Behavior of hydrogen molecules adsorbed on silica in optical fibers

It is shown that molecular hydrogen weakly adsorbed on silica in optical fibers has a dipole moment and is active in infrared spectra. This causes a loss increase at 1.3 and 1.55 μm, which are the attractive wavelengths for optical fiber communication systems. In addition, it is shown that the loss spectra are also related to the fundamental SiO4tetrahedral vibrations rather than the rotation of hydrogen molecules from the observation of the loss spectra in silica glass fibers containing hydrogen molecules and deuterium molecules. It is also shown that the loss is reversible and that the reversibility is promoted with temperature.