Spectroscopic study of neodymium doped potassium lead bromide for mid-infrared solid state lasers

We present spectroscopic results of the mid-infrared (MIR) emission (4I11/2→4I9/2) properties of neodymium (Nd) doped potassium lead bromide (KPb2Br5). Following optical excitation at either 0.808 or 0.89 μm, Nd:KPb2Br5 showed a broad MIR emission band centered at 5.25 μm with a bandwidth of 0.76 μm at full width half maximum. For low concentration samples (5×1018 cm−3), the emission lifetime was determined to be 43 ms at room temperature and increased to 57 ms at low temperature (15 K). Based on the energy-gap law, non-radiative decay through multi-phonon relaxation is predicted to be negligibly small in this low phonon energy host material with imageωmax=138 cm−1. Therefore, the modest temperature dependence of the MIR lifetime is most likely due to the existence of non-radiative decay related to residual defects in the sample. The peak emission cross-section for the 4I11/2→4I9/2 transition was determined to be 0.65×10−20 cm2. Some comparative results on Nd:KPb2Cl5 were also included in this study.