| 摘要 |
PURPOSE:To provide a process for production of the proton exchange waveguide which maintains the specified concn. of Li in a melt and does not crack a substrate in stages after an exchange by coating the specific region of the substrate with a material having a low proton exchange rate. CONSTITUTION:The region of the surface exclusive of the optical waveguide region of the substrate and the entire region of the rear surface thereof are coated with the material having the low proton exchange rate. Namely, the entire part of the rear surface is coated with an SiO2 film 3. Resist patterns 2 of a waveguide width are formed on the front surface by lithography and thereafter, the SiO2 film 3 is deposited by evaporation. The resist patterns 2 and the unnecessary SiO2 are then removed, by which a mask 4 for exchange is produced. The substrate is then immersed into the melt and is subjected to the proton exchange and thereafter, the SiO2 films 3 on the front surface and the rear surface are removed and the substrate is subjected to annealing. As a result, the outflow of the Li ions into the melt arising from the proton exchange on the rear surface is prevented and eventually the concn. of the Li in the exchange liquid is maintained constant. |
