Experimental evidence for quantum cutting co-operative energy transfer process in Pr/Yb ions co-doped fluorotellurite glass: dispute over energy transfer mechanism.

Pr/Yb doped materials have been widely reported as quantum-cutting materials in recent times. However, the question of the energy transfer mechanism in the Pr/Yb pair in light of the quantum-cutting phenomenon still remains unanswered. In view of that, we explored a series of Pr/Yb co-doped low phonon fluorotellurite glass systems to estimate the probability of different energy transfer mechanisms. Indeed, a novel and simple way to predict the probability of the proper energy transfer mechanism in the Pr/Yb pair is possible by considering the donor Pr ion emission intensities and the relative ratio dependence in the presence of acceptor Yb ions. Moreover, the observed results are very much in accordance with other estimated results that support the quantum-cutting phenomena in Pr/Yb pairs, such as sub-linear power dependence of Yb NIR emission upon visible ∼450 nm laser excitation, integrated area of the donor Pr ion's visible excitation spectrum recorded by monitoring the acceptor Yb ion's NIR emission, and the experimentally obtained absolute quantum yield values using an integrating sphere setup. Our results give a simple way of estimating the probability of an energy transfer mechanism and the factors to be considered, particularly for the Pr/Yb pair.