| 摘要 |
PURPOSE:To obtain an optical fiber of a low OH-group optical fiber which is low in transmission loss in a method for coating cladding glass onto core glass of transparent glass by forming said core glass then sticking the cladding glass thereto without exposing the glass to the external air. CONSTITUTION:A porous glass base material 15 is formed by vertically moving a target 13 of quartz glass contained in a furnace core tube 12 having a heater 11 while rotating the same and depositing the pulverous glass particles generated from a generator 14 onto the top end of the target 13. The base material 15 is made into the core. A chlorine-contg. gas essentially consisting of He is fed into the tube 12 and is heated by the heater 11, then the base material 15 is lowered down to the heating region. The base material 15 is thereby sintered to form transparent glass. The base material 15 is dehydrated by the gaseous chlorine in this stage, by which the extremely low-OH group transparent glass base material 16 is formed. The material 16 is pulled up to the front of a generator 14 in the tube 12 and the pulverous glass particles are deposited on the outside periphery of the material 16 by the generator 14, by which a cladding base material 17 is formed. |
