Silicon nanostructure cloak operating at optical frequencies

Gabrielli, Lucas H.; Cárdenas, Jaime; Poitras, Carl B.; Lipson, Michal

doi:10.1038/nphoton.2009.117

Cited by 606 publications

(451 citation statements)

References 31 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.…”

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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“…Under this circumstance, the resulting transformation function is called quasi-conformal mapping, which is more general than classical conformal mapping. As an example, carpet cloaks working at the microwave and optical frequencies have been successfully verified by experiments [6][7][8]13]. Very recently, quasiconformal mapping transformation optics has also been utilized to flatten the traditional Luneburg lens, and satisfactory results are reported [32].…”

Section: Introductionmentioning

confidence: 91%

“…Their success has aroused great interests, and the method, transformation optics, coupled with the emerging metamaterial technology, has been intensively explored in various designs such as cloaks [3][4][5][6][7][8][9][10][11][12][13], perfect lenses [14][15][16], concentrators [17,18], and other novel devices [19][20][21]. Being an indispensable part in telecommunication systems, many new types of antennas have also been proposed based on this powerful tool [22][23][24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

A Planar Focusing Antenna Design With the Quasi-Conformal Mapping

Mei¹,

Bai²,

Niu³

et al. 2010

PIER M

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Abstract-We propose a planar focusing antenna design, which has the same performance as its parabolic counterparts and can be realized using PEC-backed gradient index dielectrics. In this design, quasi-conformal transformation optics is first utilized to transform a parabolic surface into a planar one, then the anisotropy factor of the resultant material is minimized, and the material is approximately treated as isotropic. Examples with realizable material parameters are given, and the simulation results validate the design. The proposed method could be used to design planar focusing antennas with high directivity and similar devices. The idea can also be applied to new device designs in optics engineering.

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Silicon nanostructure cloak operating at optical frequencies

Cited by 606 publications

References 31 publications

Metamaterials: a new frontier of science and technology

Metamaterials: a new frontier of science and technology

A Carpet Cloak for Visible Light

A Planar Focusing Antenna Design With the Quasi-Conformal Mapping

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