MANUFACTURE OF BASE MATERIAL FOR OPTICAL FIBER CONTAINING FLUORINE IN CLAD PART

摘要

PURPOSE:To manufacture a high quality base material for an optical fiber contg. F in the clad part by forming a porous layer of quartz glass onthe outside of a glass rod having a quartz glass layer contg. F on the outside of a quartz glass rod for a core and by heating the porous layer in an atmosphere contg. F. CONSTITUTION:A porous glass body of pure quartz formed by a vapor axial deposition (VAD) method is shrunk by heating to such a degree that the glass body is not made transparent. The shrunk porous glass body is heated in an atmosphere contg. F to incorporate F into part of the glass body, and it is made transparent and drawn to a prescribed diameter. The resulting glass rod 1 is rotated in a reactor 5 as a glass rod for forming a core part, and fine glass particles 4 for forming a clad part produced by spouting gases such as SiCl4, H2 and O2 from a burner 3 and carrying out hydrolysis in a flame are deposited on the rod 1 while slowly pulling up the rod 1. The deposited particles 4 are heated in an atmosphere contg. F to incorporate F into the particles 4, and they are made transparent by melting to manufacture a base material for an optical fiber contg. F for reducing refractive index in the clad part.