ENTIRELY FLUORINE-DOPED OPTICAL FIBER

摘要

PURPOSE:To improve the transmitting characteristics of the title optical fiber by reducing the concn. of fluorine in the core. CONSTITUTION:A porous body for an optical fiber based on fine particles of quartz glass is dehydrated by heating at a temp. at which the porous body does not completely vitrify in an atmosphere contg. at least chlorine and inert gas. The dehydrated porous body is heat-treated at a temp. below the dehydration temp. in an atmosphere contg. at least chlorine, inert gas and gaseous fluoride to obtain a porous body for a fluorine-doped core-clad optical fiber. This porous body is heated in an atmosphere contg. at least chlorine and inert gas and an entirely fluorine-doped optical fiber having <=0.1 atomic% concn. of fluorine in the core is obtd.