Lidar pixel with dual-polarization receive optical antenna

Abstract

Vehicles with autonomous features use sensors to sense the environment in which the vehicle travels. Data collection and processing from the sensors allows the vehicle to drive while exploring the environment.SOLUTION: A light detection and ranging (LIDAR) system includes one or more LIDAR pixels that include a transmit optical antenna, a receive optical antenna, a first receiver, and a second receiver. The transmit optical antenna is configured to emit a transmit beam. The receiving optical antenna is configured to detect (i) a first polarization direction of the returning beam and (ii) a second polarization direction of the returning beam.SELECTED DRAWING: Figure 1a

Description

[Technical Field]

[0001] Related Applications This application claims the benefit of U.S. Non-Provisional Patent Application No. 18 / 187,827, filed June 9, 2022, which is a continuation of U.S. Non-Provisional Patent Application No. 17 / 836,280, which issued April 4, 2023, in U.S. Patent No. 11,619,739, and which has a filing date of March 22, 2023. All of these applications and patents are incorporated by reference herein in their entirety. [Background technology]

[0002] Frequency Modulated Continuous Wave (FMCW) Light Detection and Ranging (LIDAR) transmits a frequency-modulated light beam and detects the return signal to directly measure the distance and speed of an object. Currently, the automotive industry is developing autonomous functions to control vehicles in specific situations. According to SAE International Standard J3016, there are six levels of autonomy ranging from Level 0 (no autonomy) to Level 5 (vehicles that can operate without driver input in all conditions). Vehicles with autonomous functions use sensors to sense the environment in which the vehicle is traveling. Data collection and processing from the sensors allows the vehicle to navigate while exploring the environment. Summary of the Invention

[0003] An embodiment of the present disclosure includes a light detection and ranging (LIDAR) system including one or more LIDAR pixels, at least one of which includes a transmitting optical antenna, a receiving optical antenna, a first receiver, and a second receiver. The transmitting optical antenna is configured to emit a transmit beam. The receiving optical antenna is configured to detect (i) a first polarization direction of the return beam and (ii) a second polarization direction of the return beam. The first receiver is configured to generate a first signal in response to receiving the first polarization direction of the return beam from the receiving optical antenna and a first local oscillator signal having the first polarization direction. The second receiver is configured to generate a second signal in response to receiving the second polarization direction of the return beam from the receiving optical antenna and a second local oscillator signal having the second polarization direction.

[0004] In one embodiment, the receiving optical antenna includes a two-dimensional (2D) polarization splitting grating coupler configured to couple a first polarization direction of the return beam to a first receiver and a second polarization direction of the return beam to a second receiver.

[0005] In one embodiment, the receiving optical antenna includes a first single-polarization grating coupler configured to couple a first polarization direction of the return beam to the first receiver and a second single-polarization grating coupler configured to couple a second polarization direction of the return beam to the second receiver.

[0006] In one embodiment, the first single polarization grating coupler is offset from the second single polarization grating coupler.

[0007] In one embodiment, the first single polarization grating coupler is rotated relative to the second single polarization grating coupler.

[0008] In one embodiment, the first single polarization grating coupler is rotated approximately 90 degrees relative to the second single polarization grating coupler.

[0009] In one embodiment, the single polarization output coupler of the transmitting optical antenna is rotated relative to the first single polarization grating coupler and the second single polarization grating coupler.

[0010] In one embodiment, the transmitting optical antenna includes a two-dimensional (2D) polarization grating coupler, and the transmitting beam includes a first polarization direction and a second polarization direction.

[0011] In one embodiment, the first local oscillator signal and the second local oscillator signal have the same wavelength as the return beam.

[0012] In one embodiment, the transmit beam has a first polarization direction.

[0013] In one embodiment, the transmit beam is infrared and the return beam is infrared.

[0014] In one embodiment, the transmit and return beams are at narrow-band near-infrared wavelengths.

[0015] In one embodiment, the first polarization direction is orthogonal to the second polarization direction.

[0016] In one embodiment, the return beam is the transmitted beam reflected by the target.

[0017] An embodiment of the present disclosure includes an autonomous vehicle control system for an autonomous vehicle including a LIDAR device including one or more LIDAR pixels and one or more processors. At least one of the one or more LIDAR pixels includes a transmitting optical antenna, a receiving optical antenna, a first receiver, and a second receiver. The transmitting optical antenna is configured to emit a transmit beam. The receiving optical antenna is configured to detect (i) a first polarization direction of the return beam and (ii) a second polarization direction of the return beam. The first receiver is configured to generate a first electrical signal in response to receiving the first polarization direction of the return beam from the receiving optical antenna and a first local oscillator signal. The second receiver is configured to generate a second electrical signal in response to receiving the second polarization direction of the return beam from the receiving optical antenna and a second local oscillator signal. The one or more processors are configured to control the autonomous vehicle in response to the first electrical signal and the second electrical signal.

[0018] In one embodiment, the receiving optical antenna includes a two-dimensional (2D) polarization-splitting grating coupler configured to couple a first polarization direction of the return beam to a first receiver and to couple a second polarization direction of the return beam to a second receiver.

[0019] In one embodiment, the receiving optical antenna includes a first single polarization grating coupler configured to couple a first polarization direction of the return beam to the first receiver and a second single polarization grating coupler configured to couple a second polarization direction of the return beam to the second receiver.

[0020] In one embodiment, the first single polarization grating coupler is rotated relative to the second single polarization grating coupler.

[0021] In one embodiment, the transmitting optical antenna includes a two-dimensional (2D) polarization grating coupler, and the transmitting beam includes a first polarization direction and a second polarization direction.

[0022] An embodiment of the present disclosure includes an autonomous vehicle including a LIDAR sensor and one or more processors. The LIDAR sensor includes a transmitting optical antenna, a receiving optical antenna, a first receiver, and a second receiver. The transmitting optical antenna is configured to emit a transmit beam. The receiving optical antenna is configured to detect (i) a first polarization direction of the return beam and (ii) a second polarization direction of the return beam. The first receiver is configured to generate a first signal in response to receiving the first polarization direction of the return beam from the receiving optical antenna and a first local oscillator signal. The second receiver is configured to generate a second signal in response to receiving the second polarization direction of the return beam from the receiving optical antenna and a second local oscillator signal. The one or more processors are configured to control the autonomous vehicle in response to the first signal and the second signal.

[0023] An embodiment of the present disclosure includes a light detection and ranging (LIDAR) system. The LIDAR system includes one or more LIDAR pixels. At least one of the one or more LIDAR pixels includes a transmit optical antenna and a receive optical antenna configured to emit a transmit beam. The receive optical antenna includes a first single polarization grating coupler rotated +45 degrees relative to the transmit optical antenna, the first single polarization grating coupler configured to detect a first polarization direction of the return beam. The receive optical antenna includes a second single polarization grating coupler rotated -45 degrees relative to the transmit optical antenna, the second single polarization grating coupler configured to detect a second polarization direction of the return beam. The LIDAR system includes a first receiver configured to receive the first polarization direction of the return beam from the receive optical antenna and generate a first signal in response to receiving a first local oscillator signal having the first polarization direction. The LIDAR system includes a second receiver configured to receive the second polarization direction of the return beam from the receive optical antenna and generate a second signal in response to receiving a second local oscillator signal having the second polarization direction.

[0024] In one embodiment, the first single polarization grating coupler is offset from the second single polarization grating coupler.

[0025] In one embodiment, the first single polarization grating coupler is rotated relative to the second single polarization grating coupler.

[0026] In one embodiment, the first single polarization grating coupler is rotated approximately 90 degrees relative to the second single polarization grating coupler.

[0027] In one embodiment, the single polarization output coupler of the transmitting optical antenna is rotated relative to the first single polarization grating coupler and the second single polarization grating coupler.

[0028] In one embodiment, the transmitting optical antenna includes a two-dimensional (2D) polarization grating coupler, and the transmitting beam includes a first polarization direction and a second polarization direction.

[0029] In one embodiment, the first local oscillator signal and the second local oscillator signal have the same wavelength as the return beam.

[0030] In one embodiment, the transmit beam has a first polarization direction.

[0031] In one embodiment, the transmit beam is infrared and the return beam is infrared.

[0032] In one embodiment, the transmit and return beams are at a narrow band of near-infrared wavelengths.

[0033] In one embodiment, the first polarization direction is orthogonal to the second polarization direction.

[0034] In one embodiment, the return beam is the transmitted beam reflected by the target.

[0035] An embodiment of the present disclosure includes an autonomous vehicle control system for an autonomous vehicle. The autonomous vehicle control system includes a light detection and ranging (LIDAR) device including one or more LIDAR pixels. At least one of the one or more LIDAR pixels includes a transmit optical antenna and a receive optical antenna configured to emit a transmit beam. The receive optical antenna includes a first single polarization grating coupler rotated +45 degrees relative to the transmit optical antenna, the first single polarization grating coupler configured to detect a first polarization direction of the return beam. The receive optical antenna includes a second single polarization grating coupler rotated -45 degrees relative to the transmit optical antenna, the second single polarization grating coupler configured to detect a second polarization direction of the return beam. The LIDAR system includes a first receiver configured to receive the first polarization direction of the return beam from the receive optical antenna and generate a first electrical signal in response to receiving a first local oscillator signal. The LIDAR system includes a second receiver configured to receive the second polarization direction of the return beam from the receive optical antenna and generate a second electrical signal in response to receiving a second local oscillator signal. The LIDAR system includes one or more processors configured to control the autonomous vehicle in response to the first electrical signal and the second electrical signal.

[0036] In one embodiment, a first single polarization grating coupler is configured to couple a first polarization direction of the return beam to a first receiver, and a second single polarization grating coupler is configured to couple a second polarization direction of the return beam to a second receiver.

[0037] In one embodiment, the first single polarization grating coupler is rotated relative to the second single polarization grating coupler.

[0038] In one embodiment, the transmitting optical antenna includes a two-dimensional (2D) polarization grating coupler, and the transmitting beam includes a first polarization direction and a second polarization direction.

[0039] An embodiment of the present disclosure includes an autonomous vehicle. The autonomous vehicle includes a light detection and ranging (LIDAR) sensor. The LIDAR sensor includes a transmitting optical antenna and a receiving optical antenna configured to emit a transmit beam. The receiving optical antenna includes a first single polarization grating coupler rotated +45 degrees relative to the transmitting optical antenna, the first single polarization grating coupler configured to detect a first polarization direction of the return beam. The receiving optical antenna includes a second single polarization grating coupler rotated -45 degrees relative to the transmitting optical antenna, the second single polarization grating coupler configured to detect a second polarization direction of the return beam. The LIDAR sensor includes a first receiver configured to receive the first polarization direction of the return beam from the receiving optical antenna and generate a first signal in response to receiving a first local oscillator signal. The LIDAR sensor includes a second receiver configured to receive the second polarization direction of the return beam from the receiving optical antenna and generate a second signal in response to receiving a second local oscillator signal. The LIDAR sensor includes one or more processors configured to control the autonomous vehicle in response to the first signal and the second signal.

[0040] In one embodiment, the transmit and return beams are at a narrow band of near-infrared wavelengths.

[0041] In one embodiment, the transmit and return beams are at a narrow band of near-infrared wavelengths.

[0042] In one embodiment, the transmitting optical antenna includes a two-dimensional (2D) polarization grating coupler, and the transmitting beam includes a first polarization direction and a second polarization direction.

[0043] An embodiment of the present disclosure includes a light detection and ranging (LIDAR) system. The LIDAR system includes one or more LIDAR pixels. At least one of the one or more LIDAR pixels includes a transmitting optical antenna and a receiving optical antenna configured to emit a transmit beam. The receiving optical antenna includes a first grating coupler having a first rotation angle relative to the transmitting optical antenna, the first grating coupler configured to detect a return beam corresponding to the transmit beam reflected by a target. The receiving optical antenna includes a second grating coupler having a second rotation angle relative to the transmitting optical antenna, the second grating coupler configured to detect the return beam. At least one LIDAR pixel includes a first receiver configured to generate a first signal in response to the return beam and a first local oscillator signal detected by the first grating coupler, and a second receiver configured to generate a second signal in response to the return beam and a second local oscillator signal detected by the second grating coupler.

[0044] In one embodiment, the first rotation angle of the first grating coupler is orthogonal to the second rotation angle of the second grating coupler.

[0045] In one embodiment, the first grating coupler is configured to detect a first polarization direction of the return beam, and the second grating coupler is configured to detect a second polarization direction of the return beam.

[0046] In one embodiment, the first polarization direction of the return beam is orthogonal to the second polarization direction of the return beam.

[0047] In one embodiment, the first local oscillator signal has a first polarization direction and the second local oscillator signal has a second polarization direction.

[0048] In one embodiment, the first grating coupler comprises a single polarization grating coupler rotated +45 degrees relative to the transmitting optical antenna, and the second grating coupler comprises a single polarization grating coupler rotated -45 degrees relative to the transmitting optical antenna.

[0049] In one embodiment, the transmit optical antenna is coupled to a first waveguide configured to radiate a first polarization direction of the transmit beam and a second waveguide configured to radiate a second polarization direction of the transmit beam.

[0050] In one embodiment, the transmitting optical antenna includes a two-dimensional (2D) polarization grating coupler, and the transmitting beam includes a first polarization direction and a second polarization direction.

[0051] In one embodiment, the first local oscillator signal and the second local oscillator signal have the same wavelength as the return beam.

[0052] In one embodiment, the transmit beam is infrared and the return beam is infrared.

[0053] In one embodiment, the transmit and return beams are at a narrow band of near-infrared wavelengths.

[0054] An embodiment of the present disclosure includes an autonomous vehicle control system for an autonomous vehicle, the autonomous vehicle control system including a light detection and ranging (LIDAR) device including one or more LIDAR pixels. At least one of the one or more LIDAR pixels includes a transmitting optical antenna and a receiving optical antenna configured to emit a transmit beam. The receiving optical antenna includes a first grating coupler having a first rotation angle relative to the transmitting optical antenna, the first grating coupler configured to detect a return beam corresponding to the transmit beam reflected by a target. The receiving optical antenna includes a second grating coupler having a second rotation angle relative to the transmitting optical antenna, the second grating coupler configured to detect the return beam. At least one pixel includes a first receiver configured to generate a first signal in response to the return beam detected by the first grating coupler and a first local oscillator signal. At least one pixel includes a second receiver configured to generate a second signal in response to the return beam detected by the second grating coupler and a second local oscillator signal.

[0055] In one embodiment, the first rotation angle of the first grating coupler is orthogonal to the second rotation angle of the second grating coupler.

[0056] In one embodiment, the first grating coupler is configured to detect a first polarization direction of the return beam, and the second grating coupler is configured to detect a second polarization direction of the return beam.

[0057] In one embodiment, the first polarization direction of the return beam is orthogonal to the second polarization direction of the return beam.

[0058] In one embodiment, the first local oscillator signal has a first polarization direction and the second local oscillator signal has a second polarization direction.

[0059] In one embodiment, the first grating coupler comprises a single polarization grating coupler rotated +45 degrees relative to the transmitting optical antenna, and the second grating coupler comprises a single polarization grating coupler rotated −45 degrees relative to the transmitting optical antenna.

[0060] An embodiment of the present disclosure includes an autonomous vehicle. The autonomous vehicle includes a light detection and ranging (LIDAR) sensor. The LIDAR sensor includes a transmitting optical antenna configured to emit a transmit beam. The LIDAR sensor includes a receiving optical antenna. The receiving optical antenna includes a first grating coupler having a first rotation angle relative to the transmitting optical antenna, the first grating coupler configured to detect a return beam corresponding to the transmit beam reflected by a target. The receiving optical antenna includes a second grating coupler having a second rotation angle relative to the transmitting optical antenna, the second grating coupler configured to detect the return beam. The LIDAR sensor includes a first receiver configured to generate a first signal in response to the return beam detected by the first grating coupler and a first local oscillator signal. The LIDAR sensor includes a second receiver configured to generate a second signal in response to the return beam detected by the second grating coupler and a second local oscillator signal.

[0061] In one embodiment, the first grating coupler is configured to detect a first polarization direction of the return beam and the second grating coupler is configured to detect a second polarization direction of the return beam, wherein the first polarization direction of the return beam is orthogonal to the second polarization direction of the return beam. [Brief explanation of the drawings]

[0062] Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings, in which like reference numerals refer to like parts in the various drawings unless otherwise specified.

[0063] [Figure 1a] 1 illustrates a LIDAR system including a LIDAR pixel according to an embodiment of the present disclosure.

[0064] [Figure 1b] 1 illustrates an exemplary coherent receiver according to an embodiment of the present disclosure.

[0065] [Figure 2] 1 illustrates a LIDAR system including a LIDAR pixel with a two-dimensional (2D) polarization-splitting grating coupler as a receiving optical antenna according to an embodiment of the present disclosure.

[0066] [Figure 3] 1 illustrates a LIDAR system including a LIDAR pixel with a 2D polarization grating coupler as a transmitting optical antenna according to an embodiment of the present disclosure.

[0067] [Figure 4a] FIG. 1 illustrates a block diagram of an example system environment for an autonomous vehicle, according to an embodiment of the present disclosure.

[0068] [Figure 4b] FIG. 1 illustrates a block diagram of an example system environment for an autonomous commercial truck vehicle according to an embodiment of the present disclosure.

[0069] [Figure 4c]FIG. 1 illustrates a block diagram of an example system environment for an autonomous commercial truck vehicle according to an embodiment of the present disclosure.

[0070] [Figure 4d] FIG. 1 illustrates a block diagram of an example system environment for an autonomous commercial truck vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0071] An embodiment of a LIDAR pixel with a dual polarization receive optical antenna is described. The LIDAR pixel may include one or more modules, one or more integrated chips, or one or more electrical circuits. The LIDAR pixel may also be implemented as a single packaged chip or as a modular design such that the LIDAR pixel includes multiple packaged chips. In the following description, numerous specific details are presented to provide a thorough understanding of the implementation. However, those skilled in the relevant art will recognize that the techniques described herein can be implemented without one or more specific details or using other methods, components, materials, etc. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

[0072] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the invention. Thus, appearances of the phrase "in one embodiment" or "an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Also, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0073] Throughout this specification, several technical terms are used. These terms have their ordinary meaning in the technical field from which they originate, unless specifically defined herein or the context of use clearly dictates otherwise. For purposes of this disclosure, the term "autonomous vehicle" includes vehicles with autonomous capabilities having any level of autonomy according to SAE International Standard J3016.

[0074] In some embodiments of the present disclosure, visible light can be defined as having a wavelength range of approximately 380 nm to 700 nm. Invisible light can be defined as light having a wavelength outside the range of visible light, such as ultraviolet and infrared light. Infrared light, which has a wavelength range of approximately 700 nm to 1 mm, includes near-infrared light. In some embodiments of the present disclosure, near-infrared light can be defined as having a wavelength range of approximately 700 nm to 1600 nm.

[0075] Frequency-modulated continuous wave (FMCW) LIDAR transmits a frequency-modulated light beam at an object / target to directly measure the object / target's distance and velocity. The light reflected from the object / target can be combined with a tapped version of the light beam. The frequency of the resulting beat tone is proportional to the object's distance from the LIDAR system, after a second measurement is corrected for the required Doppler shift. The two measurements, which may or may not be performed simultaneously, provide both range and velocity information.

[0076] Embodiments of the present disclosure include a LIDAR device including a LIDAR pixel having a transmitting optical antenna, a receiving optical antenna, a first receiver, and a second receiver. The receiving optical antenna is a dual-polarized receiving optical antenna that detects two different polarizations (e.g., orthogonal polarization directions) of a return beam. The first receiver generates a first signal in response to receiving the first polarization direction of the return beam detected by the receiving optical antenna, and the second receiver generates a second signal in response to receiving the second polarization direction of the return beam detected by the receiving optical antenna. Detecting two different polarization directions of the return beam increases the signal-to-noise ratio (SNR) of the detected return beam, potentially improving the imaging quality of the LIDAR system. Detecting two different polarization directions of the return beam also enables the LIDAR system to detect additional information about the external environment, such as polarization-dependent surface materials of objects / targets within the LIDAR system's external environment. These and other embodiments are described in more detail with respect to FIGS. 1a-4d.

[0077] FIG. 1a illustrates a LIDAR system 100 including a LIDAR pixel 199 according to an embodiment of the present disclosure. In some embodiments, the LIDAR pixel 199 includes a transmit optical antenna 105, a receive optical antenna 110, a first coherent receiver 121, and a second coherent receiver 126. However, the present invention is not limited to the specific LIDAR pixel architecture illustrated in FIG. 1a. Any suitable chip design architecture can be used to implement the LIDAR pixel. For example, the transmit and receive optical antennas may be implemented as a single module or a single integrated chip, or as separate modules or chips. As yet another example, the first and second coherent receivers may be implemented as a single module or a single integrated chip, or as separate modules or chips. The transmit optical antenna 105 is configured to emit a transmit beam. The transmit beam may be an infrared transmit beam. The transmit beam may be a near-infrared transmit beam. The transmit beam may have a defined single polarization direction. 1a, the transmitting optical antenna 105 is shown as a single-polarization output coupler and may transmit a transmit beam in response to receiving a transmit signal 101 via a waveguide 103. The transmit signal 101 may be generated by a laser, and the transmit beam emitted by the transmitting optical antenna 105 may have a very narrow linewidth (e.g., 1 nm or less).

[0078] In some embodiments, the receiving optical antenna 110 is a dual-polarized receiving optical antenna configured to detect a first polarization direction of the return beam and a second polarization direction of the return beam. The return beam is a reflection of the transmitted beam reflected from a target in the external environment of the LIDAR system 100. The first polarization direction may be orthogonal to the second polarization direction. In FIG. 1a, the receiving optical antenna 110 includes a first single-polarization grating coupler 111 and a second single-polarization grating coupler 116. The first single-polarization grating coupler 111 is configured to couple the first polarization direction of the return beam to the first coherent receiver 121 via a waveguide 112. The second single-polarization grating coupler 116 is configured to couple the second polarization direction of the return beam to the second coherent receiver 126 via a waveguide 117.

[0079] In some embodiments, the first single polarization grating coupler 111 is rotated relative to the second single polarization grating coupler 116. In the particular illustrated embodiment of FIG. 1 a, the first single polarization grating coupler 111 is rotated 90 degrees relative to the second single polarization grating coupler 116. The single polarization output couplers of the illustrated transmitting optical antenna 105 are rotated relative to the first single polarization grating coupler 111 and the second single polarization grating coupler 116. Specifically, in FIG. 1 a, the first single polarization grating coupler 111 is rotated +45 degrees relative to the transmitting optical antenna 105, and the second single polarization grating coupler 116 is rotated −45 degrees relative to the transmitting optical antenna 105.

[0080] In some embodiments, first coherent receiver 121 is configured to generate first signal 123 in response to receiving the first polarization direction of the return beam and first local oscillator signal 131. First local oscillator signal 131 may be an optical signal having a first polarization direction. In FIG. 1a, the first polarization direction of the return beam is received by first coherent receiver 121 from first single polarization grating coupler 111 via waveguide 112, and first local oscillator signal 131 is received by first coherent receiver 121 via waveguide 132. First signal 123 may be an electrical signal provided to processing logic 150 via communication channel 122.

[0081] In some embodiments, the second coherent receiver 126 is configured to generate a second signal 128 in response to receiving the second polarization direction of the return beam and the second local oscillator signal 136. The second local oscillator signal 136 may be an optical signal having the second polarization direction. In FIG. 1a, the second polarization direction of the return beam is received by the second coherent receiver 126 from the second single polarization grating coupler 116 via the waveguide 117, and the second local oscillator signal 136 is received by the second coherent receiver 126 via the waveguide 137. The second signal 128 may be an electrical signal provided to the processing logic 150 via the communication channel 127.

[0082] Processing logic 150 is configured to generate image 155 in response to receiving first signal 123 and second signal 128 from first coherent receiver 121 and second coherent receiver 126, respectively. LIDAR system 100 may include an array of LIDAR pixels 199 configured to provide the first signal (e.g., signal 123) and the second signal (e.g., signal 128) to processing logic 150. Here, processing logic 150 may generate image 155 in response to the first signal and the second signal received by multiple LIDAR pixels 199 in the array of LIDAR pixels to processing logic 150.

[0083] During operation, the transmit signal 101 may be emitted into free space as a transmit beam by the transmit optical antenna 105. The transmit beam may propagate through one or more lenses, be deflected by a rotating mirror, and then propagate through the external environment until encountering an object / target. A portion of the transmit beam that encounters the object / target is reflected back toward the LIDAR system 100 and the LIDAR pixels 199 as a return beam. The return beam may be reflected by the rotating mirror and propagate through one or more lenses, but may be offset relative to the transmit optical antenna 105 due to time differences in mirror rotation. To compensate for this offset, the receive optical antenna 110 may be offset from the transmit optical antenna 105 by an offset dimension 191.

[0084] FIG. 1b illustrates an exemplary coherent receiver 171 according to an embodiment of the present disclosure. The exemplary coherent receiver 171 may be used, for example, as coherent receiver 121 or 126. The coherent receiver 171 includes an optical mixer 152, a return beam port 154, a local oscillator port 158, and an output port 162. According to an embodiment, the optical mixer 152 is configured to combine the return beam signal RB with a local oscillator signal LO to generate an output signal OUT. The optical mixer 152 may be coupled to receive the return beam signal RB from, for example, waveguide 112 or waveguide 117, and waveguide 156 may provide the return beam signal to the optical mixer 152. The optical mixer 152 may be coupled to receive the local oscillator signal LO from, for example, waveguide 132 or 137, and waveguide 160 may provide the local oscillator signal LO to the optical mixer 152. The optical mixer 152 may combine input signals to generate multiple combined output signals OUT1 and OUT2. The output signals OUT1 and OUT2 are fed to a photodiode pair (including photodiodes PD1 and PD2) that converts the return beam signal RB and the local oscillator signal LO into the output signal OUT. The output signal OUT may be an electrical signal. The output signal OUT may be a beat signal representing the range and / or velocity of one or more objects in the environment of the LIDAR system. For example, communication channel 122 or 127 may be coupled to output port 162.

[0085] 2 illustrates a LIDAR system 200 including a LIDAR pixel 299 according to an embodiment of the present disclosure. The LIDAR pixel 299 includes a transmit optical antenna 205, a receive optical antenna 210, a first coherent receiver 221, and a second coherent receiver 226. In FIG. 2, the receive optical antenna 210 of the LIDAR pixel 299 is illustrated as a two-dimensional (2D) polarization splitting grating coupler. The 2D polarization splitting grating coupler is configured to couple a first polarization of the return beam to the first coherent receiver 221 and a second polarization of the return beam to the second coherent receiver 226.

[0086] The transmit optical antenna 205 is configured to emit a transmit beam. The transmit beam may be an infrared transmit beam. The transmit beam may be a near-infrared transmit beam. The transmit beam may have a defined single polarization direction. In FIG. 2, the transmit optical antenna 205 is shown as a single-polarization output coupler and may transmit the transmit beam in response to receiving a transmit signal 201 via a waveguide 203. The transmit signal 201 may be generated by a laser, and the transmit beam emitted by the transmit optical antenna 205 may have a very narrow linewidth.

[0087] In some embodiments, the receiving optical antenna 210 is a dual-polarized receiving optical antenna configured to detect a first polarization direction of the return beam and a second polarization direction of the return beam. The return beam is a reflection of the transmitted beam reflected from a target in the external environment of the LIDAR system 200. The first polarization direction may be orthogonal to the second polarization direction. The 2D polarization split grating coupler 210 is configured to couple the first polarization direction of the return beam to the first coherent receiver 221 via waveguide 212 and couple the second polarization direction of the return beam to the second coherent receiver 226 via waveguide 217. In some embodiments, the exemplary coherent receiver 171 of FIG. 1b may be used as the first coherent receiver 221 and / or the second coherent receiver 226.

[0088] In some embodiments, first coherent receiver 221 is configured to generate first signal 223 in response to receiving the first polarization direction of the return beam and first local oscillator signal 231. First local oscillator signal 231 may be an optical signal having a first polarization direction. In FIG. 2 , the first polarization direction of the return beam is received by first coherent receiver 221 from 2D polarization division grating coupler 210 via waveguide 212, and first local oscillator signal 231 is received by first coherent receiver 221 via waveguide 232. First signal 223 may be an electrical signal provided to processing logic 250 via communication channel 222.

[0089] In some embodiments, the second coherent receiver 226 is configured to generate a second signal 228 in response to receiving the second polarization direction of the return beam and the second local oscillator signal 236. The second local oscillator signal 236 may be an optical signal having the second polarization direction. In FIG. 2 , the second polarization direction of the return beam is received by the second coherent receiver 226 from the 2D polarization division grating coupler 210 via waveguide 217, and the second local oscillator signal 236 is received by the second coherent receiver 226 via waveguide 237. The second signal 228 may be an electrical signal provided to the processing logic 250 via the communication channel 227.

[0090] Processing logic 250 is configured to generate image 255 in response to receiving first signal 223 and second signal 228 from first coherent receiver 221 and second coherent receiver 226, respectively. LIDAR system 200 may include an array of LIDAR pixels 299 configured to provide first signal (e.g., signal 223) and second signal (e.g., signal 228) to processing logic 250, where processing logic 250 may generate image 255 in response to the first signal and second signal received by multiple LIDAR pixels 299 in the array of LIDAR pixels to processing logic 250.

[0091] In operation, a transmit signal 201 is emitted into free space by a transmit optical antenna 205 as a transmit beam. The transmit beam may propagate through one or more lenses, be deflected by a rotating mirror, and then propagate through the external environment until it encounters an object / target. A portion of the transmit beam that encounters the object / target is reflected back toward the LIDAR system 200 and LIDAR pixels 299 as a return beam. The return beam may be reflected from the rotating mirror and propagate through one or more lenses, but may be offset relative to the transmit optical antenna 205 due to a time difference in the mirror rotation. To compensate for this offset, the receive optical antenna 210 may be offset from the transmit optical antenna 205 by an offset dimension 291.

[0092] FIG. 3 illustrates a LIDAR system 300 including a LIDAR pixel 399 according to an embodiment of the present disclosure. In the exemplary embodiment of FIG. 3, the LIDAR pixel 399 includes a transmit optical antenna 309, a receive optical antenna 310, a first coherent receiver 321, and a second coherent receiver 326. The transmit optical antenna 309 of the LIDAR pixel 399 is a 2D polarization grating coupler. The transmit optical antenna 309 may be configured to emit transmit beams having orthogonal polarizations. In the embodiment illustrated in FIG. 3, the transmit optical antenna 309 is configured to receive a first transmit signal TX1 301 via a waveguide 302 and a second transmit signal TX2 302 via a waveguide 307. In some embodiments, the amplitude and / or phase of the first transmit signal TX1 301 and the second transmit signal TX2 302 are modulated. This additional degree of freedom for the transmit beam emitted by the transmit optical antenna 309 can be useful for providing additional information about the polarization-dependent reflectivity of the environment.

[0093] The receive optical antenna 310 of the LIDAR pixel 399 is shown as a two-dimensional (2D) polarization-splitting grating coupler. The 2D polarization-splitting grating coupler 310 may be configured similarly to the 2D polarization-splitting grating coupler 210 of FIG. 2. Thus, the 2D polarization-splitting grating coupler 310 may be configured to couple a first polarization of the return beam to a first coherent receiver 321 and a second polarization of the return beam to a second coherent receiver 326. As shown in FIG. 3, the first polarization direction may be orthogonal to the second polarization direction. The transmit beam emitted by the 2D polarization-splitting grating coupler 310 may include a first polarization direction and a second polarization direction. The transmit beam may be an infrared transmit beam. The transmit beam may be a near-infrared transmit beam. The transmit signal TX1 301 and / or the transmit signal TX2 302 may be generated by a laser, and the transmit beam emitted by the transmit optical antenna 309 may have a very narrow linewidth.

[0094] In some embodiments, the receiving optical antenna 310 is a dual-polarized receiving optical antenna configured to detect a first polarization direction of the return beam and a second polarization direction of the return beam. The return beam is a reflection of the transmitted beam reflected from a target in the external environment of the LIDAR system 300. The first polarization direction may be orthogonal to the second polarization direction. The 2D polarization splitting grating coupler 310 is configured to couple the first polarization direction of the return beam to the first coherent receiver 321 via waveguide 312 and couple the second polarization direction of the return beam to the second coherent receiver 326 via waveguide 317. In some embodiments, the exemplary coherent receiver 171 of FIG. 1a may be used as the first coherent receiver 321 and / or the second coherent receiver 326.

[0095] In some embodiments, first coherent receiver 321 is configured to generate first signal 323 in response to receiving the first polarization direction of the return beam and first local oscillator signal 331. First local oscillator signal 331 may be an optical signal having a first polarization direction. In FIG. 3 , the first polarization direction of the return beam is received by first coherent receiver 321 from 2D polarization division grating coupler 310 via waveguide 312, and first local oscillator signal 331 is received by first coherent receiver 321 via waveguide 332. First signal 323 may be an electrical signal provided to processing logic 350 via communication channel 322.

[0096] In some embodiments, the second coherent receiver 326 is configured to generate a second signal 328 in response to receiving the second polarization direction of the return beam and the second local oscillator signal 336. The second local oscillator signal 336 may be an optical signal having the second polarization direction. In FIG. 3 , the second polarization direction of the return beam is received by the second coherent receiver 326 from the 2D polarization splitting grating coupler 310 via waveguide 317, and the second local oscillator signal 336 is received by the second coherent receiver 326 via waveguide 337. The second signal 328 may be an electrical signal provided to the processing logic 350 via the communication channel 327.

[0097] Processing logic 350 is configured to generate image 355 in response to receiving first signal 323 and second signal 328 from first coherent receiver 321 and second coherent receiver 326, respectively. LIDAR system 300 may include an array of LIDAR pixels 399 configured to provide first signal (e.g., signal 323) and second signal (e.g., signal 328) to processing logic 350, where processing logic 350 may generate image 355 in response to the first signal and second signal received by multiple LIDAR pixels 399 in the array of LIDAR pixels to processing logic 350.

[0098] In operation, transmit signals 301 and 306 are emitted into free space as transmit beams by transmit optical antenna 309. The transmit beams may propagate through one or more lenses, be deflected by a rotating mirror, and then propagate through the external environment until encountering an object / target. A portion of the transmit beam that encounters the object / target is reflected back toward LIDAR system 300 and LIDAR pixel 399 as a return beam. The return beams may be reflected from the rotating mirror and propagate through one or more lenses, but may be offset relative to transmit optical antenna 309 due to time differences in mirror rotation. To compensate for this offset, receive optical antenna 310 may be offset from transmit optical antenna 309 by an offset dimension 391.

[0099] 1. System Environment for Autonomous Vehicles FIG. 4a is a block diagram illustrating an example of a system environment for an autonomous vehicle according to some embodiments.

[0100] 4a, an exemplary autonomous vehicle 410A in which various techniques disclosed herein may be implemented is shown. For example, the vehicle 410A may include a powertrain 492 including a prime mover 494 driven by an energy source 496 and capable of powering a drivetrain 498, and a control system 480 including directional control 482, powertrain control 484, and brake control 486. It will be appreciated that the vehicle 410A may be implemented as any of a variety of types of vehicles, including vehicles capable of transporting people and / or cargo and operating in a variety of environments, and that the components 480-498 described above may vary significantly depending on the type of vehicle in which they are used.

[0101] For simplicity, the embodiments discussed below focus on wheeled land vehicles such as cars, vans, trucks, and buses. In these embodiments, the prime mover 494 may include (among other things) one or more electric motors and / or an internal combustion engine. The energy source may include, for example, a fuel system (e.g., providing gasoline, diesel, hydrogen, etc.), a battery system, solar panels or other renewable energy sources, and / or a fuel cell system. The drivetrain 498 may include wheels and / or tires along with a transmission and / or any other mechanical drive components for converting the power output of the prime mover 494 into vehicle motion, one or more brakes configured to controllably stop or slow the vehicle 410A, and direction or steering components suitable for controlling the trajectory of the vehicle 410A (e.g., a rack-and-pinion steering linkage that pivots one or more wheels of the vehicle 410A 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 cases multiple electric motors (e.g., dedicated to individual wheels or axles) can be used as prime movers.

[0102] Direction control 482 may include one or more actuators and / or sensors for controlling and receiving feedback from direction or steering components to cause vehicle 410A to follow a desired trajectory. Powertrain control 484 may be configured to control the output of powertrain 402, e.g., control the gears of the transmission in drivetrain 498, to control the output of prime mover 494, which can control the speed and / or direction of vehicle 410A. Brake control 416 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 410A.

[0103] Other vehicle types, including, but not limited to, off-road vehicles, all-terrain or tracked vehicles, construction equipment, etc., may necessarily use different powertrains, drivetrains, energy sources, directional control, powertrain control, and braking control. Furthermore, in some embodiments, some components may be combined, such as when vehicle directional control is primarily handled by varying the output of one or more prime movers. Accordingly, the embodiments disclosed herein are not limited to the specific application of the technology disclosed herein to autonomous land vehicles.

[0104] Various levels of autonomous control for vehicle 410A may be implemented in vehicle control system 420, which may include one or more processors 422 and one or more memories 424, each of which may be configured to execute program code instructions 426 stored in memory 424. The processors may include, for example, graphics processing units (GPU(s)) and / or central processing units (CPU(s)).

[0105] The sensors 430 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 430 may include a radar sensor 434, a LIDAR (light detection and ranging) sensor 436, and a 3D positioning sensor 438 (e.g., an accelerometer, a gyroscope, a magnetometer, or one of satellite navigation systems 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 438 can be used to determine the vehicle's position on Earth using satellite signals. The sensors 430 may include a camera 440 and / or an inertial measurement unit (IMU) 442. The camera 440 may be a monographic or stereographic camera and can record still and / or video images. The IMU 442 may include multiple gyroscopes and accelerometers capable of detecting the 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 410A. Each sensor 430 may output sensor data at a variable data rate, which may differ from the data rate of the other sensors 430.

[0106] The outputs of the sensors 430 may be provided to a set of control subsystems 450, including a localization subsystem 452, a planning subsystem 456, a perception subsystem 454, and a control subsystem 458. The localization subsystem 452 may perform functions such as precisely determining the position and orientation (also called "pose") of the vehicle 410A within the surrounding environment, and generally within some frame of reference. The autonomous vehicle's position can be compared to the positions of additional vehicles in the same environment as part of labeled autonomous vehicle data generation. The perception subsystem 454 may perform functions such as detecting, tracking, determining, and / or identifying objects in the environment surrounding the vehicle 410A. Machine learning models can be used to track the objects. The planning subsystem 456 may perform functions such as planning the trajectory of the vehicle 410A within a fixed time frame given a desired destination, as well as stationary and moving objects in the environment. Machine learning can be used for vehicle trajectory planning. The control subsystem 458 may perform functions such as generating appropriate control signals to control various controllers of the vehicle control system 420 to implement the planned trajectory of the vehicle 410A. A machine learning model can be used to generate one or more signals to control the autonomous vehicle to implement the planned trajectory.

[0107] It will be understood that the collection of components shown in FIG. 4a for vehicle control system 420 is merely illustrative. In some embodiments, individual sensors may be omitted. Additionally or alternatively, in some embodiments, multiple sensors of the type shown in FIG. 4a may be used for redundancy 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 452-458 are shown as being separate from processor 422 and memory 424, it will be understood that in some embodiments, some or all of subsystems 452-458 may be embodied in program code instructions 426 resident in one or more memories 424 and executed by one or more processors 422, and that these subsystems 452-458 may, in some cases, be implemented using the same processor and / or memory. The subsystems may be embodied, at least in part, using various dedicated circuit logic, various processors, various field programmable gate arrays (FPGAs), various application specific integrated circuits (ASICs), various real-time controllers, etc., and as previously mentioned, many subsystems may use circuits, processors, sensors, and / or other components. Additionally, the various components of vehicle control system 420 may be networked in various ways.

[0108] In some embodiments, vehicle 410A may include an auxiliary vehicle control system (not shown) that can be used as a redundant or backup control system for vehicle 410A. The auxiliary vehicle control system may be capable of fully operating autonomous vehicle 410A in the event of an adverse event occurring in vehicle control system 420, while in other embodiments, the auxiliary vehicle control system may have only limited functionality, such as, for example, performing a controlled stop of vehicle 410A in response to an adverse event detected by primary vehicle control system 420. In other embodiments, the auxiliary vehicle control system may be omitted.

[0109] In general, a variety of architectures, including various combinations of software, hardware, circuit logic, sensors, and networks, can be used to implement the various components shown in FIG. 4a. For example, each processor can be embodied as a microprocessor, and each memory can include not only the random access memory (RAM) devices that constitute main storage, but also any secondary levels of memory, such as cache memory, non-volatile or backup memory (e.g., programmable or flash memory), read-only memory, etc. Each memory can also be considered to include memory storage devices physically located elsewhere in the vehicle 410A, such as any cache memory within the processor, as well as any storage capacity used as virtual memory (e.g., stored in a mass storage device or other computer controller). One or more of the processors shown in FIG. 4a, or entirely separate processors, can be used to implement additional functions in the vehicle 410A beyond those intended for autonomous control, such as controlling the entertainment system, operating doors, lights, convenience functions, etc.

[0110] Additionally, for additional storage, vehicle 410A may include one or more mass storage devices, such as 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), a network attached storage, a storage area network, and / or a tape drive.

[0111] Vehicle 410A also includes a user interface 464 that enables vehicle 410A to receive a number of inputs from a user or operator and generate outputs, such as one or more displays, touchscreens, voice and / or gesture interfaces, buttons and other tactile controls, etc. Alternatively, user input may be received via other computers or electronic devices, such as, for example, an app or web interface on a mobile device.

[0112] Vehicle 410A may also include one or more network interfaces, such as network interface 462, which may enable vehicle 410A to communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), a wireless network, and / or the Internet) to allow communication of information with other computers and electronic devices, including, for example, a central service such as a cloud service, that receives environmental and other data for use in autonomous control. Data collected by one or more sensors 430 may be uploaded via network 470 to computing system 472 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 472 according to many embodiments is described in connection with FIG. 2.

[0113] 4a, and the various additional controllers and subsystems disclosed herein, generally operate under the control of an operating system and execute or rely on various computer software applications, components, programs, objects, modules, data structures, etc., as described in more detail below. The various applications, components, programs, objects, modules, etc. may also execute on one or more processors of other computers coupled to vehicle 410A via network 470, e.g., in a distributed, cloud-based, or client-server computing environment where the processing required to implement the functionality of a computer program may be allocated across multiple computers and / or services via the network.

[0114] Generally, the routines performed to implement various embodiments described herein are referred to herein as "program code," whether embodied as part of an operating system or a specific application, component, program, object, module, or instruction sequence, or as a subset thereof. Program code may reside at various times in various memories and storage devices and, when read and executed by one or more processors, may comprise one or more instructions that perform the steps necessary to perform the steps or elements embodying various aspects of the present disclosure. Also, while embodiments are described in the context of fully functional computers and systems, it should be understood that the various embodiments described herein may be distributed as program products in various forms, and that such embodiments may be practiced independently of the particular type of computer-readable medium used to actually achieve distribution.

[0115] Examples of computer-readable media include tangible and 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.).

[0116] Additionally, various program code described below may be identified based on the application for which it is implemented in a particular embodiment. However, it should be understood that 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 typically myriad ways in which computer programs may be organized into routines, procedures, methods, modules, objects, etc., and the various ways in which program functionality is allocated among the various software layers (e.g., operating system, libraries, APIs, applications, applets, etc.) residing within a typical computer, it should be understood that the present disclosure is not limited to the particular structure and allocation of program functionality described herein.

[0117] The environment illustrated in Figure 4a is not intended to limit the embodiments disclosed herein, and in fact, other alternative hardware and / or software environments may be used without departing from the scope of the embodiments disclosed herein.

[0118] 2. FM LIDAR for automotive applications The truck may include a LIDAR system (e.g., vehicle control system 420 in FIG. 4a). In some embodiments, the LIDAR system may encode an optical signal using frequency modulation and scatter the encoded optical signal into free space using optics. By detecting the frequency difference between the encoded optical signal and the return signal reflected from an object, a frequency modulation (FM) LIDAR system can determine the object's location using the Doppler effect and / or accurately measure the object's velocity. 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 optics.

[0119] FM or PM LIDAR systems may offer significant advantages over traditional LIDAR systems for automotive and / or commercial truck transportation applications. First, in some cases, an object (e.g., a pedestrian wearing dark clothing) may have low reflectivity because only a small amount (e.g., 10% or less) of the light reaching the object is reflected back to the FM or PM LIDAR system's sensor (e.g., sensor 430 in FIG. 4a). In other cases, an object (e.g., a shiny road sign) may have high reflectivity (e.g., 10% or more) because a large amount of the light reaching the object is reflected back to the FM LIDAR system's sensor.

[0120] 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 beyond 300 meters and high-reflectivity objects at distances beyond 400 meters.

[0121] To achieve this improved detection capability, FM LIDAR systems can use sensors (e.g., sensor 430 in FIG. 4a). In some embodiments, these sensors can be sensitive to single photons, meaning they can detect the smallest amount of light possible. In some applications, FM LIDAR systems can use infrared wavelengths (e.g., 950 nm, 1550 nm, etc.), but are not limited to infrared wavelength ranges (e.g., near-infrared: 800 nm to 1500 nm, mid-infrared: 1500 nm to 5600 nm, and far-infrared: 5600 nm to 1000000 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 not sensitive to single photons and / or operate only at near-infrared wavelengths, so their light output (and distance detection capabilities) must be limited for eye safety reasons.

[0122] Therefore, by detecting objects at greater distances, FM LIDAR systems have more time to react to unexpected obstacles. Indeed, for large vehicles (e.g., commercial trucks) traveling at high speeds, even a few extra milliseconds can improve safety and convenience.

[0123] Another advantage of FM LIDAR systems is that they provide accurate velocity instantaneously 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 less than 100 meters per second (m / s), this shift at a wavelength of 1550 nanometers (nm) corresponds to a frequency shift of less than 130 megahertz (MHz). This frequency shift is small enough to be difficult to detect directly in the optical domain. However, when using 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 received data more quickly.

[0124] Instantaneous velocity calculations also make it easier for an FM LIDAR system to identify distant or sparse data points as objects and / or track how these objects are moving over time. For example, an FM LIDAR sensor (e.g., sensor 430 in FIG. 4a) may receive only a few returns (e.g., hits) for an object 300 m away, but if these returns provide a velocity value of interest (e.g., moving toward the vehicle at a speed of 70 mph or greater), the FM LIDAR system and / or autonomous vehicle control system can determine individual weights for the probabilities associated with the object.

[0125] Faster identification and / or tracking of FM LIDAR systems provides autonomous vehicle control systems with more time to maneuver the vehicle, and a more accurate understanding of the speed at which an object is moving allows the autonomous vehicle control system to plan a better response.

[0126] Another advantage of FM LIDAR systems is that they are less static than traditional LIDAR systems. That is, traditional LIDAR systems, which are designed to be more sensitive to light, typically perform poorly in bright sunlight. These systems also tend to suffer from crosstalk (e.g., when sensors are crossed by each other's light pulses or light beams) and self-interference (e.g., when a sensor is crossed by its own previous light pulse or light beam). To overcome these drawbacks, vehicles using traditional LIDAR systems often require additional hardware, complex software, and / or more computing power to manage this "noise."

[0127] FM LIDAR systems, on the other hand, avoid this problem because each sensor is specifically designed to respond only to its own light characteristics (e.g., light beam, light wave, light pulse). 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. FM LIDAR systems therefore enable safer, smoother driving by producing (e.g., generating, deriving, etc.) more accurate data with fewer hardware or software requirements.

[0128] Finally, FM LIDAR systems are more scalable than traditional LIDAR systems. As more autonomous vehicles (e.g., cars, commercial trucks, etc.) appear on the roads, vehicles powered by FM LIDAR systems likely 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 of an FM LIDAR to be fabricated on a single chip, which provides unique advantages as described herein.

[0129] 3. Commercial Trucking FIG. 4b is a block diagram illustrating an example of a system environment for an autonomous commercial truck fleet, according to some embodiments. The environment 400B includes a commercial truck 402B for carrying cargo 406B. In some embodiments, the commercial truck 402B 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 several transportation modes to transport cargo), and / or any other road-based freight transportation application. The commercial truck 402B 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 406B may be merchandise and / or agricultural products. The commercial truck 402B may include a trailer for carrying the cargo 406B, such as a flatbed trailer, a lowboy trailer, a step deck trailer, an extendable flatbed trailer, a side kit trailer, etc.

[0130] The environment 400B includes an object 410B (shown in FIG. 4b as another vehicle) within a distance range of 30 meters or less from the truck.

[0131] The commercial truck 402B may include a LIDAR system 404B (e.g., the FM LIDAR system, vehicle control system 420 in FIG. 4a) for determining the distance to and measuring the speed of the object 410B. While FIG. 4b shows one LIDAR system 404B mounted on the front of the commercial truck 402B, the number of LIDAR systems on the commercial truck and the areas in which the LIDAR systems are mounted are not limited to any particular number or area. The commercial truck 402B may include any number of LIDAR systems 404B (or components thereof, such as sensors, modulators, coherent signal generators, etc.) mounted on any area of ​​the commercial truck 402B (e.g., the front, back, sides, top, bottom, underside, and / or bottom) to facilitate object detection in any free space about the commercial truck 402B.

[0132] As shown, LIDAR system 404B in environment 400B may be configured to detect objects (e.g., other vehicles, bicycles, trees, road signs, potholes, etc.) within close range (e.g., 30 meters or less) of commercial truck 402B.

[0133] 4c is a block diagram illustrating an example of a system environment for an autonomous commercial truck vehicle, according to some embodiments. Environment 400C includes the same components included in environment 400B (e.g., commercial truck 402B, cargo 406B, LIDAR system 404B, etc.).

[0134] Environment 400C includes object 410C (shown in FIG. 4c as another vehicle) within a distance range of (i) 30 meters or more and (ii) 150 meters or less from commercial truck 402B. As shown, LIDAR system 404B of environment 400C may be configured to detect objects (e.g., other vehicles, bicycles, trees, road signs, potholes, etc.) within a certain distance (e.g., 100 meters) from commercial truck 402B.

[0135] 4d is a block diagram illustrating an example of a system environment for an autonomous commercial truck vehicle, according to some embodiments. Environment 400D includes the same components included in environment 400B (e.g., commercial truck 402B, cargo 406B, LIDAR system 404B, etc.).

[0136] Environment 400D includes object 410D (shown in FIG. 4d as another vehicle) within a distance of 150 meters or more from commercial truck 402B. As shown, LIDAR system 404B of environment 400D can be configured to detect objects (e.g., other vehicles, bicycles, trees, road signs, potholes, etc.) within a distance (e.g., 300 meters) from commercial truck 402B.

[0137] In commercial trucking applications, effective object detection at all ranges is important due to the increasing weight of vehicles 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. Ultimately, commercial trucks equipped with these systems are better able to safely transport people and goods over short or long distances, thereby improving the safety of not only the commercial truck but also surrounding vehicles. In various embodiments, these FM or PM LIDAR systems can be used in semi-autonomous 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 PM LIDAR system, alone or in combination with other vehicle systems.

[0138] 4. Continuous Wave Modulation and Quasi-Continuous Wave Modulation 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.

[0139] 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.

[0140] In this disclosure, the term "processing logic" may include one or more processors, microprocessors, multi-core processors, application-specific integrated circuits (ASICs), and / or field programmable gate arrays (FPGAs) for performing the operations disclosed herein. In some embodiments, memory (not shown) is integrated into the processing logic to store instructions for performing operations and / or storing data. Additionally, the processing logic may include analog or digital circuitry for performing operations according to embodiments of the present disclosure.

[0141] "Memory" or "memories" as described herein may include one or more volatile or non-volatile memory architectures. "Memory" or "memories" may be removable and non-removable media embodied in any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Example memory technologies may include RAM, ROM, EEPROM, flash memory, CD-ROM, DVD (Digital Versatile Disk), high-definition multimedia / data storage disks or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage, other magnetic storage devices, or other non-transmission media that can be used to store information for access by a computing device.

[0142] The network may include, but is not limited to, any network or network system, such as a peer-to-peer network, a local area network (LAN), a wide area network (WAN), a public network such as the Internet, a private network, a cellular network, a wireless network, a wired network, a combined wired and wireless network, and a satellite network.

[0143] The communication channel may include or be routed by one or more wired or wireless communications using an IEEE 802.11 protocol, Bluetooth, Serial Peripheral Interface (SPI), Inter-Integrated Circuit (I2C), Universal Serial Bus (USB), Controller Area Network (CAN), cellular data protocols (e.g., 3G, 4G, LTE, 5G, etc.), optical communications networks, Internet Service Providers (ISPs), peer-to-peer networks, Local Area Networks (LANs), Wide Area Networks (WANs), public networks (e.g., the "Internet"), private networks, satellite networks, or others.

[0144] The computing devices may include desktop computers, laptop computers, tablet computers, phablets, smartphones, feature phones, server computers, etc. The server computers may be located remotely in a data center or stored locally.

[0145] The aforementioned processes are described in terms of computer software and hardware. The described techniques may be comprised of machine-executable instructions embodied in a tangible or non-transitory machine (e.g., computer) readable storage medium that, when executed by a machine, causes the machine to perform the described operations. Furthermore, the processes may be implemented in hardware such as an Application-Specific Integrated Circuit (ASIC).

[0146] Tangible, non-transitory, machine-readable storage media include any mechanism that provides (i.e., stores) information in a form accessible by a machine (e.g., a computer, a network device, a personal digital assistant, a manufacturing tool, any device with one or more processor sets, etc.). For example, machine-readable storage media include recordable and non-recordable media (e.g., Read Only Memory (ROM), Random Access Memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.).

[0147] The foregoing description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise form disclosed. While specific embodiments of and examples of the invention have been described herein for illustrative purposes, various modifications are possible within the scope of the invention, as will be recognized by those skilled in the relevant art.

[0148] Such modifications to the invention can be made in light of the foregoing detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.

Claims

1. 1. A LIDAR system comprising one or more LIDAR (Light Detection and Ranging) pixels, wherein at least one of the one or more LIDAR pixels comprises: a transmit optical antenna configured to emit a transmit beam; a receiving optical antenna including a first single polarization grating coupler rotated +45 degrees relative to the transmitting optical antenna and configured to detect a first polarization direction of the return beam, and a second single polarization grating coupler rotated −45 degrees relative to the transmitting optical antenna and configured to detect a second polarization direction of the return beam; a first receiver configured to generate a first signal in response to receiving the first polarization direction of the return beam from the receiving optical antenna and receiving a first local oscillator signal having the first polarization direction; a second receiver configured to receive the second polarization direction of the return beam from the receiving optical antenna and to generate a second signal in response to receiving a second local oscillator signal having the second polarization direction.

2. 10. The LIDAR system of claim 1, wherein the first single polarization grating coupler is offset from the second single polarization grating coupler.

3. 3. The LIDAR system of claim 1, wherein the first single polarization grating coupler is rotated relative to the second single polarization grating coupler.

4. 4. The LIDAR system of claim 1, wherein the first single polarization grating coupler is rotated approximately 90 degrees relative to the second single polarization grating coupler.

5. 5. The LIDAR system of claim 1, wherein a single polarization output coupler of the transmitting optical antenna is rotated relative to the first single polarization grating coupler and the second single polarization grating coupler.

6. 6. The LIDAR system of claim 1, wherein the transmitting optical antenna includes a two-dimensional (2D) polarization grating coupler, and the transmitting beam includes the first polarization direction and the second polarization direction.

7. 7. The LIDAR system of claim 1, wherein the first local oscillator signal and the second local oscillator signal have the same wavelength as the return beam.

8. 8. The LIDAR system of claim 1, wherein the transmit beam has the first polarization direction.

9. 9. The LIDAR system of claim 1, wherein the transmit beam is infrared and the return beam is infrared.

10. 10. The LIDAR system of claim 1, wherein the transmit beam and the return beam are at narrow-band near-infrared wavelengths.

11. 11. The LIDAR system of claim 1, wherein the first polarization direction is orthogonal to the second polarization direction.

12. 12. The LIDAR system of claim 1, wherein the return beam is the transmitted beam reflected by a target.

13. 13. An autonomous vehicle control system for an autonomous vehicle including a LIDAR system according to any one of claims 1 to 12.

14. 14. The autonomous vehicle control system of claim 13, further comprising one or more processors configured to control the autonomous vehicle in response to the first electrical signal and the second electrical signal.

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

Images