Upconversion luminescence and mechanisms in Yb-sensitized Tm-doped oxyhalide tellurite glasses

Effect of Yb₂O₃ content on upconversion luminescence and mechanisms in Yb³⁺-sensitized Tm³⁺-doped oxyhalide tellurite glasses were investigated under 980 nm excitation. Intense blue and relatively weak red upconversion emission centered at 476 and 649 nm corresponding to the transitions ¹G₄→³H₆ and ¹G₄→³H₄ of Tm³⁺, respectively, are simultaneously observed at room temperature. The results show that upconversion blue and red emission intensities of Tm³⁺ first increase, reach its maximum at Yb₂O₃%=3 mol%, and then decrease with increasing Yb₂O₃ content. The effect of Yb₂O₃ content on upconversion intensity is discussed, and possible effect mechanisms are evaluated. The investigated results were conducing to increase upconversion luminescence efficiency of Tm³⁺.