MANUFACTURE OF SOOT FOR OPTICAL FIBER

摘要

PURPOSE:To increase the amt. of fluorine to be doped and to form a thermally stable clad layer by supplying specified cations to the outer periphery of a glass layer for the core, and fixing fluorine stably in synthetic silica. CONSTITUTION:Cations for fixing fluorine as a dopand and the optional amt. of fluorine stably in synthetic soot is prepared. And a gaseous-phase quartz glass material and said cations are supplied onto the outer periphery of a glass layer for the core to made into a core to deposite a glass layer for the clad to be made into a clad. Fluorine having large effect on reducing the refractive index is stably fixed in synthetic silica in this way. Accordingly, fluorine is not vaporized even when heated to high temps., and a stable clad layer is formed.