| 摘要 |
PURPOSE:To provide the core rod for an optical fiber having a refractive index distribution stable in a longitudinal direction by vitrifying the part of the porous glass body of the core rod for the optical fiber where the outside diameter at the bottom end thereof is in a nonstationary state before dehydrating the porous glass body. CONSTITUTION:Gaseous raw material for forming glass for the core part, gas for combustion, gaseous raw material for forming glass for the clad part and gas for combustion are respectively supplied to burners 1, 2 for synthesizing respective glass particulates to cause the flame hydrolysis of these particulates. The synthesized glass particulates are respectively deposited on the bottom end and layer 3 of a starting member 2 to be pulled up under rotation, by which the porous glass layers 3, 5 for the core part and the clad part are formed and the porous glass body 6 for the core rod for the optical fiber is formed. The porous glass body 6 is dehydrated and vitrified, by which the core rod for the optical fiber is produced. Only the gaseous O2 and H2 are supplied to the burner 1 before the dehydration method in this method and only the surface of the part (B-C part) of the glass body 6 where the outside diameter at the bottom end thereof is in the nonstationary state is heated and vitrified. |
