Fig. 2From: Excitation-Power-Dependent Upconversion Luminescence Competition in Single β-NaYbF4:Er Microcrystal Pumped at 808 nmThe UCL spectra of single a β-NaYF4:98%Yb,2%Er, and b β-NaYF4:20%Yb,2%Er microcrystal under the excitation of 808 nm CW laser with different excitation density. The insert UCL photographs are corresponding to the relevant spectrum, respectivelyBack to article page