| 摘要 |
PURPOSE:To obtain a waveguide having an optional optical distribution structure, by forming a diffusion substance to a multistage in accordance with a refractive index distribution of a desired waveguide and performing its thermal diffusion, when forming an optical waveguide. CONSTITUTION:A Ti layer 2 of the first stage is obtained by forming the Ti layer on an LiNbO3 substrate 1 by means of vapor-deposition or sputtering, and patterning the Ti layer in accordance with a waveguide. Width of the waveguide is decided by width of the Ti layer 2. Subsequently, a Ti layer 12 of the second stage is formed in the same way by applying a resist on the whole surface and patterning the resist layer. Thereafter, when the substrate 1 is treated by heating for 4-11 hours at 950-1,050 deg.C, a single diffusion part 2' whose refractive index is varied slightly and a double diffusion part 12' whose refractive index is varied remarkably are obtained. In the same way, a multistage diffusion part is formed. In this way, a waveguide having an optional optical distribution structure is obtained. |
