We report the experimental verification of metamaterial cloaking for a 3D object in free space. We apply the plasmonic cloaking technique, based on scattering cancellation, to suppress microwave scattering from a finite-length dielectric cylinder. We verify that scattering suppression is obtained all around the object in the near- and far-field and for different incidence angles, validating our measurements with analytical results and full-wave simulations. Our near-field and far-field measurements confirm that realistic and robust plasmonic metamaterial cloaks may be realized for elongated 3D objects with moderate transverse cross-section at microwave frequencies.
Very recently Farhat et al (2011, Phys. Rev. B 84 235105) suggested that arrays of invisibility cloaks may find important applications in low-interference communication, noninvasive probing, sensing and communication networks and so on. We report on the first experimental realization of such an array of broadband invisibility cloaks that operates in the visible frequency range. The wavelength and angular dependences of the cloak array performance have been studied.
Perfect imaging with Maxwell's fish eye opens the exciting prospect of passive imaging systems with a resolution no longer limited by the wave nature of light. But it also challenges some of the accepted wisdom of super-resolution imaging and therefore has been subject to controversy and discussion. Here we describe an idea for even simpler perfect-imaging systems based on geometrical optics and prove by experiment that it works.
The perfect drain for the Maxwell fish eye (MFE) is a non-magnetic dissipative region placed in the focal point to absorb all the incident radiation without reflection or scattering. The perfect drain was recently designed as a material with complex permittivity that depends on frequency. However, this material is only a theoretical material, so it cannot be used in practical devices. The perfect drain has been claimed as necessary for achieving super-resolution (Leonhardt 2009 New J. Phys. 11 093040), which has increased the interest in practical perfect drains suitable for manufacturing. Here, we present a practical perfect drain that is designed using a simple circuit (made of a resistance and a capacitor) connected to the coaxial line. Moreover, we analyze the super-resolution properties of a device equivalent to the MFE, known as a spherical geodesic waveguide, loaded with this perfect drain. The super-resolution analysis for this device is carried out using COMSOL Multiphysics. The results of simulations predict a super-resolution of up to λ/3000.
A novel reverse design schematic for designing a metamaterial magnifier with graded negative refractive index for both the two-dimensional and three-dimensional cases has been proposed. Photorealistic rendering is integrated with trace ray trajectories in example designs to visualize the scattering magnification as well as imaging of the proposed graded-index magnifier with negative-index metamaterials. The material of the magnifying shell can be uniquely and independently determined without knowing beforehand the corresponding domain deformation. This reverse recipe and photorealistic rendering directly tackles the significance of all possible parametric profiles and demonstrates the performance of the device in a realistic scene, which provides a scheme to design, select and evaluate a metamaterial magnifier.