Synthesis and NIR-to-violet, blue, green, red upconversion fluorescence of Er3+:LaOBr

The Er3+:LaOBr powder were synthesized by a new NH4Br solid-state reaction, and the structures were studied using XRD and Raman methods. Under 785 nm laser excitation, the upconversion fluorescence spectra in Er3+:LaOBr were recorded and investigated. Four upconverted emission bands centered at about 406 nm (violet), 477 nm (blue), 542 nm (green) and 664 nm (red) were observed. All these upconverted emissions were assigned, and the dominant mechanism was deduced to be excited state absorption. The detailed study of the upconversion processes and the low phonon energy indicate that Er3+:LaOBr would be promising violet and visible upconversion laser materials.