LIDAR pixel equipped with a dual-polarization received optical antenna

Abstract

A light detection and ranging (LIDAR) system includes one or more LIDAR pixels including 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 receive 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.

Description

Technical Field

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

Background Art

[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 velocity of an object. Currently, the automotive industry is developing autonomous functions for controlling vehicles in certain situations. According to the SAE International standard J3016, there is a range of six levels of autonomy, from level 0 (no autonomy) to level 5 (a vehicle that can be operated without driver input under all conditions). Vehicles with autonomous functions sense the environment in which the vehicle is traveling using sensors. Data collection and processing from the sensors enable the vehicle to drive while exploring the environment.

Summary of the Invention

[0003] Embodiments of the present disclosure include a Light Detection and Ranging (LIDAR) system including one or more LIDAR pixels, where at least one of the one or more LIDAR pixels includes 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 receive 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 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 second receiver is 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.

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

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

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

[0009] In one embodiment, the single-polarization output coupler of the transmitting optical antenna is rotated with respect 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 transmitted 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 transmitted beam has a first polarization direction.

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

[0014] In one embodiment, the transmitted beam and the return beam are at a narrow-band near-infrared wavelength.

[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] Embodiments of the present disclosure include an autonomous vehicle control system for an autonomous vehicle that includes 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 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 receive 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 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 second receiver is 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 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 receive optical antenna includes a two-dimensional (2D) polarization splitting grating coupler configured to couple the first polarization direction of the return beam to the first receiver and the second polarization direction of the return beam to the second receiver.

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

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

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

[0022] Embodiments of the present disclosure include an autonomous vehicle that includes a LIDAR sensor and one or more processors. The LIDAR sensor includes 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 receive 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 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. The second receiver is 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. The one or more processors are configured to control the autonomous vehicle in response to the first signal and the second signal.

[0023] Embodiments of the present disclosure include 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 configured to emit a transmit beam and a receive optical antenna. The receive optical antenna includes a first single-polarization grating coupler rotated +45 degrees with respect to the transmit optical antenna, and the first single-polarization grating coupler is 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 with respect to the transmit optical antenna, and the second single-polarization grating coupler is 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 with respect to the second single-polarization grating coupler.

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

[0027] In one embodiment, the single-polarization output coupler of the transmitting optical antenna is rotated with respect 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. The transmitted 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 transmitted beam has a first polarization direction.

[0031] In one embodiment, the transmitted beam is infrared. The return beam is infrared.

[0032] In one embodiment, the transmitted beam and the return beam are narrowband 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] Embodiments of the present disclosure include an autonomous vehicle control system for an autonomous vehicle. The autonomous vehicle control system includes a light detection and ranging (LIDAR) device that 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 transmission beam. The receiving optical antenna includes a first single polarization grating coupler rotated +45 degrees with respect to the transmitting optical antenna, and the first single polarization grating coupler is 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 with respect to the transmitting optical antenna, and the second single polarization grating coupler is 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 receiving 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 receiving 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, the first single polarization grating coupler is configured to couple the first polarization direction of the return beam to the first receiver. The second single polarization grating coupler is configured to couple the second polarization direction of the return beam to the second receiver.

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

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

[0039] Embodiments of the present disclosure include autonomous vehicles. The autonomous vehicle includes a Light Detection and Ranging (LIDAR) sensor. The LIDAR sensor includes a transmitting optical antenna configured to emit a transmission beam and a receiving optical antenna. The receiving optical antenna includes a first single-polarization grating coupler rotated +45 degrees relative to the transmitting optical antenna, and the first single-polarization grating coupler is 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, and the second single-polarization grating coupler is 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 transmission beam and the return beam are narrowband near-infrared wavelengths.

[0041] In one embodiment, the transmission beam and the return beam are narrowband near-infrared wavelengths.

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

[0043] Embodiments of the present disclosure include 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 with respect to the transmitting optical antenna, and the first grating coupler is 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 with respect to the transmitting optical antenna, and the second grating coupler is 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 detected by the first grating coupler and a first local oscillator signal, and 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.

[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 includes a single polarization grating coupler rotated +45 degrees with respect to the transmitting optical antenna. The second grating coupler includes a single polarization grating coupler rotated -45 degrees with respect 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 a transmit beam and a second waveguide configured to radiate a second polarization direction of the transmit beam.

[0050] In one embodiment, the transmit optical antenna includes a two-dimensional (2D) polarization grating coupler. The transmit 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 beam and the return beam are narrowband near-infrared wavelengths.

[0054] Embodiments of the present disclosure include 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 transmit optical antenna configured to radiate a transmit beam and a receive optical antenna. The receive optical antenna includes a first grating coupler having a first rotation angle with respect to the transmit optical antenna, and the first grating coupler is configured to detect a return beam corresponding to the transmit beam reflected by a target. The receive optical antenna includes a second grating coupler having a second rotation angle with respect to the transmit optical antenna, and the second grating coupler is 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 the 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 the 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 the first polarization direction of the return beam, and the second grating coupler is configured to detect the 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 the first polarization direction, and the second local oscillator signal has the second polarization direction.

[0059] In one embodiment, the first grating coupler includes a single polarization grating coupler rotated +45 degrees with respect to the transmission optical antenna, and the second grating coupler includes a single polarization grating coupler rotated -45 degrees with respect to the transmission optical antenna.

[0060] Embodiments of the present disclosure include autonomous vehicles. The autonomous vehicle includes a light detection and ranging (LIDAR) sensor. The LIDAR sensor includes a transmission optical antenna configured to emit a transmission beam. The LIDAR sensor includes a reception optical antenna. The reception optical antenna includes a first grating coupler having a first rotation angle with respect to the transmission optical antenna, and the first grating coupler is configured to detect a return beam corresponding to the transmission beam reflected by a target. The reception optical antenna includes a second grating coupler having a second rotation angle with respect to the transmission optical antenna, and the second grating coupler is 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 the 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 the second local oscillator signal.

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

Brief Description of the Drawings

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

[0063]

Figure 1a

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Figure 1b

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Figure 2

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Figure 3

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Figure 4a

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Figure 4b

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Figure 4c

[0070]

Figure 4d

DETAILED DESCRIPTION OF THE INVENTION

[0071] Embodiments of a LIDAR pixel with a Dual Polarization Receive Optical Antenna will be described. The LIDAR pixel may include one or more modules, one or more integrated chips, or one or more electrical circuits. Also, the LIDAR pixel may be implemented as a single package chip or as a modular design such that the LIDAR pixel includes multiple package chips. In the following description, numerous specific details are presented in order to provide a thorough understanding of the implementation. However, those skilled in the relevant art will recognize that the techniques described herein can be practiced without one or more of the specific details or using other methods, components, materials, etc. In other instances, 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 the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Also, the 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 meanings in the technical fields from which they are derived, unless specifically defined in this specification or the context of use clearly indicates otherwise. For the purposes of the present disclosure, the term "Autonomous Vehicle" includes vehicles equipped with autonomous functions having any level of autonomy as defined in SAE International Standard J3016.

[0074] In some aspects of the present disclosure, visible light can be defined as having a wavelength range of approximately 380 nm to 700 nm. Non-visible light can be defined as light having wavelengths outside the range of visible light, such as ultraviolet and infrared light. Infrared light with a wavelength range of approximately 700 nm to 1 mm includes near-infrared light. In some aspects 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 to an object / target and directly measures the distance and velocity of the object / target. The light reflected from the object / target can be combined with the tapped version of the light beam. The frequency of the resulting beat tone is proportional to the distance from the LIDAR system to the object after being corrected for the Doppler shift that requires a second measurement. Two measurements, which may or may not be performed simultaneously, provide both distance and velocity information.

[0076] Embodiments of the present disclosure include a LIDAR device including a transmitting optical antenna, a receiving optical antenna, a first receiver, and a LIDAR pixel having a second receiver. The receiving optical antenna is a dual-polarization receiving optical antenna that detects two different polarizations (e.g., orthogonal polarization directions) of the 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, and thus may improve the imaging quality of the LIDAR system. Also, detecting two different polarization directions of the return beam enables the LIDAR system to detect additional information regarding the external environment, such as the polarization-dependent surface material of an object / target within the external environment of the LIDAR system. Such embodiments and other embodiments are described in more detail with respect to FIGS. 1a-4d.

[0077] Figure 1a shows a LIDAR system 100 that includes 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 shown in Figure 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 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 can be an infrared transmit beam. The transmit beam can be a near-infrared transmit beam. The transmit beam can be in a defined single polarization direction. In Figure 1a, the transmit optical antenna 105 is shown as a Single-polarization Output Coupler and can transmit a transmit beam in response to receiving a transmit signal 101 via a waveguide 103. The transmit signal 101 can be generated by a laser, and the transmit beam emitted by the transmit optical antenna 105 can have a very narrow linewidth (e.g., 1 nm or less).

[0078] In some embodiments, the received optical antenna 110 is a dual-polarization received 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 within the external environment of the LIDAR system 100. The first polarization direction may be orthogonal to the second polarization direction. In FIG. 1a, the received 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 the 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 the waveguide 117.

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

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

[0081] In some embodiments, the second coherent receiver 126 is configured to generate a second signal 128 in response to receiving a second polarization direction of the return beam and a second local oscillator signal 136. The second local oscillator signal 136 can 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 can be an electrical signal provided to the processing logic 150 via the communication channel 127.

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

[0083] During operation, the transmission signal 101 can be radiated into free space as a transmission beam by the transmission optical antenna 105. The transmission beam can 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 transmission beam that encounters the object / target is reflected back as a return beam towards the LIDAR system 100 and the LIDAR pixel 199. The return beam can be reflected by the rotating mirror and propagate through one or more lenses, but due to the time difference in mirror rotation, it can be offset relative to the transmission optical antenna 105. To compensate for this offset, the reception optical antenna 110 can be offset from the transmission optical antenna 105 by an offset dimension 191.

[0084] Figure 1b shows an exemplary coherent receiver 171 according to an embodiment of the present disclosure. The exemplary coherent receiver 171 can be used, for example, as the 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 a return beam signal RB with a local oscillator signal LO to generate an output signal OUT. The optical mixer 152 can be coupled, for example, to receive the return beam signal RB from the waveguide 112 or the waveguide 117, and the waveguide 156 can provide the return beam signal to the optical mixer 152. The optical mixer 152 can be coupled, for example, to receive the local oscillator signal LO from the waveguide 132 or 137, and the waveguide 160 can provide the local oscillator signal LO to the optical mixer 152. The optical mixer 152 can combine the input signals to generate a plurality of combined output signals OUT1 and OUT2. The output signals OUT1 and OUT2 are supplied to a photodiode pair (including photodiodes PD1 and PD2) to convert the return beam signal RB and the local oscillator signal LO into the output signal OUT. The output signal OUT can be an electrical signal. The output signal OUT can be a beat signal representing the distance and / or velocity of one or more objects in the environment of the LIDAR system. For example, the communication channel 122 or 127 can be coupled to the output port 162.

[0085] Figure 2 shows 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 Figure 2, the receive optical antenna 210 of the LIDAR pixel 299 is shown as a two-dimensional (2D) polarization splitting grating coupler. The 2D polarization splitting grating coupler is configured to couple the first polarization of the return beam to the first coherent receiver 221 and the 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 can be an infrared transmit beam. The transmit beam can be a near-infrared transmit beam. The transmit beam can be in a defined single polarization direction. In FIG. 2, the transmit optical antenna 205 is shown as a single polarization output coupler and can transmit a transmit beam in response to receiving the transmit signal 201 via the waveguide 203. The transmit signal 201 can be generated by a laser, and the transmit beam emitted by the transmit optical antenna 205 can have a very narrow linewidth.

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

[0088] In some embodiments, the first coherent receiver 221 is configured to generate a first signal 223 in response to receiving the first polarization direction of the return beam and a first local oscillator signal 231. The first local oscillator signal 231 can be an optical signal having the first polarization direction. In FIG. 2, the first polarization direction of the return beam is received by the first coherent receiver 221 from the 2D polarization splitting grating coupler 210 via the waveguide 212, and the first local oscillator signal 231 is received by the first coherent receiver 221 via the waveguide 232. The first signal 223 can be an electrical signal provided to the processing logic 250 via the 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 can 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 splitting grating coupler 210 via the waveguide 217, and the second local oscillator signal 236 is received by the second coherent receiver 226 via the waveguide 237. The second signal 228 can be an electrical signal provided to the processing logic 250 via the communication channel 227.

[0090] The processing logic 250 is configured to generate an image 255 in response to receiving the first signal 223 and the second signal 228 from the first coherent receiver 221 and the second coherent receiver 226, respectively. The LIDAR system 200 can include an array of LIDAR pixels 299 configured to provide the processing logic 250 with a first signal (e.g., signal 223) and a second signal (e.g., signal 228). Here, the processing logic 250 can generate an image 255 in response to the first and second signals received by the processing logic 250 from a plurality of LIDAR pixels 299 within the array of LIDAR pixels.

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

[0092] FIG. 3 shows 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 transmission optical antenna 309, a reception optical antenna 310, a first coherent receiver 321, and a second coherent receiver 326. The transmission optical antenna 309 of the LIDAR pixel 399 is a 2D polarization grating coupler. The transmission optical antenna 309 can be configured to radiate a transmission beam having orthogonal polarizations. In the embodiment shown in FIG. 3, the transmission optical antenna 309 is configured to receive a first transmission signal TX1 301 via a waveguide 302 and a second transmission signal TX2 302 via a waveguide 307. In some embodiments, the amplitudes and / or phases of the first transmission signal TX1 301 and the second transmission signal TX2 302 are modulated. This additional degree of freedom for the transmission beam radiated by the transmission optical antenna 309 can help provide additional information about the polarization-dependent reflectivity of the environment.

[0093] The received light antenna 310 of LIDAR pixel 399 is shown as a two-dimensional (2D) polarization splitting grating coupler. The 2D polarization splitting grating coupler 310 can be configured similarly to the 2D polarization splitting grating coupler 210 of FIG. 2. Thus, the 2D polarization splitting grating coupler 310 can be configured to couple the first polarization of the return beam to the first coherent receiver 321 and the second polarization of the return beam to the second coherent receiver 326. As shown in FIG. 3, the first polarization direction can be orthogonal to the second polarization direction. The transmission beam emitted by the 2D polarization splitting grating coupler 310 can include the first polarization direction and the second polarization direction. The transmission beam can be an infrared transmission beam. The transmission beam can be a near-infrared transmission beam. The transmission signal TX1301 and / or the transmission signal TX2302 can be generated by a laser, and the transmission beam emitted by the transmission light antenna 309 can have a very narrow linewidth.

[0094] In some embodiments, the received light antenna 310 is a dual-polarization received light antenna configured to detect the first polarization direction of the return beam and the second polarization direction of the return beam. The return beam is a reflection of the transmission beam reflected from a target in the external environment of the LIDAR system 300. The first polarization direction can 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 the waveguide 312 and the second polarization direction of the return beam to the second coherent receiver 326 via the waveguide 317. In some embodiments, the exemplary coherent receiver 171 of FIG. 1a can be used as the first coherent receiver 321 and / or the second coherent receiver 326.

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

[0096] In some embodiments, the second coherent receiver 326 is configured to generate a second signal 328 in response to receiving a second polarization direction of the return beam and a second local oscillator signal 336. The second local oscillator signal 336 can 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 the waveguide 317, and the second local oscillator signal 336 is received by the second coherent receiver 326 via the waveguide 337. The second signal 328 can be an electrical signal provided to the processing logic 350 via the communication channel 327.

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

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

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

[0100] Referring to Figure 4a, an exemplary autonomous vehicle 410A is shown in which various techniques disclosed herein can be implemented. For example, vehicle 410A can include a power train 492 that includes a prime mover 494 driven by an energy source 496 and capable of powering a drive train 498, and a control system 480 that includes direction control 482, power train control 484, and brake control 486. Vehicle 410A can be implemented as any of a variety of types of vehicles capable of transporting people and / or cargo and capable of traveling in a variety of environments, and it will be understood that the foregoing components 480-498 can vary widely depending on the type of vehicle in which these components are used.

[0101] For simplicity, the embodiments discussed below focus on wheeled land vehicles such as automobiles, vans, trucks, buses, etc. In these embodiments, the prime mover 494 may include, among other things, one or more electric motors and / or internal combustion engines. The energy source may include, for example, a fuel system (e.g., providing gasoline, diesel, hydrogen, etc.), a battery system, a solar panel or other renewable energy source, and / or a fuel cell system. The drive train 498 includes wheels and / or tires, a transmission and / or any other mechanical drive components for converting the output of the prime mover 494 into vehicle operation, one or more brakes configured to controllably stop or decelerate the vehicle 410A, and a direction or steering component (e.g., a rack and pinion steering linkage that generally pivots one or more wheels of the vehicle 410A about a vertical axis to change the angle of the rotational plane of the wheel relative to the longitudinal axis of the vehicle) suitable for controlling the trajectory of the vehicle 410A. In some embodiments, a combination of a power train and an energy source can be used (e.g., in the case of an electric / gas hybrid vehicle), and in some examples, a number of electric motors (e.g., dedicated to individual wheels or axles) can be used as the prime mover.

[0102] The direction control 482 may include one or more actuators and / or sensors for controlling and receiving feedback from the direction or steering component so that the vehicle 410A follows a desired trajectory. The power train control 484 may be configured to control the output of the power train 402, for example, to control the output of the prime mover 494, to control the gears of the transmission within the drive train 498, thereby enabling control of the speed and / or direction of the vehicle 410A. The brake control 416 may be configured to control one or more brakes that decelerate or stop the vehicle 410A, such as disc or drum brakes coupled to the wheels of the vehicle.

[0103] Other vehicle types, including but not limited to off-road vehicles, all-terrain vehicles or track-type vehicles, construction equipment, etc., can necessarily use different power trains, drive trains, energy sources, direction controls, power train controls, and brake controls. Further, in some embodiments, some components may be combined, for example, when the direction control of the vehicle is mainly processed by changing the output of one or more prime movers. Thus, the embodiments disclosed herein are not limited to specific applications in autonomous land vehicles of the technology disclosed herein.

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

[0105] Sensor 430 may include various sensors suitable for collecting information from the vehicle's surrounding environment for use in controlling the operation of the vehicle. For example, sensor 430 may include a radar sensor 434, a LIDAR (Light Detection and Ranging) sensor 436, 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, Compass). The 3D positioning sensor 438 can be used to determine the position of the vehicle on the earth using satellite signals. Sensor 430 may include a camera 440 and / or an Inertial Measurement Unit (IMU) 442. The camera 440 can be a monographic or stereographic camera and can record still images and / or videos. The IMU 442 may include a plurality of 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 can be used to monitor the rotation of one or more wheels of the vehicle 410A. Each sensor 430 can output sensor data at various data rates, which may differ from the data rates of other sensors 430.

[0106] The output of sensor 430 can 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 can perform functions such as precisely determining the position and orientation (also referred to as "pose") of vehicle 410A within the surrounding environment and generally within a partial frame of reference. The position of the autonomous vehicle 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 can perform functions such as detecting, tracking, determining, and / or identifying objects within the environment surrounding vehicle 410A. Machine learning models can be used to track objects. The planning subsystem 456 can perform functions such as planning the trajectory of vehicle 410A within a given time frame given a desired destination, as well as stationary and moving objects within the environment. Machine learning can be used for vehicle trajectory planning. The control subsystem 458 can perform functions such as generating appropriate control signals for controlling various control devices of vehicle control system 420 to implement the planned trajectory of vehicle 410A. Machine learning models can be used to generate one or more signals for controlling the autonomous vehicle to implement the planned trajectory.

[0107] It will be appreciated that the collection of components shown in FIG. 4a for vehicle control system 420 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. 4a can be used to cover redundancy and / or various regions around the vehicle, and other types of sensors can be used. Similarly, various types and / or combinations of control subsystems can be used in other embodiments. Also, although subsystems 452-458 are shown as being separate from processor 422 and memory 424, in some embodiments, some or all of subsystems 452-458 can reside in one or more memories 424 and be implemented with program code instructions 426 performed by one or more processors 422, and it will be understood that these subsystems 452-458 can, in some cases, be implemented using the same processor and / or memory. Subsystems can be implemented using at least in part various dedicated circuit logics, various processors, various field programmable gate arrays (FPGAs), various application specific integrated circuits (ASICs), various real-time controllers, etc., and as described above, many subsystems can use circuits, processors, sensors, and / or other components. Also, the various components of vehicle control system 420 can be networked in various ways.

[0108] In some embodiments, vehicle 410A can 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 can fully operate autonomous vehicle 410A if an adverse event occurs in vehicle control system 420, but in other embodiments, the auxiliary vehicle control system can have only limited functionality, such as 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] Generally, various 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 implemented as a microprocessor, and each memory can include not only random access memory (RAM) devices that make up the main memory, but also any auxiliary level of memory, such as cache memory, non-volatile or backup memory (e.g., programmable or flash memory), read-only memory, etc. Also, each memory can be considered to include not only any cache memory within the processor, which is physically located elsewhere in vehicle 410A, but also any storage capacity used as virtual memory (e.g., that stored in a mass storage device or on another computer controller). One or more of the processors shown in FIG. 4a, or completely separate processors, can be used to implement additional functions other than for autonomous control purposes, such as controlling an entertainment system, operating doors, lighting, convenience functions, etc. in vehicle 410A.

[0110] Also, for additional storage, vehicle 410A can include one or more mass storage devices, such as removable disk drives, hard disk drives, direct access storage devices (DASD), optical drives (e.g., CD drives, DVD drives, etc.), solid state storage drives (SSD), network attached storage, storage area networks, and / or tape drives, etc.

[0111] In addition, vehicle 410A includes a user interface 464, enabling the 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. Otherwise, user input can be received via other computers or electronic devices such as, for example, an app on a mobile device or a web interface.

[0112] In addition, vehicle 410A may include one or more network interfaces, such as network interface 462, which allows the vehicle 410A to communicate with other computers and electronic devices, including central services such as cloud services, to receive environmental and other data for use in autonomous control, and to communicate with one or more networks (e.g., a local area network (LAN), wide area network (WAN), wireless network, and / or the Internet) to enable communication with other computers and electronic devices. Data collected by one or more sensors 430 can be uploaded via network 470 to computing system 472 for additional processing. A timestamp may be added to each instance of vehicle data prior to upload. The additional processing of autonomous vehicle data by computing system 472 according to many embodiments is described in connection with FIG. 2.

[0113] Each of the processors shown in FIG. 4a, and the various additional controllers and subsystems disclosed herein, generally operate under the control of an operating system and perform or rely upon various computer software applications, components, programs, objects, modules, data structures, etc., as will be described in detail below. Also, the various applications, components, programs, objects, modules, etc. can be performed by one or more processors of other computers coupled to vehicle 410A via network 470, for example, where the processing required to implement the functionality of a computer program can be allocated to a number of computers and / or services via the network in a distributed, cloud-based, or client-server computing environment.

[0114] Generally, the routines performed to implement the various embodiments described herein may be embodied as part of an operating system or as a particular application, component, program, object, module, or sequence of instructions, or a subset thereof, and are referred to herein as “program code.” The program code may reside at various times in various memories and storage devices and, when read and executed by one or more processors, may include one or more instructions for performing the steps necessary to implement the steps or elements embodying the various aspects of the present disclosure. Also, the embodiments are described in the context of fully functional computers and systems, and it should be understood that the various embodiments described herein can be distributed as a variety of forms of program products and can be implemented regardless of the particular type of computer-readable media actually used to carry out the distribution.

[0115] 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-ROM, DVD, etc.).

[0116] Also, the various program codes described below can be identified based on the applications implemented in specific embodiments. However, it should be understood that any of the following specific program nomenclatures are used merely for convenience, and thus, the present disclosure should not be limited to use only in any specific application identified and / or implied by such nomenclature. Also, considering the numerous ways in which a computer program can be composed of routines, procedures, methods, modules, objects, etc., and the various ways in which program functions can be allocated among the various software layers (e.g., operating systems, libraries, APIs, applications, applets, etc.) resident in a general computer, it should be understood that the present disclosure is not limited to the specific structure and allocation of the program functions described herein.

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

[0118] 2. FM LIDAR for Automotive Applications The truck may include a LIDAR system (e.g., the vehicle control system 420 of FIG. 4a). In some embodiments, the LIDAR system can 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 use the Doppler effect to determine the position of the object and / or accurately measure the speed of the object. The FM LIDAR system 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 can encode an optical signal using phase modulation (PM) and scatter the encoded optical signal into free space using an optical device.

[0119] FM or PM LIDAR systems can offer significant advantages compared to conventional 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 a low reflectivity, because only a small amount of the light reaching the object (e.g., 10% or less) is reflected back to the sensor of the FM or PM LIDAR system (e.g., sensor 430 of FIG. 4a). In other cases, an object (e.g., a shiny road sign) may have a high reflectivity (e.g., 10% or more), because a large amount of the light reaching the object is reflected back to the sensor of the FM LIDAR system.

[0120] Regardless of the reflectivity of the object, the FM LIDAR system can detect (e.g., classify, recognize, discover, etc.) an object at a greater distance (e.g., twice as far) than a conventional LIDAR system. For example, the FM LIDAR system can detect low - reflectivity objects at 300 meters or more and high - reflectivity objects at 400 meters or more.

[0121] To achieve such an improvement in detection capabilities, an FM LIDAR system can use sensors (e.g., sensor 430 of FIG. 4a). In some embodiments, these sensors may be sensitive to single photons, which means that they can detect the smallest possible amount of light. In some applications, the FM LIDAR system can use infrared wavelengths (e.g., 950 nm, 1550 nm, etc.), but is not limited to the range of infrared wavelengths (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 the FM or PM LIDAR system at infrared wavelengths, the FM or PM LIDAR system can broadcast stronger light pulses or beams while meeting eye safety standards. Conventional LIDAR systems are not sensitive to single photons and / or operate only at near-infrared wavelengths, so it is necessary to limit the light output (and distance detection function) for eye safety.

[0122]

[0123] ​Another advantage of the FM LIDAR system is that it can instantaneously provide accurate velocity for each data point. In some embodiments, velocity measurement is achieved using the Doppler effect that shifts the frequency of the light received from the object based on at least one of the velocity in the radial direction (e.g., the direction vector between the detected object and the sensor) or the frequency of the laser signal. For example, for velocities occurring in road conditions where the velocity is 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 so small that it is difficult to directly detect in the optical domain. However, when coherent detection is used in an FMCW, PMCW, or FMQW LIDAR system, the signal can be converted to the RF domain so that various signal processing techniques can be used to calculate the frequency shift. This enables the autonomous vehicle control system to process the received data more quickly.

[0124] Also, with instantaneous velocity calculation, the FM LIDAR system can more easily distinguish 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 velocity values of interest (e.g., moving towards the vehicle at a speed of 70 mph or more), the FM LIDAR system and / or the autonomous vehicle control system can determine individual weights for the probability associated with the object.

[0125] The faster identification and / or tracking of the FM LIDAR system provides the autonomous vehicle control system with more time to maneuver the vehicle. Also, by more accurately understanding the moving speed of the object, the autonomous vehicle control system can plan more appropriate responses.

[0126] Another advantage of the FM LIDAR system is that it is less static compared to conventional LIDAR systems. That is, conventional LIDAR systems designed to be more sensitive to light generally experience a decrease in performance under bright sunlight. Also, these systems tend to be troubled by 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 pulses or light beams). To overcome these drawbacks, vehicles using conventional LIDAR systems often require additional hardware, complex software, and / or more computing power to manage this "noise".

[0127] On the other hand, since each sensor of the FM LIDAR system is specially designed to respond only to its own optical characteristics (e.g., light beam, light wave, light pulse), such problems do not occur. If the returned light does not match the timing, frequency, and / or wavelength of the light initially transmitted, the FM sensor can filter (e.g., remove, ignore, etc.) the data point. Therefore, the FM LIDAR system enables safer and smoother driving by producing (e.g., generating, deriving, etc.) more accurate data with fewer hardware or software requirements.

[0128] Finally, the FM LIDAR system is easier to expand than conventional LIDAR systems. As more autonomous vehicles (e.g., cars, commercial trucks, etc.) appear on the road, vehicles driven by the FM LIDAR system are likely to no longer have to face interference problems due to sensor crosstalk. Also, the FM LIDAR system uses less optical peak power than conventional LIDAR sensors. This allows some or all of the optical components of the FM LIDAR to be manufactured on a single chip, which provides unique advantages as described in this specification.

[0129] 3. Commercial Truck Transportation Figure 4b is a block diagram showing an example of a system environment of an autonomous commercial truck vehicle according to some embodiments. Environment 400B includes a commercial truck 402B for carrying cargo 406B. In some embodiments, commercial truck 402B can include vehicles configured for long-haul cargo transportation, regional cargo transportation, intermodal cargo transportation (i.e., where a vehicle on a road infrastructure is used as one of several modes of transportation for transporting cargo), and / or any other road infrastructure cargo transportation applications. Commercial truck 402B can be a flatbed truck, a refrigerated truck (e.g., a reefer truck), a vented van (e.g., a dry van), a moving truck, etc. Cargo 406B can be merchandise and / or agricultural products. Commercial truck 402B can include trailers for carrying cargo 406B such as flatbed trailers, lowboy trailers, step deck trailers, expandable flatbed trailers, sidekit trailers, etc.

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

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

[0132] As shown, the LIDAR system 404B in the environment 400B can 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 402B.

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

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

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

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

[0137] In the field of commercial truck transportation applications, as the weight of the vehicle increases and accordingly a longer stopping distance is required, it is important to effectively detect objects in all ranges. FM LIDAR systems (e.g., FMCW and / or FMQW systems) or PM LIDAR systems are optimal for commercial truck transportation applications due to the aforementioned advantages. Ultimately, commercial trucks equipped with these systems can improve the safety not only of the commercial trucks themselves but also of surrounding vehicles because of their improved ability to safely move people and goods over short or long distances. In various embodiments, these FM or PM LIDAR systems can be used in semi-autonomous application fields where a driver is on board the commercial truck and some functions of the commercial truck operate autonomously using the FM or PM LIDAR system, or in fully autonomous application fields where the commercial truck operates completely 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 over the entire 10 seconds. Instead, in the case of a LIDAR system using quasi-CW modulation, the modulator modulates the laser light such that it has both an active part and an inactive part. For example, in the case of a 10-second period, the modulator modulates the laser light for only 8 seconds (also called the "active part") and does not modulate the laser light for 2 seconds (also called the "inactive part"). Thereby, since the modulator does not need to provide a continuous signal, the LIDAR system can reduce power consumption for 2 seconds.

[0139] In the case of frequency-modulated continuous-wave (FMCW) LIDAR for vehicle applications, while FMCW measurement and signal processing methodologies are used, 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, transmitted, etc.). In some embodiments, the quasi-CW modulation may have a duty cycle of 1% or more and up to 50% at most. If energy is consumed in the off state (e.g., deactivated, powered off, etc.) during the actual measurement time, the signal-to-noise ratio (SNR) can be improved or the matters required for signal processing can be reduced, so that all the energy can be consistently integrated over a longer time.

[0140] In the present 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, a memory (not shown) is integrated with the processing logic to store instructions for performing operations and / or storing data. Also, the processing logic may include analog or digital circuits for performing operations according to embodiments of the present disclosure.

[0141] The "memory" or "memories" described in this specification may include one or more volatile or non-volatile memory architectures. The "memory" or "memories" can 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. Examples of memory technologies 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 tapes, magnetic disk storage, and other magnetic storage devices or other non-transmission media that can be used to store information for access by a computing device.

[0142] Networks can include, but are not limited to, all networks or network systems such as peer-to-peer networks, LANs (Local Area Networks), WANs (Wide Area Networks), public networks such as the Internet, private networks, cellular networks, wireless networks, wired networks, wired / wireless combined networks, and satellite networks.

[0143] The communication channel can include or be routed by one or more wired or wireless communications using the IEEE802.11 protocol, Bluetooth, SPI (Serial Peripheral Interface), I2C (Inter-Integrated Circuit), USB (Universal Serial Bus), CAN (Controller Area Network), cellular data protocol (such as 3G, 4G, LTE, 5G, etc.), optical communication network, ISP (Internet Service Provider), peer-to-peer network, LAN (Local Area Network), WAN (Wide Area Network), public network (such as the "Internet"), private network, satellite network or others.

[0144] The computing device can include a desktop computer, laptop computer, tablet, phablet, smartphone, feature phone, server computer, etc. The server computer can be located remotely in a data center or stored locally.

[0145] The processes described above are described in terms of computer software and hardware aspects. The described technology can be composed of machine-executable instructions embodied in a tangible or non-transitory machine (e.g., computer) readable storage medium, which, when executed by a machine, cause the machine to perform the described operations. Additionally, the process can be implemented in hardware such as an ASIC (Application-Specific Integrated Circuit).

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

[0147] The foregoing description of the exemplary embodiments of the invention, including what is described in the abstract, is not intended to be limiting of the invention as complete or as the precise form disclosed. Specific embodiments and examples of the invention are described herein for illustrative purposes, but various modifications within the scope of the invention will be apparent to those skilled in the relevant art.

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

Claims

**Claim 1** A LiDAR (Light Detection and Ranging) system comprising one or more LiDAR pixels, wherein at least one of the one or more LiDAR pixels is a transmitting optical antenna configured to emit a transmission beam, a first single polarization grating coupler rotated +45 degrees with respect to the transmitting optical antenna and configured to detect a first polarization direction of the return beam, and a receiving optical antenna comprising a second single polarization grating coupler rotated -45 degrees with respect to the transmitting optical antenna and configured to detect a second polarization direction of the return beam, 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 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 generate a second signal in response to receiving a second local oscillator signal having the second polarization direction, a LiDAR system. **Claim 2** The LiDAR system according to claim 1, wherein the first single polarization grating coupler is offset from the second single polarization grating coupler. **Claim 3** The LiDAR system according to claim 1 or 2, wherein the first single polarization grating coupler is rotated with respect to the second single polarization grating coupler. **Claim 4** The LiDAR system according to any one of claims 1 to 3, wherein the first single polarization grating coupler is rotated approximately 90 degrees with respect to the second single polarization grating coupler. **Claim 5** The LiDAR system according to any one of claims 1 to 4, wherein a single polarization output coupler of the transmitting optical antenna is rotated with respect to the first single polarization grating coupler and the second single polarization grating coupler. **Claim 6** The LiDAR system according to any one of claims 1 to 5, wherein the transmitting optical antenna includes a two-dimensional (2D) polarization grating coupler, and the transmission beam includes the first polarization direction and the second polarization direction. **Claim 7** The LiDAR system according to any one of claims 1 to 6, wherein the first local oscillator signal and the second local oscillator signal have the same wavelength as the return beam. **Claim 8** The LiDAR system according to any one of claims 1 to 7, wherein the transmission beam has the first polarization direction.

9. The LIDAR system according to any one of claims 1 to 8, wherein the transmission beam is infrared and the return beam is infrared.

10. The LIDAR system according to any one of claims 1 to 9, wherein the transmission beam and the return beam are at a narrow-band near-infrared wavelength.

11. The LIDAR system according to any one of claims 1 to 10, wherein the first polarization direction is orthogonal to the second polarization direction.

12. The LIDAR system according to any one of claims 1 to 11, wherein the return beam is the transmission beam reflected by the target.

13. An autonomous vehicle control system for an autonomous vehicle, comprising the LIDAR system according to any one of claims 1 to 12.

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

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

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