| 摘要 |
PURPOSE:To efficiently obtain a uniform optical waveguide film by placing a substrate for forming a porous oxide film in a reaction tube and by oxidizing starting materials for forming oxides at a high temp. while keeping the substrate at a temp. below the oxidation temp. in the reaction tube. CONSTITUTION:A reaction tube 2 is put in a tubular electric furnace 1, a substrate cooler 7 is placed in the tube 2, and a substrate 3 is mounted on the cooler 7. By blowing a gas 8 for cooling from a duct 9, the cooler 7 is cooled to make the temp. of the substrate 3 constant. At this time, the gas 8 is intermittently discharged from a duct 10 to intermittently keep the substrate 3 at a constant temp. A gas saturated with TiCl4, a gas saturated with SiCl4 and O2 as starting materials 5 for forming glass are introduced into the tube 2 and heated to 1,400 deg.C to cause oxidation. At this time, by keeping the substrate 3 at 1,200 deg.C, a porous film 4 of TiO2-SiO2 composite oxide glass is uniformly formed. The film is melted by heating to 1,400 deg.C to obtain a prescribed optical waveguide film. |
