Radiation Resistance of Er-Doped Silica Fibers: Effect of Host Glass Composition

With the aim to find the best-suited host glass for radiation-resistant erbium-doped fibers (EDF), radiation-induced absorption (RIA) is measured and analyzed after γ -irradiation to 3.0-4.5 kGy in 18 silica optical fibers with various concentrations of dopants: Al2O3, P2O5, GeO2and Er2O3. The RIA dependence on the content of Al2O3, P2O5and Er2O3in singly doped fibers is investigated. RIA of fibers codoped simultaneously with Al2O3and P2O5are found to be significantly lower than those of singly Al2O3-doped fibers. This is explained as the result of the formation of AlPO4-joins in the silica network. GeO2codoping of AlPO4-doped silica is shown to further reduce RIA. Nevertheless, the application of H2-loading and photobleaching of RIA by 980-nm laser radiation shows that the AlPO4- and GeO2-codoped silica is outperformed by P-free Al2O3- and GeO2-codoped silica, which is, therefore, concluded to be the best host glass composition for radiation resistant EDFs.