INFRARED-TO-VISIBLE UPCONVERSION IN RARE EARTH DOPED LATTICES

Abstract

The visible emission of $Yb^{3+}$, $Er^{3+}$ doped crystals in powder form under IR excitation has been studied. Both continuous and pulsed excitation were used. On the basis of the well characterized mechanisms operative in the $Yb^{3+}$, $Er^{3+}$, system, $Yb^{3+}$, $Ho^{3+}$ and $Y^{3+}$, $Tm^{3+}$, doped crystals were studied and the data analyzed to clarify the processes occurring in these latter upconverting phosphors. These materials provide an excellent opportunity Co Look at inter-ionic energy transfer mechanisms in crystals. The types of energy transfer processes occurring in the systems studied will be outlined along with the radiative and nonradiative deactivation processes we have detected. Some of the generalizations that are reached should be applicable to other situations not involving upconversion.