Functional plasmonic nanoantennae as optical filters

Plasmonic nanoantennae are important candidates for metamaterials in the visible range. However, the fabrication of dense nanoantennae with various designs and small dimensions is still very challenging for nanoscale features with high aspect ratios. Demonstrated is a series of geometries of plasmonic nanocrystals with different designs and ultrasmall gaps using a one-step focused ion beam milling process. Optical characterisation of plasmonic nanoantennae has also been carried out to investigate the underlying physics. Theoretical calculations were also performed to verify the experimental results. The high fabrication quality nanostructures demonstrated may enable new applications in nanophotonics, giving rise to new opportunities for nanodevices.