Patent ID: 7447399

Claim:
An optical switch comprising: a wavelength spatially dispersive optical element spatially dispersing a wavelength-multiplexed beam along a wavelength dispersion direction according to wavelengths; a plurality of output ports arranged in a column in a direction which is not parallel to the wavelength dispersion direction; a plurality of mirrors arranged along the wavelength dispersion direction, onto which beams dispersed by said wavelength spatially dispersive optical element are irradiated, each mirror able to reflect a beam irradiated onto the mirror to any one of said plurality of output ports by tilting the mirror to thereby change an angle of a reflecting surface of the mirror; and a controller, when changing an incident position of a respective reflected beam from being on a first output port of the plurality ports to being on a second output port of the plurality of output ports which is not adjacent to the first output port, tilting a respective mirror which reflects the beam so that the incident position moves in a direction perpendicular to the wavelength dispersion direction and parallel to the direction in which the plurality of output ports are arranged without exceeding an allowable crosstalk with an adjacent output port, and thereafter tilting the respective mirror so that the incident position moves in a direction parallel to the wavelength dispersion direction away from any output port.