Spectroscopic and photoluminescence properties of Sm3+ ions in Pb–K–Al–Na phosphate glasses for efficient visible lasers

Abstract

The Sm3+-doped lead phosphate glasses (PKAPbNSm:44P2O5–17K2O–9Al2O3–(24−x) PbO–6Na2O–xSm2O3, where x=0.1, 0.5, 1.0 and 2.0mol%) have been prepared by conventional melt quenching technique and are characterized through absorption and emission spectra and decay rate analysis. The partial energy level structure of Sm3+ ions in these glasses have been evaluated from the measured absorption and emission spectra using free-ion Hamiltonian model. The emission spectra of Sm3+ ions in these glasses have been measured using 488nm line of Ar+ laser as an excitation source. The decay rates for 4G5/2 level of Sm3+ ions have been measured and are found to exhibit single exponential nature at lower concentration (0.1 and 0.5mol% Sm2O3-doped glass) and turns into non-exponential at higher concentrations (≥1.0mol% Sm2O3-doped glasses). The experimental lifetimes for 4G5/2 level of Sm3+ ions are found to decrease from 2.34 to 1.24ms when the concentration is increased from 0.1 to 2.0mol% Sm2O3 due to cross-relaxation energy transfer. The non-exponential decay rates are well-fitted to Inokuti-Hirayama model for S=6, indicates that the energy transfer is of dipole–dipole type.