UV-INDUCED REACTION OF H-2 WITH GERMANOSILICATE AND ALUMINOSILICATE GLASSES

The cores of optical fiber preforms were exposed to UV light at 244 nm after molecular hydrogen loading under high pressure. The reactions b etween hydrogen and the core material were investigated by Fourier tra nsform infrared spectroscopy in the 3 mu m spectral range. Various gla ss compositions were considered: germanosilicate glasses codoped with B, Sn, or not and aluminosilicate glasses codoped with Ce or Tb. In ge rmanosilicate glasses (codoped or not), H-2 reacts at the Ge sites onl y. The major defect formed is Ge-OH, some Ge-H is detected too, but at a much smaller level. In the Ce-doped aluminosilicate plates, H-2 rea cts with Ce and forms Ce-OH. All these materials are reduced through t he UV light exposure as shown by the presence of molecular water forme d by reaction of H-2 With the glass network. The exceptions are with t he Tb aluminosilicate preforms which show no reaction with H-2 under U V exposure. (C) 1998 Elsevier Science B.V.