Optical and spectroscopic studies on Eu³⁺ doped LCBB glasses for photonic device applications

Herein we report the optical and spectroscopic properties of lithium–calcium–bismuth–borate (LCBB) glasses containing Eu³⁺ prepared via the melt-quenching method, and the prepared samples were systematically characterised through X-ray diffraction (XRD), Raman, ultraviolet–visible–near-infrared (UV–Vis-NIR) and photoluminescence (PL) spectroscopic techniques. The absence of XRD peaks evidenced the amorphous nature of glass. Different borate functional groups were identified from Raman spectra. Urbach energy and radiative properties were evaluated from the UV–Vis–NIR absorption spectra. The phonon energy of the glass samples was estimated by considering the energy differences between the zero-phonon level (ZPL) and phonon side bands (PSBs) present in excitation spectra. Judd–Ofelt (JO) parameters have been evaluated from the luminescence intensity ratios of ⁵D₀ → ⁷F_J (J = 2, 4) to ⁵D₀ → ⁷F₁ transitions. These parameters have been used to derive radiative properties such as transition probabilities, branching ratios, radiative lifetimes and peak stimulated emission cross-sections for the ⁵D₀ → ⁷F_J transitions. The JO results and the lifetime decay studies showed that LCBBEu2 glass exhibits higher stimulated cross-section (16.74 × 10^–22 cm²) and quantum efficiency (67.80%), which is highest among the reported by other research groups. Also, the LCBB doped with Eu³⁺ glasses exhibit strong emission in the red region, making them potential candidates for photonic device applications.