Patent ID: 7406221

Claim:
A two-dimensional photonic crystal multiplexer/demultiplexer, comprising: a) a slab-shaped body; b) a plurality of areas arranged in a lattice pattern with a predetermined cycle within the body, where a refractive index of the areas differs from that of the body; c) a first optical input/output section consisting of a waveguide formed in the body, where the waveguide is made of a linear defect of modified refractive index areas; d) a second optical input/output section formed in the body; and e) two point-like defect resonators composed of point-like defects having substantially the same resonance wavelength and arranged in series between the first and second optical input/output sections, each point-like defect consisting of a point-like region devoid of the modified refractive index areas, wherein a value of a coupling ratio defined as μ 2 /[(ω 0 /2)×(1/Q in +1/Q v )] 2 is 0.2˜10, where ω 0 is a resonance frequency of the point-like defect resonators, Q in is a Q-value between one of the first and second optical input/output sections and the point-like defect resonator closest to the section, Q v is a Q-value between each of the point-like defect resonators and an outside of the crystal, and μ is a mutual coupling coefficient between the point-like defect resonators.