LIDAR pixel with dual polarization receive optical antenna

1. A light detection and ranging (LIDAR) system comprising:

one or more LIDAR pixels, wherein at least one of the one or more LIDAR pixels includes:

a transmit optical antenna configured to emit a transmit beam;

a receive optical antenna comprising:

a first single-polarization grating coupler rotated +45 degrees with respect to the transmit optical antenna, wherein the first single-polarization grating coupler is configured to detect a first polarization orientation of a returning beam, and

a second single-polarization grating coupler rotated −45 degrees with respect to the transmit optical antenna, wherein the second single-polarization grating coupler is configured to detect a second polarization orientation of the returning beam;

a first receiver configured to generate a first signal in response to receiving the first polarization orientation of the returning beam from the receive optical antenna and a first local oscillator signal having the first polarization orientation; and

a second receiver configured to generate a second signal in response to receiving the second polarization orientation of the returning beam from the receive optical antenna and a second local oscillator signal having the second polarization orientation.

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

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

4. The LIDAR system of claim 3 , wherein the first single-polarization grating coupler is rotated by approximately 90 degrees with respect to the second single-polarization grating coupler.

5. The LIDAR system of claim 3 , wherein a single-polarization output coupler of the transmit optical antenna is rotated with respect to the first single-polarization grating coupler and the second single-polarization grating coupler.

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

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

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

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

10. The LIDAR system of claim 9 , wherein the transmit beam and the returning beam are a narrow-band near-infrared wavelength.

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

12. The LIDAR system of claim 1 , wherein the returning beam is the transmit beam reflecting off of a target.

13. An autonomous vehicle control system for an autonomous vehicle, the autonomous vehicle control system comprising:

a light detection and ranging (LIDAR) device including one or more LIDAR pixels, wherein at least one of the one or more LIDAR pixels includes:

a transmit optical antenna configured to emit a transmit beam;

a receive optical antenna comprising:

a first single-polarization grating coupler rotated +45 degrees with respect to the transmit optical antenna, wherein the first single-polarization grating coupler is configured to detect a first polarization orientation of a returning beam, and

a second single-polarization grating coupler rotated −45 degrees with respect to the transmit optical antenna, wherein the second single-polarization grating coupler is configured to detect a second polarization orientation of the returning beam;

a first receiver configured to generate a first electrical signal in response to receiving the first polarization orientation of the returning beam from the receive optical antenna and a first local oscillator signal; and

a second receiver configured to generate a second electrical signal in response to receiving the second polarization orientation of the returning beam from the receive optical antenna and a second local oscillator signal; and

one or more processors configured to control the autonomous vehicle in response to the first electrical signal and the second electrical signal.

14. The autonomous vehicle control system of claim 13 , wherein the

first single-polarization grating coupler is configured to couple the first polarization orientation of the returning beam to the first receiver; and

wherein the second single-polarization grating coupler is configured to couple the second polarization orientation of the returning beam to the second receiver.

15. The autonomous vehicle control system of claim 14 , wherein the first single-polarization grating coupler is rotated with respect to the second single-polarization grating coupler.

16. The autonomous vehicle control system of claim 13 , wherein the transmit optical antenna includes a two-dimensional (2D) polarization grating coupler, and wherein the transmit beam includes the first polarization orientation and the second polarization orientation.

17. An autonomous vehicle comprising:

a light detection and ranging (LIDAR) sensor including:

a transmit optical antenna configured to emit a transmit beam;

a receive optical antenna comprising:

a first single-polarization grating coupler rotated +45 degrees with respect to the transmit optical antenna, wherein the first single-polarization grating coupler is configured to detect a first polarization orientation of a returning beam, and

a second single-polarization grating coupler rotated −45 degrees with respect to the transmit optical antenna, wherein the second single-polarization grating coupler is configured to detect a second polarization orientation of the returning beam;

a first receiver configured to generate a first signal in response to receiving the first polarization orientation of the returning beam from the receive optical antenna and a first local oscillator signal; and

a second receiver configured to generate a second signal in response to receiving the second polarization orientation of the returning beam from the receive optical antenna and a second local oscillator signal; and

one or more processors configured to control the autonomous vehicle in response to the first signal and the second signal.

18. The autonomous vehicle control system of claim 13 , wherein the transmit beam and the returning beam are a narrow-band near-infrared wavelength.

19. The autonomous vehicle of claim 17 , wherein the transmit beam and the returning beam are a narrow-band near-infrared wavelength.

20. The autonomous vehicle of claim 17 , wherein the transmit optical antenna includes a two-dimensional (2D) polarization grating coupler, and wherein the transmit beam includes the first polarization orientation and the second polarization orientation.