Patent ID: 7599587

Claim:
A wavelength selective switch comprising: an input/output terminal provided with a plurality of input ports from which input lights including one or more wavelengths are input and at least one output port to which an output light is output arranged in a straight row; a lens array disposed to face the input/output terminal to convert the respective input lights from the input ports into parallel lights and to couple the output light to the output port; an isolator disposed on an opposite side to the input/output terminal with the lens away interposed therebetween, having an isolator element provided on light paths of the input lights and shared among the light paths of the respective input lights to intercept lights propagating in an opposite direction to the input lights, and having a transmitting element provided on a light path of the output light to transmit the output light and couple it to the lens array; a first lens disposed on an opposite side to the lens array with the isolator interposed therebetween to converge the respective input lights from the isolator on a focus and diffuse them and to convert the output light into a parallel light and couple it to the transmitting element of the isolator; a second lens disposed on an opposite side to the isolator with the first lens interposed therebetween to convert the respective input lights from the first lens into parallel lights and to converge the output light on a focus, then diffuse it, and couple it to the first lens; a spectral element disposed on an opposite side to the first lens with the second lens interposed therebetween to reflect the respective input lights at different angles for the respective wavelengths on a grating surface formed by forming a plurality of gratings parallel to an arranged direction of the input ports and the output port at the input/output terminal on a face receiving the input lights and couple them again to the second lens and to reflect the output light as it is and couple it to the second lens; and a mirror array disposed on an opposite side to the spectral element with the second lens interposed therebetween while displaced from a central axis connecting the first lens and the second lens, having micromirrors for the respective wavelengths which lights of the respective wavelengths of the input lights enter individually after the input lights are reflected by the spectral element and the respective wavelengths of the input lights are converged by the second lens, and reflecting a light of a desired wavelength of a desired input light as the output light to couple it to the output port via the second lens, the spectral element, the second lens again, the first lens, the isolator, and the lens array, in this order.