Patent ID: 7603002

Claim:
An optical device comprising: a substrate having an electro-optical effect; an optical waveguide formed in said substrate; and an electrode section which has a signal electrode and a ground electrode for applying an electric field to said optical waveguide, wherein a part of said optical waveguide is formed on a position where said optical waveguide is under said signal electrode of said electrode section and another part of said optical waveguide is formed on a position where said optical waveguide is under said ground electrode of said electrode section, and a length of said optical waveguide from a position in which light is exposed to said electric field emitted from said signal electrode of said electrode section to a position in which said light is exposed to said electric field converging to said ground electrode of said electrode section is set to (N+½) times an electrical length of a wavelength of a signal applied to said signal electrode, where N is an integer.