Improvement of spectroscopic properties and luminescence of Er3+ions in phospho-tellurite glass ceramics by formation of ErPO4 nanocrystals

Abstract

Er3+ doped phospho-tellurite glass was prepared by melt-quenching method. A limited partial crystallization of the glass samples was controlled by thermal annealing process in order to obtain a transparent glass-ceramic. The X-ray diffraction (XRD) patterns indicate the precipitation of nanocrystalline phases after heat treatment. A particular interest is devoted to the formation of ErPO4 nanoparticles (NPs) dispersed in the glassy host. The optical band gap (Eg) has been found to decrease from 3.37 to 2.75eV as the sample changes from glass to glass-ceramic. The Judd–Ofelt (JO) phenomenological intensity parameters (Ω2, Ω4, Ω6) have been estimated by means of the absorption spectrum. Radiative parameters of Er3+ ions have been predictedusing JO intensity parameters. Significant improvements of both the near infrared emission relative to the 4I13/2 → 4I15/2 transition and the corresponding luminescence lifetime were obtained after heat treatment. We show that an efficient excitation transfer occurs from the formed ErPO4 NPs to Er3+ ions. The Mc-Cumber method is used to calculate the absorption cross-section σa, the emission cross-section σe and the gain cross-section G(λ) relative to the 4I13/2 → 4I15/2 transition.Compared with other glass hosts, the results indicate that erbium doped phospho-tellurite glass-ceramic has good prospect as a gain medium applied for 1.53 μm band broad and high-gain erbium-doped fiber amplifiers (EDFA).