OPTICAL FIBER AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain an optical fiber capable of preventing residual stress in wire drawing and giving a fiber having excellent transmission characteristics. SOLUTION: This optical fiber is composed of a core having high refractive index and a clad existing at an outer periphery of the core and having a refractive index lower than the core. The core has a central region wherein at least an amount of GeO2 dope decreases from central part to an outer periphery and an amount of fluorine dope decreases from the outer periphery to center in an at least a part of the region from the outer periphery to inside of the central region, then glass viscosity in the fiber cross section is almost uniformly adjusted.