We report on the 5 μm emission characteristics and energy transfer properties of Tb3+ doped KPb2Br5 and Nd3+ doped
KPb2Br5 sensitized by Tm3+ ions. A series of co-doped samples of Tm,Tb: KPb2Br5 and Tm,Nd: KPb2Br5 samples were
prepared from purified starting materials of PbBr2, KBr, and rare earth halides. Resonant excitation into the 3H6 → 3F4
absorption transition of Tm3+ at ~1760 nm resulted in an enhanced 5 μm emission from Tb3+ and Nd3+ ions in Tm,Tb:
KPb2Br5 and Tm,Nd: KPb2Br5, respectively. The existence of energy transfer between Tm → Tb and Tm → Nd was
further evidenced by the quenching of the emission decay times of the 3F4 → 3H6 transition of Tm3+ in doubly doped
Tm,Tb: KPb2Br5 and Tm,Nd: KPb2Br5 compared to singly doped Tm: KPb2Br5.