Optical switch with improved switching efficiency

Patent metadata

Field	Value
Publication number	US-9638981-B2
Application number	US-201514630093-A
Country	US
Kind code	B2
Filing date	Feb 24, 2015
Priority date	Feb 24, 2015
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

An optical device comprises a first optical coupler configured to receive a light signal and provide a first output and a second output, a first optical waveguide in optical communication with the first output and configured to provide a first optical path for a first portion of the light signal, and a second optical waveguide in optical communication with the second output and configured to provide a second optical path for a second portion of the light signal, wherein the first optical waveguide is configured to provide a phase differential between the first optical path and the second optical path, wherein the second optical waveguide is positioned according to a lateral thermal diffusion length associated with the first optical waveguide, and wherein the lateral thermal diffusion length is a spreading distance of a thermal effect in a direction about perpendicular to the first optical path.

First claim

What is claimed is:

1. An optical device comprising:
a first optical coupler configured to receive a light signal and provide a first output and a second output;
a first optical waveguide in optical communication with the first output and configured to provide a first optical path for a first portion of the light signal;
a phase shifter comprising a p-i-n junction and configured to introduce a phase shift to the first optical path by a carrier injection of free carriers; and
a second optical waveguide in optical communication with the second output and configured to provide a second optical path for a second portion of the light signal,
wherein at least the first optical waveguide is configured to provide a phase differential between the first optical path and the second optical path,
wherein the second optical waveguide is positioned with respect to the first optical waveguide based on the carrier injection, the p-i-n junction, and a lateral thermal diffusion length associated with the first optical waveguide,
wherein the lateral thermal diffusion length is a spreading distance of a thermal effect in a direction about perpendicular to the first optical path, and
wherein the lateral thermal diffusion length is a distance at which a temperature is about 20 percent (%) of a maximum temperature.

2. The optical device of claim 1 , wherein the first optical waveguide is constructed from a silicon material, wherein to provide the phase differential, the first optical waveguide is doped with dopants to cause the carrier injection of the free carriers into the silicon material, and wherein the carrier injection of the free carriers causes the thermal effect.

3. The optical device of claim 2 , wherein the dopants are disposed in two regions separated by the first optical waveguide, and wherein the lateral thermal diffusion length increases when a level of the dopants decreases in at least one of the regions.

4. The optical device of claim 2 , wherein the dopants are disposed in two regions separated by the first optical waveguide, and wherein the lateral thermal diffusion length increases when at least one of the regions comprises a decreasing level of dopants towards the first optical waveguide.

5. The optical device of claim 1 , wherein the second optical waveguide is positioned such that the second optical waveguide and the first optical waveguide are separated by a distance less than the lateral thermal diffusion length.

6. The optical device of claim 1 , wherein a distance between the first optical waveguide and the second optical waveguide is less than 10 micrometers (μm).

7. The optical device of claim 1 , wherein the first optical waveguide is disposed on a silicon substrate layer, and wherein the lateral thermal diffusion length increases when the silicon substrate layer is thermally undercut to form air cavities between the first optical waveguide and the silicon substrate layer.

8. The optical device of claim 1 , further comprising a second optical coupler in optical communication with the first optical waveguide and the second optical waveguide, wherein the first optical waveguide and the second optical waveguide are positioned between the first optical coupler and the second optical coupler, and wherein the optical device is an N×N optical switch.

9. The optical device of claim 1 , wherein the first optical waveguide and the second optical waveguide are further configured to:
extend together in a first direction; and
turn together to a second direction opposite to the first direction without intersecting each other.

10. The optical device of claim 1 , wherein the optical device is a Mach-Zehnder interferometer.

11. The optical device of claim 1 , wherein the optical device is a Michelson's interferometer.

12. A method comprising:
coupling a first optical waveguide to an optical splitter to provide a first optical path for a first portion of light split from a light signal;
coupling a phase shifter to the first optical waveguide, wherein the phase shifter comprises a p-i-n junction and is configured to implant the first optical waveguide with dopants that cause a carrier injection of free carriers upon an electrical field, and wherein the carrier injection is associated with a thermal effect that spreads within a lateral thermal diffusion length in a direction about perpendicular to the first optical path;
coupling a second optical waveguide to the optical splitter to provide a second optical path for a second portion of light split from the light signal;
determining a distance based on the carrier injection, the p-i-n junction, and the lateral thermal diffusion length; and
positioning the second optical waveguide such that the second optical waveguide and the first optical waveguide are about parallel and are separated by the distance.

13. The method of claim 12 , wherein the distance is less than the lateral thermal diffusion length.

14. The method of claim 12 , wherein the distance is less than 10 micrometers.

15. The method of claim 12 , further comprising:
extending the first optical waveguide and the second optical waveguide together in a first direction; and
turning the first optical waveguide and the second optical waveguide together to a second direction at about 180 degrees with respect to the first direction without the first optical waveguide and the second optical waveguide intersecting each other.

16. The method of claim 12 , further comprising coupling an optical combiner to the first optical waveguide and the second optical waveguide such that the first optical waveguide and the second optical waveguide are positioned between the optical splitter and the optical combiner.

17. The optical device of claim 1 , wherein the lateral thermal diffusion length is no more than 10 micrometers (μm).

18. The optical device of claim 1 , wherein the lateral thermal diffusion length is time varying.

19. The optical device of claim 1 , wherein the lateral thermal diffusion length is a distance at which a temperature is about 50 percent (%) of a maximum temperature increase relative to a background.

20. The optical device of claim 1 , wherein the first optical waveguide comprises a substrate layer, and wherein the substrate layer comprises drilled holes configured to increase thermal conductivity.

Assignees

• Huawei Tech Co Ltd

Inventors

• Dumais Patrick
• Chrostowski Lukas

Classifications

• G02F1/2257 Primary

  the optical waveguides being made of semiconducting material · CPC title

• G02F2203/60

  Temperature independent · CPC title

• G02F2001/212

  Physics · mapped topic

• G02F2001/0152

  Physics · mapped topic

• G02F1/0152

  using free carrier effects, e.g. plasma effect · CPC title