HIGH-VISCOSITY SYNTHETIC SILICA GLASS TUBE FOR THERMAL CVD METHOD AND SILICA GLASS PREFORM FOR OPTICAL FIBER USING THE SAME

摘要

PURPOSE: To obtain a synthetic silica glass tube having high softening point and high viscosity and suitable for thermal CVD reaction, by incorporating silica glass with a thickening dopant selected from carbon, nitrogen, Al, Zr and/or compounds thereof. ;CONSTITUTION: In producing synthetic silica glass by e.g. exterior method, raw material silica glass is incorporated with a thickening dopant selected from carbon, nitrogen, aluminum, zirconium and/or compounds thereof (specifically, SiCl₃CH₃, ammonia, aluminum chloride, etc. Besides, the thickening dopant-contg. silica glass tube may be incorporated with fluorine, boron, germanium, titanium, aluminum, phosphorus, tellurium, or compound(s) thereof to alter the refractive index of the silica glass. High-grade optical fibers excellent in transmission characteristics can be produced by wire drawing of an optical fiber preform made from such a thickening dopant-contg. synthetic silica glass tube.;COPYRIGHT: (C)1995,JPO