Patent ID: 8090226

Claim:
An optical waveguide device comprising: a substrate having an electro-optical effect; an optical waveguide section formed on the substrate; and a plurality of modulating electrodes for modulating optical waves propagating in the optical waveguide section, wherein the optical waveguide section branches into two parts in a propagating direction of an optical wave, thus forming two main optical waveguides, and each of the main optical waveguides branches into two parts in the propagating direction of the optical waves, thus forming two sub optical waveguides; and wherein the two main optical waveguides constitute a main Mach-Zehnder type optical waveguide, and the two sub optical waveguides are incorporated into the main Mach-Zehnder type optical waveguide to constitute a sub Mach-Zehnder type optical waveguide so that a heat conduction suppressing zone is defined on a portion of the substrate disposed between two opposite sub Mach-Zehnder type optical waveguides.