Fig. 4From: Excitation-Power-Dependent Upconversion Luminescence Competition in Single β-NaYbF4:Er Microcrystal Pumped at 808 nma The ratios of R/G for single β-NaYbF4:x%Er microcrystal doped with different Er3+ concentrations as a function of the excitation intensity. b The UCL spectra of single β-NaYF4:2%Er microcrystal under the excitation of 808 nm CW laser with different excitation densityBack to article page