| 摘要 |
PURPOSE:To improve the threshold value of an optical damage, coupling efficiency and modulating efficiency by forming an optical waveguide by ion implantation or thermal diffusion on the surface of a substrate, forming electrodes to a region where part of said ions are neither implanted nor thermally diffused and changing the depth of the implantation or thermal diffusion of the ions in the optical coupling part and optical function part. CONSTITUTION:A thin Ti film 11 is deposited by evaporation and is heated to be thermally diffused onto an LiNbO3 crystal plate 1 which is a Y or X plate. A thin Cr film 12 is deposited by evaporation to form a mask on the optical function part and electrode forming part and the substrate is heated in a crucible contg. a mixture composed of benzoic acid and lithium benzoate by which the substrate is subjected to an ion exchange treatment and a proton exchange layer 13 is formed in the maskless pat. The thin Cr film 25 is deposited by evaporation only on the electrode forming pat to form a proton exchange layer 14 by a proton exchange treatment and after the film 25 is removed, the optical waveguide 15(2) where the depth of the proton implantation is shallow only in the optical function part and increases toward the end faces 3, 4 of the optical waveguide is formed by the annealing treatment. Comb-shaped electrodes 7, 20 are formed in the electrode part. The thin film type optical element having the high coupling efficiency and modulating efficiency is thus obtd. |
