Patent ID: 8391654

Claim:
A wavelength selection switch comprising: an input/output end in which a plurality of input ports to which input light having one or more wavelengths is input and at least one output port from which output light is output are arranged in a straight line so as to be parallel to each other; a lens array that is provided so as to face the input/output end, converts each input light component from the input ports into parallel light, and couples output light to the output port; a first lens that is provided so as to face the input/output end with the lens array interposed therebetween, converges each input light component from the lens array on a focus to be diffused, converts output light into parallel light, and couples the parallel light to the lens array; a second lens that is provided so as to face the lens array with the first lens interposed therebetween, converts each input light component from the first lens into parallel light, converges output light on a focus to be diffused, and couples the diffused light to the first lens; a spectral element that is provided so as to face the first lens with the second lens interposed therebetween, reflects and diffracts each input light component at different angles for each wavelength from a lattice plane obtained by forming a plurality of lattices in parallel to an arrangement direction of the input and output ports of the input/output end on a plane receiving the input light such that each input light component is coupled to the second lens again, and reflects and diffracts output light components at different angles for each wavelength, similar to the input light components, such that the output light components are coupled to the second lens; a mirror array that is provided so as to face the spectral element with the second lens interposed therebetween, deviates from a central axis connecting the first lens and the second lens, has micromirrors for each wavelength on which the input light that has been reflected from the spectral element and then focused for each wavelength by the second lens is incident for each wavelength and which are shared by the input light components for each wavelength, reflects light with a desired wavelength of the desired input light as output light such that the output light passes through the second lens, the spectral element, the second lens, the first lens, and the lens array in this order and is coupled to the output port; and an optical component for adjusting an optical path that is provided on an optical path common to input light from the second lens to the mirror array and output light from the mirror array to the second lens and reduces the focal lengths of the first lens and the second lens.