Effect of phonon energy on 2 μm emission in Tm3+/Yb3+ co-doped bismuth-tellurite glasses based on WO3 or B2O3 adjustment

Tm3+/Yb3+ co-doped TeO2–Bi2O3–ZnO glass has been synthesized by using the melt-quenching method in this paper. According to Gaussian fitting and J-O theory, the impact of phonon energy on both structure and fluorescence properties has been investigated by introducing different phonon energy oxides. It was shown that various glass network units were observed in Raman spectra. Moreover, the Te–O–Te can be destroyed via the addition of WO3 and B2O3, resulting in [TeO4] transformed to [TeO3] and [TeO3+δ] groups, while thermal stability and fluorescence properties were enhanced. And the phonon energy (ħω0) increased from 758 to 926 (WO3) and 1097 cm−1 (B2O3). Meanwhile, the intensities of the absorption and fluorescence spectra were improved significantly by the change of glass network units. The effective fluorescent bandwidth (Δλeff) was raised from 223 to 227 and 231 nm, and the gain coefficient was from 1.60 cm−1 to 1.71 cm−1 and 1.72 cm−1. Finally, the micro-parameters for energy transfer processes have been calculated by using a spectral overlap method. Results indicate that the energy transfer process between Tm3+ and Yb3+ was more efficient with the high phonon energy oxide introduction (WO3 and B2O3), which provides practical significance that will be beneficial for obtaining the 2 μm high gain material.