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

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 Ω_λ (λ = 2, 4, 6) by including and omitting ³H₄ → ³P₂ transition. Utilizing Ω₂, Ω₄, and Ω₆ values and refractive indices, radiative transition probabilities (A_R), branching ratios (β_R), 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 A_R and β_R, large stimulated emission cross-section (σ_em), 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 A_R (1938 s⁻¹), moderate β_R (26%), and large σ_em (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.