Patent ID: 6965717

Claim:
An optical device, in which a clad and a core whose refractive index is relatively higher than that of said clad are formed on a substrate and light is guided in said core to be able to propagate through said core, wherein: said core, comprising: an input pattern section, including an exposing section in which a core pattern cross section is exposed at one end of said optical device, that is provided with a pattern in which light inputted from said exposing section is able to be transmitted; a diffraction pattern section that is formed to connect to said input light transmitting pattern section and has a pattern in which said light from said input pattern section is able to be freely diffracted and becomes divergent; and a phase shifting pattern section that is comprised of a plurality of waveguide patterns in which effective optical path lengths are formed different from each other, wherein one end of said a plurality of waveguide patterns are connected to said diffraction pattern section, and said phase shifting pattern section including output end on the other end side opposite to said diffraction pattern section, and said phase shifting pattern section is able to generate phase difference for said light from said diffraction pattern section and output diffracted light beam via said output end, wherein at least said phase shifting pattern section comprises a birefringent part where the refractive indexes of light, having a vibration plane of electric field vector parallel to a main plane of said substrate, are different from the refractive indexes of light, having a vibration plane of electric field vector perpendicular to the main plane, wherein a boundary section between the side of said phase shift pattern section and said diffraction pattern section is arc shaped, and an effective path length difference of said waveguide patterns adjacent to each other is a constant.