Spectroscopic properties and concentration effects on luminescence behavior of Nd3+ doped Zinc–Boro–Bismuthate glasses

A detail investigation on laser spectroscopic properties as a function of Nd3+ ions concentration in a new heavy metal oxide based Zinc–Boro–Bismuthate glasses is reported. The Judd–Ofelt analysis indicated an enhancement in Nd–O bond covalency as well as the local asymmetry of active ions on increase in dopant concentration from 0.1 to 1.5 mol%. Based on the Judd–Ofelt intensity parameters, several radiative properties such as transition probability, radiative lifetime, branching ratio and stimulated emission cross-section of Nd3+ ions have been derived. The luminescence intensity has showed a strong increase up to 0.5 mol% Nd2O3, which then attains maximum at 1 mol% and falls down for further increase in dopant concentration. The luminescence quenching behavior at higher dopant concentration has been attributed to the hopping migration assisted energy transfer mechanism leading to the cross-relaxation among active ions. The energy transfer micro-parameters for cross-relaxation (CDA) and donor energy migration (CDD) have been derived from the luminescence decay analysis as well as spectral overlap function respectively. The high stimulated emission cross-section and smaller cross-relaxation micro-parameters along with high quantum yield from the present glasses suggests their potential for compact infrared lasers and waveguide applications.