Method of arranging cores of multi-core fiber

• US 8,503,847 B2
• Filed: 10/02/2009
• Issued: 08/06/2013
• Est. Priority Date: 10/03/2008
• Status: Expired due to Fees

• Current Assignee: National University Corporation Hokkaido University, National University Corporation Yokohama National University
• Original Assignee: National University Corporation Hokkaido University, National University Corporation Yokohama National University
• Inventors: Kokubun, Yasuo, Koshiba, Masanori, Morioka, Toshio
• Primary Examiner(s): PAK, SUNG H
• Application Number:
  US13/122,335
• Publication Number:
  US 20110243517A1
• Time in Patent Office: 1,404 Days
• Field of Search: None
• US Class Current: 385/126
• CPC Class Codes: G02B 6/02042 Multicore optical fibres
• CPC Class Codes: G02B 6/2804 forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
• CPC Class Codes: H04B 10/2581 Multimode transmission
• CPC Class Codes: H04J 14/04 Mode multiplex systems
• CPC Class Codes: H04J 14/052 using multicore fibre mode multiplex systems H04J14/04

Abstract

A multi-core fiber of the present invention employs the multi-core fiber mode, which corresponds to the “uncoupled” operation aspect in which individual cores are used independently for single-mode transmission, to perform space division multiplexing transmission using a multi-core fiber in which multiple single-mode cores are stored in one optical fiber. More specifically, the multi-core fiber of the present invention forms an uncoupled multi-core fiber that makes individual cores correspond to single-mode, independent transmission channels.

Claims

1. A method of arranging cores of a multi-core fiber in which a plurality of single-mode cores are accommodated in one optical fiber comprising the steps of:

in an electric field distribution of eigen modes propagating through the fiber,

fundamental eigen modes of individual cores being spatially localized to form fundamental eigen modes that do not couple each other but are isolated, and

signal transmission channels being made to correspond to the basic fundamental eigen modes of the individual cores to comprise a space division multiplexing system in which the transmission channels are multiplexed through space division,

a plurality of types of three or more cores being arranged two-dimensionally in a cross section of the multi-core fiber, said plurality of types of cores having different fundamental-mode propagation constants in single-mode fibers, and

between neighboring cores,

heterogeneous cores having different propagation constants being placed in an uncoupled state by a difference in the propagation constants, and homogeneous cores having the same propagation constant being placed in an uncoupled state by a core-to-core distance, to comprise an uncoupled transmission system in which the cores are spatially divided,

in forming the uncoupled state between the heterogeneous cores, the different propagation constants being determined by calculating a propagation constant difference from a power-conversion efficiency, which is set based on a power-conversion efficiency whose parameter is the propagation constant difference and by selecting different propagation constants that satisfy the calculated propagation constant difference, and cores having the selected different propagation constants being arranged to form the uncoupled state between the heterogeneous cores,

in forming the uncoupled state between the homogeneous cores, the core-to-core distance being determined as the core-to-core distance between the neighboring homogeneous cores by the propagation constant of the cores and a specified coupling length based on a coupling length relation determined by a weak coupling approximation including the propagation constant and the core-to-core distance as parameters, and the homogeneous cores being arranged with the determined core-to-core distance between the cores to form the uncoupled state between the homogeneous cores, and

a space division multiplexing transmission system being comprised by making said cores correspond, one to one, to single-mode, independent transmission channels.

2. The method of arranging cores of multi-core fiber according to claim 1 wherein

a plurality of three types of cores having the different propagation constants being provided, and

in arranging said plurality of cores,

the cores being most densely arranged in a triangular arrangement where a distance between neighboring cores having different propagation constants is Λ

and a distance between cores having the same propagation constant is ·

3Λ

, and

cores having the same propagation constant being arranged with a distance √

3Λ

between the cores to comprise an uncoupled transmission system, said distance √

3Λ

being a distance to form an uncoupled state.

3. The method of arranging cores of multi-core fiber according to claim 1 wherein

a plurality of two types of cores having the different propagation constants being provided, and

in arranging said plurality of cores,

said two types of cores being alternately arranged in a grid pattern in a rectangular form.