Spectroscopic and fluorescence properties of Sm3+-doped zincfluorophosphate glasses

Abstract

Optical absorption and fluorescence spectra of Sm3+-doped zincfluorophosphate glasses with molar composition of 44P2O5+17K2O+9Al2O3+(30–x)ZnF2+xSm2O3 (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 (AR), radiative lifetimes (τR), branching ratios (βR), effective bandwidths (Δλeff) and stimulated emission cross-section (σ(λp)) for the excited 4G5/2 luminescent level. The decay curve for the 4G5/2 level was single exponential for lower concentration and became non-exponential for higher concentrations. The non-exponential nature of the decay curves of the 4G5/2 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.