MANUFACTURE OF BASE MATERIAL FOR OPTICAL FIBER

摘要

PURPOSE:To obtain the titled base material contg. less impurities and less water by regulating the concn. of gaseous halogen or halide and heating temp. with the passage of treating time when a preform is heated in the quartz glass core tube of a furnace together with gaseous halogen or halide to manufacture the titled base material. CONSTITUTION:While introducing a gas contg. halogen or halide such as Cl2 or SOCl2 and having dehydrating action, an aggregate of fine glass particles or a porous glass body is heated to about 950-1250 deg.C in the core tube of a furnace lined with quartz glass to well remove water. To avoid the corrosion of the glass surface due to the dehydrating gas the introduction of the halogen or halide is reduced or stopped. The core tube is then separated and further heated to manufacture a transparent glass body. This base material for an optical fiber has controlled surface irregularity and contains residual water restricted to <=about 0.1ppm.