The development of nonlinear nanoantennas that strongly interact with the incoming light to transform its frequency, radiation, and polarization patterns, has been an active field of research. However, after more than a decade of intensive research in the area of nonlinear plasmonic nanoantennas, these nanostructures have been almost abandoned due to nonradiative Ohmic losses. High-index semiconductor and dielectric nanoantennas have shown to overcome this challenge because of their negligible losses and their ability to exhibit Mie-type resonances.
My PhD project is focused in the generation and control of nonlinear signals from high-quality semiconductor nanoantennas. In this seminar, I will demonstrate the capability of AlGaAs nanoantennas to emit second harmonic signals in preferential directions and simultaneously generate complex vector polarized beams when excited by a linearly-polarized excitation beam. Furthermore, by rotating the linearly-polarized excitation beam, we can control the continuous transition between electric and magnetic nonlinearities. I will also discuss the effect of cylindrical vector beam excitation used to observe resonant harmonic generation driven by anapole-like modes as well as to determine the crystal orientation of a nanoantenna from a single scanning map. These techniques will potentially open new opportunities for sensing and nonlinear imaging applications.