Characterization of Tm3+ doped mixed alkali borate glasses—spectroscopic investigations Original Research Article

The effect of mixed alkalis on the optical absorption spectra of Tm3+ in xNa2O·(30−x)K2O·70B2O3 glasses has been studied. The optical band gap values (Eopt) for both direct and indirect transitions have been obtained using Davis and Mott theory. Spectroscopic parameters like Racah (E1, E2 and E3), spin-orbit (ξ4f) and Judd–Ofelt intensity parameters (, and ) have been calculated for different x values. Radiative transition probabilities (Arad), radiative lifetimes (τR), branching ratios (β), integrated absorption cross sections (Σ) and multiphonon relaxation rates (WMPR) are calculated for certain excited states of Tm3+ ion. The observed trends in the above parameters as a function of x in these borate glasses have been discussed keeping in view the effect of mixed alkalies in borate glasses. Certain potential lasing transitions have been identified for laser action among the various transitions of Tm3+ in these mixed alkali borate glasses.