Metasurface-based illusion optics

Abstract

Metasurface, an optically thin layer of metarmaterials (MTMs), has recently attracted great interest for its capability to manipulate the phase of a propagating wave [1-3]. Such a surface approach of metamaterials has paved a way to escape from the difficulties in fabricating three-dimension (3D) metamaterials. Recently, optically thin metasurface has been demonstrated to achieve invisibility carpet cloaking devices from microwave [4] to optical frequencies [5]. The present design paradigm of metasurface cloaks is based on using a tailor-made reflection phase profile to compensate the distortion introduced by the curved surface. In the view of light, it is equivalent to reshape a curved to a flat wavefront and vice versa. On the other hand, it is not straight-forward to achieve more complicated transformation optics devices, for example, illusion optics: cloaking an external object and creating a perception of another object with different shape and material properties [6]. Here, we propose a generic metasurface design scheme to achieve illusion optics. In particular, we are interested on the realizations using completely passive metasurfaces. Our simulation results show that the passive metasurfaces can already conceal an external object as well as restore another object with a tolerable range of incident angles. Our scheme for metasurface-enabled illusion optics provides an alternative way for performing transformation optics applications beyond a carpet cloak.