Average phonon energy governs Mid-IR performance in thermally stable Ta2O5-modified TeO2-ZnO-Na2O glass

The TeO 2 -ZnO-Na 2 O glass system demonstrates significant promise for mid-infrared laser applications due to its high refractive index and low phonon energy, although it is inherently limited by poor thermal stability. Traditional methods aimed at enhancing thermal stability, such as the incorporation of intermediates, typically result in compromised optical performance. However, this study introduces a synergistic optimization strategy through strategic Ta 2 O 5 doping. A systematic analysis utilizing Differential Scanning Calorimetry (DSC), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), and photoluminescence (PL) spectroscopy has uncovered a novel correlation between optical performance and average rather than maximum phonon energy. This discovery provides a refined theoretical framework for the design of tellurite glasses. The optimized Tm 3 -doped TZNT4 glass, with a glass transition temperature ( T g ) of 388 °C and a thermal stability range ( ΔT ) of 137 °C, demonstrates excellent absorption (9.1 ×10 −21 cm 2 ) and emission cross-sections (7.1 ×10 −21 cm 2 ) at 2 μm. This work establishes a structure-property-performance paradigm for tellurite glasses, effectively addressing the critical trade-off between thermal robustness and mid-infrared emission performance through rational composition engineering.