Methods and systems for optical beam steering

Patent metadata

Field	Value
Publication number	US-10649306-B2
Application number	US-201916284161-A
Country	US
Kind code	B2
Filing date	Feb 25, 2019
Priority date	Jun 22, 2016
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

An integrated optical beam steering device includes a planar dielectric lens that collimates beams from different inputs in different directions within the lens plane. It also includes an output coupler, such as a grating or photonic crystal, that guides the collimated beams in different directions out of the lens plane. A switch matrix controls which input port is illuminated and hence the in-plane propagation direction of the collimated beam. And a tunable light source changes the wavelength to control the angle at which the collimated beam leaves the plane of the substrate. The device is very efficient, in part because the input port (and thus in-plane propagation direction) can be changed by actuating only log2 N of the N switches in the switch matrix. It can also be much simpler, smaller, and cheaper because it needs fewer control lines than a conventional optical phased array with the same resolution.

First claim

The invention claimed is:

1. An optical beam steering apparatus comprising:
a substrate;
a plurality of waveguides formed on the substrate;
a planar dielectric lens, formed on the substrate in optical communication with the plurality of waveguides, to collimate light emitted by each waveguide in the plurality of waveguides at an angle in a plane of the substrate determined by a position of the waveguide in the plane of the substrate; and
an output coupler, formed on the substrate in optical communication with the planar dielectric lens, to couple the light collimated by the planar dielectric lens out of the plane of the substrate at an angle with the plane of the substrate determined by a wavelength of the light.

2. The optical beam steering apparatus of claim 1 , wherein the planar dielectric lens is one of a parabolic lens, bifocal lens, bootlace lens, Luneburg lens, Rotman lens, gradient index (GRIN) lens, or compound lens.

3. The optical beam steering apparatus of claim 1 , wherein the planar dielectric lens has a field of view of at least 110 degrees.

4. The optical beam steering apparatus of claim 1 , wherein the planar dielectric lens has a field of view of about 180 degrees.

5. The optical beam steering apparatus of claim 1 , wherein the output coupler is configured to resolve at least 100 wavelengths.

6. The optical beam steering apparatus of claim 1 , further comprising:
a tunable light source, in optical communication with the plurality of waveguides, to tune the wavelength of the light.

7. The optical beam steering apparatus of claim 6 , further comprising:
a network of optical switches, formed on the substrate in optical communication with the tunable light source and the plurality of waveguides, to guide the light from the tunable light source to a first waveguide in the plurality of waveguides when in a first state and to guide the light emitted by the second waveguide in the plurality of waveguides when in a second state.

8. The optical beam steering apparatus of claim 7 , wherein the plurality of waveguides comprises N waveguides and wherein up to log 2 N optical switches in the network of optical switches are actuated to switch from the first state to the second state.

9. The optical beam steering apparatus of claim 7 , further comprising:
a plurality of optical amplifiers, formed on the substrate in optical communication with the network of optical switches and the plurality of waveguides, to amplify the light emitted by the first waveguide and the light emitted by the second waveguide.

10. A method of optical beam steering with a plurality of waveguides, a planar dielectric lens, and an output coupler formed on a substrate, the method comprising:
guiding light with a first waveguide in the plurality of waveguides to the planar dielectric lens;
collimating the light emitted by the first waveguide with the planar dielectric lens in a first direction within a plane of the substrate at an angle in the plane of the substrate determined by a position the first waveguide in the plane of the substrate; and
coupling at least a portion of the light out of the plane of the substrate at an angle with the plane of the substrate determined by a wavelength of the light.

11. The method of claim 10 , further comprising:
tuning a wavelength of the light so as to change the angle with the plane of the substrate.

12. The method of claim 10 , further comprising:
guiding the light to the first waveguide with a network of optical switches formed on the substrate.

13. The method of claim 12 , wherein the plurality of waveguides comprises N waveguides and further comprising:
actuating up to log 2 N optical switches in the network of optical switches to switch the light from the first waveguide to a second waveguide in the plurality of waveguides.

14. The method of claim 10 , further comprising:
amplifying the light guided by the first waveguide with an optical amplifier formed on the substrate in optical communication with the plurality of waveguides.

15. The method of claim 10 , further comprising:
receiving light via the output coupler;
guiding the light via the output coupler to the planar dielectric lens; and
coupling the light into a waveguide in the plurality of waveguides with the planar dielectric lens.

16. A lidar comprising:
a tunable light source to emit a beam of light;
N waveguides, where N is a positive integer;
log 2 N optical switches, in optical communication with the tunable light source, to guide the beam of light to a waveguide in the N waveguides;
a planar dielectric lens, in optical communication with the plurality of waveguides, to collimate the beam of light emitted by the waveguide as a collimated beam propagating in a first direction in a plane of the planar dielectric lens; and
a periodic structure, in optical communication with the planar dielectric lens, to diffract at least a portion of the collimated beam at an angle with respect to the plane of the planar dielectric lens.

17. The optical beam steering apparatus of claim 16 , wherein the tunable light source is tunable over a bandwidth of at least 100 nm.

18. The optical beam steering apparatus of claim 16 , wherein the planar dielectric lens is one of a parabolic lens, bifocal lens, bootlace lens, Luneburg lens, Rotman lens, gradient index (GRIN) lens, or compound lens.

19. The optical beam steering apparatus of claim 16 , wherein the planar dielectric lens has a field of view of at least 110 degrees.

20. The optical beam steering apparatus of claim 16 , wherein the planar dielectric lens has a field of view of about 180 degrees.

21. The optical beam steering apparatus of claim 1 , wherein the planar dielectric lens is patterned in a slab waveguide coupled to the plurality of waveguides.

22. The optical beam steering apparatus of claim 1 , wherein the planar dielectric lens has a plurality of input ports, each of which is coupled to a corresponding waveguide in the plurality of waveguides.

Assignees

• Massachusetts Inst Technology

Inventors

• Skirlo Scott A
• Sorace-Agaskar Cheryl Marie
• Soljacic Marin
• Verghese Simon
• Herd Jeffrey S
• Juodawlkis Paul William
• Yang Yi
• Englund Dirk Robert
• PRABHU Mihika

Classifications

• G01S7/4814 Primary

  of transmitters alone · CPC title

• G02F1/2955

  by controlled diffraction or phased-array beam steering (controlled diffraction for optical waveguide switching G02F1/313) · CPC title

• G01S7/4817

  relating to scanning · CPC title

• G02F2201/02

  fibre · CPC title

• G02F2203/70

  Semiconductor optical amplifier [SOA] used in a device covered by G02F · CPC title