| 摘要 |
PURPOSE:To produce a preform for an optical fiber having stable transmission characteristics, by using SiF4 as an F source in the production of a preform for an optical fiber made of a quartz glass doped with F acting as an agent for controlling refractive index difference. CONSTITUTION:A soot preform 1 (fine powder of glass) composed mainly of SiO2 is inserted into an electric furnace 2. An inert gas added with Cl2 gas is introduced into the furnace through an inlet port 5 to effect the dehydration of the soot, an inert gas (e.g. He) containing SiF4 is introduced into the furnace through a gas inlet port 4 and the glass soot is heated at 1,100 deg.C with a carbon heater to obtain transparent glass. The preform produced by the above process gives an optical fiber consisting of a center core made of high-purity quartz glass and a transparent glass clad having lower refractive index than the core material by the presence of F. |
