optical antenna:
Optical antennas are an emerging concept in physical optics. Similar to radiowave
and microwave antennas, their purpose is to convert the energy of free
propagating radiation to localized energy, and vice versa. Optical antennas exploit
the unique properties of metal nanostructures, which behave as strongly
coupled plasmas at optical frequencies. The tutorial provides an account of the
historical origins and the basic concepts and parameters associated with optical
antennas. It also reviews recent work in the field and discusses areas of application,
such as light-emitting devices, photovoltaics, and spectroscopy.