Correlation between Ge E' centers and optical absorption bands in SiO2:GeO2 glasses

Correlations between optical absorptions in ultraviolet and vacuum ultraviolet regions and Ge E' centers were examined using 9SiO(2) . 1GeO(2) glasses irradiated with ArF excimer laser light in order to determine the optical absorption bands due to Ge E' centers and the oscillator strength. A good correlation between the band peaking at 6.3 eV and Ge E' centers was found in the isochronal annealing experiment. The oscillator strength of the 6.3 eV band was determined to be 0.5+/-0.1 on the assumption of the above correlation. The large oscillator strength of the 6.3 eV band due to Ge E' centers is compatible with the Kramers-Kronig mechanism for photoinduced Bragg grating formation.