| 摘要 |
PURPOSE:To prepare an optical fiber preform containing a reduced amount of OH group exising in the core glass as a contaminant, by bubbling O2 gas passed through a dehydrating catalyst consisting of porous glass fine powder into a liquid raw material, and introducing the raw material gas into the heated quartz tube. CONSTITUTION:The raw material gas is introduced from the raw material supplying system 4 through a swivel connector 11 into the hollow part of the quartz tube 1. The raw material gas is O2 gas containing SiCl4 (raw material of glass), GeCl4, POCl3 and BBr3 (raw materials of dopant for regulating refractive index of the glass), and obtained by bubbling O2 gas in the liquid mixture of the above compounds contained in the bubbler 41 of the raw material gas supplying system 4. When the raw material gas is introduced into the quartz tube 1, glass fine powder containing metal oxides is produced by the gas-phase material reaction, and is deposited on the inner surface of the quartz tube forming a core glass. The O2 gas is dehydrated before bubbling by passing through the catalyst column 52 containing a dehydrating catalyst 51 consisting of porous glass fine powder. |
