PRODUCTION OF PREFORM FOR OPTICAL FIBER

摘要

PURPOSE:To obtain a high-strength optical fiber by subjecting a glass rod to heat treatment and depositing fine particles of quartz glass containing no fluorine on the glass rod, in the process of forming a porous glass layer on a glass rod by external chemical vapor deposition method. CONSTITUTION:Before glass fine particles are deposited on a quartz glass rod 11 containing fluorine, this glass rod 11 is subjected to heat treatment. By this treatment, fluorine contained near the surface of the glass rod 11 is ejected and the fluorine density near the surface is decreased. Then fine particles of quartz glass containing no fluorine prepared by flame hydrolysis of a vapor- phase glass source material are deposited on outer circumference of the glass rod 11 to form the porous glass layer 14.