Spectroscopic Properties of and Energy Transfer in PbO–Bi 2 O 3 –Ga 2 O 3 Glass Doped with Er 2 O 3

Er 2 O 3 ‐doped PbO‐Bi 2 O 3 ‐Ga 2 O 3 glasses were prepared through the conventional melt‐quenching method, and the energy transfer mechanisms in Er 3+ were investigated. The fluorescent emission at 2.73 μm, which is normally quenched in silicate glasses, became evident because of the low phonon energy of PbO‐Bi 2 O 3 ‐Ga 2 O 3 glasses. The measured lifetime of the upper level of 4 I 11/2 was 0.9 ms, and it decreased to ∼0.6 ms with increased Er 3+ concentration. When the concentration of Er 2 O 3 was 0.05 wt%, the coefficient of the cross‐relaxation rate for the 4 I 11/2 level was ∼18 times larger than that of the 4 I 13/2 level. On the other hand, the interaction parameter of energy migration was considerably larger for the 4 I 13/2 level (∼52 × 10 −40 cm 6 ·s −1 ) compared with the 4 I 11/2 level (∼3.1 × 10 −40 cm 6 ·s −1 ). Therefore, the major energy transfer mechanism associated with the 4 I 13/2 level was migration induced, whereas that for the 4 I 11/2 level was direct cross relaxation of 4 I 11/2 : 4 I 11/2 → 4 F 7/2 : 4 I 15/2 .