Patent ID: 11888584
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Telecommunications (Electrical engineering)
Classification: CPC H | IPC H

Claim 6:
7. An optical transmission method in an optical transmission system including a plurality of transmission lines through which a mode-multiplexed signal obtained by multiplexing a plurality of optical signals of different types of modes is transmitted, and one or more mode group permutation units provided between the plurality of transmission lines, the optical transmission method comprising:
by each of the one or more mode group permutation units, changing, on a mode-group-by-mode-group basis, an optical signal of a mode belonging to a mode group to an optical signal of another mode belonging to a mode group after permutation corresponding to the mode group in such a manner that the modes are interchanged between at least some of the plurality of optical signals multiplexed into the mode-multiplexed signal input from one of the plurality of transmission lines on an input side, and outputting the mode-multiplexed signal after mode interchange to one of the plurality of transmission lines on an output side including:
separating the optical signals of the plurality of types of modes multiplexed into the mode-multiplexed signal input from the transmission line on the input side, and
outputting a mode-multiplexed signal obtained by multiplexing the optical signals of a single mode output from mode group permutation devices corresponding to a plurality of mode groups to the transmission line on the output side, and
receiving the optical signals of modes belonging to the mode group before permutation corresponding to the mode group permutation device and changing a mode of at least some of the received optical signals to another mode belonging to a mode group after permutation corresponding to the mode group permutation device, and outputting the optical signals after mode change.