Multicolor up-conversion luminescence in Rare-Earth doped NaLaF₄

In this work we tried to achieve multicolor up-conversion luminescence in low phonon energy material NaLaF₄ doped with different Er ³⁺ Tm³⁺ and Yb³⁺ concentrations. Up-conversion luminescence was measured and main luminescence bands from Er³⁺ and Tm³⁺ in red, green and blue spectral regions were observed. The relative intensities of the luminescence bands could be changed by changing the doping levels of rare-earth ions. Changes in the up-conversion luminescence color could be achieved by applying different infrared pump power density. The color coordinates of the multicolor up-conversion luminescence depending on doping level as well as on the pump power density were presented in CIE (x, y) chromaticity diagram (1931).