METHOD FOR MANUFACTURING OPTICAL FIBER PREFORM, OPTICAL FIBER PREFORM AND OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical fiber preform with a large diameter while decreasing deviation or non-circularity degree of the core by a rod-in-collapse method, to provide an optical fiber preform having a preferable non-circularity degree and a complicated structure of the refractive index even when the preform has a large diameter, and to provide an optical fiber which can be used as a dispersion compensated fiber. SOLUTION: The rod-in-collapse process is carried out by fixing a glass rod in a glass pipe (or in a dummy pipe attached to the end of the pipe) by using an aligning tool. The rod is fixed by the tool at one end or both ends. The aligning tool is in a cylindrical form or a cylindrical form having one or more parts with decreased diameters. When the rod is fixed at one end, the process of heating and integrating is preferably carried out from the other end. A complicated structure can be obtained by using the core rod and the glass pipe having distribution of refractive indices.