Patent ID: 8165470

Claim:
A wavelength selecting switch comprising: an input/output optical system in which at least one input port and a plurality of output ports are arranged in a first direction; a spectral element that angularly disperses light output from the input port of the input/output optical system in a second direction different from the first direction according to a wavelength thereof; a light collecting optical system that collects the light output from the spectral element; a mirror section having a plurality of reflecting mirrors in which angle-variable reflecting surfaces are respectively arranged at light collecting positions of the lights of respective wavelengths collected by the light collecting optical system; and a control section that controls an angle of the respective reflecting mirrors so that the lights of respective wavelengths reflected by the respective reflecting mirrors of the mirror section are coupled to an output port, which is set as an output destination, of the input/output optical system via the light collecting optical system and the spectral element, and shifts the angle of the respective reflecting mirrors from an optimum coupled state, thereby enabling adjustment of the intensity of the output light according to a preset variable range of attenuation, wherein the respective output ports of the input/output optical system each have a lens that couples reflected lights input from the reflecting mirrors via the light collecting optical system and the spectral element to an end face of the optical fiber, and the respective lenses have a structure where a focal length of a first region on a lens surface, to which the reflected light is input when the reflecting mirror is controlled to an angle corresponding to inside the variable range of the attenuation, is different from a focal length of a second region on a lens surface, to which the reflected light is input when the reflecting mirror is controlled to an angle corresponding to outside the variable range of the attenuation.