Tapered photonic waveguide to optical fiber proximity coupler

• US 9,563,018 B2
• Filed: 10/09/2014
• Issued: 02/07/2017
• Est. Priority Date: 10/09/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Budd, Russell A.
• Primary Examiner(s): Stahl, Mike
• Application Number:
  US14/510,373
• Publication Number:
  US 20160103279A1
• Time in Patent Office: 852 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G02B 2006/12061 Silicon
• CPC Class Codes: G02B 2006/12147 Coupler
• CPC Class Codes: G02B 6/12004 Combinations of two or more optical elements
• CPC Class Codes: G02B 6/1228 Tapered waveguides, e.g. integrated spot-size transformers for coupling with fibres G02B6/305
• CPC Class Codes: G02B 6/13 Integrated optical circuits characterised by the manufacturing method
• CPC Class Codes: G02B 6/245 Removing protective coverings of light guides before coupling
• CPC Class Codes: G02B 6/305 and having an integrated mode-size expanding section, e.g. tapered waveguide

Abstract

A photonic waveguide structure may include a tapered photonic waveguide structure within a photonic substrate, such that the tapered photonic waveguide structure has a tapered region that progressively tapers in width along a longitudinal length of the tapered photonic waveguide structure. The photonic waveguide structure also includes an optical fiber waveguide having a core region and a cladding region, whereby a portion of the core region is partially exposed by removing a portion of the cladding region. An outer surface of the portion of the core region that is partially exposed is substantially coupled to the tapered photonic waveguide structure. An optical signal propagating along the tapered photonic waveguide structure is coupled from the tapered region of the tapered photonic waveguide structure to the core region of the optical fiber waveguide via the core region that is partially exposed.

Claims

1. A photonic waveguide structure comprising:

a tapered photonic waveguide structure within a photonic substrate, the tapered photonic waveguide structure having a tapered region that progressively tapers in width along a longitudinal length of the tapered photonic waveguide structure; and

an optical fiber waveguide having a core region and a cladding region, a portion of the core region partially exposed by removing a portion of the cladding region, an outer surface of the portion of the core region that is partially exposed substantially coupled to the tapered photonic waveguide structure,

wherein an optical signal propagating along the tapered photonic waveguide structure is coupled from the tapered region of the tapered photonic waveguide structure to the core region of the optical fiber waveguide via the core region that is partially exposed, and wherein the tapered region of the tapered photonic waveguide structure and the core region of the optical fiber waveguide that is partially exposed comprise an orientation that is substantially parallel.

2. The structure of claim 1, further comprising:

a polysiloxane layer located between the outer surface of the fiber core region that is partially exposed and the tapered region of the tapered photonic waveguide structure.

3. The structure of claim 2, wherein the polysiloxane layer comprises a thickness of about 50-200 micrometers (μ

m).

4. The structure of claim 1, further comprising:

a bulk silicon region; and

a buried oxide (BOX) layer located directly on the bulk silicon region, wherein the tapered photonic waveguide structure is created from a silicon-on-insulator (SOI) layer located directly on the BOX layer.

5. The structure of claim 1, wherein the tapered photonic waveguide structure comprises a silicon nitride (SiN) material having an un-tapered width of about 1.0 micrometers (μ

m) and a thickness of about 0.3 micrometers (μ

m).

6. The structure of claim 5, wherein the tapered region of the tapered photonic waveguide structure comprises a length of between 20 μ

m to 1000 μ

m.

7. The structure of claim 6, wherein the core region comprises a diameter of about 6-10 μ

m.

8. A photonic waveguide structure comprising:

a first tapered photonic waveguide structure located within a photonic substrate for guiding an optical signal, the first tapered photonic waveguide structure having a tapered region that progressively tapers in width along a longitudinal length of the first tapered photonic waveguide structure;

a second tapered photonic waveguide located within the photonic substrate, the second tapered photonic waveguide located adjacent one side of the first tapered photonic waveguide structure and separated from the first tapered photonic waveguide structure by a dielectric material;

a third tapered photonic waveguide located within the photonic substrate, the third tapered photonic waveguide located adjacent an opposing side to the one side of the first tapered photonic waveguide structure and separated from the first tapered photonic waveguide structure by the dielectric material; and

an optical fiber waveguide having a core region and a cladding region, a portion of the core region partially exposed by removing a portion of the cladding region, an outer surface of the portion of the core region that is partially exposed substantially coupled to the first tapered photonic waveguide structure,

wherein the optical signal propagating along the first tapered photonic waveguide structure is coupled from the tapered region of the first tapered photonic waveguide structure to the core region of the optical fiber waveguide via the core region that is partially exposed, the optical signal propagating along the first tapered photonic waveguide structure undergoing, based on the second and the third tapered photonic waveguide structure, a mode broadening prior to being coupled from the tapered region of the first tapered photonic waveguide structure to the core region of the optical fiber waveguide, and wherein the tapered region of the first tapered photonic waveguide structure and the core region of the optical fiber waveguide that is partially exposed comprise an orientation that is substantially parallel.

9. The structure of claim 8, further comprising:

a bulk silicon region; and

a buried oxide (BOX) layer located directly on the bulk silicon region, wherein the first, the second, and the third tapered photonic waveguide structure is created from a silicon-on-insulator (SOI) layer located directly on the BOX layer.

10. A method of forming a photonic waveguide coupling device from a fiber optic ferrule device having a single row of substantially parallel fiber holes for receiving a plurality of optical fibers and a pair of alignment holes, the method comprising:

forming a fiber mounting block by removing a top portion of the fiber optic ferrule device, the removed top portion converting the single row of substantially parallel fiber holes into a single row of substantially parallel channels and converting the pair of alignment holes into a pair of alignment channels;

placing a plurality of optical fibers having end facets in the single row of substantially parallel channels, the end facets being substantially flush with end portions of the single row of substantially parallel channels; and

polishing the plurality of optical fibers for exposing the core regions of the plurality of optical fibers and generating a downward sloping angle along the length of the core regions towards the end facets,

wherein the exposed core regions of the plurality of optical fibers having the downward sloping angle along the length of the core regions towards the end facets provide optical coupling with a plurality of tapered photonic waveguide structures in an integrated circuit.

11. The method of claim 10, further comprising:

rotating the mounting block for orienting the exposed core regions of the plurality of optical fibers having the downward sloping angle to face the plurality of tapered photonic waveguide structures in the integrated circuit; and

placing the pair of alignment channels over an alignment mesa pair located within the integrated circuit for mechanically aligning the plurality of tapered photonic waveguide structures with the exposed core regions of the plurality of optical fibers having the downward sloping angle.

12. The method of claim 11, wherein the plurality of tapered photonic waveguide structures mechanically aligned with the exposed core regions of the plurality of optical fibers having the downward sloping angle are coupled with a refractive index matching adhesive.

13. The method of claim 12, wherein the refractive index matching adhesive comprises a polysiloxane material.

14. The method of claim 13, wherein the downward sloping angle is in a range of angles between about 1-30 degrees.

15. The method of claim 14, wherein the plurality of optical fibers comprise a plurality of single mode fibers.

16. The method of claim 10, wherein the optical coupling between the exposed core regions of the plurality of optical fibers having the downward sloping angle and the plurality of tapered photonic waveguide structures occurs via an overlapping region between the exposed core regions and the plurality of tapered photonic waveguide structures.