Patent ID: 6922509

Claim:
An optical device comprising: a photonic crystal having a periodic refractive index distribution due to a periodic arrangement of a plurality of materials of different refractive indices; an input-side optical waveguide for coupling light into the photonic crystal; an output-side optical waveguide for emitting light from the photonic crystal; and an external drive portion for changing a relative position of the photonic crystal and at least one of the input-side optical waveguide and the output-side optical waveguide; wherein the photonic crystal has a two-dimensional or a three-dimensional lattice structure in which a plurality of materials with different refractive indices are arranged periodically; one or more two-dimensional lattice structures composed of a group of primitive lattice vectors are present in the photonic crystal; and each of the two-dimensional lattice structures composed of a group of primitive lattice vectors has a lattice structure having no rotation axis of more than three-fold.