| 摘要 |
PURPOSE:To produce a tubular wet get at a low cost, by adding a dopant- containing silica fine powder to a hydrolyzed solution of an alkyl silicate and gelatinizing the resultant sol solution under rotation. CONSTITUTION:Silica fine powder containing a dopant to decrease the refractive index of glass is added to a hydrolyzed solution obtained by using an alkyl silicate (e.g. ethyl silicate) as at least one of raw material. The obtained sol solution is transferred to a rotary vessel and gelatinized under rotation to obtain a tubular wet gel. The dopant is preferably fluorine having low transmission loss at long-wavelength band, however, boron may be used as a dopant in the case of an optical fiber for the use in short wavelength range. A depressed-type optical fiber preform can be produced by this process at a low cost. |
