Optical waveguide device, and optical modulation device and optical transmission apparatus using same

An optical waveguide device comprising:

• an optical waveguide substrate having a rib type optical waveguide obtained by forming a part corresponding to a optical waveguide to have a protruding shape in a substrate having an electro-optic effect;
• a reinforcing substrate disposed under the optical waveguide substrate;
• a lower buffer layer disposed between the optical waveguide substrate and the reinforcing substrate to join both of the optical waveguide substrate and the reinforcing substrate;
• and
• an upper buffer layer disposed on an upper side of the optical waveguide substrate in contact with the optical waveguide substrate,
• wherein a thickness of the optical waveguide substrate is set to 1 μm or lower, the upper buffer layer and the lower buffer layer are configured with the same material,
• a thickness of the upper buffer layer is formed to be smaller than a thickness of the lower buffer layer, and
• density of the lower buffer layer is higher than density of the upper buffer layer.