Judd-Ofelt analysis, optical and structural features of borate glass doped with erbium oxide

Abstract

This article presents a description of the structural-optical relationship in amorphous borate glass, with a decent investigation of Judd-Ofelt parameters to understand the effect of structural changes on optical properties due to the erbium oxide addition. Using density measurements, the effect of heavy molecular weight and larger ionic radius of erbium oxide was demonstrated. FT-IR analysis revealed the BO3 to BO4 conversion, confirming the network polymerization and connectivity. Astonishingly, the effect of erbium oxide on the increased band gap energy and the mitigated Urbach energy was demonstrated. Interestingly, Judd-Ofelt analysis was utilized to demonstrate the impact of the composition changes on the relation between the structural changes and optical properties. The influence of excited configurations of Er3+ ions was measured from the line strengths. The hypersensitive transitions from I15/24toH11/24 and G9/24 were observed at 375 nm and 519 nm, which have relatively higher intensities compared to other ones. Thus, they are attractive transitions for light emitting devices, LEDs, and solid lasers. The decreased values of Ω2 parameter is related to the increase in symmetry and high polarization around Er3+ ions. Consequently, the decrement in Ω2 suggests that the bond nature between Er3+ and O2− ions tends to be more ionic. Calculations of radiative parameters such as spontaneous radiative transition probability, radiative lifetime, and branching ratio were presented. The hypersensitive transitions have the highest values of the spontaneous radiative transition probability, predicting their high luminescence efficiency in glass host, besides the effectiveness of their usability in designing photonic devices. The obtained high branching ratio confirmed the lasing action of Er3+ ions in the glass host, especially the hypersensitive transitions of Er3+ ions.