Mid-IR spectroscopy of Er3+doped low-phonon CsCdCl3and CsPbCl3crystals

The mid-IR spectroscopic properties of Er3+ doped low-phonon CsCdCl3 and CsPbCl3 crystals grown by the Bridgman technique have been investigated. Using optical excitations at ∼800nm and ∼660nm , both crystals exhibited IR emissions at ∼1.55 , ∼2.75 , ∼3.5 , and ∼4.5µm at room temperature. The mid-IR emission at 4.5 µm, originating from the 4I9/2→4I11/2 transition, showed a long emission lifetime of ∼11.6ms for Er3+ doped CsCdCl3 , whereas Er3+ doped CsPbCl3 exhibited a shorter lifetime of ∼1.8ms . The measured emission lifetimes of the 4I9/2 state were nearly independent of the temperature, indicating a negligibly small nonradiative decay rate through multiphonon relaxation, as predicted by the energy-gap law for low-maximum-phonon energy hosts. The room temperature stimulated emission cross sections for the 4I9/2→4I11/2 transition in Er3+ doped CsCdCl3 and CsPbCl3 were determined to be ∼0.14×10−20cm2 and ∼0.41×10−20cm2 , respectively. The results of Judd–Ofelt analysis are presented and discussed.