METHOD FOR MAKING LOW BEND LOSS OPTICAL FIBER PREFORMS

摘要

A method of making an optical fiber preform comprising in order: (i) manufacturing a glass preform with at least one porous layer; (ii) exposing the glass preform with at least one porous layer to a fluorine precursor at temperature below 1295° C. to make a fluorine treated preform, and (iii) exposing the fluorine treated glass preform with at least one porous silica based layer the temperatures above 1400° C. to completely sinter the preform. Preferably, the porous silica based layer of the glass preform exposed to fluorine precursor has average density of at least 0.7 g/cm3 but less than 1.9 g/cm3.

主权项

1. A method of making an optical fiber preform comprising in order:
(i) manufacturing a glass preform with at least one porous layer; (ii) pre-densifying said preform to increase the average density of said porous glass layer to at least 0.7 g/cm3 but less than 1.9 g/cm3 thereby forming a pre-densified preform; (iii) exposing the pre-densified preform to a fluorine precursor at a temperature at 1290° C. or less to make a pre-densified fluorine doped preform, (iv) exposing the pre-densified fluorine doped preform to temperatures above 1400° C. to completely sinter the pre-densified fluorine doped preform to form the fluorine doped sintered preform; and thereby (v) forming a fluorine doped profile in said fluorine doped sintered preform such that the ratio of the concentration of fluorine in an inner region of the preform to concentration of fluorine in the outermost region of the preform is less than 0.4.