Patent ID: 7715668

Claim:
A polarization-independent two-dimensional photonic crystal multiplexer/demultiplexer created on a two-dimensional photonic crystal formed of a plate-shaped body with a periodic distribution of refractive index created therein and having a photonic band gap for TE polarization, comprising: a) a first waveguide and a second waveguide separately provided in the two-dimensional photonic crystal, each waveguide formed by creating a linear defect of the periodic distribution of the refractive index; b) a first resonator and a second resonator separately provided between the first and second waveguides, both resonators having a same resonance wavelength, and each resonator formed by creating a point-like defect of the periodic distribution of the refractive index; c) a first polarization converter provided on the first waveguide between a first closest point, which is a point closest from the first resonator on the first waveguide, and a second closest point, which is a point closest from the second resonator on the first waveguide, the first polarization converter being capable of converting a TM-polarized light propagated from the first closest point toward the second closest point to a TE-polarized light; and d) a second polarization converter provided on the second waveguide between a third closest point, which is a point closest from the first resonator on the second waveguide, and a fourth closest point, which is a point closest from the second resonator on the second waveguide, the second polarization converter being capable of converting a TE-polarized light propagated from the third closest point toward the fourth closest point to a TM-polarized light.