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

Abstract Intense near-infrared emission located at 1.23 μm wavelength originating from the erbium (Er 3+ ): 4 S 3/2  →  4 I 11/2 transition is observed in Er 3+ -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 Er 3+ ions and ligands in the host matrix. The emission cross-section was calculated to be 2.85 × 10 −21  cm 2 by the Fuchtbauer–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.