Pr3+-doped B2O3-Bi2O3-ZnO-NaF glasses comprising alkali/mixed alkali oxides for potential warm white light generation, blue laser, and E-+ S-+ C-optical bands amplification applications

Abstract

For six 1 mol% Pr3+-doped B2O3–Bi2O3–ZnO–NaF glasses consisting of single and mixed alkali oxides, optical absorption and visible and near-infrared (NIR) luminescence traits including visible fluorescence decay times were investigated. Judd–Ofelt (J‒O) analysis from absorption spectra was performed to calculate J‒O parameters Ωλ (λ = 2, 4, 6) by including and omitting 3H4 → 3P2 transition. Utilizing Ω2, Ω4, and Ω6 values and refractive indices, radiative transition probabilities (AR), branching ratios (βR), and radiative lifetimes for all Pr3+ ion's luminescent levels were estimated. For observed intense blue fluorescence band upon 443 nm optical pumping, various parameters considered in designing visible laser systems were evaluated. Pr3+: Na + K ions comprising glass possesses large spectroscopic quality factor, high AR and βR, large stimulated emission cross-section (σem), high quantum efficiency, large gain bandwidth, and significant optical gain for 3P0 → 3H4 transition for a potential blue lasing action among all samples. Further, Commission Internationale de l'éclairage (CIE) coordinates, correlated color temperature (CCT), color rendering index, and luminous efficiency of radiation were derived from visible luminescence spectra and deduced CIE and CCT values represent the neutral or warm white light region. Upon 3H4 → 3P2 excitation, NIR luminescence spectra show 3P1 + 1I6 → 1G4, 1D2 → 3F4, and 1D2 → 1G4 transitions in which broadband (1D2 → 1G4) at 1.3–1.65 μm range with effective bandwidth ~157 nm was obtained for Pr3+: Na + K ions constituting glass with high AR (1938 s−1), moderate βR (26%), and large σem (2.64 × 10−20 cm2) at 1.472 μm, and its gain profile covers the E-+S-+C-optical communication bands' range for effective broadband amplification operation.