Optical waveguide element, optical modulator, optical modulation module, and optical transmission apparatus

An optical waveguide element comprising:

• a substrate;
• an optical waveguide formed in the substrate;
• and
• an electrode for controlling a light wave propagating through the optical waveguide, wherein
• the optical waveguide and the electrode have an intersection in which the optical waveguide and the electrode intersect with each other,
• at the intersection, the electrode has a multilayer structure including a plurality of metal layers made of a metal material, and a resin layer made of a resin material is formed between the electrode and the substrate,
• an adjacent metal layer, which is one of the plurality of metal layers that is adjacent to the resin layer, is formed such that a length of the adjacent metal layer along a waveguide direction of the optical waveguide is equal to or longer than a length of another metal layer, of the plurality of metal layers, adjacent to the adjacent metal layer along the waveguide direction of the optical waveguide, and
• the adjacent metal layer is formed such that a length of a part of the adjacent metal layer where the other metal layer is not formed along the waveguide direction of the optical waveguide is longer than a wavelength of light propagating through the optical waveguide.