2.0 μm band emission enhancement and energy transfer in Ho3+/Yb3+/Er3+ tri-doped tellurite glasses

Improving the infrared-band luminescent property of rare-earth doped materials is a challenging task. In this work, the enhanced 2.0 mu m band emission study in Ho3+/Yb3+/Er3+ tri-doped tellurite glasses with composition TeO2-ZnO-WO3-La2O3 was given. The tellurite glasses were prepared by conventional melt-quenching technique and characterized by absorption spectrum, emission spectrum, fluorescence decay curve, differential scanning calorimeter (DSC) curve, X-ray diffraction (XRD) pattern and Raman spectrum. The DSC curve displays the good thermal stability with glass transition temperature larger than 420 degrees C, the XRD pattern reveals the amorphous state nature and Raman spectrum clarifies the vibrational units of glass network. Based on the absorption spectrum, important spectroscopic parameters like spontaneous radiative transition probability, radiative lifetime, absorption and emission cross-sections, and gain coefficient are determined to predict the potential luminescent properties in near-infrared band, while the fluorescence spectrum demonstrates the enhanced 2.0 mu m band emission of Ho3+:I-5(7) -> I-5(8) radiative transition aroused by Er3+ introduction. Compared with the Ho3+/Yb3+ co-doped sample, an enhancement of about 93% in 2.0 mu m band emission intensity is appeared in the tri-doped tellurite glass after introducing 0.8 mol% amount of Er2O3 under the excitation of 980 nm. The enhanced 2.0 mu m band emission is attributed to the energy transfers among Yb3+, Er3+ and Ho3+ ions, and fluorescence decay curves together with the energy transfer mechanism are analyzed to elucidate the observed luminescent enhanced phenomena. The results indicate that Ho3+/Yb3+/Er3+ tri-doped tellurite glass possesses excellent 2.0 mu m band luminescent property and can be an attractive candidate for solid-state lasers.