PREFORM FOR OPTICAL FIBER, AND ITS MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To prevent breakage, the generation of cracks, or the like at a specific part such as the end part of a porous glass layer in a method of manufacturing a preform for an optical fiber, to which various additives are added. SOLUTION: In the method of manufacturing the preform for the optical fiber, comprising depositing a porous glass layer containing quartz glass as a main component on the inner surface of a glass pipe, and making the glass pipe solid by heating/transparently vitrifying the porous glass layer, after forming the porous glass layer, a part of the porous glass layer having a bulk density of <0.20 g/cm3is previously heated and transparently vitrified before making the glass pipe solid. COPYRIGHT: (C)2004,JPO