WAVELENGTH SELECTION SWITCH

摘要

PROBLEM TO BE SOLVED: To decrease influences on an unintended port during a non-operation period when a deflection element is not driven.SOLUTION: In a port array 11, a plurality of ports including an input port 11a and output ports 11b to 11f is arranged in an X direction at intervals including a first interval S1 and a second interval S2 wider than the first interval S1. A spectral element spectrally disperses wavelength-multiplexed light input from the input port 11a into a Y direction to output a plurality of wavelength component beams. A deflection element 16 deflects the light output from the spectral element into a predetermined direction. In a non-operation period when the deflection element 16 is not driven, a deflected beam Da deflected by the deflection element 16 based on the light input from the input port 11a is guided to a retreat position P1 to retreat from the plurality of ports 11a to 11f in the X direction. The retreat position P1 is determined in such a manner that a deflected beam Db to Df deflected by the deflection element 16 based on light input from any of the ports 11b to 11f excluding the input port 11a in the non-operation period is not guided to between the ports adjoining to each other at the first interval S1.