PRODUCTION OF GLASS BASE MATERIAL

摘要

PURPOSE:To provide a method capable of forming the distribution of refractive index of a core and clad into a desired form and producing an optical glass fiber excellent in properties and low in loss. CONSTITUTION:This method a 1st heat treating step to heat a porous glass base material, manufactured by a vapor phase synthetic method such as VAD method, at 800-1100 deg.C in an inert gas atmosphere containing gaseous halogen, a 2nd step to heat at 1100-1300 deg.C in an inert gas atmosphere containing gaseous oxygen and a 3rd step to heat to transparently vitrify at 1450-1700 deg.C in an inert gas atmosphere.