Electromagnetic metasurface
An electromagnetic metasurface is an artificially engineered, two-dimensional material designed to control the behavior of electromagnetic waves through arrays of subwavelength features. Unlike bulk metamaterials, which achieve unusual properties through three-dimensional structuring, metasurfaces manipulate waves at an interface by imposing abrupt changes in amplitude, phase, or polarization.
Source: Wikipedia — Electromagnetic metasurface (CC BY-SA 4.0)