Ultraviolet and infrared photon-excited synergistic effect in Er3+-doped YbF3 phosphors.

A synergistic effect between UV down-conversion and IR up-conversion is witnessed in YbF3:Er3+ phosphors by employing the dual wavelength (369 nm and 980 nm) excitation source. The synergistic effect originates from an abnormal energy transfer between Er3+ ions, in which the Er3+ ions in metastable states excited by 369 nm photons are excited again by the 980 nm IR photons. The dual wavelength excited red emission intensity is 1.1 times the total red emission intensities from 369 nm and 980 nm single excitation. The synergistic effect refers us to a way to convert both high-energy and low-energy photons into one middle-energy photon with high quantum yield.