| 摘要 |
PURPOSE:To increase the coupling efficiency at the time of the input and output of guided light by injecting or diffusing thermally protons into the surface of a substrate and forming an optical waveguide. CONSTITUTION:Parallel light 8 from a laser is converted on an end surface 3 of the optical waveguide by a cylindrical lens 5 in the thickness direction of the optical waveguide 2 and coupled with the waveguide 2. This coupled light 9 is diffracted with a surface acoustic wave 10 generated at a comb-shaped electrode 7 and the diffracted light is projected from an optical waveguide end surface 4 to become parallel light. At this time, the width of the luminous flux converged by the lens 5 on the end surface 3 is nearly equal to the width of the light 9 and the waveguide 2 is buried in low refractive index layers 20 and 21 nearby the end surfaces 3 and 4, so the input/output light and light 9 are very close in electric field intensity distribution and high coupling efficiency is obtained. Further, the light coupled from the end surface 3 increases in the density of protons nearby the surface of a substrate 1 as it travels toward a light function part, so the electric field intensity distribution of the light 9 is drawn up to the surface side of the substrate 1 and the efficiency of diffraction by the surface acoustic wave of the light 9 is increased. |
