Structural and spectroscopic behavior of Er3+:Yb3+ co-doped lithium telluroborate glasses

A new series of Er3+:Yb3+ co-doped Lithium telluroborate glasses were prepared following the melt quenching technique. The structural analyzes were made through XRD, Raman, FTIR spectra to explore the different vibrations of borate and tellurite network. The absorption spectra have been used to determine the nature of the metal-ligand and further Band gap and Urbach's analysis have also been carried out. The oscillator strength value of the E-2(11/2) -> I-4(15/2) hypersensitive transition is found to be higher and increases as the concentration of the RE ion increases which emphasis the asymmetry nature of the glasses. The magnitude of the JO intensity parameters follow the trend as Omega(2)> Omega(4) > Omega(6), uniformly for all the prepared glasses. A bright green emission corresponding to the H-2(11/2) vertical bar S-4(3/2) I-4(15/2) transition and luminescence from I-4(13/2) -> I-4(15/2) in eye safe region have also been observed. The radiative parameters such as radiative transition probability, stimulated emission cross-section, branching ratios, radiative lifetime, gain bandwidth and gain linewidth for the S-4(3/2) and I-4(13/2) level of the title glasses have also been determined. The absorption and emission cross-section corresponding to the I-4(13/2) level has been calculated using McCumber theory. Lifetime measurements were made under 980 nm excitation and the quantum efficiency were also calculated to evaluate the appropriateness of the host matrix for the fabrication of laser materials and broad band amplifiers. (C) 2014 Elsevier B.V. All rights reserved,