Extending the bandwidth of electromagnetic cloaks

Chen, Huanyang; Liang, Zixian; Yao, Peng-Fei; Jiang, Xunya; Ma, Hongru; Chan, Che Ting

doi:10.1103/physrevb.76.241104

Cited by 150 publications

(108 citation statements)

References 21 publications

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“…Other kinds of simplifications have also been considered, including those based on high order transformations to minimize the inherent reflection at the outer surface of the simplified cloak [8,9], or the use of simplified parameters for non-magnetic optical cloaks [10]. Further analytical scattering models of imperfect cloaks [11][12][13][14][15][16][17][18] and theoretical studies on other intrinsic problems associated with cloaks [19][20][21][22][23][24][25][26][27][28] and transformation optics [29][30][31][32][33] have also been presented [18][19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Ultrathin Cylindrical Cloak

Zhang¹,

Mortensen²

2011

PIER

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Abstract-We propose a cylindrical invisibility cloak achieved utilizing two dimensional split-ring resonator structured metamaterials at microwave frequencies. The cloak has spatially uniform parameters in the axial direction, and can work very well even when the cloak shell is very thin compared with the concealed object and the working wavelength. Numerical simulation is performed to verify the functionality of the cloak, where the cloak layer is only around 1/4 of the operating wavelength. Our work provides a feasible solution to the experimental realization of cloaks with ideal parameters.

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Section: Introductionmentioning

confidence: 99%

Ultrathin Cylindrical Cloak

Zhang¹,

Mortensen²

2011

PIER

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“…Recently, Chen et al [11] have investigated a transformation medium aiming at extending the bandwidth of an invisibility cloak. To do so, the frequency dispersion of the metamaterial was taken into account through a Lorentz material model, resulting in a dispersive cloak.…”

Section: Introductionmentioning

confidence: 99%

An Extended FDTD Method for the Analysis of Electromagnetic Field Rotators and Cloaking Devices

Silva-Macêdo¹,

Romero²,

Borges³

2008

PIER

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Abstract-This paper presents a dispersive finite difference time domain (FDTD) method suitable for the analysis of electromagnetic field rotator (and cloaking) devices. The method employs a coordinate transformation which accurately accounts for the radial dependence of the permittivity and permeability tensors, with Drude material models applied to the respective diagonal elements. The key aspect of the present formulation is the inclusion of the radial dependence of the plasma frequency, which makes this formalism quite attractive for the modeling of a general class of cloaking and field rotator geometries. Firstly, the method is validated by comparing its results with a previously published simulation of a cloaking device. Then, it is applied for the first time to the analysis of dispersive effects on the performance of field rotators.

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“…The most celebrated example is the invisibility cloaks. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Other examples include field concentrators, 19 field rotators, [20][21][22] electromagnetic wormholes, 23 impedance-matched hyperlenses, 24 field shifters, 25,26 anticloaks, 27 cylindrical superlenses, 28 superscatterers, 29 superabsorbers, 30 and remote cloaks ͑or invisibility umbrellas͒. 31,32 However, the experimental fabrication of these novel devices requires sophisticated man-made metamaterial, which may not be always feasible to make.…”

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confidence: 99%

“…Indeed, the "reduced devices" will become those that shall be useful for real applications as the ideal devices are probably too difficult or expensive to make. So, there is a good reason that much effort 8,9,[11][12][13] has been devoted to study the reduced cloaks. For example, a reduced cloak working in the microwave frequency was realized experimentally in 2006.…”

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confidence: 99%

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General transformation for the reduced invisibility cloak

Chen

Lee

et al. 2009

Phys. Rev. B

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We present a generalized perspective for "reduced" invisibility cloaks, which formulates a general way to "reduce" the cloak so that it can be realized more easily. We show explicitly that several published reduced cloak designs are in fact special cases of a more general transformation. Furthermore, we showed that a cylindrical reduced cloak is linked to a cylindrical isotropic inhomogeneous object by exactly the coordinate transformation that one applies on an ideal cloak. This perspective also suggests an alternative but easier way to calculate the scattering properties of the reduced cloaks. DOI: 10.1103/PhysRevB.80.085112 PACS number͑s͒: 41.20.Jb, 42.25.Fx, 42.79.Ϫe, 42.25.Gy Transformation optics 1,2 is a powerful and versatile theoretical tool that enables the design of various kinds of novel metamaterial devices. The most celebrated example is the invisibility cloaks. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Other examples include field concentrators, 19 field rotators, 20-22 electromagnetic wormholes, 23 impedance-matched hyperlenses, 24 field shifters, 25,26 anticloaks, 27 cylindrical superlenses, 28 superscatterers, 29 superabsorbers, 30 and remote cloaks ͑or invisibility umbrellas͒. 31,32 However, the experimental fabrication of these novel devices requires sophisticated man-made metamaterial, which may not be always feasible to make. For this reason, researchers have attempted to "reduce" the complexity of the required constitutive parameters. The functionalities of these reduced devices, such as the reduced cloak, 3,5-7 are slightly less perfect compared to the original ideal devices, but they are designed to perform satisfactorily while having the advantage that they are much easier to fabricate. Indeed, the "reduced devices" will become those that shall be useful for real applications as the ideal devices are probably too difficult or expensive to make. So, there is a good reason that much effort 8,9,11-13 has been devoted to study the reduced cloaks. For example, a reduced cloak working in the microwave frequency was realized experimentally in 2006. 5 More recently, the "ground-plane cloak" 16 ͑also known as the "one-dimensional cloak 14,26 "͒, which has a broad working frequency spectrum, was also realized.For simplicity, we shall only consider the two dimensional case in this paper. The spatially varying constitutive parameters for the transverse electric ͑TE͒ ideal cloak are given bywhere f͑r͒ is the mapping function. The constitutive parameters for transverse magnetic ͑TM͒ ideal cloak can be obtained by making the substitution ͕ r → r , → , z → z ͖ in ͑1͒. By varying the functional form, we can achieve a varieties of functionalities such as the concentrator 21 ͑or the impedance-matched hyperlens 24 ͒, the anticloak 27 and the superscatterer, 29 cylindrical superlenses, 28 etc. However, these parameters involve spatially varying, anisotropy permittivity, and permeability, which can be formidably difficult to fabricate. Consequently, it is essential for one to "reduce" or ...

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Extending the bandwidth of electromagnetic cloaks

Cited by 150 publications

References 21 publications

Ultrathin Cylindrical Cloak

Ultrathin Cylindrical Cloak

An Extended FDTD Method for the Analysis of Electromagnetic Field Rotators and Cloaking Devices

General transformation for the reduced invisibility cloak

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