Controllable and white upconversion luminescence in LiNbO3:Ln3+ (Ln = Ho, Yb, Tm) single crystals

Ho3+, Yb3+ and Tm3+ tri-doped LiNbO3 single crystals with various dopant concentrations were prepared by Czochralski method. Controllable and white upconversion emissions are generated under 980 nm excitation at room temperature. The variations of upconversion spectra and CIE coordinates with dopant concentrations and pump powers are studied in details on the basis of energy transfer processes. Ideal white-light emissions can be obtained even though the pump power is varied from 100 to 900 mW. Based on the present experiments, great inspirations are given in realizing the target color of interest by varying dopant concentrations and pump powers.