A simplified approach to 3D spherical cloaking using shell based dielectric metamaterials.

In the past, all the cloaks based on transformation optics or scattering cancellation posed some insufficiencies, for example, only two-dimensional concealment in experiments for the transformation-optics-based cloak and custom made and small hidden objects for scattering cancellation. Therefore, in this work, we proposed a spherical reciprocal cloak composed of shell-based dielectric metamaterials that could be realized by sophisticated ceramic manufacturing procedure. Field distributions of the integrated reciprocal cloaks without and with multiple objects suggested that although some scattering fields appeared, yet, the normalized differences of the scattering cross section when hidden objects were put within the cloak were only 8.44% and 1.11% along θ and ϕ directions, and field distributions for the cloak without and with hidden objects revealed an average relative deviation of 7.2%, demonstrating the capability of the cloak to conceal multiple different objects. Furthermore, the design procedure of the reciprocal cloak was further simplified since the thicknesses of the shell played the major role in the performances of the cloak and were the same within the same regime according to the previous simulation results. Again, the simplified cloak demonstrated the normalized differences of the scattering cross section of 29.93% and 4.58% along θ and ϕ directions and an average relative deviation of 6.1%. We believe such design strategy could be extended to other transformation optics based optical devices such as concentrators, rotators, illusion devices, etc., and pave a route toward a practical three-dimensional concealment in the field of stealth technology.