OPTICAL WAVEGUIDE DEVICE AND METHOD OF MAKING THE SAME

The optical waveguide device comprises an optical waveguide formed as a region having a high index of refraction on a surface or in an interior including the surface of a base plate made of a ferroelectric crystal, and a film covering the surface of said optical waveguide in the direction along the c axis of said crystal phase plate and having electrical conductance higher than that of the optical waveguide. The optical waveguide is formed by thermal diffusion or a chemical reaction. This optical waveguide device is affected little by the optical damage and can be manufactured easily.