Extremely thin dielectric metasurface for carpet cloaking

Abstract

We demonstrate a novel and simple geometrical approach to cloaking a scatterer on a ground plane. We use an extremely thin dielectric metasurface to reshape the wavefronts distorted by a scatterer in order to mimic the reflection pattern of a flat ground plane. To achieve such carpet cloaking, the reflection angle has to be equal to the incident angle everywhere on the scatterer. We use a graded metasurface and calculate the required phase gradient to achieve cloaking. Our metasurface locally provides additional phase to the wavefronts to compensate for the phase difference amongst light paths induced by the geometrical distortion. We design our metasurface in the microwave range using highly sub-wavelength dielectric resonators. We verify our design by full-wave time-domain simulations using micro-structured resonators and show that results match theory very well. This approach can be applied to hide any scatterer under a metasurface of class C1 (first derivative continuous) on a ground plane not only in the microwave regime, but also at higher frequencies up to the visible.