Beam displacement apparatus for light detection and ranging

1. A light detection and ranging (LIDAR) system comprising a silicon chip that includes:

a transmitter configured to emit a transmit beam;

a receiving pixel that includes a grating coupler and is configured to receive a returning beam through the grating coupler;

a rotating mirror configured to direct the transmit beam to an object and direct the returning beam to the receiving pixel;

a beam displacement apparatus disposed between the receiving pixel and the rotating mirror, wherein the beam displacement apparatus is configured to introduce a displacement to the returning beam to compensate for a spacing between the transmitter and the receiving pixel, wherein the beam displacement apparatus includes a switchable beam rotator; and

a fixed mirror configured to direct the transmit beam to the beam displacement apparatus from the transmitter.

2. The LIDAR system of claim 1 , wherein the beam displacement apparatus is configured to compensate for a reflection angle difference between the transmit beam and the returning beam reflecting from the rotating mirror.

3. The LIDAR system of claim 1 , wherein the beam displacement apparatus includes a beam displacer element including a birefringent material, and wherein the birefringent material introduces the displacement with a second polarization orientation of the returning beam that is defined with reference to a first polarization orientation of the transmit beam.

4. The LIDAR system of claim 3 , wherein the switchable beam rotator is disposed between the transmitter and the beam displacer element, and wherein the switchable beam rotator is configured to rotate a transmit polarization of the transmit beam.

5. The LIDAR system of claim 4 , wherein the rotating mirror is configured to rotate in a first direction or in a second opposite direction alternatively during a regular.

6. The LIDAR system of claim 4 , wherein the beam displacement apparatus includes a waveplate disposed between the beam displacer element and the rotating mirror.

7. The LIDAR system of claim 6 , wherein the waveplate is a quarter waveplate.

8. The LIDAR system of claim 4 , wherein the beam displacement apparatus includes a lens disposed between the beam displacer element and the rotating mirror, wherein the lens is configured to collimate the transmit beam.

9. The LIDAR system of claim 1 , wherein the returning beam is the transmit beam reflecting from the object.

10. The LIDAR system of claim 1 , wherein the transmitter includes at least one edge coupler, wherein the fixed mirror is configured to receive the transmit beam from the at least one edge coupler, wherein the fixed mirror is angled to direct the transmit beam vertically from a surface of the silicon chip.

11. The LIDAR system of claim 1 , wherein the switchable beam rotator is configured to change a polarization orientation of the transmit beam based on a direction of rotation of the rotating mirror.

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

a light detection and ranging (LIDAR) device including:

a silicon chip including:

a transmitter configured to emit a transmit beam;

a receiving pixel that includes a grating coupler and is configured to receive a returning beam through the grating coupler; and

a fixed mirror configured to receive and redirect the transmit beam;

a rotating mirror configured to direct the transmit beam to an object and direct the returning beam to the receiving pixel; and

a beam displacement apparatus configured to introduce a displacement to the returning beam to compensate for a spacing between the transmitter and the receiving pixel, wherein the beam displacement apparatus includes a switchable beam rotator, wherein the fixed mirror is configured to direct the transmit beam from the transmitter to the beam displacement apparatus from the silicon chip; and

one or more processors configured to control the autonomous vehicle in response to an output of the receiving pixel.

13. The autonomous vehicle control system of claim 12 , wherein the beam displacement apparatus is configured to compensate for a reflection angle difference between the transmit beam and the returning beam reflecting from the rotating mirror.

14. The autonomous vehicle control system of claim 12 , wherein the beam displacement apparatus includes a beam displacer element including a birefringent material, and wherein the birefringent material introduces the displacement with a second polarization orientation of the returning beam that is defined with reference to a first polarization orientation of the transmit beam.

15. The autonomous vehicle control system of claim 14 , wherein the switchable beam rotator is disposed between the transmitter and the beam displacer element, and wherein the switchable beam rotator is configured to rotate a transmit polarization of the transmit beam.

16. The autonomous vehicle control system of claim 15 , wherein the rotating mirror is configured to rotate in a first direction or in a second opposite direction alternatively during a regular operation.

17. An autonomous vehicle comprising:

at least one silicon chip including:

transmitters configured to emit infrared transmit beams;

receiving pixels configured to receive infrared returning beams, wherein at least one of the receiving pixels includes a grating coupler, wherein the at least one of the receiving pixels is configured to receive at least one of the infrared returning beams through the grating coupler; and

at least one fixed mirror configured to receive and redirect the infrared transmit beams;

a rotating mirror configured to direct the infrared transmit beams to an object and direct the infrared returning beams to the receiving pixels;

a beam displacement apparatus disposed along on an optical path between the receiving pixels and the rotating mirror, wherein the beam displacement apparatus is configured to introduce a displacement to the infrared returning beams to compensate for a spacing between the transmitters and the receiving pixels and configured to introduce the displacement to compensate for a reflection angle difference between the infrared transmit beams and the infrared returning beams reflecting off of the rotating mirror, wherein the beam displacement apparatus includes a switchable beam rotator, wherein the at least one fixed mirror is configured to direct the infrared transmit beams from the transmitters to the beam displacement apparatus from the at least one silicon chip; and

a control system configured to control the autonomous vehicle in response to the infrared returning beams.

18. The autonomous vehicle of claim 17 , wherein the beam displacement apparatus includes a beam displacer element including a birefringent material, and wherein the birefringent material introduces the displacement with a second polarization orientation of the infrared returning beams that is defined with reference to a first polarization orientation of the infrared transmit beams.

19. The autonomous vehicle of claim 18 , wherein the switchable beam rotator is disposed between the transmitters and the beam displacer element, and wherein the switchable beam rotator is configured to rotate a transmit polarization of the infrared transmit beams.