| 摘要 |
PURPOSE:To expand the rate of dopants that are applicable to optical fibers and obtain a base material of superior characteristics by impregnating a dopant in a barlike porous glass sintered body and vitrifying the same then heating the same to form transparent glass. CONSTITUTION:A barlike porous glass sintered body 1 is fixed to an elevating device 11, and the entire part is inserted into a vessel 9, thence a shutter 10 is closed. Next, a dopant raw material soln. is supplied into a glass forming raw material vessel 9 for dopant to allow said soln. to percolate uniformly to the inside of the porous glass sintered body. This sintered body is pulled up from the vessel 9, and is held in a tubular heater 12, thence te shutter 10 is closed and a gaseous oxygen contg. saturated water vapor is supplied to a vessel 15, whereby the hydrolysis reaction of the raw material for dopant is allowed to take place. Thence, while a dehydrating agent of a gaseous phase state is being supplied together with He into the vessel 15, the heater temp. is raised up to about 500 deg.C. As the furnace temp. rises, the reaction is accelerated, and this yields a transparent glass base material without containing any OH group. As said dopant, an alkoxy compound, a halogenide, or salt is used. |
