Optical properties and spectroscopic study of different modifier based Pr^3 +:LiFB glasses as optical amplifiers

In this paper, we report the preparation and optical characterization of Pr^3 + doped lithium fluoro borate (LiFB) glasses for six different chemical compositions of Li₂B₄O₇-BaF₂-NaF-MO (where M = Mg, Ca, Cd and Pb), Li₂B₄O₇-BaF₂-NaF-MgO-CaO and Li₂B₄O₇-BaF₂-NaF-CdO-PbO. The structural and optical properties of these glasses were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), optical absorption and photoluminescence techniques. The optical absorption spectra of Pr^3 + ions in LiFB glasses have been recorded in the UV–VIS-NIR region. The optical absorption data are used to calculate various spectroscopic parameters such as Racah (E¹, E², E³) and spin-orbit interaction (ξ_4f) parameters. Judd-Ofelt (J-O) (Ω_λ where λ = 2, 4 and 6) intensity parameters were determined by applying J-O theory, which in turn used to calculate the radiative properties such as radiative transition probabilities (A), radiative lifetimes (τ_R), integrated absorption cross-sections (Σ) and branching ratios (β_r) for all emission levels of Pr^3 + ion in different LiFB glass matrices. By using the J-O theory and luminescence parameters, stimulated emission cross sections (σ_p) of prominent transitions, ³P₀ → ³H₄ and ¹D₂ → ³H₄ of Pr^3 + ion in all LiFB glasses were calculated. ³P₀ → ³H₄ possesses higher branching ratios and stimulated emission cross-sections for the Pr^3 +:LiFB(Mg-Ca) glass, which can be used as a best laser excitation. The optical gain parameter (σ_pxτ_R) was noticed higher in Pr^3 +:LiFB(Mg-Ca) and Pr^3 +:LiFB(Cd-Pb) glasses for the transition ³P₀→ ³H₄ transition_, and these glasses have potential for optical amplification at 488 nm wavelength.