Spectroscopic properties ofMO-WO3-P2O5: Ho3+ glasses

ESR, IR, optical absorption and photoluminescence spectra of Ho3+ doped tungsten phosphate glasses modified with three different modifier oxides viz., PbO, ZnO and CaO have been studied. The ESR spectral studies indicate tungsten ions are present in W5+ state in all the three glasses with the highest concentration in CaO modified glasses. From the measured intensities of various absorption bands of these glasses, the Judd-Ofelt (JO) parameters $\Omega_2$, $\Omega_4$ and $\Omega_6$ have been evaluated. The JO theory could successfully be applied to characterise the absorption and luminescence spectra of these glasses. From this theory various radiative properties like radiative transition probabilities, A, branching ratios, $\beta_r$, the radiative lifetimes, $\tau_R$, and the emission cross-sections, σE, for various emission levels of Ho3+ in these glasses have been determined and reported. An attempt has also been made to throw some light on the environment of Ho3+ ions in all the three glasses.