Judd–Ofelt intensity parameters and laser analysis of Pr 3+ doped phosphate glasses sensitized by Mn 2+ ions

Abstract

In this paper, we report the preparation and optical characterization of Mn 2+ activated Pr 3+ doped phosphate glasses in four different chemical compositions. The optical absorption spectra of Pr 3+ ions in phosphate glasses have been recorded in the UV–VIS–NIR region. From the data available in the optical absorption spectra, various spectroscopic parameters such as Slater–Condon ( F 2, F 4, F 6), Racah ( E 1, E 2, E 3), spin-orbit interaction ( ξ 4f) and Judd–Ofelt (J–O) ( Ω 2, Ω 4, Ω 6) parameters are derived. The calculated values of the J–O parameters are utilized in evaluating the various radiative parameters such as electric dipole line strengths ( S ed), magnetic dipole line strengths ( S md), radiative transition probabilities ( A RAD), radiative lifetimes ( τ RAD), fluorescence branching ratios ( β R) and the integrated absorption cross-sections ( σ a) for stimulated emission from various excited states of Pr 3+ ion. The principal fluorescence transitions of interest are identified by recording the fluorescence spectrum and measuring their stimulated emission cross-section and optical gain. Quantum efficiencies of the prominent lasing transitions are estimated by measuring their radiative and fluorescence lifetimes. The dependence of effective radiative lifetime on Pr 3+ ion concentration is discussed in the light of non-radiative processes such as multiphonon relaxation and energy transfer between like and unlike ions.