Study of optical absorption, visible emission and NIR–vis luminescence spectra of Tm3+/Yb3+, Ho3+/Yb3+ and Tm3+/Ho3+/Yb3+ doped tellurite glasses

Abstract Tm 3+ /Yb 3+ , Ho 3+ /Yb 3+ co-doped and Tm 3+ /Ho 3+ /Yb 3+ triply doped TeO 2 –Bi 2 O 3 –ZnO–Li 2 O–Nb 2 O 5 (TBZLN) tellurite glasses were prepared by melt quenching method. Judd–Ofelt intensity parameters ( Ω λ , λ =2, 4 and 6), radiative transition probabilities, branching ratios and radiative lifetimes of Tm 3+ , Ho 3+ ions in co-doped TBZLN glasses were calculated from the optical absorption spectra. Excitation, visible luminescence and decay lifetimes in visible region were also investigated. The stimulated emission and gain cross-sections for the Tm 3+ : 3 F 4 → 3 H 6 (1700 nm) and Ho 3+ : 5 I 7 → 5 I 8 (1956 nm) transitions in co-doped TBZLN glasses have been analyzed and compared with those of other reported glasses. Up-conversion luminescence was observed in TBZLN glasses under 980 nm laser excitation and energy transfer mechanisms have been discussed. Finally, CIE color co-ordinates were calculated and it is observed that the color co-ordinates fall in blue and green regions for Tm 3+ /Yb 3+ and Ho 3+ /Yb 3+ co-doped TBZLN glasses, respectively. A subsequent shift in color co-ordinates from green to greenish-yellow region has been observed with an increase in the concentration (0.1, 0.5 and 1.0 mol%) of Tm 3+ ions in Tm 3+ /Ho 3+ /Yb 3+ triply doped TBZLN glasses.