Opical waveguide device

An optical waveguide device comprising:

• a single crystal conductive or semiconductive lower electrode;
• an epitaxial or single orientational buffer layer formed on a plane of said lower electrode;
• a ferroelectric epitaxial or single orientational thin film optical waveguide formed on said buffer layer;
• a cladding layer formed on said optical waveguide;
• and
• a metal thin film served as an upper electrode formed on said cladding layer.

An optical waveguide device comprising:

• a lower electrode made of a single crystal conductive or semiconductive SrTiO.sub.3 in which an impurity element is doped by 0.01 wt. % through 5.0 wt. %;
• an epitaxial or single orientational oxide buffer layer formed on a plane of said lower electrode;
• an epitaxial or single orientational oxide thin film optical waveguide displaying the electo-optic effect, formed on said buffer layer;
• and
• an upper electrode of a conductive thin film or a semiconductive thin film formed on said optical waveguide.

An optical waveguide device comprising:

• a single crystal conductive or semiconductive lower electrode;
• a ferroelectric epitaxial or single orientational thin film optical waveguide formed on a plane of the single crystal substrate;
• a cladding layer formed on said optical waveguide;
• and
• a metal thin film served as an upper electrode formed on said cladding layer.