| 摘要 |
PURPOSE:To stably obtain the preform for the optical fiber low in transmission loss over a long period by specifying the gas to be used in the treatment when a porous glass body is dehydrated, purified, and vitrified in a carbon furnace core tube coated with SiC. CONSTITUTION:A porous optical fiber preform 11 is inserted into the carbon furnace core tube 12 having an SiC film on the inside. A furnace body 15 provided with a heater 13 for heating the preform 11 and an insulating material 14 is furnished around the tube 12. A pipe 16 for introducing the dehydrated high-purity gas G necessary for the dehydrating and sintering treatment is connected to the lower part of the tube 12, and a gaseous siliconhalide generated in a bubbler 17 is introduced. In this case, a mixture of an inert gas such as He, Ar, and N2 and a gaseous silicon halide (SiCl4) or the mixture further added with a halogenous gas is used as the gas G. |
