Patent ID: 6907200

Claim:
A line switching device comprising: a branching section branching sianals in a predetermined wavelength band contained in a signal wavelength band from signals propagating through an optical transmission line in an optical communication network; and a dispersion compensating module comprising: an input end for introducing signals which propogate in said optical transmission line; an output end for launching the signals introduced from the input end to said optical transmission line; a plurality of dispersion compensators provided between said input end and said output end, each of said dispersion of said optical transmission line in the signal wavelength band; and one or more branching optical switches provided between each of said plurality of dispersion compensators, each of said branching optical switches having a first port for inputting the signals from an adjacent dispersion compensator positioned upstream as viewed from a traveling direction of the signals, a second port for outputting the signals from said first port to an adjacent dispersion compensator positioned downstream, and a third port for conducting the signals from said first port to a branch line different from an optical path constituted by said plurality of dispersion compensators, said dispersion compensating for the dispersion of said optical transmission line, in the predetermined wavelength band containing the signal branched by said branching section, wherein the signals branched by said branching section includes a pilot signal indicative of a signal source which has transmitted the signals, and wherein said line switching device further comprises a receiving section receiving the pilot signal contained in the signals and a control section for controlling a port switching operation in each of said optical switches in said dispersion compensating module on the basis of the pilot signal received by said receiving section.