Correlations between optical absorption, in the ultra-violet and vacuum ultra-violet regions, and Ge E’ centers were studied in 9SiO2-GeO2 glasses that had been irradiated with ArF excimer laser light. A good correlation was found, in isochronal annealing experiments, between a band which peaked at 6.3eV and the Ge E’ centers. On the basis of this correlation, the oscillator strength of the 6.3eV band was estimated to be equal to 0.5. The large oscillator strength of the 6.3eV band was consistent with the Kramers-Kronig mechanism for photo-induced Bragg grating formation.

H.Hosono, M.Mizuguchi, H.Kawazoe, J.Nishii: Japanese Journal of Applied Physics, 1996, 35[2-2B], L234-6