| 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 implanting or diffusing ions to a substrate surface thereby forming an optical waveguide. CONSTITUTION:Parallel light 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 and are coupled in the waveguide 2. The guided light 9 coupled therein is diffracted by a surface acoustic wave 2 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 3 is approximately the same as the width of the light 9; therefore, the high coupling efficiency is obtd. The depth of the implanted ions is smaller and the ion density is higher the nearer an optical function part 41 from the optical coupling part near the end faces 3, 4 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. |
