| 摘要 |
PURPOSE:To prevent bubbling by depositing a boron doped porous glass layer on the outside of a starting member of quartz glass and carrying out sintering in an atmosphere contg. a gaseous fluorine compd., Cl2 or a gaseous chlorine compd., O2 and He. CONSTITUTION:A porous quartz glass base material is dehydrated, sintered and drawn to obtain a starting member 4. A porous glass layer contg. B2O3 is deposited on the outside of the member 4 while feeding BCl3 into an oxyhydrogen burner. The resulting porous base material 1 for an optical fiber is slowly introduced into a sintering furnace and sintered by heating to a prescribed temp. with a heater 2 while feeding a gaseous fluorine compd. such as SiF4, gaseous Cl2 or a gaseous chlorine compd. such as BC3, gaseous O2 and gaseous He into the furnace at prescribed flow rates. A base material for an optical fiber is obtd. with little bubbling phenomenon. |
