# US 2025/0085478 A1 · Optical waveguide device

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- Number: US 2025/0085478 A1
- Document ID: US20250085478A1
- Status: Published application
- Kind: A1
- Application number: 18/824,111
- Filed: 2024-09-04
- Published: 2025-03-13
- Earliest claimed: 2023-09-08
- Assignees: Shinko Electric Industries Co., Ltd.; Keio University
- Applicants: Shinko Electric Industries Co., Ltd.; Keio University
- Inventors: Yuji FURUTA; Takaaki Ishigure; Fumimasa Kondo
- Web page: https://patentgrep.com/patent/US20250085478A1

## CPC

- G02B 6/138: by using polymerisation
- G02B 6/262: {Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements}
- G02B 6/02033: {Core or cladding made from organic material, e.g. polymeric material (G02B1/04 takes precedence)}
- G02B 6/1228: {Tapered waveguides, e.g. integrated spot-size transformers (for coupling with fibres G02B6/305)}
- G02B 6/125: Bends, branchings or intersections
- G02B 2006/12097: {Ridge, rib or the like}
- G02B 2006/12147: {Coupler}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An optical waveguide device includes a substrate, a first waveguide disposed on or in the substrate, and a second waveguide disposed on a first surface of the substrate, wherein the second waveguide includes a core and a cladding covering the core, wherein throughout an entirety of a predetermined region, a portion of the core overlaps the first waveguide when viewed from a direction normal to the first surface, in wherein the predetermined region, the core has a bottom surface in contact with the first surface and a convex surface connected to the bottom surface, and wherein the core includes a portion whose thickness gradually decreases from a widthwise center to widthwise ends in a transverse cross-sectional view.

## Claims

### Claim 1

An optical waveguide device comprising:
a substrate;
a first waveguide disposed on or in the substrate; and
a second waveguide disposed on a first surface of the substrate,
wherein the second waveguide includes a core and a cladding covering the core,
entirety wherein throughout an of a predetermined region, a portion of the core overlaps the first waveguide when viewed from a direction normal to the first surface,
wherein in the predetermined region, the core has a bottom surface in contact with the first surface and a convex surface connected to the bottom surface, and
wherein the core includes a portion whose thickness gradually decreases from a widthwise center to widthwise ends in a transverse cross-sectional view.

### Claim 2 (depends on 1)

The optical waveguide device as claimed in claim 1, wherein
in a transverse cross-section, the core has a laterally oblong shape with a height thereof less than a width thereof.

### Claim 3 (depends on 1)

The optical waveguide device as claimed in claim 1, wherein the convex surface is a curved surface.

### Claim 4 (depends on 1)

The optical waveguide device as claimed in claim 1, wherein in the predetermined region, when viewed from the direction normal to the first surface, the first waveguide includes a portion whose width gradually decreases toward one side in a longitudinal direction thereof.

### Claim 5 (depends on 1)

The optical waveguide device as claimed in claim 1, wherein, when viewed from the direction normal to the first surface, the core includes a longitudinal portion whose width gradually decreases or gradually increases toward one side in a longitudinal direction thereof.

### Claim 6 (depends on 5)

The optical waveguide device as claimed in claim 5, wherein a thickness of the longitudinal portion gradually decreases or gradually increases toward the one side in the longitudinal direction.

### Claim 7 (depends on 1)

The optical waveguide device as claimed in claim 1, wherein outside the predetermined region, the core includes a circular portion in a transverse cross-sectional view.

### Claim 8 (depends on 1)

The optical waveguide device as claimed in claim 1, wherein the first waveguide is embedded in the substrate.

### Claim 9 (depends on 1)

The optical waveguide device as claimed in claim 1, wherein the first waveguide contains silicon, silicon nitride, gallium arsenide, or lithium niobate.

### Claim 10 (depends on 1)

The optical waveguide device as claimed in claim 1, wherein the second waveguide is a polymer waveguide.