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 different physical mechanisms take place depending on whether H<sub>2</sub> is present. Without H<sub>2</sub> the principal photosensitivity pathway involves excitation of a germanium oxygen-deficient center to its triplet state. In H<sub>2</sub> -loaded fibers the UV light excites the regular Ge—O bond, which then reacts with H<sub>2</sub> to produce Si—OH or Ge—OH and a GeE<sup>′</sup> center.
© 1999 Optical Society of America
V. Grubsky, D. S. Starodubov, and J. Feinberg, "Photochemical reaction of hydrogen with germanosilicate glass initiated by 3.4 5.4-eV ultraviolet light," Opt. Lett. 24, 729-731 (1999)