Radiation-induced defects in glasses: Origin of power-law dependence of concentration on dose

We propose, and verify in the case of a Ge-doped-silica-core optical fiber, a general explanation for the power-law dependencies on dose frequently observed for the concentrations of radiation-induced defect centers in insulating glasses. This insight permits detailed prediction of the postirradiation recovery curves given just the empirical exponent of the power law, 0f1, and the experimental irradiation time tirrad. The time constant of the recovery is given by tirrad/(1-f), independent of the order of kinetics. We establish a microscopic model (radiolytic oxygen molecules) for the {γ}-ray-induced absorption at 1.3 {μ}m in our test fibers and we infer a diffusion-limited bimolecular recombination process.