| 摘要 |
PURPOSE:To increase the threshold value of an optical damage and to improve the coupling efficiency in the input and output stage of guided light by providing an optical waveguide formed by implanting or thermally diffusion ions to a substrate surface and a region where the ions are neither implanted nor thermally diffused. CONSTITUTION:Parallel light 8 from a laser are condensed by a cylindrical lens 5 onto the end face 3 of the optical waveguide in the thickness direction of the optical waveguide 2. The condensed light is coupled into the waveguide 2. The guided light 9 coupled therein is diffracted by a surface acoustic wave 10 generated in a comb- shaped electrode 7. The diffracted light is emitted as parallel light from the end face 4 of the optical waveguide. The width of the condensed luminous flux at the end face 2 is approximately the same as the width of the light 9; therefore, the high coupling efficiency is obtd. The depth of the implanted protons is smaller and the proton density is higher nearer an optical function part 41 of the waveguide 2. The light 9 is, therefore, confined near the surface of the substrate 1 in the function part 41 and the high diffraction efficiency is obtd. Since the electrodes 7 and 20 are formed on diffused titanium layers 21, 22 in the regions where the protons are not implanted, the decrease in the piezo-electric characteristic by the proton implantation is obviated. |
