Optical waveguide element, optical waveguide device, and optical transmission apparatus

Abstract

An optical waveguide element includes a substrate, an optical waveguide disposed inside the substrate or on the substrate, and an electrode provided along the optical waveguide, working on the optical waveguide to generate a phase change in a light wave propagating through the optical waveguide. The electrode is a traveling-wave electrode. In a modulation section where the light wave is controlled by the electrode, the electrode and the optical waveguide are configured so that the phase change generated in a first modulation section located within a predetermined distance range from a downstream side end portion along a propagation direction of a traveling wave of an electrical signal propagating through the electrode has a sign opposite to a sign of the phase change generated in a second modulation section located within a predetermined distance range from an input end of the electrical signal on an upstream side along the propagation direction.