Luminescence and optical absorption properties of Nd3+ ions in K-Mg-Al phosphate and fluorophosphate glasses

Absorption and emission properties and fluorescence lifetimes for the transition of Nd3+ ions embedded in P2O5-K 2O-MgO-Al2O3 (PKMA)-based glasses modified with AlF3 and BaF2 are reported at room temperature. The observed energy levels of Nd3+ ions in these glasses have been analysed through a semi-empirical free-ion Hamiltonian model. The spin-orbit interaction and net electrostatic interaction experienced by the Nd3+ ions follow the trend as PKMA>PKMA+AlF3> PKMA+BaF2 glasses. Judd-Ofelt analysis has been carried out on the absorption spectra of 1.0 mol% Nd3+-doped glasses to predict the radiative properties for the fluorescent levels of the Nd3+ ion. Branching ratios and stimulated emission cross-sections show that the transition of the glasses under investigation has the potential for laser applications. The Inokuti-Hirayama model has been applied to investigate the non-radiative relaxation of the Nd3+ ion emitting state, 4F3/2. Based on the decay curve analysis, concentration quenching of the 4F3/2 emission has been attributed to a cross-relaxation process between the Nd 3+ ions.