Influence of Plasmonic Effect on the Upconversion Emission Characteristics of NaYF4 Hexagonal Microrods.

The influence of plasmonic effect on the upconversion emission characteristics of Yb3+-Er3+-Tm3+ tridoped β-NaYF4 hexagonal microrods is studied. Upconversion spontaneous emission can be improved by 10 times if the microrod is deposited on an Ag-coated substrate. The enhancement is also dependent on the emission wavelength and the polarization of the excitation source. Furthermore, upconversion lasing is supported by the geometry of the microrods via the formation of whispering gallery modes. The corresponding excitation threshold can also be reduced by 50% through the influence of plasmonic effect, the coupling between the whispering gallery modes and the surface plasmonic resonance modes.