Transient electron paramagnetic resonance hydrogen hyperfine doublet in low-OH content synthetic silica optical fibers during isothermal annealing

Abstract

A transient 75 G electron paramagnetic resonance (EPR) hydrogen hyperfine doublet was observed for the first time in low-OH content silica optical fibers during isothermal annealing in the temperature range between 250 and 400 °C in air. The results are consistent with the diffusion of hydrogen molecules into the glass with subsequent interaction with E′ centers to form an intermediate E′/H and, in turn, an EPR-inactive end product. The response of the doublet to trace amounts of hydrogen was used to monitor hydrogen diffusion and the reaction between E′ and hydrogen in the glass.