| 摘要 |
PURPOSE:To produce a preform for a large-diameter optical fiber in high yield of raw material, by filling and shaping glass soot produced by vapor-phase reaction on the circumference of a glass rod consisting of a core and a part of a clad under vibration and pressure and sintering the filled glass soot. CONSTITUTION:A transparent glass rod 4 consisting of an optical fiber core and a part of clad is inserted into a rubber tube 3 which is closed at the upper and lower ends with rubber lids 1, 2. Glass soot produced by vapor-phase reaction of raw material gas such as SiCl4, SiHCl3, SiH2Cl2, etc., is filled in the space surrounding the glass rod 4 under vibration or pressure. The rubber tube containing the glass rod, etc., is put into a liquid pressure medium and formed under 2,000kg/cm<2> pressure for 10min. The formed article is taken out of the rubber tube 3 and heat-treated in a furnace at about 1,800 deg.C to effect sintering and clarification of the glass. A preform for a large-sized optical fiber can be produced by this process in high raw material yield. |
