Intense near-infrared emission of 1.23 μm in erbium-doped low-phonon-energy fluorotellurite glass

•The 1.23 μm emission from Er3+:4S3/2 → 4I11/2 transition in fluorotellurite glass is observed.•Low phonon energy of the glass host (∼776 cm−1) contributes to the 1.23 μm emission.•Strong asymmetry and covalent environment of Er3+ are indicated by Judd–Ofelt analysis.•The population inversion between the upper and lower lasing levels is achieved.

Intense near-infrared emission located at 1.23 μm wavelength originating from the erbium (Er3+):4S3/2 → 4I11/2 transition is observed in Er3+-doped fluorotellurite glasses. This emission is mainly contributed by the relatively low phonon energy of the fluorotellurite glass host (∼776 cm−1). Judd–Ofelt analysis indicates a strong asymmetry and covalent environment between Er3+ ions and ligands in the host matrix. The emission cross-section was calculated to be 2.85 × 10−21 cm2 by the Füchtbauer–Ladenburg equation, and the population inversion is realized according to a simplified evaluation. The results suggest that the fluorotellurite glass system could be a promising candidate for the development of optical amplifiers and lasers operating at the relatively unexplored 1.2 μm wavelength region.

Graphical abstractNear-infrared emissions in erbium (Er3+)-doped fluorotellurite glass, and the excitation and emission routes for the 1.23 μm emission.Figure optionsDownload full-size imageDownload as PowerPoint slide