Optical spectroscopy of Sm3+ ions in phosphate and fluorophosphate glasses

Spectral characterization of Sm3+-doped phosphate (PKBAS: P2O5 + K2O + BaO + Al2O3 + SM2O3) and fluorophosphate (PKBFAS: P2O5 + K2O + BaO + BaF2 + Al2O3 + SM2O3) glasses through absorption, emission and decay curves are presented. The observed bands in absorption spectra, responsible for transitions from ground state to various excited states, are assigned and analyzed using free-ion Hamiltonian (HFI) model. Radiative properties are predicted using Judd-Ofelt theory. Experimental branching ratios and lifetimes of the (4)G(5/2) level are compared with theoretical values. The decay curves of Sm3+-doped phosphate and fluorophosphate glasses are perfectly single exponential for lower concentration (0.01 mol%) and gradually change to non-exponential for higher concentrations. The analysis of non-exponential behavior of decay curves through Inokuti-Hirayama model indicates that the energy transfer between Sm3+ ions is of dipole-dipole type. Our systematic analysis on decay measurements reveals that energy transfer mechanism strongly depends on concentration as well as glass composition. (c) 2006 Elsevier B.V. All rights reserved.