Method of modifying mode size of an optical beam, using a waveguide mode expander having non-crystalline silicon features

• US 10,345,521 B2
• Filed: 05/15/2018
• Issued: 07/09/2019
• Est. Priority Date: 05/27/2014
• Status: Active Grant

• Current Assignee: Skorpios Technologies Inc.
• Original Assignee: Skorpios Technologies Inc.
• Inventors: Li, Guoliang, Lambert, Damien, Kumar, Nikhil
• Primary Examiner(s): Ullah, Akm E
• Application Number:
  US15/980,536
• Publication Number:
  US 20180364416A1
• Time in Patent Office: 420 Days
• CPC Class Codes: G02B 2006/12038 Glass (SiO2 based materials)
• CPC Class Codes: G02B 2006/12061 Silicon
• CPC Class Codes: G02B 2006/12097 Ridge, rib or the like
• CPC Class Codes: G02B 2006/12147 Coupler
• CPC Class Codes: G02B 2006/12152 Mode converter
• CPC Class Codes: G02B 6/1228 Tapered waveguides, e.g. integrated spot-size transformers for coupling with fibres G02B6/305
• CPC Class Codes: G02B 6/132 by deposition of thin films
• CPC Class Codes: G02B 6/136 by etching
• CPC Class Codes: G02B 6/14 Mode converters
• CPC Class Codes: G02B 6/305 and having an integrated mode-size expanding section, e.g. tapered waveguide

Abstract

A waveguide mode expander couples a smaller optical mode in a semiconductor waveguide to a larger optical mode in an optical fiber. The waveguide mode expander comprises a shoulder and a ridge. In some embodiments, the ridge of the waveguide mode expander has a plurality of stages, the plurality of stages having different widths at a given cross section.

Claims

1. A method of modifying mode size of an optical beam, comprising:

propagating the optical beam, with an initial mode size, into an input end of a waveguide mode expander, wherein the waveguide mode expander comprises;

a shoulder portion, comprising non-crystalline silicon, that is disposed on a substrate and traverses the substrate from the input end to an output end of the waveguide mode expander, and

a ridge portion, comprising non-crystalline silicon, that is disposed on the shoulder portion;

propagating the optical beam through the waveguide mode expander, wherein at least the ridge portion changes in width from the input end to the output end, so as to modify the optical beam propagating from the input end to the output end from the initial mode size to a final mode size; and

propagating the optical beam, with the final mode size, out of the output end of the waveguide mode expander.

2. The method of claim 1, wherein the ridge portion becomes wider from the input end to the output end, so that the final mode size is larger than the initial mode size.

3. The method of claim 2, wherein the ridge portion comprises a plurality of stages disposed atop the shoulder portion, wherein

each of the stages comprises non-crystalline silicon, and

each of the stages becomes wider from a first end to a second end, where the first end of each stage is nearer the input end than the second end along a direction of beam propagation.

4. The method of claim 3, wherein ones of the stages that are further from the shoulder portion are taller than ones of the stages that are closer to the shoulder portion.

5. The method of claim 2, wherein propagating the optical beam out of the output end comprises coupling the optical beam into an optical fiber.

6. The method of claim 1, wherein propagating the optical beam into the input end comprises coupling the optical beam from a waveguide disposed on the substrate into the waveguide mode expander.

7. The method of claim 6, wherein the waveguide is contiguous with the shoulder portion at the input end.

8. The method of claim 6, wherein propagating the optical beam into the input end comprises coupling the optical beam through an angled interface between the shoulder portion and the waveguide, wherein the angled interface forms a plane that is not orthogonal with respect to a propagation direction of the optical beam.

9. The method of claim 1, wherein the ridge portion becomes narrower from the input end to the output end, so that the final mode size is smaller than the initial mode size.

10. The method of claim 9, wherein propagating the optical beam into the input end comprises coupling the optical beam from an optical fiber into the waveguide mode expander.

11. The method of claim 9, wherein propagating the optical beam out of the output end comprises coupling the optical beam into a waveguide disposed on the substrate.

12. The method of claim 11 wherein the waveguide is contiguous with the shoulder portion at the output end.