The spectroscopic properties of Er 2 O 3 -doped PbO–Ga 2 O 3 –GeO 2 glasses were investigated. The measured lifetime and stimulated emission cross-section of the 4 I 13/2 level were 4.73±0.05ms and 6.8×10 −21 cm 2 , respectively. The measured lifetime and stimulated emission cross-section were 0.31±0.02ms and 1.9×10 −21 cm 2 for the 4 I 11/2 level, respectively. The lifetimes of 4 I 13/2 levels were almost constant up to the Er 3+ concentration of ∼1.3×10 20 cm −3 . The constant α (6) for energy migration of the 4 I 13/2 level was considerably higher than that of the 4 I 11/2 level. On the other hand, the coefficient of cooperative upconversion for the 4 I 13/2 level was 10 4 times smaller than that for the 4 I 11/2 level at the concentration of 2.57×10 20 cm −3 . These results suggest that the contribution of the migration-accelerated energy transfer among Er 3+ ions to the non-radiative transition from the 4 I 13/2 level is larger than that from the 4 I 11/2 level, whereas the non-radiative transition from the 4 I 11/2 level is mainly due to the cooperative upconversion effect via 4 I 11/2 : 4 I 11/2 → 4 F 7/2 : 4 I 15/2 process. The obtained results also indicate that the PbO–Ga 2 O 3 –GeO 2 glass is a good candidate for short optical fiber amplifiers.