Efficient plasmonic functional lens constructed via a nano-dichroic element

Abstract

The plasmonic functional lens can realize an efficient and functional focusing of surface plasmon polaritons (SPPs), making it have great potential in applications including nano-electron point sources, smart pixels, and particle manipulation. Here, we report for the first time a novel plasmonic functional lens constructed via a nano-dichroic element. The results show that the wavelength-selective nano-focusing of SPPs in the plasmonic functional lens can be achieved. Different from the conventional plasmonic lens that equally splits SPP power to propagate inward and outward from the boundaries, the plasmonic functional lens directs all of the SPP power of the matched wavelength inward for the focusing, resulting in higher collecting efficiency and SPP focusing intensity. Furthermore, we have demonstrated that a much higher focal spot intensity can be obtained even under the condition of a smaller inner radius. These findings provide a new way for the design of plasmonic functional lenses and can be facilitated to develop high-efficiency miniaturized focusing devices.