| 摘要 |
PURPOSE:To obtain an optical control element with which low loss coupling is possible and low-voltage operation is possible by diffusing thin film patterns only to the substrate and both of the substrate and laminated dielectric material between an optical waveguide and input/output waveguides connecting said optical waveguide and light input/output end faces. CONSTITUTION:The pattern of the optical waveguide is first formed on the LiNbO3 substrate 301 by using a photolithography technique and thereafter a Ti film is deposited by evaporation over the entire surface. A photoresist film is then dissolved and the part of directional couplers 302 is covered by a shielding plate. Ti and LiNbO3 films are laminated on the substrate in the input/output optical waveguides and the optical waveguide pattern consisting of only the Ti is formed on the optical control part when an LiNbO3 film 305 is formed by a sputtering method or the like. The substrate installed with the pattern of the optical waveguide is heated for about 5-10 hours at 1,000-1,100 deg.C in a diffusion furnace by which the Ti is diffused into the LiNbO3 and the optical waveguide is formed with a slight increase in the refractive index. An SiO3 film is formed on the substrate and a pair of electrodes 4 laminated with Cr, Au or Cr, Al on the SiO2 are formed right above the waveguide of the directional couplers. |
