| 摘要 |
PURPOSE:To obtain a thin film type optical element having the high threshold value of an optical damage, high coupling efficiency and modulating efficiency by forming an optical waveguide having the optical coupling part and optical function part in which the depth of ion implantation or thermal diffusion by the ion implantation or thermal diffusion is different to the front of a substrate. CONSTITUTION:A thin Ti film 11 is deposited by evaporation on an LiNbO3 crystal substrate 1 which is a Y or X plate and a thin Cr film 12 is deposited by evaporation onto the optical function part. The substrate is heated in a crucible contg. a mixture composed of benzoic acid and lithium benzoate to form a proton exchange layer 13. The Cr layer 12 is removed and further the substrate is subjected to the proton exchange treatment then to annealing to form the optical waveguide layer 15 of which the depth of the proton implantated layer is smaller in the optical function part only and is larger toward the end faces 20, 21 of the substrate. Comb-shaped electrodes 16 are formed on the optical waveguide 15. Laser beam 8 is condensed through a cylindrical lens 5 onto the end face 3 (20) of the optical waveguide. The guided light 9 is diffracted by the phase lattice generated when a voltage is impressed to the electrode 7(16). Said light is emitted from the end face 4 (21). |
