Focused scalar and vector Laguerre-Gauss beams in nanophotonics

Breaking the paraxial approximation leads to unusual phenomena in optics, that can become of relevance to light-matter interactions at the nanoscale. Tight focusing may either result in unusual behaviour of the electromagnetic field in such strongly nonparaxial scenarios or be exploited for harnessing novel optical properties of nanomaterials. In this talk, we will discuss experimental and theoretical results on the properties of tightly focused complex beams, which can be either scalar or vectorial in nature. Their propagation in free space can lead to the emergence of novel angular momentum properties of light, while their interaction with plasmonic anisotropic metamaterials can be used for manipulation of high-order modes contained in Laguerre-Gauss beams, polarization control and beam shaping. These effects rely on the longitudinal and higher-order transverse fields generated by the focused beam, which in turn depends on the polarization and modal content of the beam itself. Their understanding can pave the way for the next generation of nanophotonic devices for beam shaping and polarization control.