Photochemical reaction of hydrogen with germanosilicate glass initiated by3.4-5.4-eV ultraviolet light

By measuring the photosensitivity of Ge-doped silica fibers over the 3.4-5. 4-eV spectral range and from T = 95 K to T = 375 K, we demonstrate that dif ferent physical mechanisms take place depending on whether H-2 is present. Without H-2 the principal photosensitivity pathway involves excitation of a germanium oxygen-deficient center to its triplet state. In Ha-loaded fiber s the UV light excites the regular Ge-O bond, which then reacts with H-2 to produce Si-OH or Ge-OH and a GeE' center. (C) 1999 Optical Society of Amer ica.