METHOD OF CONVERTING POROUS PARENT MATERIAL FOR OPTICAL FIBER INTO CLARIFIED GLASS

摘要

PURPOSE:A porous parent material is heat-treated in a specific atmosphere containing a gas which reduces and dissipates dopants and clarified in a specific atmosphere to give the clarified parent material which has appropriate distribution in refractive indexes in the core and clad parts and causes no dimensional fluctuation. CONSTITUTION:The porous parent material is heat-treated in an atmosphere containing a gas which reduces and dissipates dopants such as GeO2 in the porous material of doped quartz optical fibers such as an atmosphere containing SOCl2 but no oxygen at such a temperature as the material is not completely shrunk. Then, the material is clarified by treating it in an oxygen-containing and reducing agent-free atmosphere such as an atmosphere containing 5-50% of oxygen and the rest of inactive gases. Thus, distribution of refractive index becomes appropriate in the core and clad parts and the dimensional accuracy becomes high in individual parts.