Manifestation of up-conversion in Yb3+/Tm3+ doped Li2O-Y2O3-SiO2 glass system

In this study, we have investigated the principal role of Y2O3 on the emission features of Tm3+ ion and up-conversion phenomenon in Tm3+ and Yb3+ co-doped Li2O-Y2O3-SiO2 glass system. The concentration of Y2O3 is varied from 0 to 5 mol% while that of Yb3+ and Tm3+ is fixed. When the glasses are doped with Tm3+ ions, the intense blue and red emissions were observed, whereas Yb3+ doped glasses exhibited NIR emission at about 980 nm. When the glasses are co-doped with Tm3+ and Yb3+ ions and excited at 900 nm, the blue and red emission lines were observed to be reinforced and strengthened with increase in the concentration of Y2O3. The IR emission band detected at about 1.8 mu m due to F-3(4) -> H-3(6) transition of Tm3+ ions is also observed to be strengthened due to co-doping. The reasons for enhancement in the intensity of various emission bands due to co-doping have been identified and discussed with the help of rate equations for various emission transitions.