Optical antennas to control light at the nanoscale

The diffraction limit seems to impose a limit on light confinement, making it apparently impossible to localize or manipulate light in dimensions much smaller than the wavelength. However, this limitation is not fundamental, with metallic optical antennas emerging as a very attractive option. These nanostructures respond to visible and infrared light in a similar manner as conventional antennas to radio or microwaves. As a fundamental difference, exciting the metallic structures at optical frequencies leads to resonant oscillations of the free electrons called plasmons, which are behind an often surprising behavior. On the other hand, there is a growing interest in using dielectric nanoantennas, which have the advantages of not suffering from absorption losses.

The objective of the internship will be to better understand the fundamental principles behind the optical response of optical nanoantennas and to identify possible limitations. The student will use analytical methods and numerical simulations to study aspects such as the effective volume of the excited mode or the directionality of the emitted light. As an example of a research question to be studied, we are interested in analyzing the ultimate energy confinement achievable with dielectric nanoantennas, which is of importance for quantum optics.