Comparative study of the spectroscopic properties of Yb3+/Er3+ codoped tellurite glasses modified with R2O (R=Li, Na and K)

► R2O modifier on spectroscopic properties of Yb3+/Er3+ codoped tellurite glasses. ► K2O improves ion solubility and reduces quenching concentration. ► Li2O increases emission cross-section but decreases fluorescence signal. ► Laser glasses can be designed by properly choosing the alkali metal modifier.