Spectroscopy of thulium and holmium heavily doped tellurite glasses

In this study, we report spectroscopic properties of Tm3þ and Ho3þ codoped tellurite glasses over a wide dopant concentration range in order to assess their potential laser performance under 790 nm diode laser excitation. The impact of Tm3þ and Ho3þ concentrations is investigated to identify specific candidates for fiber laser operation. The emission cross section is calculated and discussed, as well as the gain coefficient of this type of glasses. Energy transfer microparameters and critical ion distances are determined for 3H4, 3F4 (Tm3þ), and 5I7 (Ho3þ) emission levels in the framework of diffusionlimited regime and dipole–dipole interaction. We also report thermal properties of tested glasses.