Patent ID: 8503836

Claim:
A wavelength domain optical switch comprising: an integrated element formed by laminating in a thickness direction three or more waveguide type demultiplexing circuits, each of which includes one or more input/output waveguides for inputting or outputting light, a slab waveguide connected to the input/output waveguide, and an array waveguide constituted by a plurality of waveguides connected to the slab waveguide such that entrance/exit ends of a plurality of waveguides are arranged in the thickness direction in relation to each array waveguide; a first lens having a focal length of F1 which is disposed at a distance F1 from the entrance/exit ends of the integrated element and collects light emitted from the entrance/exit ends; a polarization separation element which is disposed at the distance F1 from the first lens and separates the light emitted from the entrance/exit ends of the integrated element and passed through the first lens into mutually orthogonal X polarization and Y polarization, and emits the X polarization and the Y polarization; a second lens having a focal length F2, which is disposed at a distance F2 from the polarization separation element so as to face the polarization separation element and collects the X polarization and the Y polarization; a ½-wavelength plate which rotates only one of the X polarization and the Y polarization emitted from the second lens spatially by 90 degrees such that the X polarization and the Y polarization have identical polarization directions; a first reflective optical phase modulator which is disposed at the distance F2 from the second lens and reflects the polarization emitted from the second lens and passed through the ½-wavelength plate and the other polarization emitted from the second lens on the second lens; and a second reflective optical phase modulator which is disposed at the distance F2 from the second lens on an identical side to the polarization separation element so as to face the second lens, and inputs light reflected by the first reflective optical phase modulator into one of the waveguide type demultiplexing circuits.