Ultra-Thin Unidirectional Carpet Cloak and Wavefront Reconstruction With Graded Metasurfaces

Using a suitably designed, ultra-thin graded metasurface, we demonstrate the possibility of hiding an arbitrarily shaped/sized object from an impinging plane wave. The metasurface is tailored to provide an abrupt, inhomogeneous discontinuity to the electromagnetic field that compensates for the unwanted scattering created by the object. The desired field distribution is generated based on the equivalence principle through reconstruction of the electric/magnetic fields at the metasurface location, resembling a flat conducting surface for an external observer. We apply this concept to hide electrically large, cylindrical (two-dimensional, 2-D) and spherical (3-D) domes at optical frequencies and discuss practical cloaking designs for microwave and terahertz regimes. The presented graded metasurface-based cloaks may find interesting applications as low-profile, tunable covers for low observability and noise reduction in wireless commutation systems.