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.