Ce-doped and Ce/Au-codoped alumino-phospho-silicate fibers: Spectral attenuation trends at high-energy electron irradiation and posterior low-power optical bleaching

We report a study of attenuation spectra' transformations in a couple of Cerium (Ce) doped alumino-phospho-silicate fibers (one of them codoped with gold (Au)), occurring under irradiation by a beam of high-energy beta-electrons. The experimental data reveals an essential effect of beta-irradiation upon the absorptive properties of the fibers, given by noticeable susceptibility of Ce ions in Ce3+/Ce4+ valence states to the treatment, arisen as growth followed by saturation of induced absorption. We also report posterior bleaching of the beta-darkened fibers, also in terms of attenuation spectra' transformations, at exposing them to low-power green (a He-Ne laser) and UV (mercury lamp) light, the effect never reported for Ce-doped fibers. It is shown that both phenomena are less expressed in Ce fiber codoped with Au than in Au-free one and that the spectral changes in the former are more regular and plain vs. irradiation dose and bleaching time. Possible mechanisms responsible for the phenomena and their impact at using such fibers for dosimetry and other applications are discussed. (C) 2013 Optical Society of America