| 摘要 |
PURPOSE:To prepare optical fiber preform glass having refractive index distribution, easily, by forming a hollow gel by the hydrolysis of a Si alkoxide doped with a dopant element compound, and then forming gel having high refractive index at the center of the hollow gel. CONSTITUTION:A mixed solution is obtained by adding water and a diluent to a raw material liquid selected from the group of the liquid compositions composed of Si(OR)4 (R is alkyl) capable of forming silica gel by hydrolysis and a compound of dopant element such as Ge, P, B, etc. which changes the refractive index of transparent quartz glass. A hollow gel rod is prepared from the mixed solution. The center cavity of the hollow gel is filled with an aqueous solution of Si(OR)4 having a composition different from the above solution and giving a gel having higher refractive index than the above hollow gel, and the solution is gelatinized. The composite gel rod thus obtained is dried, heated in a proper atmosphere, and sintered at or below the melting point of the dried gel. |
