| 摘要 |
PURPOSE:To manufacture inexpensively a base material for an optical fiber by converting two kinds of silica sol regulated so as to provide different refractive indexes into two-layered hollow gel in a rotating body, drying the gel, and converting it into quartz glass by sintering. CONSTITUTION:When a base material for an optical fiber is manufactured by a sol-gel method, silica sol prepd. by hydrolyzing a suitable alkyl silicate is charged into a rotating body, and the sol is converted into gel under rotation to form the 1st gel 4. silica sol prepd. by regulating the composition so as to provide a refractive index which is different from the refractive index of the gel 4 is charged into the hollow of the gel 4 in the rotating body, and the sol is similarly converted into gel under rotation to form the 2nd gel 5. The gel layers 4, 5 are dried at a proper drying speed, and the resulting hollow cylindrical two- layered dry gel is sintered to obtain a two-layered quartz glass pipe having different refractive indexes at the outside and inside. A base material for an optical fiber is manufactured by making the glass pipe solid by heating. |
