OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To prevent an optical fiber from the increase of a transmission loss caused by residual stress generating in the boundary between a core and a clad and a core part adjacent to the clad or the like after being formed into the optical fiber after wire drawing and a deviation of characteristics caused by a change in a distribution of a refractive index in wire drawing. SOLUTION: In the optical fiber which is composed by incorporating the core and the clad, a place where viscosity at a high temperature is maximized exists in a region wherein a distance from the center of the optical fiber is >=1.3 times the mode field diameter in the specific wavelength within range of wavelength enabling a single mode operation and the outer surface of the optical fiber is not contained.