# US 10,310,176 B2 · Multi-core fiber

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- Number: US 10,310,176 B2
- Document ID: US10310176B2
- Status: Granted
- Kind: B2
- Application number: 15/571,530
- Filed: 2016-05-20
- Published: 2018-05-03
- Granted: 2019-06-04
- Earliest claimed: 2015-05-27
- Assignees: Fujikura Ltd.; National University Corporation Hokkaido University
- Applicants: Fujikura Ltd.; National University Corporation Hokkaido University
- Inventors: Yusuke Sasaki; Katsuhiro Takenaga; Kunimasa Saitoh
- Web page: https://patentgrep.com/patent/US10310176B2

## CPC

- G02B 6/02042: {Multicore optical fibres}
- G02B 6/02: Optical fibres with cladding {with or without a coating}
- G02B 6/02023: {Based on higher order modes, i.e. propagating modes other than the LP01 or HE11 fundamental mode (mode converters G02B6/14)}
- G02B 6/03694: {Multiple layers differing in properties other than the refractive index, e.g. attenuation, diffusion, stress properties}
- G02B 6/03633: {arranged - -}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A multi-core fiber performs communication using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multi-core fiber includes: a plurality of signal light propagation cores that propagate light up to an (x+1)th-order LP mode; and at least one high-loss core that has a higher loss of propagated light than the signal light propagation cores. Crosstalk occurs between light of the (x+1)th-order LP mode propagated through at least one signal light propagation core and light of a primary LP mode propagated through at least one high-loss core.

## Claims

### Claim 1

A multi-core fiber for performing communication using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band, the multi-core fiber comprising:
a plurality of signal light propagation cores that propagate light up to an (x+1)th-order LP mode; and
at least one high-loss core that has a higher loss of propagated light than the signal light propagation cores, wherein
crosstalk occurs between light of the (x+1)th-order LP mode propagated through at least one signal light propagation core and light of a primary LP mode propagated through at least one high-loss core, and
a distance between the signal light propagation cores adjacent to each other is a distance at which crosstalk of the light up to the xth-order LP mode becomes less than or equal to −40 dB/km and crosstalk of the light of the (x+1)th-order LP mode becomes greater than or equal to −30 dB/km.

### Claim 2

A multi-core fiber for performing communication using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band, the multi-core fiber comprising:
a plurality of signal light propagation cores that propagate light up to an (x+1)th-order LP mode; and
at least one high-loss core that has a higher loss of propagated light than the signal light propagation cores, wherein
crosstalk occurs between light of the (x+1)th-order LP mode propagated through at least one signal light propagation core and light of a primary LP mode propagated through at least one high-loss core, and
the high-loss core is disposed at a position surrounded by the three or more signal light propagation cores.

### Claim 3

A multi-core fiber for performing communication using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band, the multi-core fiber comprising:
a plurality of signal light propagation cores that propagate light up to an (x+1)th-order LP mode;
at least one high-loss core that has a higher loss of propagated light than the signal light propagation cores; and
an extension portion that extends such that diameters of the plurality of signal light propagation cores decrease, in a part of the plurality of signal light propagation cores, in a longitudinal direction, wherein
crosstalk occurs between light of the (x+1)th-order LP mode propagated through at least one signal light propagation core and light of a primary LP mode propagated through at least one high-loss core, and
in the extension portion, the plurality of signal light propagation cores propagate the light up to the xth-order LP mode and propagation of the light of the (x+1)th-order LP mode is suppressed.

### Claim 4 (depends on 3)

The multi-core fiber according to claim 3, wherein, in the extension portion, a loss of the light of the (x+1)th-order LP mode propagated through the plurality of signal light propagation cores is greater than or equal to 20 dB.