Resonant dielectric metasurfaces: active tuning and nonlinear effects

Resonant dielectric metasurfaces were extensively studied in the linear and static regime of operation, targeting mainly wavefront shaping, polarization control and spectral filtering applications. Recently, an increasing amount of research focused on active tuning and nonlinear effects of these metasurfaces, unveiling their potential for novel nonlinear and reconfigurable optical devices. These may find many applications in imaging systems, compact adaptive optical systems, beam steering, holographic displays, and quantum optics, to just name a few. This review provides an overview of the recent progress in this field. Following a general introduction to resonant dielectric metasurfaces, the current state-of-the-art regarding the enhancement and tailoring of nonlinear frequency conversion processes using such metasurfaces is discussed. Next, we review different approaches to realize tunable dielectric metasurfaces, including ultrafast all-optical switching of the metasurface response. Finally, future directions and possible applications of nonlinear and tunable dielectric metasurfaces will be outlined.