Metamaterial Electromagnetic Cloak at Microwave Frequencies

Schurig, David; Mock, Jack J.; Justice, B.J.; Cummer, Steven A.; Pendry, J. B.; Starr, Anthony F.; Smith, David R.

doi:10.1126/science.1133628

Cited by 6,871 publications

(4,445 citation statements)

References 21 publications

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“…The invariance of Maxwell's equations under optical coordinate transformation allows the space around the object to be reshaped such that the light can propagate in the desired way. Such transformations usually require EM properties with extreme values that are only achievable in metallic metamaterials, and have been experimentally demonstrated for cloaking in microwave frequencies [9,10]. Due to the significant metallic loss at optical frequencies, the implementation of such cloaks for visible light has been difficult.…”

Section: Introductionmentioning

confidence: 99%

A Carpet Cloak for Visible Light

et al. 2011

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ABSTRACT:We report an invisibility carpet cloak device, which is capable of making an object undetectable by visible light. The cloak is designed using quasi conformal mapping and is fabricated in a silicon nitride waveguide on a specially developed nano-porous silicon oxide substrate with a very low refractive index. The spatial index variation is realized by etching holes of various sizes in the nitride layer at deep subwavelength scale creating a local effective medium index. The fabricated device demonstrates wideband invisibility throughout the visible spectrum with low loss. This silicon nitride on low index substrate can also be a general scheme for implementation of transformation optical devices at visible frequency. KEYWORDS:Optical metamaterials, invisibility cloak, optical transformation Invisibility cloaks, a family of optical illusion devices that route electromagnetic (EM) waves around an object so that the existence of the object does not perturb light propagation, are still in their infancy. Artificially engineered materials with specific EM properties, known as metamaterials [1,2], have been used to control the propagation of EM waves, and have recently 2 been applied to cloaking through transformation optics [3][4][5][6][7][8]. The invariance of Maxwell's equations under optical coordinate transformation allows the space around the object to be reshaped such that the light can propagate in the desired way. Such transformations usually require EM properties with extreme values that are only achievable in metallic metamaterials, and have been experimentally demonstrated for cloaking in microwave frequencies [9,10]. Due to the significant metallic loss at optical frequencies, the implementation of such cloaks for visible light has been difficult. Recently another innovative strategy was developed based on exploiting uniaxial crystals [11,12]. These devices have demonstrated cloaking in visible frequencies for a certain polarization of light based on intrinsic anisotropy in the crystals. As an alternative, conformal mapping, where an inverse transformation of the electrical permittivity and magnetic permeability leads to a spatially variable refractive index profile [13], can be applied to isotropic dielectric metamaterials. While 3D conformal mapping leads to anisotropic index profiles [14], a 2D quasi conformal mapping (QCM) can be employed to minimize anisotropy. The 2D QCM is the basis for the carpet cloak [15], where the object is hidden under a reflective layer (the carpet). To achieve cloaking, the raised protrusion (the bump) created in the reflective layer is mapped to a flat plane and the resulting 2D index profile forms a carpet cloak device. In contrast to resonant optical structures [16,17], QCM carpet cloak provides a broadband loss-less design and may be invariably extended in the third direction with some limitations [18], experimentally demonstrated to operate for a range of viewing angles [19]. The relatively modest materials requirement from QCM enabled the implementation of the...

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Section: Introductionmentioning

confidence: 99%

A Carpet Cloak for Visible Light

et al. 2011

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“…The resonance induced by the electric fi eld is at the same frequency as that induced by magnetic fi eld. [20][21][22] Therefore, the resonance excited by magnetic and electric fi elds reinforce each other, making the resonance stronger.…”

Section: Doi: 101002/adma201104575mentioning

confidence: 99%

Realization of Variable Three‐Dimensional Terahertz Metamaterial Tubes for Passive Resonance Tunability

et al. 2012

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“…Despite its elegance, the proposed general cloaking theory1, 2, 3, 4, 5, 6, 7, 8 is tremendously difficult to implement; as a result, all previous implementations have involved special cases 9, 10, 11, 12, 13, 14, 15, 16, 17, 18. The first experimental validation of an invisibility cloak was a 2D microwave cloak9 for single‐frequency transverse electric (TE) waves.…”

Section: Introductionmentioning

confidence: 99%

“…The first experimental validation of an invisibility cloak was a 2D microwave cloak9 for single‐frequency transverse electric (TE) waves. A nonmagnetic metamaterial cloak for transverse magnetic (TM) waves at microwave frequencies was subsequently proposed 10.…”

Section: Introductionmentioning

confidence: 99%

3D Visible‐Light Invisibility Cloak

et al. 2018

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The concept of an invisibility cloak is a fixture of science fiction, fantasy, and the collective imagination. However, a real device that can hide an object from sight in visible light from absolutely any viewpoint would be extremely challenging to build. The main obstacle to creating such a cloak is the coupling of the electromagnetic components of light, which would necessitate the use of complex materials with specific permittivity and permeability tensors. Previous cloaking solutions have involved circumventing this obstacle by functioning either in static (or quasistatic) fields where these electromagnetic components are uncoupled or in diffusive light scattering media where complex materials are not required. In this paper, concealing a large‐scale spherical object from human sight from three orthogonal directions is reported. This result is achieved by developing a 3D homogeneous polyhedral transformation and a spatially invariant refractive index discretization that considerably reduce the coupling of the electromagnetic components of visible light. This approach allows for a major simplification in the design of 3D invisibility cloaks, which can now be created at a large scale using homogeneous and isotropic materials.

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Metamaterial Electromagnetic Cloak at Microwave Frequencies

Cited by 6,871 publications

References 21 publications

A Carpet Cloak for Visible Light

A Carpet Cloak for Visible Light

Realization of Variable Three‐Dimensional Terahertz Metamaterial Tubes for Passive Resonance Tunability

3D Visible‐Light Invisibility Cloak

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