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, 0<f<1, and the experimental irradiation time ${\mathit{t}}_{\mathrm{irrad}}$. The time constant of the recovery is given by ${\mathit{t}}_{\mathrm{irrad}}$/(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 μm in our test fibers and we infer a diffusion-limited bimolecular recombination process.