Spectral investigations of Sm3+-doped niobium phosphate glasses

Phosphate glasses modified with niobium and doped with different concentrations of Sm3+ ions (P2O5+K2O + Al2O3+Nb2O5+Sm2O3) were prepared by conventional melt quenching technique. Structural and optical characterizations have been carried out through X-ray diffraction (XRD), absorption, excitation, emission and decay measurements. With the help of well known Judd-Ofelt theory (JO), various radiative properties such as radiative transition probabilities (A(R)), branching ratios (beta(R)) and radiative lifetime (tau(R)) for certain luminescent levels of Sm3+ ions have been determined. The emission spectra consists of four emission bands in the visible region that corresponds to the (4)G(5/2) -> H-6(J) (J = 5/2, 7/2, 9/2 and 11/2) transitions of Sm3+ ions. The stimulated emission cross-section found to be higher for (4)G(5/2) -> H-6(7/2) (11.52 x 10(-22) cm(2)) and (4)G(5/2) -> H-6(9/2) (13.75 x 10(-22) cm(2)) transitions. Experimental lifetimes (tau(exp)), quantum efficiencies (eta), energy transfer parameter (Q) and donor-acceptor interaction parameter (C-DA) for all these glasses were evaluated under the frame work of Inokuti-Hirayama model. From the analyzed spectroscopic properties, such as quantum efficiency (98%) and CIE chromaticity coordinates, it is suggested that the 1.0 mol % of Sm3+ ions doped glasses are most suitable for the development of gain media for visible orange-red lasers. (C) 2017 Elsevier B.V. All rights reserved.