MODEL FOR THE DOSE, DOSE-RATE AND TEMPERATURE-DEPENDENCE OF RADIATION-INDUCED LOSS IN OPTICAL FIBERS

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 radiation-induced attenuation in optical fibers. This insight permits detailed prediction of the post-irradiation recovery curves, given just the empirical exponent of the power law, 0<f<1, and the experimental irradiation time, t(irrad). The time constant of the recovery is given by t(irrad)/(1-f), in both first- and second-order kinetics. We establish a microscopic model of radiolytic oxygen molecules for the gamma-ray-induced absorption at 1.3 mum in our test fibers and infer a diffusion-limited bimolecular recombination process.