Based on two-step coordinate transformation along the radial direction,an optical device with three functions is proposed.The proposed device functions as a transparent device,a vision-enabling internal cloak,and a movement-allowing external cloak.The general expressions of material parameters for the optical device are determined,and each function of the device is confirmed using full-wave simulation.The effect of material loss on device performance is also investigated.Future applications for the proposed device include antenna protection and military stealth.
We propose an inverse method to determine the material parameters of a transparent device without any knowledge of the corresponding transformation function. The required parameters are independently obtained and expressed as functions of the introduced generator. Moreover, to remove the inhomogeneity and anisotropy of material parameters, a layered transparent device composed of only homogeneous and isotropic materials is presented based on the effective medium theory. The feasibility of using the layered device in antenna protection is also investigated. Full-wave simulation is carried out for verification. This work paves a new way toward designing metamaterial devices without specifying the underlying coordinate transformation, and has great guiding significance for the practical fabrication of transparent devices.
