Patent ID: 7054526

Claim:
An optical multiplexer/demultiplexer for multiplexing or demultiplexing lights of different wavelengths using a diffraction grating, comprising: a slab waveguide through which the lights are freely propagated along a waveguide plane of layer shape; an input waveguide group consisting of one or more input waveguides connected to an end face of said slab waveguide; a plurality of output waveguide groups each consisting of one or more output waveguides, which is positioned on the same side of said input waveguide group to be connected to the end face of said slab waveguide; and a diffraction grating in which a grating plane is arranged on an end face of said slab waveguide positioned on an opposite side of said input waveguide group, and grating grooves each including a plurality of reflection planes respectively blazed corresponding to arrangement directions of said plurality of output waveguide groups, are consecutively formed on said grating plane, wherein said respective output waveguide groups are arranged so that diffracted lights of wavelengths different from each other, which appear because the lights incident from said input waveguide group are propagated through said slab waveguide to be reflected by the respective reflection planes of said diffraction grating, respectively reach the output waveguides of said plurality of output waveguide groups.