In recent years, there has been renewed interest in engineered ultrathin surfaces (metasurfaces) that can be used to manipulate incident electromagnetic waves with a large degree of control, all the way from microwaves to optics. A particular driver for this interest is the possibility of enabling the control and shaping of light wavefronts using nanostructured metasurfaces, which can be now achieved thanks to modern nanofabrication techniques. Emerging metasurfaces make it possible to tailor both the electric and magnetic response of light with deeply subwavelength resolution, thus offering unprecedented levels of design flexibility and performance. Such metasurfaces can ultimately control and shape the amplitude, phase, and polarization state of the electromagnetic wavefront with extreme precision. Ultimately, reconfigurable metasurfaces may also provide a pathway to the full control of electromagnetic waves at will, with applications from radio frequencies to visible wavelengths and beyond.

This special issue features both invited and contributed papers presenting the latest results and timely overviews on experimental and theoretical efforts exploring several topics of relevant interest in the area of electromagnetic metasurfaces. The presented works include several research highlights: optical metamirrors offering unprecedented possibilities to tailor the local reflection coefficient and its variation across a surface of choice, accurate modeling of tensor metasurfaces to enable ultimate control of the impinging wavefront and unique design capabilities, fabrication of nanostructured optical metasurfaces with 3D nanoscale features, aberration-free flat lenses based on advanced metasurface designs, an optical analog of the Wheatstone bridge enabled by the application of optical nanocircuit concepts based on metasurfaces, the latest advances in nonlinear plasmonic metasurfaces, and the use of these ultrathin structures for femtosecond pulse shaping, and finally the modeling of metascreens to realize the unusual phenomenon of extraordinary transmission. This feature issue also presents two review articles on gradient-index metasurfaces and on Huygens’ metasurfaces, offering an overview of the recent progress in ultrathin structures that enable full vectorial control of electromagnetic waves.

This special issue has the goal of taking a snapshot of the state-of-the-art in this exciting and inherently interdisciplinary research field and inspiring future progress on ultrathin engineered surfaces for radio frequency and optical applications.