Production method null of basic material for dispersed shihutohuaiba

摘要

PURPOSE:To produce the title base material for a low-loss dispersed shift fiber at a low cost by heating and dehydrating the soot body for a core consisting of the inner SiO2 contg. GeO2 and the outer SiO2, heating the material at a low temp., adding F to the material, and then vitrifying the material. CONSTITUTION:The inner core soot body of SiO2 added with GeO2 and the outer core soot body of pure SiO2 are formed by the VAD method by using plural burners for synthesizing fine glass particles. The obtained soot body for a core is heated and dehydrated. The dehydrated soot body is heated in an atmosphere free of F at a low temp. of 1,300-1,600 deg.C which is lower than the vitrification temp. of the core soot body to increase the bulk density of the inner core soot body. The soot body for a core is heated in an atmosphere contg. F at a temp. where the soot body for a core is vitrified, and the transparent glass body for a core consisting of the inner core part of SiO2 contg. GeO2 and the outer core part of SiO2 contg. F, having 0.1-0.8 specific refractive index difference, and having 0.2-1.0 diameter ratio is obtained. A clad part consisting of SiO2 and added with F is formed on the outer periphery of the glass body, and the base material for a low-loss dispersed shift fiber is obtained.