Dispersion compensating module, line switching apparatus and optical communication system

A dispersion compensating module for compensating for a dispersion of an optical transmission line in a signal wavelength band, comprising:

• an input end for introducing signals which propagate 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 compensators having a dispersion of sign opposite to that of a 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.