It was recalled that O-deficient defects in germano-silicate glass were generally thought to play a crucial role in the photosensitivity of this material to ultra-violet radiation. It was shown here that germano-silicate glass which was defect-free, but H-loaded, also exhibited a photosensitivity to 248nm light. In fact, photosensitivity in defect-free germano-silicate glass was shown to require the presence of H. However, O-deficient defects increased the photosensitivity of germano-silicate glass to light, with a wavelength of 248nm, in both the H-free and H-loaded conditions. Comparisons were made of 4 types of otherwise identical germano-silicate glass. Each sample either did or did not contain O-deficient defects and each sample either did or did not contain H.

The Significance of Oxygen-Deficient Defects to the Photosensitivity of Hydrogen-Loaded Germanosilicate Glass. A.D.Heaney, T.Erdogan, N.Borrelli: Journal of Applied Physics, 1999, 85[11], 7573-8