An optical cloak made of dielectrics

Valentine, Jason; Li, Jensen; Zentgraf, Thomas; Bartal, Guy; Zhang, Xiang

doi:10.1038/nmat2461

Cited by 1,257 publications

(878 citation statements)

References 52 publications

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“…A number of new designs are proposed to mitigate these constraints. [89][90][91][92][93][94][95] In particular, the carpet cloak can significantly relax the variation range of the material properties, [89][90][91][92] since the carpet cloak compresses the curved surface in only one direction into a conducting sheet and hence a quasi-conformal mapping technique can be applied to the two-dimensional system. Any arbitrarily shaped object placed behind the curved bump will maintain the reflectance of a smooth, flat surface, rendering the object invisible.…”

Section: Transformation Opticsmentioning

confidence: 99%

Metamaterials: a new frontier of science and technology

Liu¹,

2011

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Metamaterials, artificial composite structures with exotic material properties, have emerged as a new frontier of science involving physics, material science, engineering and chemistry. This critical review focuses on the fundamentals, recent progresses and future directions in the research of electromagnetic metamaterials. An introduction to metamaterials followed by a detailed elaboration on how to design unprecedented electromagnetic properties of metamaterials is presented. A number of intriguing phenomena and applications associated with metamaterials are discussed, including negative refraction, sub-diffraction-limited imaging, strong optical activities in chiral metamaterials, interaction of meta-atoms and transformation optics. Finally, we offer an outlook on future directions of metamaterials research including but not limited to three-dimensional optical metamaterials, nonlinear metamaterials and ''quantum'' perspectives of metamaterials (142 references).

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Section: Transformation Opticsmentioning

confidence: 99%

Metamaterials: a new frontier of science and technology

Liu¹,

2011

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“…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 cloaking devices in the infrared [20,21] using a silicon waveguide. The index variation in these systems is realized through a spatial modulation of the filling fraction of dielectrics at subwavelength dimensions, providing a weighted average index according to effective medium approximation.…”

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confidence: 99%

“…Also, the waveguide confinement at longer wavelength reduces the mode index, creating a waveguide cut-off in the infrared. Although the waveguide test structure and coupling gratings were designed for demonstration of the cloaking effect using light with transverse electric polarization, in principal the QCM transformation operates for both polarizations [15,19,20].…”

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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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“…A fascinating term, metamaterials, is thus created and continues to develop rapidly [3][4][5][6]. In 2006, the power full means of transformation optics generalized by Leonhardt and Pendry et al [7,8] built up a bridge between the function of metamaterials and material parameter distribution, and provided a complete prescription for controlling and guiding electromagnetic wave at will [3,[9][10][11][12][13][14][15][16][17][18]. One of the most popular and intriguing topics in this field is perhaps the "invisible cloak" [3], which was experimentally verified at microwave frequency band by Schurig et al It makes the incident wave detor around the cloaked region without disturbance, thus an arbitrary object might be hidden inside.…”

Section: Introductionmentioning

confidence: 99%

Reciprocal Invisible Cloak With Homogeneous Metamaterials

Yang¹,

Huang²,

Li³

et al. 2011

PIER M

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Abstract-Based on linear optical transformation method, a diamond shaped reciprocal cloak with perfect invisibility in a certain direction is proposed. Compared with traditional cloaks, the object hidden inside the reciprocal cloak is not blind and can receive information from the outer region. Moreover, the reciprocal cloak is constructed of nonsingular homogeneous material parameters with reduced anisotropy that is relatively easy for practical realization. Full wave simulations validate the performance of the cloak.

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An optical cloak made of dielectrics

Cited by 1,257 publications

References 52 publications

Metamaterials: a new frontier of science and technology

Metamaterials: a new frontier of science and technology

A Carpet Cloak for Visible Light

Reciprocal Invisible Cloak With Homogeneous Metamaterials

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