Metamaterial-based optical cloaks have thus far used volumetric distribution of the material properties to gradually bend light and thereby obscure the cloaked region. Hence, they are bulky and hard to scale up and, more critically, typical carpet cloaks introduce unnecessary phase shifts in the reflected light, making the cloaks detectable. Here, we demonstrate experimentally an ultrathin invi...

Acoustic cloak using anisotropic density or pentamode (PM) material is capable of concealing target from any detective acoustic wave. The pentamode material scheme is more promising due to its solid phase feature and broadband efficiency [1, 2]. However, perfect PM material in theory doesn’t have static stability, and therefore some imperfection in practically designed microstructure PM materia...

The performance of simplified cylindrical cloaks with various material parameters was investigated. The performance metric was the overall scattering width of the cloak with various objects in the hidden region. COMSOL was used to simulate three cloaks with different material parameters to determine the total field in the simulation domain. The fields were then transformed to the far zone and s...

Metamaterial cloaks control the propagation of waves to make an object invisible or insensible. To manipulate elastic waves in space, a metamaterial cloak is typically embedded in a base system that includes or surrounds a target object. The embedding is undesirable because it structurally weakens or permanently alters the base system. In this study, we propose a new add-on metamaterial elastic...

As invisibility cloaking has recently become experimental reality, it is interesting to explore ways to reveal remaining imperfections. In essence, the idea of most invisibility cloaks is to recover the optical path lengths without an object (to be made invisible) by a suitable arrangement around that object. Optical path length is proportional to the time of flight of a light ray or to the opt...