Spectroscopic and fluorescence properties of Sm3+-doped zincfluorophosphate glasses

Optical absorption and fluorescence spectra of Sm3+-doped zincfluorophosphate glasses with molar composition of 44P(2)O(5)+17K(2)O+9Al(2)O(3)+(30-x)ZnF2+xSm(2)O(3) (x=0.01 mol.%, 0.05 mol.%, 0.1 mol.%, 0.5 mol.%, 1.0 mol.%, 2.0 and 3.0 mol.%) referred as PKAZFSm were prepared by melt quenching technique and were characterized through Raman, absorption, emission and decay curve analysis. From the absorption spectra, Judd-Ofelt intensity parameters were determined and were used to predict radiative properties such as transition probabilities (A(R)), radiative lifetimes (tau(R)), branching ratios (beta(R)), effective bandwidths (Delta lambda(eff)) and stimulated emission cross-section (sigma(lambda(p))) for the excited (4)G(5/2) luminescent level. The decay curve for the (4)G(5/2) level was single exponential for lower concentration and became non-exponential for higher concentrations. The non-exponential nature of the decay curves of the (4)G(5/2) level increased with increase in Sm3+ ions concentration accompanied by decrease in lifetime due to energy transfer processes among the Sm3+ ions. The non-exponential decay curves was well fitted to the generalized Inokuti-Hirayama model for S=6, indicating that the energy transfer among optically active ions was of dipole-dipole interaction. The cross-relaxation mechanism responsible for the quenching of lifetimes and the effect of variation of concentration on the spectroscopic properties were also discussed.