Enhancing yellow-green emission in Eu/Tb co-doped tellurite glasses controlled by Lu2O3

In this research, Lu₂O₃ was incorporated into Eu³⁺ and Tb³⁺ co-doped tellurite glasses to enhance structural stability and modify the yellow-green emission. A series of microstructural analyses, including Differential Scanning Calorimetry (DSC), Raman spectroscopy, and density measurements, confirmed that the addition of Lu₂O₃ causes the long-chain or cyclic Te–O–Te network structure to break, resulting in the formation of more [TeO₃], which in turn leads to an increase in non-bridging oxygens (NBO) and lowers the phonon energy of the matrix material. Fluorescence spectral characterization revealed that both green and yellow luminescence intensities peaked when Lu₂O₃ concentration reached 15 %. Additionally, the Judd-Ofelt theory supports its superior laser performance. With the addition of Lu₂O₃,The radiative transition probability (Arad), lifetime (τ_rad), and branching ratio (β) of the excited states of Tb³⁺ and Eu³⁺ have all been enhanced. Under the regulation of 15 % Lu₂O₃, The maximum absorption cross-section of at 544 nm is 1.88 × 10⁻²⁰ cm², and the maximum emission cross-section is 2.14 × 10⁻²⁰ cm². At 611 nm, the maximum absorption cross-section is 1.05 × 10⁻²⁰ cm², and the maximum emission cross-section is 1.44 × 10⁻²⁰ cm². The decay curve indicates a fluorescence lifetime enhancement from 0.6 ms to 1 ms with Lu₂O₃. These results underscore the potential of Lu₂O₃ modulated Eu³⁺/Tb³⁺ co-doped tellurium glass as an effective yellow-green laser gain medium.