Abstract
•Covalent nature of bonding between Er3+ ions and their surrounding ligands was observed through bonding parameter and Judd-Ofelt parameters.•Hypersensitive transitions of Er3+ ion namely 4I15/2 → 2H11/2 &4I15/2 → 4G11/2 were interpreted through their higher oscillator strengths when compared to other transitions.
Family of lithium zinc fluoroborate glasses with 15ZnF2-10BaO-8Al2O3–12Li2O-(55-x) B2O3-xEr2O3 (x = 0.5, 0.7, 1.1, 1.3 and 1.5 mol%) composition were prepared by conventional melt-quench method. The glasses were characterized to study their structural, physical, optical and radiative properties. The amorphous characteristic of glass was noticed in X-Ray Diffraction pattern. A modification in structure was observed as density values increased with Er2O3 content. UV–Vis–NIR transitions of Er3+ in the host matrix were identified through absorption spectra. Covalent nature of bonding between Er3+ ions and their surrounding ligands was observed through bonding parameter and Judd-Ofelt parameters. Red shift of the fundamental absorption edge in the absorption spectra and decreasing indirect and direct band gaps with increasing Er3+ concentration jointly confirmed the role of Er3+ ions as network modifier. Hypersensitive transitions of Er3+ ion namely 4I15/2 → 2H11/2 &4I15/2 → 4G11/2 were interpreted through their higher oscillator strengths when compared to other transitions. Emission spectra recorded at 980 nm excitation showed a peak corresponding to 4I13/2 → 4I15/2 NIR transition of erbium ion. Stimulated emission cross section of Er0.5 sample, gain bandwidth and Figure of Merit were found to be 16.79 × 10−21 cm2, 1225.83 × 10−28 cm3 and 37.36 × 10−24 cm2 s respectively. Photoluminescence decay curve of Er0.5 sample was well-fitted to single exponential first order function. The experimental decay lifetime τexp for the 4I13/2 level was measured to be 0.34 ms. The wide frequency range of FWHM (1.02–1.67 × 1013 Hz) and high values of radiative parameters make the glass a suitable candidate as optical amplifier and NIR laser material.