Er,Yb

LaF₃:Er,Yb structures were synthesized and studied for their optimal optical properties. We have taken a systematic approach in identifying the mechanism by which the radiative energy levels are populated – a topic of dispute for the erbium-ytterbium doped system. Up-conversion emissions of ²H_11/2 and ⁴S_3/2 are populated by a two-photon absorption process from 980nm excitation. Long lifetimes of these energy levels have been observed by fluorescence-lifetime, and have allowed for the quantum-yield (QY) measurements on the population of ⁴F_9/2 and ²H_9/2 coinciding to red, and blue emitting states, respectively. Furthermore, the increase in down-conversion emissions; namely, the ⁴I_13/2–⁴I_15/2 (1541 nm), and ⁴I_11/2–⁴I_13/2 (2755) nm states; have also been investigated under 980 nm excitation, and their QY has been analyzed to provide an understanding on the structural dependence on low-energy radiative emissions.