Chromium doped nano-phase separated yttria-alumina-silica glass based optical fiber preform: fabrication and characterization

Effects of electron-irradiation darkening and its posterior bleaching by light in novel Cr–Mg–YAS fiber

“…Moreover, in Cr-Mg-YAS fiber, darkening takes slightly elliptical shape, most probably, indicating stronger stresses arising after βI. A trend of darkening degree to dominate on the core-cladding interface can be explained by the already referred [1,2] property of partially losing a considerable amount of Cr ions at the collapsing/ drawing stages at fabricating preform/fiber of this type. As seen from figure 4 (compare top and middle versus bottom photos), this pattern of darkening arises in both Cr-doped fibers-Cr-Mg-YAS (in a higher degree) and Cr-YAS (in a lesser degree) but not-in the un-doped SMF-28 one.…”

“…In this letter, we report the effects of high-energy β-electron irradiation (βI), resulting in spectrally peculiar induced absorption, or 'darkening', and its posterior low-power optical bleaching (OB) for the recently fabricated yttria-alumino-silicate (YAS) fiber co-doped with chromium (Cr) and magnesium (Mg) [1][2][3] (further-Cr-Mg-YAS).…”

“…Cr-Mg-YAS fibers, fabricated entirely through the modified chemical vapor deposition/solution-doping (MCVD/SD) technique, were recently shown to be capable-when pumped at wavelengths falling into the Cr-related absorption bandsof pronounceable fluorescence in VIS-to-NIR (much more intensive in NIR as compared to fibers free from co-doping with Mg). This feature was revealed to stem from Cr 4+ ions in such Cr-Mg-YAS fibers, formed due to charge compensation [2,3]. Details of fabrication of Cr-Mg-YAS fibers are provided in [1].…”