Equilibrium Degradation Levels in Irradiated and Pumped Erbium-Doped Optical Fibers

This paper investigates the local interplay between radiation-induced darkening and pump-induced bleaching in erbium-doped silica optical fibers. Thanks to proper characterization conditions using short fiber samples, we demonstrate that degradation levels can be tuned reversibly between equilibrium levels by varying the pump power and/or the dose rate while the dose is being accumulated. This novel finding inspires a local physical model of the radiation-induced degradation of erbium-doped fibers in active conditions. This model is shown to reproduce all empirical features, including dose rate and pump power dependencies. This validated local model could be implemented in long fiber amplifier simulations.