Dielectric resonator nano-antennas: A pathway to efficient optical antennas

The tremendous advances in nano-fabrication techniques in the last decades have opened huge opportunities for the creation of structures that manipulate light at sub-wavelength scales. In particular, the development of resonant “optical antennas” has evolved from being scientific curiosities, e.g. the infrared antennas of the 1990´s [1], to become a hot topic of research today [2]. Optical antennas usually concentrate fields from an incident free-space wave into a very small area (feed), or act as resonant scatterers in an array configuration. They open new perspectives with promising applications in sub-diffraction sensing, spectroscopy, lightemission, solar power collection, or on-chip communications. They also allow the realization of flat nano-structured optical components inspired from microwave technologies such as reflectarrays, lens-arrays or frequency-selective surfaces.