| 摘要 |
PURPOSE:To obviate the generation of foam between a glass film for clad and thermally oxidized film and to obtain a transparent film by forming the thermally oxidized film having >=1.0mum thickness on a silicon substrate, then forming a porous glass film for clad and porous glass film for core on the oxidized film, and heating these glass films to a high temp. to sinter the glass films. CONSTITUTION:Steam is blown into the heated Si substrate 1 and the thermally oxidized film (SiO2)2 having >=1.0mum thickness is preliminarily formed in order to form the glass film for an optical waveguide on the substrate 1. The porous glass film 3 for the clad and the porous glass film 4 for the core are formed thereon and are sintered by heating the same to a high temp., by which the transparent glass film is obtd. The fit between the clad glass film 3 after the vitrification and the thermally oxidized film 2 is good and the generation of the foam at the boundary therebetween is obviated if the thermally oxidized film 2 is formed on th e substrate 1 in the above-mentioned manner. The generation of the foam in the glass films 3, 4 is, therefore, obviated even if the porous glass films 3, 4 are heated for a long period at the high temp. The formation of the transparent glass is thus easily attained. |
