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

摘要

PROBLEM TO BE SOLVED: To provide: a method for manufacturing an optical fiber porous preform, capable of suppressing the occurrence of cracks of a porous body in the optical fiber porous preform; an optical fiber porous preform using the same; and a method for manufacturing optical fiber.;SOLUTION: In the method for manufacturing an optical fiber porous preform, capable of depositing glass fine particles formed by supplying glass raw material gas to a burner on a starting rod while rotating the starting rod and pulling it upward to grow a porous body consisting of the glass fine particles in a lower portion of the starting rod, the porous body is grown so that a ratio of the outer diameter change of the portion to the length change of the porous body in the outer periphery of the portion at the point of growing a portion having an outer diameter of 75% of the maximum diameter of the porous body is 0.2 when the porous body is grown.;SELECTED DRAWING: Figure 2;COPYRIGHT: (C)2019,JPO&INPIT