Article

# Cylindrical Invisibility Cloak with Simplified Material Parameters is Inherently Visible

Department of Microelectronics and Applied Physics, Royal Institute of Technology, Electrum 229, 16440 Kista, Sweden.
(Impact Factor: 7.51). 01/2008; 99(23):233901. DOI: 10.1103/PhysRevLett.99.233901
Source: PubMed

ABSTRACT

It was proposed that perfect invisibility cloaks can be constructed for hiding objects from electromagnetic illumination [J. B. Pendry, D. Schurig, and D. R. Smith, Science 312, 1780 (2006)10.1126/science.1125907]. The cylindrical cloaks experimentally demonstrated [D. Schurig, Science 314, 977 (2006)10.1126/science.1133628] and theoretically proposed [W. Cai, Nat. Photon. 1, 224 (2007)10.1038/nphoton.2007.28] have however simplified material parameters in order to facilitate easier realization as well as to avoid infinities in optical constants. Here we show that the cylindrical cloaks with simplified material parameters inherently allow the zeroth-order cylindrical wave to pass through the cloak as if the cloak is made of a homogeneous isotropic medium, and thus visible. To all high-order cylindrical waves, our numerical simulation suggests that the simplified cloak inherits some properties of the ideal cloak, but finite scatterings exist.

### Full-text

Available from: Min Qiu, Sep 01, 2014
• Source
• "This singular structure implies not only difficulties in practice, but also in analysis. To avoid using the singular structure, regularized schemes have been proposed in [46] [8] [52] [45] [23] [17]. "
##### Article: On a regularized scheme for approximate acoustic cloaking using transformation optics
[Hide abstract]
ABSTRACT: In this paper, we study approximate cloaking for the Helmholtz equation in 3d where the cloaking device is based on transformations which blow up a cylinder of fixed height and small cross section of radius $\eps$ into the cloaked region. Assuming the zero Dirichlet boundary condition is imposed on the boundary of the cloaked region, we show that the degree of visibility is of order $\eps$ as $\eps$ goes to 0. This fact is quite surprising since it is known that the degree of visibility, for the scheme using transformations which blow up a small region of diameter $\eps$ into the cloaked region, is of order $\eps$ in 3d and $1/ |\ln \eps|$ in 2d. To understand the relation between these contexts, we as well revisit the known estimates and show that the degree of visibility is of order $\eps^{d-1}$ ($d=2,3$) for the scheme using transformations which blow up a small {\it ball} of diameter $\eps$ into the cloaked region as long as the zero Dirichlet boundary condition is imposed on the boundary of the cloaked region. The symmetry of the cross section and of the ball are crucial so that these results hold.
SIAM Journal on Mathematical Analysis 09/2013; 45(5). DOI:10.1137/120902124 · 1.27 Impact Factor
• Source
• "Transformation optics [1], [2] provides a new design methodology allowing unprecedented manipulation of electromagnetic wave propagation, with the invisible cloak as the most prominent example [3] [4] [5] [6]. Besides, a wide variety of applications other than cloaking has been recently presented, such as field concentrators [6], [7], transparent device [8] [9] [10], beam shifters [11], field rotator [12], waveguide bends and corners [13], etc. "
##### Article: Arbitrary Shape Electromagnetic Transparent Device Based on Laplace's Equation
[Hide abstract]
ABSTRACT: Transparent device is deliberately-designed elec-tromagnetic structure that is transparent to electromag-netic wave. It can be used as a radome structure which is capable of protection antenna inside without sacrificing its performance. In this paper, two-dimensional (2D) arbi-trary shape electromagnetic transparent device is designed based on transformation optics. Laplace's equation is adopted to construct the coordinate mapping between the original space and the transformed space. The design method is flexibly extended to three-dimensional (3D) case, which greatly enhances the applicability of transparent device. The protection of a horn antenna is taken as an example to show the effectiveness of the transparent device. Since the performance of the transparent device is independent on the inner antenna, it can be designed sepa-rately. Full-wave simulations are made to validate the results.
Radioengineering 04/2011; 20(1). · 0.65 Impact Factor
• Source
• "Inspired by the pioneering work above, many further investigations on invisible cloaking have been conducted. Chen et al. [10] analysed spherical cloaks analytically in the Mie scattering model; Noor et al. [11] analysed isotropic, homogeneous plasmonic cloak; Zharova et al. [12] investigated the inverse cloak and proposed that the concept could be used as the perfectly matched layers (PMLs); Isic et al. [13] studied the imperfect cylindrical cloak and Yan et al. [14] discussed the cylindrical cloak with simplified parameters. Also, there are many full-wave simulations on the cloak based on the finite-element method (FEM) and/or finite-difference time-domain method [15] [16]. "
##### Article: Electromagnetic characteristics of metamaterial cloak covered dielectric cylinder illuminated by electric line source
[Hide abstract]
ABSTRACT: Electromagnetic characteristics of the dielectric cylinder covered by the cylindrical cloak are investigated in detail. Analytical expressions of electric field are derived and validated. Furthermore, effects of different kinds of loss on the performance of the cloak are studied. It is shown that if loss does not follow the same property as the constitutive tensor of the anisotropic and inhomogeneous cloak, electric fields could transmit into the inner dielectric cylinder. The authors believe that the results are helpful for practical applications.
IET Microwaves Antennas & Propagation 11/2010; 4(10-4):1680 - 1688. DOI:10.1049/iet-map.2009.0256 · 0.91 Impact Factor