| 摘要 |
PROBLEM TO BE SOLVED: To provide a base material for an optical fiber enabling to shorten the time from the start of fiber drawing generating off-spec fiber to the time of running stable fiber drawing, especially to provide a base material for an optical fiber having a specified tip profile just before the fiber drawing, and to provide a method of forming the base material. SOLUTION: This base material for an optical fiber has a tip profile of which function R(z) satisfies relationship (1), provided that R(z) means a tip profile of the base material just before the fiber drawing, r(z) is a tip profile of the base material running good fiber drawing obtained as a radius distribution function r(z) to the center axis z, z1 is a position at which r(z)=R(z)=kr0 r0 is an effective stationary radius of the base material and kr0 is either larger one of 0.3r0 or tip radius of the base material), z2 is a position at which r(z)=0.9r0, and z2 is a position locating behind the position z1 of R(z) by|z2-z1|. This method of forming the base material comprises processing by grinding or drawing so that the function R(z) of the tip profile satisfies the equation (1). |
