| 摘要 |
PURPOSE:To satisfactorily control the size of an optical waveguide layer and to improve the coupling efficiency to an optical fiber by repeating plural times a stage for immersing a substrate into a soln. contg. a metallic alkoxide and heat-treating the substrate to form a thin film. CONSTITUTION:Quartz glass is used for the substrate 1 and the stage for immersing the substrate into a soln. essentially consisting of tetraethoxysilane, tetraethoxy germanium, alcohol and water then pulling up the substrate and heat-treating the same is repeated. A 0.5mum thickness is obtd. by one time of thin film formation at a pulling up speed of 5mm/sec when the component ratio of the tetraethoxysilane + tetraethoxy germanium : alcohol : water is 1:10:10 and therefore, the above-mentioned stage is repeated 20 times in order to form the optical waveguide of 10mum which is the same as the core diameter of the optical fiber to be coupled. The optical waveguide of which the refractive index changes successively in the thickness direction of the thin film is formed by repeating such stage. The stage is basically not limited by the size of the substrate and productivity is improved.
|
