Managing evanescent optical coupling in photonic integrated circuits

Patent metadata

Field	Value
Publication number	US-2025123441-A1
Application number	US-202318487205-A
Country	US
Kind code	A1
Filing date	Oct 16, 2023
Priority date	Oct 16, 2023
Publication date	Apr 17, 2025
Grant date	—

Abstract

A first waveguide core structure (WCS) is configured to confine an optical wave (OW) at a first wavelength to a first mode and a second wavelength to a second mode, each over a coupling region (CR). A second WCS is configured to confine an OW at the first wavelength to a third mode and the second wavelength to a fourth mode, each over the CR. The CR comprises a structure in which portions of the first and second WCS are in proximity over a coupling distance and provides a first coupling between the first and third mode, at a first location, that is greater than a second coupling between the second and fourth mode at the first location, and a third coupling between the second and fourth mode, at a second location, that is greater than a fourth coupling between the first and third mode at the second location.

First claim

What is claimed is:

1 . An article of manufacture comprising:
a first waveguide core structure configured to
confine an optical wave at a first wavelength to a first mode over a coupling region, and
confine an optical wave at a second wavelength to a second mode over the coupling region; and
a second waveguide core structure configured to
confine an optical wave at the first wavelength to a third mode over the coupling region, and
confine an optical wave at the second wavelength to a fourth mode over the coupling region;
wherein the coupling region comprises a structure in which a portion of the first waveguide core structure is in proximity to a portion of the second waveguide core structure over a coupling distance and is configured to
provide a first coupling between the first mode and the third mode, at a first location along the coupling distance, that is greater than a second coupling between the second mode and the fourth mode at the first location, and
provide a third coupling between the second mode and the fourth mode, at a second location along the coupling distance different from the first location, that is greater than a fourth coupling between the first mode and the third mode at the second location.

2 . The article of manufacture of claim 1 , wherein the first waveguide core structure comprises a semi-rib waveguide core structure comprising a guiding portion characterized by a thickness that is larger than a thickness of a non-guiding region extending from only one side of the guiding portion of the semi-rib waveguide core structure.

3 . The article of manufacture of claim 2 , wherein the second waveguide core structure comprises a rib waveguide core structure comprising a guiding portion characterized by a thickness that is larger than a thickness of non-guiding regions extending from both sides of the guiding portion of the rib waveguide core structure.

4 . The article of manufacture of claim 1 , wherein the first waveguide core structure is configured to define transverse intensity profiles of the first mode and the second mode that spatially vary along the first waveguide core structure.

5 . The article of manufacture of claim 4 , wherein the second waveguide core structure is configured to define transverse intensity profiles of the third mode and the fourth mode that spatially vary along the second waveguide core structure.

6 . The article of manufacture of claim 1 , wherein the portion of the first waveguide core structure is separated from the portion of the second waveguide core structure by less than five times a mode field diameter of a guided mode of the first or second waveguide core structure.

7 . The article of manufacture of claim 1 , wherein an edge of the portion of the first waveguide core structure is separated from an edge of the portion of the second waveguide core structure by a first distance at the first location and by a second distance larger than the first distance at the second location.

8 . The article of manufacture of claim 7 , wherein the second wavelength is larger than the first wavelength.

9 . The article of manufacture of claim 1 , wherein the first waveguide core structure is characterized by at least one of a width or a thickness that varies along the first waveguide core structure.

10 . The article of manufacture of claim 9 , wherein the second waveguide core structure is characterized by at least one of a width or a thickness that varies along the second waveguide core structure.

11 . The article of manufacture of claim 1 , wherein at least one of the width or the thickness of the first waveguide core structure is not equal to the width or the thickness of the second waveguide core structure at the first location.

12 . The article of manufacture of claim 1 , wherein the first waveguide core structure is composed of a first material and the second waveguide core structure is composed of a second material different from the first material.

13 . The article of manufacture of claim 1 , wherein the first waveguide core structure is in contact with a first cladding composed of a first material and the second waveguide core structure is in contact with a second cladding composed of a second material different from the first material.

14 . The article of manufacture of claim 1 , further comprising at least one stress-modifying formation located closer to the first waveguide core structure than to the second waveguide core structure, where the stress-modifying formation modifies a stress within a portion of a cladding in contact with the first waveguide core structure.

15 . The article of manufacture of claim 14 , where the modified stress within the portion of the cladding modifies an index of refraction associated with the cladding.

16 . An article of manufacture comprising:
a first waveguide structure including a first guiding portion of the first waveguide structure that is located in a coupling region; a second waveguide structure including a second guiding portion of the second waveguide structure that is located in the coupling region; a first non-guiding region extending from the first guiding portion and comprising a slab structure characterized by a first thickness and a first index of refraction; and a second non-guiding region extending from the second guiding portion, wherein the second non-guiding region is characterized by one or both of a thickness smaller than the first thickness, or an index of refraction smaller than the first index of refraction.

17 . The article of manufacture of claim 16 , further comprising a third non-guiding region extending between the first guiding portion and the second guiding portion, on an opposite side of the first guiding portion from the first non-guiding region, and on an opposite side of the second guiding portion from the second non-guiding region.

18 . The article of manufacture of claim 16 , further comprising one or more stress-modifying formations located closer to the first waveguide structure than to the second waveguide structure, where the stress-modifying formations modify a stress within a portion of the first cladding.

19 . The article of manufacture of claim 16 , wherein the first guiding portion is characterized by at least one of a width or a thickness that varies along the first guiding portion.

20 . A method comprising:
forming a first waveguide core structure configured to
confine an optical wave at a first wavelength to a first mode over a coupling region, and
confine an optical wave at a second wavelength to a second mode over the coupling region; and
forming a second waveguide core structure configured to
confine an optical wave at the first wavelength to a third mode over the coupling region, and
confine an optical wave at the second wavelength to a fourth mode over the coupling region;
wherein the coupling region comprises a structure in which a portion of the first waveguide core structure is in proximity to a portion of the second waveguide core structure over a coupling distance and is configured to
provide a first coupling between the first mode and the third mode, at a first location along the coupling distance, that is greater than a second coupling between the second mode and the fourth mode at the first location, and
provide a third coupling between the second mode and the fourth mode, at a second location along the coupling distance different from the first location, that is greater than a fourth coupling between the first mode

Assignees

• Ciena Corp

Inventors

• Painchaud Yves
• Picard Marie-Josee
• Bois Antoine

Classifications

• G02B6/29332

  Wavelength selective couplers, i.e. based on evanescent coupling between light guides, e.g. fused fibre couplers with transverse coupling between fibres having different propagation constant wavelength dependency · CPC title

• G02B6/29331

  operating by evanescent wave coupling · CPC title

• G02B6/125

  Bends, branchings or intersections · CPC title

• G02B2006/12097

  Ridge, rib or the like · CPC title

• G02B2006/12147

  Coupler · CPC title