Patent ID: 7808705

Claim:
A wavelength-selective switch, comprising: a switch unit having a lens array arranged so as be opposed to a plurality of optical input/output ports horizontally linearly provided for inputting and outputting light including one or more wavelengths, for making the light from the optical input/output ports parallel light, a first lens arranged on a side opposite to the optical input/output ports across the lens array, for making the light from the lens array converging light, and a beam expander arranged on a side opposite to the optical input/output ports across the first lens and between the first lens and a focal point of the first lens for directly focusing the converging light from the first lens in an array direction of the optical input/output ports and focusing the light transmitted through the first lens so as to be larger in a direction orthogonal to the array direction of the optical input/output ports on the focal point of the first lens; and a branching unit having a second lens arranged so as to make the light from the beam expander the parallel light, a diffraction grating for transmitting the light transmitted through the second lens at angles different for each wavelength on a grating surface obtained by forming a plurality of gratings parallel to the array direction of the optical input/output port on a surface receiving the light transmitted through the second lens out of the light input and output from the optical input/output ports, a third lens arranged on a side opposed to the second lens across the diffraction grating, and a plurality of mirrors in each of which a light reflection angle is set such that each of the mirrors reflects the light output from the optical input/output ports and transmitted through the lens array, the first lens, the beam expander, the second lens, the diffraction grating and the third lens, and each reflected light is transmitted again through the third lens, the diffraction grating, the second lens, the beam expander, the first lens and the lens array to converge on any one of the optical input/output ports; wherein the switch unit and the branching unit are accommodated in independent casings, and a confocal point of the light transmitted through the first lens and the light transmitted through the second lens is arranged on a connecting surface of the casing of the switch unit and the casing of the branching unit.