Radiation-Induced Attenuation in Silica Optical Fibers Fabricated in High O<sub>2</sub> Excess Conditions

Abstract

Radiation-induced attenuation (RIA) in undoped-silica-core optical fibers, of which the preform cores are synthesized in high O2 excess conditions in the vapor–gas mixture (“high oxygen excess fibers, HOE-fibers”), is investigated in the spectral range 1.1–1.7 μm under γ-irradiation from a 60Co-source. The O2 excess degree, the F content in the cladding, the drawing speed, and tension are varied among the fibers. RIA is found to strongly depend on the balance between the O2 excess degree in the core and the F content in the cladding and also on the fiber drawing tension. RIA anticipated in HOE-fibers with optimized O2 excess and a practicably low drawing tension at $\lambda = 1.55$ μm is estimated to be a few times lower than that in the commercial radiation-resistant F-doped-silica-core fibers.