signals. In this way, the device can slowly modulate the input optical signal to stabilize the phase of the input optical signal (eg, no phase shift), and can perform modulation and multiplexing simultaneously.

[0102] In some embodiments, the control circuitry (which may or may not be included in the seed modulator) may be configured to modify or vary the drive currents of each of the one or more first optical amplifiers and the plurality of second optical amplifiers based on the electrical signal to AM or PM the input optical signal. In some embodiments, the electrical signal may include one or more electromagnetic signals, e.g., one or more RF signals. In some embodiments, the control signal may indicate (1) a time sequence for turning each optical amplifier on or off and / or (2) the drive current for each optical amplifier.

[0103] In some embodiments, the seed modulation device may include all components (e.g., optical path, optical amplifier, phase modulator, etc.) formed or disposed on a single substrate. In some embodiments, the seed modulation device may be a III-V semiconductor-based integrated optics (IPO) in which all components are made of III-V materials and formed / disposed on a single substrate made of III-V materials. The III-V materials may include at least one of indium phosphide (InP), indium monoarsenide (InAs), or gallium and arsenide (GaAs).

[0104] In some embodiments, the seed modulation device may include at least one of a silicon photonics circuit, a photonic lightwave circuit (PLC), or a III-V semiconductor circuit, in which all components (e.g., optical path, optical amplifier, phase modulator, etc.) are formed or disposed on a single substrate. In some embodiments, all components of the device may be formed in a single layer to form a horizontal structure of the integrated circuit. In some embodiments, components of the device may be formed or disposed in multiple layers stacked on a single substrate to form a vertical structure of the integrated circuit. For example, the device may include a phase modulator implemented as one or more PLC modules, an optical path implemented as a silicon photonics circuit, and an SOA implemented as a III-V module, all of which are disposed / formed on a single substrate.

[0105] According to certain aspects, an embodiment of the present disclosure relates to an apparatus including an input optical path, a first optical path, a plurality of second optical paths, a first optical amplifier, a plurality of second optical amplifiers, and a control circuit. The input optical path may receive a beam from a laser source at one end of the input optical path. The first optical path and the plurality of second optical paths may each branch at the other end of the input optical path. The first optical amplifier may be coupled to the first optical path. The plurality of second optical amplifiers may each be coupled to the plurality of second optical paths. The control circuit may selectively turn on one of the plurality of second optical amplifiers to output a modulated optical signal of the beam. The control circuit may turn on the first optical amplifier synchronously with turning on one of the plurality of second optical amplifiers to output a local oscillator (LO) signal.

[0106] In some embodiments, the plurality of second optical amplifiers may include a plurality of semiconductor optical amplifiers (SOAs). The control circuit may be configured to turn on or off the plurality of SOAs to temporally multiplex output signals of the plurality of SOAs. The control circuit may be configured to vary a drive current of one of the plurality of SOAs to perform at least one of amplitude modulation or phase modulation of the beam.

[0107] In some embodiments, the device may include at least one of a silicon photonics circuit, a PLC, or a III-V semiconductor circuit. The device may be a III-V semiconductor circuit.

[0108] In some embodiments, the first optical amplifier may be a first SOA. The control circuit may be configured to turn the first SOA on or off to output the LO signal according to a time sequence. The control circuit may be configured to vary a drive current of the first SOA to perform at least one of amplitude modulation or phase modulation of the beam.

[0109] In some embodiments, the first optical amplifier may include a plurality of third optical amplifiers, and the control circuit may be configured to selectively turn on one of the plurality of third optical amplifiers to output a corresponding LO optical signal.

[0110] In some embodiments, the apparatus may further include one or more phase modulators coupled to the second optical path. The apparatus may further include one or more phase modulators coupled to the first optical path. The number of the one or more phase modulators coupled to the first optical path may be the same as the number of the one or more phase modulators coupled to the second optical path.

[0111] In some embodiments, the apparatus may further include a first output port coupled to one end of the first optical path and a plurality of second output ports coupled to one end of each of the plurality of second optical paths, and the control circuit may be configured to output the modulated optical signal of the beam to a corresponding one of the plurality of second output ports and output the LO signal to the first output port.

[0112] In some embodiments, a LIDAR system may include a device, a laser source configured to generate a beam, a plurality of transmit (TX) channels, and one or more optical components. The one or more optical components may be configured to receive a first modulated optical signal and a first LO signal associated with the first modulated optical signal from the device. The one or more optical components may be configured to receive a second modulated optical signal and a second LO signal associated with the second modulated optical signal from the device. The one or more optical components may be configured to transmit the first and second modulated optical signals into an environment on first and second TX channels, respectively, of the plurality of TX channels. The one or more optical components may be configured to receive first and second return optical signals reflected from one or more objects in the environment. The one or more optical components may be configured to pair the first and second return optical signals with the first and second LO signals, respectively.

[0113] According to certain aspects, an embodiment of the present disclosure relates to a method for generating a modulated optical signal in a circuit. The method may include a circuit receiving a beam from a laser source on an input optical path of the circuit. The circuit may include the input optical path, a first optical path and multiple second optical paths each branching from the input optical path, a first optical amplifier coupled to the first optical path, and multiple second optical amplifiers coupled to each of the multiple second optical paths. The method may include the circuit receiving a beam from a laser source on the input optical path. The method may include the circuit selectively turning on one of the multiple second optical amplifiers to output a modulated optical signal of the beam. The method may include the circuit turning on the first optical amplifier synchronously with turning on one of the multiple second optical amplifiers to output a local oscillator (LO) signal.

[0114] In some embodiments, the plurality of second optical amplifiers may include a plurality of semiconductor optical amplifiers (SOAs). The method may include turning on or off one of the plurality of SOAs to temporally multiplex output signals of the plurality of SOAs. The method may include varying a drive current of one of the plurality of SOAs to perform at least one of amplitude modulation or phase modulation of the beam.

[0115] Various embodiments of the present disclosure have one or more of the following advantages and benefits.

[0116] First, embodiments of the present disclosure may provide a useful technique for efficiently time-multiplexing TX and / or LO signals using optical amplifiers (e.g., SOAs) to overcome hardware requirements. For example, a seed modulator according to some embodiments may generate multiple modulated optical signals and time-multiplex the multiple modulated optical signals onto multiple transmit (TX) channels and / or multiple (LO) channels. This multiplexing enables sharing of limited hardware resources (e.g., analog-to-digital converters (ADCs) or optical receivers / detectors).

[0117] Second, embodiments of the present disclosure may provide a useful technique for stably performing modulation (e.g., AM or PM) by changing or varying the drive current of an SOA. For example, the device may perform AM and / or PM of an input optical signal intertwined with multiplexing of the modulated optical signal. In this way, the device may slowly modulate the input optical signal to stabilize the phase of the input optical signal (e.g., no phase shift) and simultaneously perform modulation and multiplexing.

[0118] Third, embodiments of the present disclosure may provide techniques useful for incorporating components of a seed modulator into an integrated circuit, thereby achieving significant cost savings (e.g., 5x less cost than conventional embodiments comprising circuitry on a printed circuit board (PCB)). For example, the seed modulator may include at least one of a silicon photonics circuit, a PLC, or a III-V semiconductor circuit in which all components (e.g., optical paths, optical amplifiers, phase modulators, etc.) are formed or disposed on a single substrate. In some embodiments, the seed modulator may be a III-V semiconductor-based integrated photonic device in which all components are made of III-V materials and formed / disposed on a single substrate made of III-V materials.

[0119] 3a is a block diagram illustrating an example of a LIDAR system according to some embodiments. The environment 300 includes a LIDAR system 301 including a transmit (TX) path and a receive (RX) path, and one or more optical systems 310. The TX path may include a laser source 302, a seed modulator 350. The TX path may include an amplifier (not shown) between the seed modulator 350 and the one or more optical systems 310. The RX path may include a mixer 308, a detector 312, and a transimpedance amplifier (TIA) 314. The laser source 302, the detector 312, and the TIA 314 may have configurations similar to those of the laser source 202, the detector 212, and the TIA 214, respectively.

[0120] The laser source 302 may be configured to provide an optical signal to the seed modulator 350, which may be configured to modulate the amplitude, phase, and / or frequency of the optical signal using continuous wave (CW) modulation or quasi-CW modulation based on one of the radio frequency (RF) signals 321-1, 321-2, ..., 321-N to generate respective corresponding modulated optical signals 341-1, 341-2, ..., 341-N. The seed modulator 350 may be configured to time-multiplex the modulated optical signal to an amplifier (not shown). The amplifier may be configured to amplify the (multiplexed) modulated optical signal to generate an amplified optical signal to the optical system 310.

[0121] In some embodiments, the optical system 310 may (1) receive multiple amplified optical signals (e.g., N amplified optical signals generated based on the modulated optical signals 341-1, 341-2, ..., 341-N) via multiple different input channels (e.g., N different input channels), (2) transmit or steer the received multiple amplified optical signals into an environment via multiple different TX channels (e.g., N different TX channels), and (3) receive multiple return signals reflected back from one or more objects via multiple different RX channels (e.g., N different RX channels) and provide the return signals to the mixer 308. In some embodiments, the mixer 308 may receive the return signals via multiple different channels (e.g., N different channels). For example, the optical system 310 may be configured to steer the amplified optical signals received from the TX path via each input channel toward an object 318 into the environment within a given field of view via a corresponding TX channel, receive the return signals reflected back from the object 318 via a corresponding RX channel, and provide the return signals to the mixer 308 for the RX path.

[0122] The seed modulator 350 may be configured to modulate the amplitude, phase, and / or frequency of the optical signal using continuous wave (CW) modulation or quasi-CW modulation based on the RF signal 325 to generate a modulated LO signal 345 and transmit the modulated LO signal to the mixer 308 of the RX path.

[0123] In some embodiments, the seed modulation device 350 may include a control circuit 320 configured to generate control signals for turning on or off one or more first optical amplifiers (e.g., optical amplifier 362 of FIG. 3b) and each of a plurality of second optical amplifiers (e.g., optical amplifiers 364-1, 364-2 of FIG. 3b) based on an electrical signal (e.g., RF signals 321-1, 321-2, ..., 321-N). In some embodiments, the control circuit is not included in the seed modulation device 350 but is included in the LIDAR sensor system 301. The control signals can indicate a time sequence for turning on / off each optical amplifier, thereby time-multiplexing the outputs of the optical amplifiers. For example, the device can time-multiplex the output signals of the plurality of second optical amplifiers (e.g., output optical signals 341-1, 341-2, ..., 341-N) according to the time sequence and activate / deactivate the output signal of one or more first optical amplifiers (e.g., output optical signal 345) in synchronization with the time sequence of the plurality of second optical amplifiers. In some embodiments, the control circuit 320 may be configured to change or vary the drive current of each of the one or more first optical amplifiers and the plurality of second optical amplifiers based on the electrical signal to perform amplitude modulation (AM) or phase modulation (PM) of the input optical signal. In some embodiments, the control circuit 320 may be configured to generate one or more control signals that indicate (1) a time sequence for turning each optical amplifier on or off and / or (2) the drive current of each optical amplifier. Details of the seed modulation device 350 are described in the following section with reference to Figures 3b and 3c.

[0124] In some embodiments, the mixer 308 may be configured to mix (e.g., combine, multiply, etc.) the modulated LO signal with a return signal received from the optical system 310 in the channel to generate a downconverted signal and transmit the downconverted signal to the detector 312. In some configurations, the mixer 308 may be configured to transmit the modulated LO signal to the detector 312.

[0125] In some embodiments, the seed modulator 350 may be configured to time multiplex a first modulated optical signal (e.g., modulated optical signal 341-1) and a second modulated optical signal (e.g., modulated optical signal 341-1) to transmit them to an amplifier (not shown in FIG. 3a). The amplifier may be configured to amplify the first and second modulated optical signals to generate an amplified optical signal in the optical system 310. The seed modulator 350 may be configured to (1) generate a first modulated LO signal associated with the first modulated optical signal in synchronization with generating the first modulated optical signal (e.g., generate modulated LO signal 345 associated with modulated optical signal 341-1 in synchronization with generating modulated optical signal 341-1), and (2) generate a second modulated LO signal associated with the second modulated optical signal in synchronization with generating the first modulated optical signal (e.g., generate modulated LO signal 345 associated with modulated optical signal 341-2 in synchronization with generating modulated optical signal 341-2).

[0126] The optical system 310 may be configured to steer the first and second modulated optical signals received from the TX path (at different times) toward an object 318 in an environment within a given field of view, receive corresponding first and second return signals reflected back from the object 318, and provide the first and second return signals to the mixer 308 of the RX path. The seed modulator 350 may be configured to send the first and second modulated LO signals to the mixer 308 of the RX path. The mixer 308 may be configured to pair (e.g., connect, link, identify, etc.) the first return optical signal with 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 downconverted signal, and send the first downconverted signal to the detector 312. Similarly, mixer 308 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 downconverted signal, and send the second downconverted signal to detector 312. Detector 312 may be configured to generate first and second electrical signals based on the first and second downconverted signals, respectively. Vehicle control system 120 may be configured to determine a distance to object 318 and / or measure a velocity of object 318 based on the first and second electrical signals received via TIA 314.

[0127] FIG. 3b is a block diagram illustrating an example of a seed modulation device according to some embodiments.

[0128] In some embodiments, seed modulation device 350 may include an input optical path 351, a first optical path 355 branching off from input optical path 351 at one end of input optical path 351 (e.g., the left end of first optical path 355), and a second optical path 353 branching off from input optical path 351 at one end of input optical path 351 (e.g., the left end of second optical path 353). Input optical path 351 may be formed / disposed / located between first optical path 355 and second optical path 353. For example, as shown in FIG. 3b, input optical path 351 may be formed in a middle portion of device 350, and the first and second optical paths may be formed at the top and bottom of device 350, respectively. Seed modulation device 350 may receive an optical beam (or optical signal) at input optical path 351. Device 350 may receive an optical signal from a laser source (e.g., laser source 302 in FIG. 3a) at the input optical path. The first optical path 355 can function as a local oscillator (LO) path, and the second optical path 353 can function as a TX path. The device can include multiple TX paths (e.g., TX paths 353-1 and 353-2) branching off from the second optical path 353 at one end of the second optical path 353 (e.g., at the left ends of TX paths 353-1 and 353-2).

[0129] In some embodiments, seed modulation device 350 may include an input port 381 coupled to input optical path 351 and configured to receive an optical signal from a laser source. Device 350 may include an LO output port 385 coupled / connected to the other end of first optical path 355 (e.g., the right end of first optical path 355), and multiple TX output ports (e.g., TX output ports 383-1, 383-2) coupled / connected to the other ends of multiple TX paths, respectively.

[0130] In some embodiments, the seed modulation device 350 may include one or more first optical amplifiers (e.g., optical amplifier 362) coupled to the first optical path 355. The one or more first optical amplifiers may include an SOA (e.g., SOA 362). In some embodiments, the device may include a plurality of first phase modulators (e.g., phase modulators 361, 363) coupled to the first optical path 355. The plurality of first phase modulators may include electro-optic modulators or liquid crystal modulators. The one or more first optical amplifiers (e.g., optical amplifier 362) may be formed / disposed / located between the plurality of first phase modulators (e.g., phase modulators 361, 363) and the LO output port (e.g., LO output port 385).

[0131] In some embodiments, the seed modulation device 350 may include a plurality of second optical amplifiers (e.g., optical amplifiers 364-1, 364-2) coupled to a plurality of TX paths (e.g., TX paths 353-1, 353-2), respectively. Each of the plurality of second optical amplifiers may be an SOA (e.g., SOA 364-1, 364-2). The device may include a plurality of second phase modulators (e.g., phase modulators 365, 367) coupled to the second optical path 353. The plurality of second phase modulators may include electro-optic modulators or liquid crystal modulators. Each of the plurality of second optical amplifiers may be formed / disposed / located between a corresponding one of the plurality of second phase modulators and a corresponding one of the TX output ports. For example, optical amplifier 364-1 may be formed between phase modulators 365, 367 and TX output port 383-1.

[0132] In some embodiments, the seed modulation device 350 may include a control circuit 320 configured to generate control signals (e.g., control signals 375-1, 375-2, 371) for turning on or off one or more first optical amplifiers and each of a plurality of second optical amplifiers based on electrical signals (e.g., RF signals 321-1, 321-2, 325). For example, the control circuit 320 may receive the RF signals 321-1, 321-2, 325 and generate the control signals 375-1, 375-2, 371 for turning on or off each of the optical amplifiers 364-1, 364-2, 362 based on the RF signals 321-1, 321-2, 325. The control signals may indicate a time sequence for turning each optical amplifier on or off, thereby allowing the outputs of the optical amplifiers to be time multiplexed. For example, the control circuit 320 can time-multiplex output signals of multiple second optical amplifiers (e.g., optical amplifiers 364-1, 364-2) according to a time sequence and turn on or off output signals of one or more first optical amplifiers (e.g., optical amplifier 362) in synchronization with the time sequence of the multiple second optical amplifiers. The control circuit 320 can turn on the first optical amplifier (e.g., optical amplifier 362) in synchronization with turning on one of the multiple TX paths (e.g., TX paths 353-1, 353-2) via the second optical amplifiers (e.g., optical amplifiers 364-1, 364-2). The control circuit 320 can turn on the first optical path (e.g., optical path 355) via the first optical amplifier in synchronization with turning on one of the multiple TX paths (e.g., TX paths 353-1, 353-2) via the second optical amplifiers. For example, the control circuit 320 can turn on or off one of the multiple second optical amplifiers 364-1, 364-2 and turn on or off the first optical amplifier 362. That is, the control circuit 320 can control multiple second optical amplifiers (e.g., SOAs) to time-multiplex TX channels by turning on or off the multiple TX paths 353-1, 353-2.

[0133] In some embodiments, the control circuit 320 can turn each of the multiple second optical amplifiers on or off with high fidelity (e.g., a suppression ratio of 20 to 25 dB). The control circuit can forward or reverse bias the SOAs to turn each SOA (e.g., SOAs 362, 364-1, 364-2) on or off. For example, if the multiple SOAs are all forward biased, when the input optical path 351 receives a 20 milliwatt (mW) optical beam, the optical beam may be split into two 10 mW optical beams for the first and second optical paths 355, 353, and further split into multiple optical beams (e.g., 2 to 5 mW) for the multiple TX paths 353-1, 353-2, respectively. On the other hand, if none of the multiple second SOAs are biased (either forward or reverse biased), a 1 mW optical beam may flow through each of the multiple TX paths 353-1, 353-2. When one of the SOAs is forward biased, it can output a 2-5 mW optical beam through the corresponding TX path, but when it is reverse biased, it can output virtually no optical beam.

[0134] In some embodiments, the seed modulation device 350 may perform amplitude modulation (AM) or phase modulation (PM) using one or more SOAs (e.g., SOAs 362, 364-1, 364-2). In some embodiments, the electro-optic modulation effect can be implemented with InP-SOAs using different quantum well (QW) structures or without QWs (using only the intrinsic pn junction of InP). For example, the device 350 may perform AM or PM of an input optical signal (e.g., an input optical signal received from input port 381) to generate modulated TX signals using multiple SOAs coupled to multiple second optical paths (e.g., TX paths 353-1, 353-2). Similarly, the device 350 may perform AM or PM of an input optical signal (e.g., an input optical signal received from input port 381) to generate modulated LO signals using one or more SOAs coupled to a first optical path (e.g., optical path 355). The apparatus 350 may perform AM or PM of the input optical signal by changing or varying the drive current of each of the multiple SOAs. The apparatus 350 may simultaneously perform AM and PM of the input optical signal by changing or varying the amplitude of the drive current of the SOA. In some embodiments, the apparatus 350 may change or vary the drive current of the SOA (e.g., the current of the control signal 371 of the SOA 362) based on an electrical signal (e.g., RF signal 325) to change the effective length of the active region of the SOA, thereby performing PM of the input optical signal. The apparatus 350 may perform AM or PM of the input optical signal (by changing the drive current of the SOA) intertwined with multiplexing of the modulated optical signal (by turning the SOA on or off). In this way, the apparatus 350 may slowly modulate the input optical signal to stabilize the phase of the input optical signal (e.g., no phase shift) and simultaneously perform modulation and multiplexing.

[0135] In some embodiments, control circuitry 320 (which may or may not be included in the seed modulator) may be configured to change or vary the drive currents of each of one or more first optical amplifiers and multiple second optical amplifiers (e.g., SOAs 364-1, 364-2, 362) based on electrical signals (e.g., RF signals 321-1, 321-2, 325) to perform AM or PM of an input optical signal (e.g., an input signal received at input port 381). Control circuitry 320 may change or vary the drive current of each optical amplifier using control signals that indicate (1) a time sequence for turning each optical amplifier on or off and / or (2) the drive current of each optical amplifier.

[0136] In FIG. 3b, seed modulation device 350 may include a photodiode 367, an electrical pad 373, and an optical input port 389 for a photodiode monitor.

[0137] 3c is a block diagram illustrating an example of a seed modulation assembly 3000 according to some embodiments. The seed modulation assembly may include a housing 3010, a heat sink 3020, a cooler 3030, a seed modulation device / module / chip 350, a chip carrier 3040 housing the seed modulation device 350, an optical fiber array 3060, an optical fiber cable 3070, an electric feedthrough 3080, and / or an optical fiber feedthrough 3090. The housing may be made of a nickel-cobalt-iron alloy (e.g., Kovar). The heat sink 3020 may be made of tungsten copper (CuW). The cooler 3040 may be a thermoelectric cooler (TEC). The chip carrier 3040 may be made of ceramic or plastic. The optical fiber array 3060 may be a fiber array unit (FAU). The electrical feedthrough 3080 may be configured to provide an electrical signal (e.g., an RF signal) to the seed modulator 350. The optical fiber feedthrough 3090 may be configured to provide an optical signal (e.g., an optical beam from a laser source) to the seed modulator 350.

[0138] In some embodiments, seed modulation apparatus 350 may include all components (e.g., optical paths 351, 353, 355), optical amplifiers 362, 364-1, 364-2, phase modulators 361, 363, 365, 367, etc.) formed or disposed on a single substrate. Seed modulation apparatus 350 may be a III-V semiconductor-based integrated photonic device in which all components are made of III-V materials and formed / disposed on a single substrate made of III-V materials. The III-V materials may include at least one of indium phosphide (InP), indium arsenide (InAs), or gallium arsenide (GaAs).

[0139] In some embodiments, the seed modulation device 350 may include at least one of a silicon photonics circuit, a PLC, or a III-V semiconductor circuit in which all components (e.g., optical paths 351, 353, 355, optical amplifiers 362, 364-1, 364-2, phase modulators 361, 363, 365, 367, etc.) are formed or arranged on a single substrate. In some embodiments, all components of the device may be formed in a single layer to form a horizontal structure of an integrated circuit. In some embodiments, components of the device may be formed or arranged in multiple layers stacked on a single substrate to form a vertical structure of an integrated circuit. For example, device 350 may include phase modulators implemented as one or more PLC modules (e.g., phase modulators 361, 363, 365, 367), optical paths implemented as silicon photonics circuits (e.g., optical paths 351, 353, 355), and SOAs implemented as III-V modules (e.g., 362, 364-1, 364-2), all of which may be disposed / formed on a single substrate.

[0140] FIG. 4 is a block diagram illustrating yet another example of a LIDAR system in accordance with some embodiments.

[0141] The environment 400 includes a LIDAR system 401 including a transmit (TX) path and a receive (RX) path, and one or more optical systems 410. The TX path may include a laser source 402 and a seed modulator 450. The TX path may include an amplifier (not shown) between the seed modulator 450 and the one or more optical systems 410. The RX path may include a mixer 408, a detector 412, and a transimpedance amplifier (TIA) 414. The laser source 402, the detector 412, and the TIA 414 may have configurations similar to the laser source 302, the detector 312, and the TIA 314, respectively, shown in FIG. 3a.

[0142] The laser source 402 may be configured to provide an optical signal to a seed modulator 450 configured to modulate the amplitude, phase, and / or frequency of the optical signal using continuous wave (CW) or quasi-CW modulation based on one of the radio frequency (RF) signals 421-1, 421-2, ..., 421-N to generate each of the corresponding modulated optical signals 441-1, 441-2, ..., 441-N. The seed modulator 450 may be configured to time-multiplex the modulated optical signal to an amplifier (not shown). The amplifier may be configured to amplify the (multiplexed) modulated optical signal to generate an amplified optical signal to the optical system.

[0143] In some embodiments, the optical system 410 may (1) receive multiple amplified optical signals (e.g., N amplified optical signals generated based on modulated optical signals 441-1, 441-2, ..., 441-N) via multiple different input channels (e.g., N different input channels), (2) transmit or steer the received multiple amplified optical signals into an environment via multiple different TX channels (e.g., N different TX channels), and (3) receive multiple return signals reflected back from one or more objects via multiple different RX channels (e.g., N different RX channels) and provide the return signals to the mixer 408. In some embodiments, the mixer 408 may receive the return signals via multiple different channels (e.g., N different channels). For example, the optical system 410 may be configured to steer amplified optical signals received from the TX path via each input channel towards an object 418 into the environment within a given field of view via the corresponding TX channel, receive return signals reflected back from the object 418 via the corresponding RX channel, and provide the return signals to the mixer 408 for the RX path.

[0144] In some embodiments, the seed modulator 450 may be configured to modulate the amplitude, phase, and / or frequency of the optical signal using continuous wave (CW) modulation or quasi-CW modulation based on any of the radio frequency (RF) signals 425-1, 425-2, ..., 425-N to generate corresponding modulated LO signals 445-1, 445-2, ..., 445-N, respectively. The seed modulator 450 may be configured to time-multiplex the modulated LO signal into the mixer 408 of the RX path. In some embodiments, the mixer 408 may receive multiple modulated LO signals (e.g., N modulated LO signals 445-1, 445-2, ..., 445-N) via multiple different LO channels (e.g., N different LO channels).

[0145] In some embodiments, the seed modulation device 450 may include multiple TX paths branching off from the second optical path (e.g., optical path 353 in FIG. 3b) at one end of the second optical path. The device 450 may include multiple second optical amplifiers respectively coupled to the multiple TX paths. Each of the multiple second optical amplifiers may be an SOA. The device may time-multiplex output signals of the multiple second optical amplifiers according to a time sequence. That is, the device 450 may control the multiple second optical amplifiers (e.g., SOAs) to time-multiplex the TX channels by turning on or off the multiple TX paths.

[0146] Similarly, the seed modulation device 450 may include multiple LO paths branched from the first optical path (e.g., optical path 355 in FIG. 3b) at one end of the first optical path. The device may include multiple third optical amplifiers respectively coupled to the multiple LO paths. Each of the multiple third optical amplifiers may be an SOA. The device may time-multiplex the output signals of the multiple third optical amplifiers according to a time sequence. That is, the device 450 may control the multiple third optical amplifiers (e.g., SOAs) to time-multiplex the LO channels by turning on or off the multiple LO paths. In some embodiments, there may be a one-to-one correspondence between (1) the multiple LO paths (and the multiple third optical amplifiers coupled thereto) and (2) the multiple TX paths (and the multiple second optical amplifiers coupled thereto).

[0147] In some embodiments, the seed modulation device 450 may include a control circuit 420 configured to generate a control signal for turning on or off each of the plurality of second optical amplifiers based on an electrical signal (e.g., RF signals 421-1, 421-2, ..., 421-N). In some embodiments, the control circuit is not included in the seed modulation device 450 but is included in the LIDAR sensor system 401. The control signal can indicate a time sequence for turning on or off each of the second optical amplifiers, thereby time-multiplexing the outputs of the optical amplifiers. For example, the device can time-multiplex the output signals of the plurality of second optical amplifiers according to the time sequence and activate / deactivate corresponding output signals of the plurality of third optical amplifiers (e.g., output optical signals 445-1, 445-2, ..., 445-N) in synchronization with the time sequence of the plurality of second optical amplifiers.

[0148] In some embodiments, the control circuit 420 may be configured to change or vary the drive current of each of the plurality of third optical amplifiers and the plurality of second optical amplifiers based on the electrical signal to perform amplitude modulation (AM) or phase modulation (PM) of the input optical signal. The control circuit 420 may be configured to generate one or more control signals indicating (1) a time sequence for turning each optical amplifier on or off and / or (2) a drive current for each optical amplifier.

[0149] In some embodiments, mixer 408 may be configured to mix (e.g., combine, multiply, etc.) a modulated LO signal received on a particular LO channel with a return signal received from optical system 410 on an RX channel corresponding to the particular LO channel to generate a downconverted signal and send the downconverted signal to detector 412. In some configurations, mixer 408 may be configured to send the modulated LO signal to detector 412.

[0150] In some embodiments, the seed modulator 450 may be configured to perform time multiplexing to transmit a first modulated optical signal (e.g., modulated optical signal 441-1) and a second modulated optical signal (e.g., modulated optical signal 441-1) to an amplifier (not shown in FIG. 4 ). The amplifier may be configured to amplify the first and second modulated optical signals to generate amplified optical signals to the optical system 410 via individual TX channels. The seed modulation device 450 may be configured to (1) generate a first modulated LO signal associated with the first modulated optical signal in synchronization with generating the first modulated optical signal (e.g., generate a modulated LO signal 445-1 associated with modulated optical signal 441-1 in synchronization with generating modulated optical signal 441-1), and (2) generate a second modulated LO signal associated with the second modulated optical signal in synchronization with generating the first modulated optical signal (e.g., generate a modulated LO signal 445-2 associated with modulated optical signal 441-2 in synchronization with generating modulated optical signal 441-2).

[0151] The optical system 410 may be configured to steer the first and second modulated optical signals received from the TX path (at different times) toward an object 418 in an environment within a given field of view, receive corresponding first and second return signals reflected back from the object 418, and provide the first and second return signals to the mixer 408 of the RX path. The seed modulator 450 may be configured to transmit the first and second modulated LO signals to the mixer 408 of the RX path via individual LO channels. The mixer 408 may be configured to pair (e.g., connect, link, identify, etc.) the first return optical signal with 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 downconverted signal, and transmit the first downconverted signal to the detector 412. Similarly, mixer 408 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 downconverted signal, and send the second downconverted signal to detector 412. Detector 412 may be configured to generate first and second electrical signals based on the first and second downconverted signals, respectively. Vehicle control system 120 may be configured to determine a distance to object 418 and / or measure a velocity of object 418 based on the first and second electrical signals received via TIA 414.

[0152] FIG. 5 is a flowchart illustrating an exemplary methodology for generating a modulated optical signal using a seed modulator (e.g., seed modulator 350 of FIG. 3a, 3b, 3c, or 4) according to some embodiments. In some embodiments, the seed modulator can be a circuit including an input optical path (e.g., input optical path 351 of FIG. 3b), first optical paths (e.g., optical paths 355 of FIG. 3b) each branching from the input optical path, multiple second optical paths (e.g., TX paths 353-1, 353-2 of FIG. 3b), a first optical amplifier (e.g., optical amplifier 362 of FIG. 3b), and multiple second optical amplifiers (e.g., optical amplifiers 364-1, 364-2 of FIG. 3b) coupled to the multiple second optical paths (e.g., TX paths 353-1, 353-2 of FIG. 3b), respectively. In some embodiments, the seed modulator can include at least one of a silicon photonics circuit, a PLC, or a III-V semiconductor circuit. The device can be a III-V semiconductor circuit. For example, referring to Figures 3b and 3c, device 350 may include phase modulators implemented as one or more PLC modules (e.g., phase modulators 361, 363, 365, 367), optical paths implemented as silicon photonics circuits (e.g., optical paths 351, 353, 355), and SOAs implemented as III-V modules (e.g., 362, 364-1, 364-2), all of which may be disposed / formed on a single substrate.

[0153] In some embodiments, the first optical amplifier and the plurality of second optical amplifiers (e.g., optical amplifiers 362, 364-1, 364-2 in FIG. 3b ) may include one or more semiconductor optical amplifiers (SOAs). In some embodiments, the apparatus may further include one or more phase modulators (e.g., phase modulators 365, 367 in FIG. 3b ) coupled to the second optical path (e.g., optical path 353 in FIG. 3b ). The apparatus may further include one or more phase modulators (e.g., phase modulators 361, 363 in FIG. 3b ) coupled to the first optical path (e.g., optical path 355 in FIG. 3b ). The number of the one or more phase modulators coupled to the first optical path (e.g., two phase modulators on optical path 355 in FIG. 3b ) may be the same as the number of the one or more phase modulators coupled to the second optical path (e.g., two phase modulators on optical path 353 in FIG. 3b ). In some embodiments, the device may further include a first output port (e.g., output port 385 in FIG. 3b) coupled to one end of the first optical path (e.g., optical path 355 in FIG. 3b) and a plurality of second output ports (e.g., output ports 383-1, 383-2 in FIG. 3b) coupled to one end of each of a plurality of second optical paths (e.g., optical paths 353-1, 353-2 in FIG. 3b).

[0154] Referring again to FIG. 5, in this exemplary methodology, process 500 begins in step 520 by a circuit (e.g., a circuit implementing seed modulator 350) receiving a beam from a laser source (e.g., laser source 202, 302, 402) on an input optical path (e.g., input optical path 351) of the circuit.

[0155] In step 540, in some embodiments, the circuitry (e.g., control circuit 320) may selectively turn on one of the plurality of second optical amplifiers (e.g., optical amplifier 364-1 in FIG. 3b) to output the modulated optical signal of the beam (e.g., modulated optical signal 341-1 in FIG. 3a). The circuitry may be configured to output the modulated optical signal of the beam to a corresponding one of the plurality of second output ports (e.g., output port 383-1 in FIG. 3b).

[0156] In some embodiments, the plurality of second optical amplifiers may include a plurality of semiconductor optical amplifiers (SOAs). The control circuit may be configured to turn on or off the plurality of SOAs to temporally multiplex the output signals of the plurality of SOAs. The circuit may be configured to vary the drive current of one of the plurality of SOAs to perform at least one of amplitude modulation (AM) or phase modulation (PM) of the beam. For example, the circuit may be configured to perform at least one of AM or PM of the beam by generating one or more control signals (e.g., control signals 371, 375-1, 375-2 in FIG. 3b) indicating (1) a time sequence for turning on or off each optical amplifier and / or (2) a drive current for each optical amplifier.

[0157] In step 560, in some embodiments, a circuit (e.g., control circuit 320) may turn on a first optical amplifier (e.g., optical amplifier 362) synchronously with turning on any of a plurality of second optical amplifiers (e.g., optical amplifiers 364-1, 364-2) to output a local oscillator (LO) signal (e.g., LO signal 345 in FIG. 3a). The circuit may be configured to output the LO signal to a first output port (e.g., output port 385 in FIG. 3b).

[0158] In some embodiments, the first optical amplifier (e.g., optical amplifier 362) may be a first SOA. The circuit may be configured to turn the first SOA on or off to output the LO signal according to a time sequence. The circuit may be configured to vary a drive current of the first SOA to perform at least one of AM or PM of the beam.

[0159] In some embodiments, the first optical amplifier may include multiple third optical amplifiers, and a circuit (e.g., control circuit 420 in FIG. 4) may be configured to selectively turn on one of the multiple third optical amplifiers to output a corresponding LO optical signal (e.g., LO optical signals 445-1, 445-2, ..., 445-N).

[0160] 6 is a flowchart illustrating an example methodology for controlling a LIDAR system using a seed modulation apparatus (e.g., apparatus 350 of FIGS. 3a-3c, apparatus 450 of FIG. 4) according to some embodiments. In some embodiments, the LIDAR system (e.g., LIDAR sensor system 301 of FIG. 3a, LIDAR sensor system 401 of FIG. 4) may include a seed modulation apparatus, a laser source configured to generate a beam (e.g., laser 302 of FIG. 3a, laser 402 of FIG. 4), a plurality of transmit (TX) channels (e.g., TX channels 341-1, ..., 341-N of FIG. 3a, or TX channels 441-1, ..., 441-N of FIG. 4), and one or more optical components (e.g., optical system 310 of FIG. 3a, optical system 410 of FIG. 4).

[0161] In this exemplary methodology, process 600 begins by one or more optical components (e.g., optical system 310) receiving a first modulated optical signal and a first LO signal associated with the first modulated optical signal from a seed modulation device (e.g., device 350) at step 610. In some embodiments, one or more optical components (e.g., optical system 310) may be configured to receive a second modulated optical signal and a second LO signal associated with the second modulated optical signal from the device (e.g., device 350).

[0162] For example, referring to Figure 3a, seed modulator 350 may be configured to time multiplex a first modulated optical signal (e.g., modulated optical signal 341-1) and a second modulated optical signal (e.g., modulated optical signal 341-1) to transmit to an amplifier (not shown in Figure 3a). The amplifier may be configured to amplify the first and second modulated optical signals to generate an amplified optical signal in optical system 310. The seed modulation device 350 may be configured to (1) generate a first modulated LO signal associated with the first modulated optical signal in synchronization with generating the first modulated optical signal (e.g., generate a modulated LO signal 345 associated with modulated optical signal 341-1 in synchronization with generating modulated optical signal 341-1), and (2) generate a second modulated LO signal associated with the second modulated optical signal in synchronization with generating the first modulated optical signal (e.g., generate a modulated LO signal 345 associated with modulated optical signal 341-2 in synchronization with generating modulated optical signal 341-2).

[0163] In step 630, in some embodiments, one or more optical components may be configured to transmit first and second modulated optical signals to the environment in first and second TX channels, respectively, of the plurality of TX channels. For example, with reference to Figure 3a, the optical system 310 may be configured to steer the first and second modulated optical signals received from the TX path (at different times) toward an object 318 in the environment within a given field of view.

[0164] In step 650, in some embodiments, one or more optical components may be configured to receive first and second return optical signals reflected back from one or more objects in the environment. For example, with reference to FIG. 3a, optical component 310 may be configured to receive corresponding first and second return signals reflected back from object 318 and provide the first and second return signals to mixer 308 in the RX path.

[0165] In step 650, in some embodiments, one or more optical components may be configured to pair the first and second return optical signals with the first and second LO signals, respectively. For example, referring to FIG. 3a, the seed modulation device 350 may be configured to send the first and second modulated LO signals to the mixer 308 of the RX path. The mixer 308 may be configured to pair (e.g., connect, link, identify, etc.) the first return optical signal with 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 downconverted signal, and send the first downconverted signal to the detector 312. Similarly, the mixer 308 may be configured to pair the second return optical signal with the second modulated LO signal, mix (e.g., combine, multiply, etc.) the second return optical signal with the second modulated LO signal to generate a second downconverted signal, and send the second downconverted signal to the detector 312. Detector 312 may be configured to generate first and second electrical signals based on the first and second downconverted signals, respectively. Vehicle control system 120 may be configured to determine a distance to object 318 and / or measure a velocity of object 318 based on the first and second electrical signals received via TIA 314.

[0166] FIG. 7 is a block diagram illustrating an example of a computing system in accordance with some embodiments.

[0167] 7, the illustrated computing system 700 includes one or more processors 710 in communication with memory 760 via a communication system 740 (e.g., a bus), at least one network interface controller 730 having a network interface port for connecting to a network (not shown), and an input / output ("I / O") component interface 750 connected to other components, such as a display (not shown) and input devices (not shown). Generally, the processor 710 executes instructions (or computer programs) received from memory. The illustrated processor 710 either integrates with or is directly connected to a cache memory 720. In some cases, instructions are read from memory 760 into the cache memory 720 and executed by the processor 710 from the cache memory 720.

[0168] More particularly, processor 710 may be any logic circuitry that processes instructions, for example, instructions fetched from memory 760 or cache 720. In some embodiments, processor 710 is a microprocessor unit or a special purpose processor. Computing device 700 may be based on any processor or set of processors capable of operating as described herein. Processor 710 may be a single-core or multi-core processor. Processor 710 may be multiple different processors.

[0169] Memory 760 may be any device suitable for storing computer-readable data. Memory 760 may be a device for reading fixed storage or removable storage media. For example, it may include all forms of non-volatile memory, media, and memory devices, semiconductor memory devices (e.g., EPROM, EEPROM, SDRAM, and flash memory devices), magnetic disks, magneto-optical disks, and optical disks (e.g., CD-ROM, DVD-ROM, or Blu-Ray® disks). Computing system 700 may have any number of memory devices as memory 760.

[0170] Cache memory 720 is a type of computer memory that is typically located close to processor 710 for fast read times. In some embodiments, cache memory 720 may be part of processor 710 or located on the same chip as the processor. In some embodiments, there may be multiple levels of cache 720 (e.g., L2 and L3 cache layers).

[0171] The network interface controller 730 manages data exchange through network interfaces (also referred to as network interface ports). The network interface controller 730 handles the physical and data link layers of the OSI model for network communication. In some embodiments, some of the network interface controller's tasks are handled by one or more processors 710. In some embodiments, the network interface controller 730 is part of the processor 710. In some embodiments, the computing system 700 has multiple network interfaces controlled by a single controller 730. In some embodiments, the computing system 700 has multiple network interface controllers 730. In some embodiments, each network interface is a connection point for a physical network link (e.g., a Cat-5 Ethernet link). In some embodiments, the network interface controller 730 supports wireless network connections, and the interface ports are wireless (e.g., radio) receiver / transmitters (e.g., for either the IEEE 802.11 protocol, Near Field Communication "NFC," Bluetooth, ANT, or other wireless protocols). In some embodiments, the network interface controller 730 implements one or more network protocols, such as Ethernet. Generally, computing device 700 exchanges data with other computing devices over a physical or wireless link via a network interface, which may be directly connected to the other devices or may be connected to the other devices through an intermediary device (e.g., a network device such as a hub, bridge, switch, or router) that connects computing device 700 to a data network such as the Internet.

[0172] Computing system 700 may include or provide an interface to one or more input or output ("I / O") devices. Input devices include, but are not limited to, keyboards, microphones, touchscreens, foot pedals, sensors, MIDI devices, pointing devices such as mice or trackballs. Output devices include, but are not limited to, video displays, speakers, refreshable Braille terminals, lighting, MIDI devices, 2D or 3D printers, etc.

[0173] Other components may include I / O interfaces, external serial device ports, and any additional coprocessors. For example, computing system 700 may include an interface (e.g., a Universal Serial Bus (USB) interface) for connecting input devices, output devices, or additional memory devices (e.g., a portable flash drive or external media drive). In some embodiments, computing device 700 includes additional devices such as coprocessors (e.g., a Math Co-Processor can support processor 710 with high-precision or complex calculations).

[0174] The foregoing description is provided to enable those skilled in the art to practice the various embodiments described herein. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments. Accordingly, the claims are not limited to the embodiments described herein but are to be accorded the full scope consistent with the claim language. Reference to a component in the singular does not mean "one and only one," unless expressly stated otherwise, but rather "one or more." The term "some" means one or more, unless otherwise stated. All structural and functional equivalents known or later known to those skilled in the art to elements of the various embodiments described herein are expressly incorporated by reference herein and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be publicly available, regardless of whether it is explicitly recited in the claims. No claim element is to be construed as a means-plus-function claim unless expressly recited using the term "means."

[0175] It is understood that the particular order or hierarchy of the blocks in the disclosed processes is an example of an illustrative approach. Based on design preferences, it is understood that the particular order or hierarchy of the blocks in the processes can be rearranged within the scope of the foregoing description. The accompanying method claims present components of the various blocks in an example order and are not limited to the particular order or hierarchy presented.

[0176] The foregoing description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the disclosed subject matter. Various modifications to such embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the foregoing description. Therefore, the foregoing description is not intended to be limited to the embodiments disclosed herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0177] The various embodiments shown and described are provided merely as examples to illustrate various features of the claims. However, features shown and described with respect to a particular embodiment are not necessarily limited to the associated embodiment, and may also be used or combined with other embodiments shown and described. Furthermore, the claims are not intended to be limited by any one embodiment.

[0178] The foregoing method descriptions and process flow charts are provided only as illustrative examples and do not require or imply that the blocks of the various embodiments be performed in the order presented. As one skilled in the art would understand, the order of the blocks of the foregoing embodiments may be performed in any order. Words such as "follows," "then," and "next" are not intended to limit the order of the blocks; these words are merely used to guide the reader through the method descriptions. Additionally, references to claim components referred to in the singular, for example, using "a," "an," or "the," should not be construed as limiting that element to the singular.

[0179] The various illustrative logic blocks, modules, circuits, and algorithm blocks described in connection with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability of hardware and software, the various illustrative components, blocks, modules, circuits, and blocks are described generally according to their functionality. Whether these functions are implemented in hardware or software depends on the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality for each particular application in various ways, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

[0180] The hardware used to implement the various exemplary logic, logic blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed by a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, individual gate or transistor logic, individual hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but the processor may alternatively be a conventional processor, controller, microcontroller, or state machine. A processor may also be implemented in a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or other similar configurations. Alternatively, some blocks or methods may be performed by circuitry adapted for a given function.

[0181] In some exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a non-transitory computer-readable or processor-readable storage medium. Blocks of methods or algorithms disclosed herein may be implemented in processor-executable software modules, which may reside on a non-transitory computer-readable or processor-readable storage medium. A non-transitory computer-readable or processor-readable storage medium may be any storage medium accessible by a computer or processor. For example, such non-transitory computer-readable or processor-readable storage media may include, but are not limited to, RAM, ROM, EEPROM, flash memory, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. As used herein, disk and disc include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, while discs reproduce data optically using lasers. Combinations of the foregoing are also included within the scope of non-transitory computer-readable and processor-readable media. Also, the operations of a method or algorithm may reside as one or any combination or set of code and / or instructions in a non-transitory processor-readable storage medium and / or computer-readable storage medium, which may be incorporated into a computer program product.

[0182] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to some embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments disclosed herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A vehicle LIDAR (Light Detection and Ranging) system, an input optical path configured to receive a beam from a laser source; a first optical path and a plurality of second optical paths each branching from the input optical path; a first optical amplifier coupled to the first optical path and configured to output a local oscillator (LO) signal; a plurality of second optical amplifiers respectively coupled to the plurality of second optical paths, one of the plurality of second optical amplifiers being selectively turned on to modulate the beam received via the second optical paths and output a modulated optical signal of the beam.

2. 2. The LIDAR system of claim 1, wherein the plurality of second optical amplifiers include one or more semiconductor optical amplifiers (SOAs).

3. 3. The LIDAR system of claim 2, wherein one of the one or more SOAs is turned on or off to provide signal modulation of the beam.

4. 3. The LIDAR system of claim 2, wherein one of the one or more SOAs is configured to vary a drive current of the one of the one or more SOAs to provide signal modulation of the beam.

5. 2. The LIDAR system of claim 1, wherein the optical system includes at least one of a Silicon Photonics circuit, a Photonic Lightwave Circuit (PLC), or a III-V semiconductor circuit.

6. the optical system is a III-V semiconductor circuit; 10. The LIDAR system of claim 1, wherein the III-V semiconductor circuit includes at least one of indium phosphide (InP), indium monoarsenide (InAs), or gallium arsenide (GaAs).

7. the first optical amplifier includes a plurality of third optical amplifiers; 10. The LIDAR system of claim 1, wherein one of the plurality of third optical amplifiers is selectively turned on to output a corresponding LO optical signal.

8. 10. The LIDAR system of claim 1, wherein the first optical amplifier comprises a first semiconductor optical amplifier (SOA).

9. 9. The LIDAR system of claim 8, wherein the first SOA is turned on or off to provide signal modulation of the beam.

10. 10. The LIDAR system of claim 8, wherein the first SOA is configured to vary a drive current of the first SOA to provide signal modulation of the beam.

11. further comprising one or more phase modulators coupled to the first optical path or the second optical path; 10. The LIDAR system of claim 1, wherein the one or more phase modulators are configured to phase modulate the beam.

12. further comprising a control circuit configured to generate one or more control signals for turning on or off the first optical amplifier and the plurality of second optical amplifiers; 12. The LIDAR system of claim 11, wherein the one or more control signals indicate a time sequence for turning on or off the plurality of second optical amplifiers.

13. 13. The LIDAR system of claim 12, wherein the control circuit is configured to turn on or off the output signal of the first optical amplifier in synchronization with a time sequence for turning on or off the plurality of second optical amplifiers.

14. an input optical path configured to receive a beam from a laser source; a first optical path and a plurality of second optical paths each branching from the input optical path; a first optical amplifier coupled to the first optical path and configured to output a local oscillator (LO) signal; a LIDAR (Light Detection and Ranging) system including: a plurality of second optical amplifiers respectively coupled to the plurality of second optical paths, one of the plurality of second optical amplifiers being selectively turned on to modulate the beam received via the second optical paths and output a modulated optical signal of the beam; one or more of a steering system or a braking system; a vehicle controller comprising one or more processors configured to operate the LIDAR system to transmit the modulated optical signal into an environment, receive return optical signals reflected from objects in the environment, pair the return optical signals with the LO signal to generate electrical signals, and control one or more of the steering system or the braking system using the electrical signals.

15. 14. An autonomous vehicle control system comprising a LIDAR system according to any one of claims 1 to 13.

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