Influence of La2O3 on the structural and luminescence properties in Er3+/Ho3+ co-doped TeO2-BaF2-ZnF2 glass

Abstract

In this study, Er³⁺/Ho³⁺ co-doped fluorotellurite glass (TeO₂-BaF₂-ZnF₂) were prepared by high-temperature melting method. With the introduction of the network modifier La₂O₃, the optical active center (Er³⁺/Ho³⁺) was improved, leading to the enhancement of 2.7 μm emission. Raman spectra and DSC curve were utilized to evaluate the structural of glass and thermal stability of the glass. La³⁺ ions increase the thermal stability (ΔT = 147 °C) of the glass, accelerates the transition from [TeO₄] to [TeO₃₊₁]/[TeO₃] in the glass. Under 808 nm excitation, the maximum fluorescence intensity of 2.7 μm at the La₂O₃ concentration of 6 mol%. La³⁺ ions lead to a more compact network structure. Meanwhile, the luminescent center coordination environment is improved, thus reducing the energy loss of ion resonance. The fluorescence intensity of 2.7 μm is enhanced. In addition, a large emission cross-section (8.29 × 10⁻²¹ cm⁻²) and gain coefficient (7.43 cm⁻¹) were obtained. The forward energy transfer coefficient C_D-A (Er³⁺:⁴I_13/2→Ho³⁺:⁵I₇) in the glass is 2.39 × 10⁻⁴⁰ cm⁶/s. The results show that the introduction of La₂O₃ improves the luminescence efficiency of this system of glass in the ∼2.7 μm band. Er³⁺/Ho³⁺ co-doped fluorotellurite glass (TeO₂-BaF₂-ZnF₂) glass modified by La₂O₃ is an ideal gain medium material for mid-infrared fiber lasers.