Raman spectra of hydrogen-treated optical fibres

Chemical reactions in a Ge-P-silicate optical fibre exposed to hydrogen at 100 bar and 150°C for times up to 120 h are studied by Raman spectroscopy. Hydride and hydroxyl groups are formed, as Si-H and P-OH. The reaction kinetics are consistent with a defect-related mechanism. The saturation concentration of hydroxyl is about 103 ppm.