WAVELENGTH SELECTION SWITCH

摘要

Provided is a wavelength selection switch having a simple configuration with a small number of component items. The wavelength selection switch is provided with a first lens; a diffraction grating arranged on the opposite side to a plurality of light input/output ports by having the first lens in between; a cylindrical concave lens arranged on the opposite side to the diffraction grating by having the first lens in between; and a plurality of mirrors arranged on the opposite side to the first lens by having the cylindrical concave lens in between. The cylindrical concave lens transmits light that passed through the first lens, among light outputted from the light input/output ports and reflected by the diffraction grating, functions as a concave lens in the arrangement direction of the light input/output ports, converts convergent light from the first lens into parallel luminous fluxes, does not function as a lens in a direction orthogonally intersecting with the arrangement direction of the light input/output ports, and converges the convergent light from the first lens as it is.