Modern high-resolution lithography techniques enable the fabrication of nearly arbitrarily designed metal or dielectric nanoparticles. Such particles can show strong light-matter interaction. The plasmonic characteristics of nanoparticles depend strongly on their shape and therefore can be tailored very precisely. Benefitting from a subtle arrangement of several nanoantennas, the plasmonic effects can be enhanced or used for the realisation of novel optical devices, e.g. flat lenses.
While a characterization of fabricated nanoantennas via far field optical spectroscopy reveals information about an ensemble of such antennas, electron energy loss spectroscopy (EELS) permits the measurement of plasmonic fingerprints of single nanoparticles in a transmission electron microscope (TEM). The obtained results can be compared with theoretical calculations.