Infrared to visible upconversion in Pr3+-doped KPb2Cl5 crystal

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 D-1(2) level, and less intense blue, green, and red emissions from the P-3(0.1) levels have been observed under infrared excitation inside the (1)G(4) level and compared with those obtained under one photon excitation. The upconverted fluorescence from the D-1(2) 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 P-3(0) is nearly cubic, which indicates a three photon mechanism. The possible excitation mechanisms responsible for these upconversion processes are discussed. (C) 2003 Elsevier B.V. All rights reserved.