Up-conversion and 2 µm mid-infrared emission effective enhancements in Ho3+/Yb3+ co-doped tellurite glass

Rare-earth ions doped fiber lasers at 2 µm can supply various applications in daily life. In this paper, Ho3+/Yb3+ co-doped tellurite glasses were prepared by the high temperature melting method to obtain a strong 2 µm mid-infrared fluorescence emission. The characterization results of the X-ray diffraction (XRD) and differential scanning calorimeter (DSC) show that this glass possesses good crystallization resistance and thermal stability, and its ΔT is 136 °C, which can be successfully drawn. Under the 980 nm LD excitation, strong green (550 nm) and red (660 nm) up-conversion emission were obtained, meanwhile, intensive 2 µm mid-infrared emission was also achieved, and the emission intensity was significantly improved with the increase of Yb3+ concentration, when the Yb3+ content was 2.0, the 2 µm mid-infrared emission intensity was increased by about 28% compared with the content of 0.5, it should be noted that the concentration of Yb3+ is required to be strictly controlled to prevent concentration quenching. In addition, the luminescence process of Ho3+ was further elaborated through the energy transfer mechanism. All results indicate that the Ho3+/Yb3+ co-doped tellurite glass can be an attractive candidate for up-conversion and mid-infrared fiber laser materials.