# US 12,001,050 B2 · Manufacturing method of multicore fiber preform, multicore fiber preform, and multicore fiber

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- Number: US 12,001,050 B2
- Document ID: US12001050B2
- Status: Granted
- Kind: B2
- Application number: 17/448,077
- Filed: 2021-09-20
- Published: 2022-01-06
- Granted: 2024-06-04
- Earliest claimed: 2019-03-27
- Assignees: Furukawa Electric Co., Ltd.
- Applicants: Furukawa Electric Co., Ltd.
- Inventors: Masanori Takahashi; Koichi Maeda; Shinichi Arai; Ryuichi Sugizaki; Masayoshi Tsukamoto
- Web page: https://patentgrep.com/patent/US12001050B2

## CPC

- G02B 6/02042: {Multicore optical fibres}
- C03B 37/012: Manufacture of preforms for drawing fibres or filaments
- C03B 37/01222: {for making preforms of multiple core optical fibres (preforms of multifibres C03B37/01214)}
- C03B 37/01231: {to form a longitudinal hole, e.g. by drilling}
- C03B 2203/34: Plural core other than bundles, e.g. double core
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES

## Abstract

A multicore fiber includes: n pieces of first core regions in a circular shape with a radius r1 that are arranged about points P11 to P1n, and that has a first core portion and a first cladding portion; a second core region in a circular shape with a radius R1 that is arranged about the point a1, and that has a second core portion and a second cladding portion; and a cladding region that is formed on an outer circumferences of the first core region and the second core region. Further, abutting surfaces that are flat surfaces abutting on each other are formed in portions on the outer circumferences of the first core region and the second core region.

## Claims

### Claim 1

A multicore fiber comprising:
n pieces of first core regions in a circular shape with a radius r1 that are arranged about points P11 to P1n, and that has a first core portion and a first cladding portion formed on an outer circumference of the first core portion by setting the points P11 to P1n at positions, distances of which are X11 to X1n, respectively, from a point a1, on straight lines dividing an end surface in to n pieces to have an equal central angle about the point a1 of the end surface such that X1max−r1<R1<X1min is satisfied, where a maximum value of X11 to X1n is X1max, and a minimum value thereof is X1min;
a second core region in a circular shape with a radius R1 that is arranged about the point a1, and that has a second core portion and a second cladding portion formed on an outer circumference of the second core portion; and
a cladding region that is formed on outer circumferences of the first core region and the second core region, wherein;
abutting surfaces that are flat surfaces abutting on each other are formed in portions on the outer circumferences of the first core region and the second core region, and
another cladding region having a softening temperature lower than the first cladding portion and the cladding region is arranged in place of the second core region.

### Claim 2

A multicore fiber comprising:
n pieces of first core regions in a polygonal shape that are arranged to have a center of gravity at points P21 to P2n, and that has a first core portion and a first cladding portion formed on an outer circumference of the first core portion, by setting the points P21 to P2n at positions, distances of which are X21 to X2n, respectively, from a point a2, on straight lines dividing an end surface into n pieces to have an equal central angle about the point a2 of the end surface such that a plurality of overlap portions in which adjacent polygons overlap each other at least in a part thereof are formed;
a second core region in a polygonal shape that is arranged about the point a1, that has a second core portion and a second cladding portion formed on an outer circumference of the second core portion, and that includes all of the overlap portions; and
a cladding region that is formed on an outer circumferences of the first core region and the second core region, wherein
abutting surfaces that are flat surfaces abutting on each other are formed in portions on the outer circumferences of the first core region and the second core region, and
another cladding region having a softening temperature lower than the first cladding portion and the cladding region is arranged in place of the second core region.