Recent twists in twisted light: A Perspective on optical vortices from dielectric metasurfaces

Abstract

Optical vortices are the electromagnetic analogue of fluid vortices studied in hydrodynamics. In both cases, the traveling wavefront, either made of light or fluid, is twisted like a corkscrew around its propagation axis - an analogy that also inspired the first proposition of the concept of optical vortices. Even though vortices are one of the most fundamental topological excitations in nature, they are rarely found in their electromagnetic form in natural systems, for the exception of energetic sources in astronomy, such as pulsars, quasars, and black holes. Mostly, optical vortices are artificially created in the laboratory by a rich variety of approaches. Here, we provide our Perspective on a technology that shook up optics in the last decade - metasurfaces, i.e., planar nanostructured metamaterials - with a specific focus on its use for molding and controlling optical vortices.