Infrared to visible and ultraviolet upconversion processes in Nd3+-doped potassium lead chloride crystal

Abstract Infrared to visible and ultraviolet upconversion in Nd 3+ doped KPb 2 Cl 5 crystal is reported. Three intense bands have been observed at 535, 595, and 668 nm coming mainly from levels 4 G 7/2 – 4 G 9/2 , together with emissions at 362, 388, 420 and 456 nm coming from level 4 D 3/2 , and a peak at 435 nm, corresponding to the 2 P 1/2 → 4 I 9/2 transition. A study of the upconversion mechanisms has been carried out that includes the upconversion emission dependence on the wavelength and intensity of the pumping light together with a comparison of the luminescence decays after infrared excitation and after direct one photon excitation of the emitting levels. The results indicate that two- and three-body energy transfer upconversion processes are responsible for emissions from levels 4 G 7/2 – 4 G 9/2 and 4 D 3/2 respectively, while level 2 P 1/2 is populated by either energy transfer upconversion or excited state absorption depending on the pumping wavelength.