The tetraphosphate glasses with Er 3+ and Yb 3+ /Er 3+ dopant were prepared. The absorption and fluorescence emission spectra were measured, and the emission cross-section for 4I 13/2 → 4I 15/2 transition of Er 3+ was calculated by using McCumber theory. Spectroscopic properties, concentration quenching, and the effect of -OH groups on the emission at 1.54 μm in these glasses were investigated with diode laser at 970 nm. The optimization of Yb 3+ and Er 3+ ion concentrations are 1.82×10 21 ions/cm 3 and 0.96×10 20 ions/cm 3 respectively in the glasses.