ABSTRACT
Fano resonances and optical vortices are two well-known in-
terference phenomena associated with the scattering of light.
Usually, these two phenomena are considered to be completely
independent, and in many cases, Fano resonances are observed
without vortices and the vortices with the singular phase structure
are not accompanied by Fano resonances. However, this situation
changes dramatically when we move to the nanoscale. In this
chapter, we demonstrate that Fano resonances observed for the
light scattering by nanoparticles are accompanied by the singular
phase effects (usually associated with topological optics) and the
generation of optical vortices with the characteristic core size well
beyond the diffraction limit. Such effects are found for weakly
dissipative metallic nanoparticles within the Mie theory. Important
peculiarities of the far-field scattering and near-field Poynting flux
are manifested in the so-called “nano-Fano resonances” introduced
and discussed here. Control of the orbital momentum of photons
with the help of nanostructures is a novel research direction, which
is very attractive for many applications in quantum optics and
information technologies, and it opens an unprecedented way for
manipulating optical vortices at the nanoscale.
