TRANSIENT ELECTRON-PARAMAGNETIC RESONANCE HYDROGEN HYPERFINE DOUBLET IN LOW-OH CONTENT SYNTHETIC SILICA OPTICAL FIBERS DURING ISOTHERMAL ANNEALING

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-degrees-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.