Patent ID: 8098997

Claim:
An optical modulator comprising: an optical coupler that is formed in a substrate having electro-optic effects and, branches and couples light input thereto, an optical waveguide that is formed in the substrate and, includes a turnback section and ends into which the light branched by the optical coupler is input; and a first signal electrode provided in the substrate along the optical waveguide and into which a first modulation signal for modulating the light passing through the optical waveguide is input, wherein the optical waveguide includes a first waveguide section into which a first branched light output from the optical coupler is input, a second waveguide section into which a second branched light output from the optical coupler is input, and the turnback section optically connecting the first waveguide section and the second waveguide section at respective ends thereof farthest from the optical coupler, a polarization non-inversion region and a polarization inversion region having a polarization direction reversed to that of the polarization non-inversion region are formed at an interaction section, where the optical waveguide and the first signal electrode interact, and the first signal electrode is provided along the first waveguide section in the polarization non-inversion region, and along the second waveguide section in the polarization inversion region.