The significance of oxygen-deficient defects to the photosensitivity of hydrogen-loaded germano-silicate glass

It is widely believed that oxygen-deficient defects in germano-silicate gla ss play a crucial role in the photosensitivity of this material to ultravio let radiation. In this article, it is shown that germano-silicate glass tha t is defect-free and hydrogen-loaded also exhibits photosensitivity to 248 nm light. In fact, photosensitivity in defect-free germano-silicate glass i s shown to require the presence of hydrogen. However, oxygen-deficient defe cts increase the photosensitivity of germano-silicate glass to light with a wavelength of 248 nm, in both the hydrogen-free and the hydrogen-loaded ca se. Comparisons are made among four types of otherwise identical germano-si licate glass. Each glass sample studied either does or does not contain oxy gen-deficient defects and, each glass sample either does or does not contai n hydrogen. (C) 1999 American Institute of Physics. [S0021-8979(99)05211-1] .