METHOD OF MANUFACTURING GLASS PREFORM FOR OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To provide a method of manufacturing a glass preform of an optical fiber by which variation of J-magnification in the end part of a transparent glass body is reduced and stable characteristics in the longitudinal direction are obtained. SOLUTION: Shrinkage stress is prevented from being concentrated to a glass rod due to the difference of viscosity when a heated glass fine particle is shrunk in a transparently vitrifying treatment by making the viscosity of a dummy rod 11 connected to the glass rod 12 including a core part in the vicinity of the boundary between the dummy rod 11 and the glass rod 12 equal to or above the viscosity of the glass rod in the melting starting temperature of the glass rod and smaller than the viscosity of pure SiO2and close to the viscosity of the glass rod and forming the dummy rod to have a diameter smaller than the diameter of the glass rod. Since a phenomenon that the diameter of the glass rod in the end part is made larger than that of the glass rod in the stationary part is suppressed, the J-magnification variation in the end part is reduced and the glass preform 10 for the optical fiber which has the stable characteristics in the longitudinal direction is manufactured. COPYRIGHT: (C)2004,JPO