Plasmonic emission of hybrid Au/Ag bullseye nanostructures

Abstract

Bullseye nanostructures with different central disk diameters and numbers of concentric rings have been fabricated in Au/Ag metallic films on glass substrates by focused ion beam milling. The Au/Ag bimetallic nanoresonator is expected to provide chemical stability and outstanding plasmonic property. A novel hybrid plasmonic emission has been observed by cathodoluminescence in the scanning electron microscope. It is found that the hybrid plasmon amplitude of the bullseye structure highly depends on the excitation position. The plasmonic intensity is the maximum when the beam is located at the edge of the central disk, and it can be tuned by selecting the disk size and the number of grooves. Additionally, the finite element simulation reveals that the bimetallic bullseye structure strongly confines the optical radiation, and the electric field distribution directly relates to the emission wavelength.