Influence of Hydrogen on the Radiation-Induced Attenuation of Ge-Doped Optical Fibers

The radiation-induced attenuation (RIA) levels and kinetics depend on several parameters, including silica-based optical fiber composition, operation wavelengths, and preirradiation treatments. We studied in this work how the ${X}$ -ray RIA in the visible and near-infrared domains, up to a total ionizing dose (TID) of 100 kGy(SiO2), of a standard telecom Ge-doped fiber, changes when this optical fiber is subjected to different preirradiation treatments such as an H-2-loading, with or without an additional thermal treatment at 50 degree celsius. The performed systematic study, at room temperature (RT), allows to better characterize the influence of the presence of either molecular H(2 )or bonded atomic hydrogen on the generation and bleaching mechanisms of radiation-induced point defects. Our results show that if the hydrogen can passivate point defects at lower doses (< a few kGy), it globally negatively impacts the visible and near-IR RIA at doses larger than a few kGy. This hardening solution can then not be employed for this class of optical fibers (OFs).