Enhancing the concentration quenching threshold and mid-infrared emission in Er3+/Yb3+ co-doped fluorotellurite glasses

We aim to investigate the sensitization effect of Yb3+ sensitizer on the mid-infrared luminescence of Er3+ ions at 2.7 μm in fluorotellurite glasses, with particular emphasis on the variation in concentration quenching behavior of Er3+, for the purpose of developing high-performance mid-infrared luminescent materials. A series of glass samples with the nominal composition 65TeO2–15ZnF2–10Nb2O5–5Bi2O3–5La2O3–1Yb2O3–xEr2O3 (mol%) were prepared using the conventional melt-quenching technique. The differential scanning calorimeter results indicate that the average ΔT value for all prepared fluorotellurite glass samples exceeds 133°C, confirming their high thermal stability. The measured full width at half maximum values of the emission bands are 178 nm for 2.7 μm and 212 nm for 3.1 μm, respectively. More importantly, compared with a solely Er3+-doped system, the incorporation of Yb2O3 effectively raises the critical concentration for quenching of Er3+. Even at higher Er3+ concentrations (4.0 mol%), an intense mid-infrared fluorescence can still be detected. The emission cross section calculated by McCumber theory is 1.02×10−20 cm−2, confirming the outstanding laser gain potential of the as-prepared material. This work successfully validates that Yb3+ sensitization is an effective strategy to mitigate concentration quenching under high-concentration Er3+ doping in TeO2–ZnF2-based glasses, thereby enabling strong 2.7 μm luminescence. The developed glass exhibits optimal optical performance when the Er3+ concentration is 4 mol%, making it a highly promising candidate for mid-infrared laser gain applications.