8 - Nonlinear and ultrafast effects

Abstract

Nonlinear optics is a field that studies how light interacts with light mediated by a material. The signature nonlinear optical effects are generation of optical harmonics and wave-mixing, self-action, and all-optical modulation, and these effects find applications in microscopy, imaging, spectroscopy and all-optical telecommunications. It has been common knowledge for the past decades that light localization in nanostructures can enhance significantly otherwise weak optical nonlinearities. Among the most efficient nonlinear nanostructured materials to date are those made from dielectrics, such as Mie-resonant nanoparticles and their arrangements, often called metasurfaces. The latter have negligible non-radiative losses, can be controlled using free carriers and are compatible with current nanofabrication flows. In this chapter we review the progress in nonlinear all-dielectric nanoantennas and metasurfaces, surveying some of the most important achievements in this area. We describe state-of-the-art designs, fabrication approaches, measurement techniques, as well as key results in efficient frequency conversion, all-optical modulation and other key metrics of nonlinear optical processes. We conclude with an outlook on future directions of research.