Patent ID: 8503847

Claim:
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.