Patent ID: 7630587

Claim:
An optical waveguide device, comprising: a substrate having an electro-optic effect; an optical waveguide formed on said substrate; an electrode section adapted to supply an electric field for carrying out phase modulation, synchronized with a clock signal to said optical waveguide and having a phase modulation amplitude of π, to light propagating through the optical waveguide; and a Mach-Zehnder interferometer connected to the downstream side of said optical waveguide and including two branching waveguides having optical lengths different from each other by an optical length corresponding to a half wavelength of the clock signal, a branching portion adapted to branch propagation light from said optical waveguide into two propagation lights and connect the two propagation lights individually to said two branching waveguides, a coupling portion adapted to couple said branching waveguides and generate a clock modulation light having a light intensity that is switched on and off in a cycle equal to twice a frequency of the clock signal, and a single-mode waveguide connected to said coupling portion and adapted to propagate the clock modulation light.