# US 2022/0035099 A1 · Optical Connection Structure

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- Number: US 2022/0035099 A1
- Document ID: US20220035099A1
- Status: Published application
- Kind: A1
- Application number: 17/276,312
- Filed: 2019-10-08
- Published: 2022-02-03
- Earliest claimed: 2018-10-18
- Assignees: Nippon Telegraph and Telephone Corporation
- Applicants: Nippon Telegraph and Telephone Corporation
- Inventors: Yusuke Muranaka; Kota Shikama; Hidetaka Nishi; Ai Yanagihara
- Web page: https://patentgrep.com/patent/US20220035099A1

## CPC

- G02B 6/30: for use between fibre and thin-film device
- G02B 6/3652: {the additional structures being prepositioning mounting areas, allowing only movement in one dimension, e.g. grooves, trenches or vias in the microbench surface, i.e. self aligning supporting carriers}
- G02B 6/368: {with pitch conversion between input and output plane, e.g. for increasing packing density}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

There is provided an optical connection structure in which an optical fiber and an optical semiconductor waveguide are easily connected with low loss. The present invention relates to an optical connection structure configured to connect an optical waveguide device and an optical fiber including cores having different refractive indexes, wherein an optical connection component using a planar lightwave circuit is bonded and fixed on an end surface of an input/output waveguide of the optical waveguide device, a value of a refractive index of a core of the planar lightwave circuit is between a value of the refractive index of the core of the optical waveguide device and a value of the refractive index of the core of the optical fiber, and the optical waveguide device and the optical fiber are optically connected via the planar lightwave circuit.

## Claims

### Claim 1

An optical connection structure configured to connect an optical waveguide device and an optical fiber including cores having different refractive indexes, comprising:
an optical connection component using a planar lightwave circuit bonded and fixed on an end surface of an input/output waveguide of the optical waveguide device,
a value of a refractive index of a core of the planar lightwave circuit is between a value of the refractive index of the core of the optical waveguide device and a value of the refractive index of the core of the optical fiber, and
the optical waveguide device and the optical fiber are optically connected via the planar lightwave circuit.

### Claim 2 (depends on 1)

The optical connection structure according to claim 1, further comprising:
a spot-size converter on an end surface of an input/output waveguide of the planar lightwave circuit.

### Claim 3 (depends on 1)

The optical connection structure according to claim 1, further comprising:
a spot-size converter on the end surface of the input/output waveguide of the optical waveguide device.

### Claim 4 (depends on 1)

The optical connection structure according to claim 1,
wherein in a case of a single mode, the core of the optical fiber connected to the planar lightwave circuit includes a portion having a core diameter smaller than 10 μm.

### Claim 5 (depends on 1)

The optical connection structure according to claim 1,
wherein an optical fiber guide component including a guide hole for positioning the optical fiber is bonded and fixed on an input/output end surface of the planar lightwave circuit, the input/output end surface of the planar lightwave circuit on which the optical fiber guide component is bonded and fixed being different from the input/output end surface of the planar lightwave circuit on which the optical waveguide device is bonded and fixed.

### Claim 6 (depends on 1)

The optical connection structure according to claim 1, further comprising:
an optical fiber array in which the optical fiber is provided in a groove of a substrate; and
the planar lightwave circuit which adjusts a pitch of the input/output waveguide of the optical waveguide device and a pitch of the optical fiber,
wherein the planar lightwave circuit includes a plurality of the cores, and
the plurality of the cores have different longitudinal directions and lengths, so that the pitch of the input/output waveguide and the pitch of the optical fiber are set.

### Claim 7 (depends on 1)

The optical connection structure according to claim 1,
wherein the pitch of the input/output waveguide is narrower than the pitch of the optical fiber.