Absorption and fluorescence properties of Sm3+ ions in fluoride containing phosphate glasses

Optical absorption, fluorescence and lifetime characteristics of Sm3+-doped fluoride containing phosphate glasses (PKFBASm) with molar composition of (56−x/2) P2O5 + 14 K2O + 6KF + (15−x/2) BaO + 9Al2O3 + x Sm2O3, (x = 0.01, 0.05, 0.1, 1.0, 2.0, 4.0 and 6.0 mol%) were studied. From the measured energies of absorption bands, different free-ion energy level parameters along with calculated energies were determined using the free-ion Hamiltonian (HFI) model. Judd–Ofelt (J–O) theory was applied to the experimental oscillator strengths to evaluate three phenomenological J–O intensity parameters Ωλ (λ = 2, 4 and 6). Using these J–O parameters as well as from the emission and decay measurements, various radiative parameters such as transition probabilities (AR), radiative lifetimes (τR), measured lifetimes (τmes), calculated branching ratios (βR), measured branching ratios (βmes), effective bandwidths (Δλeff) and stimulated emission cross-sections (σλp) have been calculated for the excited 4G5/2 luminescent level. The nature of decay curves of 4G5/2 level for different Sm3+ ion concentrations in all PKFBASm glasses has been analyzed using Inokuti–Hirayama (I–H) model and the lifetimes are noticed to decrease with increase of concentration. The cross-relaxation mechanism responsible for the quenching of measured lifetimes with concentration is also discussed.