PRODUCTION OF GLASS PREFORM FOR OPTICAL FIBER

摘要

PURPOSE:To produce a glass preform homogeneously containing fluorine in both the radial and longitudinal directions thereof and used for producing an optical fiber by controlling the condition of a heat treatment on the heat treat ment for adding the fluorine to the SiO2 glass particle material synthesized by a gaseous phase reaction. CONSTITUTION:In a method for producing a glass preform for an optical fiber by subjecting a SiO2 glass particle material synthesized by a gaseous phase reaction to the first thermal treatment for dehydrating the material and to the second thermal treatment for adding fluorine to the material and subsequent ly converting the treated material into transparent glass, the second thermal treatment is performed by heating the SiO2 glass particle material at 1150 deg.C to 1300 deg.C for at least 20min in an atmosphere containing the fluorine gas.