Patent ID: 7831124

Claim:
A photonic crystal optical device comprising: an active area and a passive area integrated on a semiconductor substrate, the active area including a photonic-crystal optical waveguide formed by periodically arranging a plurality of holes in a primary plane of an active-area core layer from an active-area upper cladding layer to a position deeper than a lower surface of the active-area core layer, excluding a line defect portion that guides a light of a predetermined wavelength, in an active-area growth portion in which the active-area core layer including an active layer is grown between the active-area upper cladding layer and an active-area lower cladding layer, the passive area including a passive optical waveguide, which is optically coupled to the photonic-crystal optical waveguide, formed in a passive-area growth portion formed by growing a passive-area core layer between a passive-area upper cladding layer and a passive-area lower cladding layer, wherein an effective refractive index of a growth structure of the active-area growth portion is larger than an effective refractive index of a growth structure of the passive-area growth portion, and the active layer has a gain at a zero group-velocity point positioned on a high-frequency side of a dispersion curve of the photonic-crystal optical waveguide, wherein, even when a patterning misalignment deviation occurs during formation of the plurality of holes, said light of the predetermined wavelength passes between the active area and the passive area without substantial additional reflection loss, and efficient optical coupling between the active area and the passive area is maintained.