Mid-infrared emission characteristics and energy transfer processes in doubly doped Tm, Tb: KPb2Br5 and Tm, Nd: KPb2Br5

We present spectroscopic studies on the ∼5 μm mid-infrared emission and energy transfer properties of Tb3+ doped KPb2Br5 and Nd3+ doped KPb2Br5 sensitized by Tm3+ ions. A series of co-doped Tm, Tb: KPb2Br5 and Tm, Nd: KPb2Br5 samples were prepared from purified starting materials of PbBr2, KBr, and rare-earth bromides. Resonant excitation into the 3H6 → 3F4 absorption transition of Tm3+ at ∼1.76 μm 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 in KPB 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.