Figure 9

Schematic of ordered arrays of GNR@SiO₂@CaF₂:Yb³⁺,Er³⁺ hybrid nanostructure assembled on patterned templates. (a) When the polarization of the excitation laser (deep-red arrow) is parallel to the long axis of the hybrid nanostructures, both the enhanced green and red UC emissions (dictated by green and red arrows, respectively) would have the same polarization as the excitation laser. (b) In the case of the excitation laser with a perpendicular polarization, the resulting green UC emission would have the same polarization as the excitation laser, whereas the polarization of the red emission would be perpendicular to that of the green emission.