GLASS BASE MATERIAL, OPTICAL FIBER, METHOD FOR MANUFACTURINGTHEREOF, AND METHOD FOR DETERMINING CAUSE OF DEFECT THEREOF

摘要

A glass base material, which is a base material of an optical fiber, comprising: a core; and a clad surrounding the core; wherein: a rate of change in a relative-refractive-index-difference between the core and the clad in a longitudinal direction of the glass base material is substantially 6 % or less.