Effect of Er3+ ions on the structural, optical and Judd-Ofelt (JO) intensity parameters of (Bi2O3-BaTiO3) glass system and their application as fiber-amplifier

Barium titanate-based bismuthate glasses doped with Er3+ ions have been fabricated by employing the conventional melt quench technique. Various characterization studies have been performed on the samples for their physical, structural and optical analysis such as the density and molar volume measurements, X-Ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, and UV–Vis spectroscopies. The amorphous nature of the prepared glass samples has been confirmed by the broad humps observed in the X-Ray diffractograms. The FTIR spectra confirmed an increment in the non-bridging oxygen atoms (NBOs) and also the transformation of [BiO6] units to [BiO3] pyramidal units in the structural network of the glass matrix. Raman spectra in the high-frequency region have also been recorded which provided information related to the structural changes in the glass system upon the building of Er-O linkages. Absorption spectra of UV–Vis spectroscopy depicted six transition states such as 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I11/2, and 4I13/2. The spectroscopic and optical parameters such as energy band gap, optical conductivity, penetration depth, Judd-Ofelt (JO) parameters, refractive index, dielectric constant, Urbach energy, and transmission coefficient for the glasses have been determined, among others. The nephelauxetic ratio (β) and bonding parameters (δ) obtained from transitions of rare-earth ions have revealed the ionic character of the glasses. The calculated values of indirect and direct energy bandgap (Eg) of the prepared samples have been found to decrease from 2.04 to 1.93 and 2.67 to 2.45 resp. on increasing Er3+ ions. Judd-Ofelt (JO) parameters follow the order given by Ω2> Ω6> Ω4 and have been consistent with the literature. A decrement in the values of Ω2 from 3.761 to 2.699, confirmed the lowest asymmetry in the crystal field of rare-earth ions of glass system. The obtained values of refractive index, Urbach energy, dielectric constant, electronic & ionic polarizability and the metallization criterion suggest that the presently studied glass samples are amorphous semiconducting, optically non-linear and are suitable for the applications in erbium-doped fiber-amplifier (EDFA), lasers and optoelectronic devices.