Infrared to visible upconversion in Pr3+-doped KPb2Cl5 crystal

Abstract In this work we report the infrared to visible upconversion luminescence in the low phonon-energy host material KPb2Cl5 doped with Pr3+ ions. A strong orange luminescence from the 1D2 level, and less intense blue, green, and red emissions from the 3P0,1 levels have been observed under infrared excitation inside the 1G4 level and compared with those obtained under one photon excitation. The upconverted fluorescence from the 1D2 level shows a quadratic dependence on the pump power indicating a two photon process, whereas the pump power dependence of the blue fluorescence from level 3P0 is nearly cubic, which indicates a three photon mechanism. The possible excitation mechanisms responsible for these upconversion processes are discussed.