Abstract
In this work we report the upconversion luminescence of Pr3+ doped Kpb2Cl5 crystal upon excitation in the near infrared region inside the 1G4 level. Direct excitation in the visible region has been also carried out. A strong orange luminescence from the 1D2 leve, and a less intense blue, green, and red emission from the 3P0,1 levels have been observed under infrared excitation 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 (2.62), which indicates a three photon mechanism. Emission from levels 3P0,1 is also observed under pulsed excitation in the 1D2 state. The possible excitation mechanisms responsible for these upconversion processes are discussed.