Optical metasurfaces based on gap plasmon resonators

Plasmonic metasurfaces, i.e., nm-thin surface metal nanostructures with subwavelength-sized lattice units, that are composed of gap plasmon resonators and used for controlling reflected light are overviewed, emphasizing the unique possibility to simultaneously and independently control the reflection direction of orthogonal linear polarizations as well as to realize efficient unidirectional polarization-controlled surface plasmon-polariton excitation.