Optical coupler for LIDAR sensor

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

a waveguide configured to route an infrared optical field;

a cladding disposed around the waveguide; and

a scattering array formed in the cladding, wherein the scattering array is configured to perturb the infrared optical field routed by the waveguide to direct the infrared optical field into an infrared beam propagating toward a surface of the cladding, wherein the scattering array is spaced apart from the waveguide by a spacing distance to allow a tail of the infrared optical field to interact with the scattering array and to scatter light out of the waveguide as the infrared beam.

2. The LIDAR device of claim 1 , wherein the waveguide is disposed between the scattering array and the surface of the cladding.

3. The LIDAR device of claim 1 further comprising:

a substrate layer interfacing with the cladding, wherein the scattering array is disposed between the waveguide and an interface of the substrate layer and the cladding.

4. The LIDAR device of claim 3 further comprising:

a reflector layer formed in the cladding, wherein the waveguide is disposed between the reflector layer and the scattering array, and wherein the reflector layer is configured to direct the infrared beam to exit through the substrate layer.

5. The LIDAR device of claim 3 , wherein a thickness between the scattering array and the interface and the spacing distance between the waveguide and the scattering array are configured to increase an intensity of the infrared beam by destructively interfering down-scattered portions of the infrared optical field.

6. The LIDAR device of claim 1 , wherein the scattering array is also configured to couple a received infrared beam into the waveguide, wherein the received infrared beam is a reflection of the infrared beam by a target in an external environment of the LIDAR device.

7. The LIDAR device of claim 1 , wherein the cladding is transparent to the infrared optical field.

8. The LIDAR device of claim 1 , wherein the waveguide has a first refractive index that is higher than a second refractive index of the cladding.

9. The LIDAR device of claim 1 , wherein the waveguide is tapered and flares outward as the waveguide approaches the scattering array, and wherein the scattering array progressively flares outward.

10. The LIDAR device of claim 1 , wherein a polarization orientation of the infrared beam matches a long direction of scatterers in the scattering array.

11. The LIDAR device of claim 1 further comprising:

a second waveguide, wherein a first taper of the waveguide extends into a second taper of the second waveguide,

and wherein the scattering array is a two-dimensional coupler configured to scatter the infrared optical field in a first polarization orientation and configured to scatter a second infrared optical field in a second polarization orientation, the second infrared optical field routed by the second waveguide.

12. The LIDAR device of claim 11 , wherein the infrared optical field routed in the waveguide propagates orthogonal to the second infrared optical field propagating in the second waveguide.

13. The LIDAR device of claim 11 , wherein the waveguide and the second waveguide are formed in a same layer.

14. The LIDAR device of claim 1 , wherein the waveguide is silicon nitride.

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

a light detection and ranging (LIDAR) device including:

a waveguide configured to route an infrared optical field;

a cladding disposed around the waveguide; and

a scattering array formed in the cladding, wherein the scattering array is configured to perturb the infrared optical field routed by the waveguide to direct the infrared optical field into an infrared transmit beam, wherein the scattering array is spaced apart from the waveguide by a spacing distance to allow a tail of the infrared optical field to interact with the scattering array and to scatter light out of the waveguide as the infrared transmit beam; and

one or more processors configured to control the autonomous vehicle in response to an infrared returning beam that is a reflection of the infrared transmit beam.

16. The autonomous vehicle control system of claim 15 , wherein a polarization orientation of the infrared transmit beam matches a long direction of scatterers in the scattering array.

17. The autonomous vehicle control system of claim 15 , wherein the LIDAR device further includes:

a second waveguide, wherein the scattering array is a two-dimensional coupler configured to scatter the infrared optical field in a first polarization orientation and configured to scatter a second infrared optical field in a second polarization orientation, the second infrared optical field routed by the second waveguide.

18. An autonomous vehicle comprising:

a light detection and ranging (LIDAR) sensor including:

a waveguide configured to route an infrared optical field;

a cladding disposed around the waveguide; and

a scattering array formed in the cladding, wherein the scattering array is configured to perturb the infrared optical field routed by the waveguide to direct the infrared optical field into an infrared transmit beam, wherein the scattering array is spaced apart from the waveguide by a spacing distance to allow a tail of the infrared optical field to interact with the scattering array and to scatter light out of the waveguide as the infrared transmit beam; and

one or more processors configured to control the autonomous vehicle in response to an infrared returning beam that is a reflection of the infrared transmit beam.

19. The autonomous vehicle of claim 18 , wherein a polarization orientation of the infrared transmit beam matches a long direction of scatterers in the scattering array.