Judd-Ofelt intensity parameters and laser analysis of Pr³⁺ doped phosphate glasses sensitized by Mn²⁺ ions

Abstract

In this paper, we report the preparation and optical characterization of Mn²⁺ activated Pr³⁺ doped phosphate glasses in four different chemical compositions. The optical absorption spectra of Pr³⁺ 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 (F₂, F₄, F₆), Racah (E¹, E², E³), spin-orbit interaction (ξ_4f) and Judd-Ofelt (J-O) (Ω₂, Ω₄, Ω₆) 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 Pr³⁺ 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 Pr³⁺ ion concentration is discussed in the light of non-radiative processes such as multiphonon relaxation and energy transfer between like and unlike ions.