Multi-core silicon waveguide in a mode-converting silicon photonic edge coupler

Patent metadata

Field	Value
Publication number	US-10345522-B2
Application number	US-201816011155-A
Country	US
Kind code	B2
Filing date	Jun 18, 2018
Priority date	Sep 20, 2017
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A mode-converting optical coupler may include a secondary waveguide to guide light in one or more secondary optical modes, and a primary waveguide to guide light in one or more primary optical modes, each adiabatically coupled to a secondary optical mode of the secondary waveguide having a secondary mode index. Each primary optical mode of the primary waveguide may have a first primary mode index near a first end and a second primary mode index near a second end. The first primary mode index may be lower than the second primary mode index. The secondary mode index may be between the first primary mode index and the second primary mode index. The primary waveguide may include a plurality of silicon core structures including a central core structure arranged between a first neighboring core structure and a second neighboring core structure.

First claim

What is claimed is:

1. A mode-converting optical coupler, comprising:
a secondary waveguide to guide light in one or more secondary optical modes; and
a primary waveguide, to guide light in one or more primary optical modes, each adiabatically coupled to a secondary optical mode of the secondary waveguide having a secondary mode index,
wherein the primary waveguide is between the secondary waveguide and a substrate layer of the mode-converting optical coupler,
wherein each primary optical mode of the primary waveguide has a first primary mode index near a first end and a second primary mode index near a second end,
wherein the first primary mode index is lower than the second primary mode index, and
wherein the secondary mode index is between the first primary mode index and the second primary mode index, and

wherein the primary waveguide comprises a plurality of core structures including a central core structure arranged between a first neighboring core structure and a second neighboring core structure, and
wherein a width of each of the plurality of core structures tapers towards the first end of the primary waveguide,
wherein each of the plurality of core structures is arranged in a direction that is substantially parallel to the direction in which light propagates through the primary waveguide, and
wherein the plurality of core structures comprises silicon (Si).

2. The mode-converting optical coupler of claim 1 , wherein the secondary waveguide has a facet that is butt coupled to an optical fiber.

3. The mode-converting optical coupler of claim 1 , wherein the secondary waveguide is coupled to a free-space beam.

4. The mode-converting optical coupler of claim 1 , wherein the mode-converting optical coupler is a chip-chip coupler.

5. The mode-converting optical coupler of claim 1 , wherein the mode-converting optical coupler is an on-chip device coupler.

6. The mode-converting optical coupler of claim 1 , wherein the one or more secondary optical and the one or more primary optical modes include one or more TE modes, one or more TM modes, or some combination thereof.

7. The mode-converting optical coupler of claim 1 , wherein the one or more secondary optical modes are larger than the one or more primary optical modes.

8. The mode-converting optical coupler of claim 1 , wherein the central core structure is at least as wide as the first neighboring core structure and the second neighboring core structure at a given location along a length of the central core structure.

9. The mode-converting optical coupler of claim 1 , wherein the secondary waveguide comprises silicon oxynitride (SiON).

10. The mode-converting optical coupler of claim 1 , wherein the primary waveguide is arranged on or in a cladding layer,
wherein the cladding layer comprises silicon dioxide (SiO 2 ).

11. The mode-converting optical coupler of claim 1 , wherein the secondary waveguide tapers toward the first end of the primary waveguide.

12. The mode-converting optical coupler of claim 1 , wherein the plurality of core structures includes a third neighboring core structure,
wherein the first neighboring core structure is arranged between the central core structure and the third neighboring core structure.

13. The mode-converting optical coupler of claim 1 , wherein the central core structure has a first width in a first section along a length of the central core structure, transitions from the first width to a second width in a second section along the length of the central core structure, and transitions from the second width to a third width in a third section along the length of the central core structure,
wherein the second section is between the first section and the third section, and
wherein the second width is less than the first width and greater than the third width.

14. The mode-converting optical coupler of claim 1 , wherein at a given location along a length of the central core structure, a pitch between central core structure and the first neighboring core structure matches a pitch between the central core structure and the second neighboring core structure.

15. The mode-converting optical coupler of claim 1 , wherein at a given location along a length of the central core structure, a width of the first neighboring core structure matches a width of the second neighboring core structure.

16. The mode-converting optical coupler of claim 1 , wherein the central core structure has a first thickness in a first section along a length of the central core structure, has the first thickness in a first portion of a second section along the length of the central core structure, has a second thickness in a second portion of the second section along the length of the central core structure, and has the second thickness in a third section along the length of the central core structure,
wherein the second section is between the first section and the third section,
wherein the second thickness is different from the first thickness.

17. The mode-converting optical coupler of claim 1 , wherein the first neighboring core structure has a first thickness in a first section along a length of the first neighboring core structure, has the first thickness in a first portion of a second section along the length of the first neighboring core structure, has a second thickness in a second portion of the second section along the length of the first neighboring core structure, and has the second thickness in a third section along the length of the first neighboring core structure,
wherein the second section is between the first section and the third section,
wherein the second thickness is different from the first thickness.

18. A mode-converting optical coupler, comprising:
a secondary waveguide to guide light in one or more secondary optical modes; and
a primary waveguide, to guide light in one or more primary optical modes, each adiabatically coupled to a secondary optical mode of the secondary waveguide having a secondary mode index,
wherein the primary waveguide is between the secondary waveguide and a substrate layer of the mode-converting optical coupler,
wherein each primary optical mode of the primary waveguide has a first primary mode index near a first end and a second primary mode index near a second end,
wherein the first primary mode index is lower than the second primary mode index, and
wherein the secondary mode index is between the first primary mode index and the second primary mode index, and

wherein the primary waveguide comprises a central core structure and multiple neighboring core structures,
wherein the central core structure is arranged between at least two of the multiple neighboring core structures, and
wherein a width of the central core structure tapers toward the first end of the primary waveguide, and

wherein the central core structure and the multiple neighboring core structures comprise silicon (Si).

19. The mode-converting optical coupler of claim 18 , wherein the central core structure and the multiple neighboring core structures are arranged in a direction that is substantially parallel to a direction in which light propagates through the primary waveguide.

20. A method, comprising:
guiding, by a secondary waveguide of a mode-converting optical coupler, light in one or more secondary optical modes; and
guiding, by a primary waveguide of the mode-converting optical coupler, light in one or more primary optical modes, each being adiabatically coupled to a secondary optical mode of the s

Assignees

• Lumentum Operations Llc

Inventors

• Daniel Brian

Classifications

• G02B6/122

  Basic optical elements, e.g. light-guiding paths · CPC title

• G02B2006/12038

  Glass (SiO2 based materials) · CPC title

• G02B6/14 Primary

  Mode converters · CPC title

• G02B6/105

  having optical polarisation effects · CPC title

• G02B6/305

  and having an integrated mode-size expanding section, e.g. tapered waveguide · CPC title