| 摘要 |
PURPOSE:To retard external diffusion of an optical waveguide without impairing a substrate by providing an enclosure to a part between both substrates, and causing thermal diffusion by forming a minutes distance between the both substrates. CONSTITUTION:An LiNbO3 substrate 1 is arranged to face oppositely and close to a face for forming another LiNbO3 substrate on which a waveguide pattern is formed with Ti. The LiNbO3 substrate is superposed on another LiNbO3 substrate or faced closely to each other with thin Pt pieces or thin films 2 locally between said substrates, and thermal diffusion is caused. Since each LiNbO3 substrate is arranged closely with about several tens micron distance to each other, the diffusion toward outside of Li2O is remarkbly retarded. Moreover, the surface of the substrates is not impaired due to the presence of the enclosure between the substrates. Pt is used stably without causing reaction with LiNbO3 at a usual thermal diffusion temp. about 1000 deg.C). By this constitution, a satisfactory waveguide capable of retarding external diffusion without impairing the substrate 1 is provided. |
