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Proceedings ArticleDOI

Effect of Position Randomness on Absorption Bandwidth of Disordered Metamaterial Absorbers

TL;DR: In this paper, position randomness is introduced in a supercell, which transforms a periodic metamaterial structure into a random metammaterial structure, where the constituent resonators are interacting with each other.
Abstract: In this work, absorption properties of spatially disordered metamaterials are analysed using numerical simulations. For this purpose, position randomness is introduced in a supercell, which transforms a periodic metamaterial structure into a random metamaterial structure, where the constituent resonators are interacting with each other. It is demonstrated that the disorder can be used to enhance the absorption bandwidth. This enhancement is obtained due to the coupling among the nearby resonators, which results in broadening of collective resonance. The proposed disordered metamaterial absorbers also exhibit polarisation-insensitivity and have wide-band absorption for both normal and oblique incidences, which makes them a promising candidate for a variety of applications.
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Journal ArticleDOI
TL;DR: The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established and Insight is given into what the authors can expect from this rapidly expanding field and future challenges will be addressed.
Abstract: The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch–the metamaterial perfect absorber (MPA)–has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed.

1,419 citations


"Effect of Position Randomness on Ab..." refers background in this paper

  • ...A class of metamaterials, known as metamaterial perfect absorbers (MPAs) have the ability to achieve the unit absorption of electromagnetic (EM) waves across the electromagnetic spectrum [1]....

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Journal ArticleDOI
TL;DR: In this article, a polarization-insensitive metamaterial absorber for terahertz frequencies is presented, which achieves an absorptivity of 77% at 1.145 THz.
Abstract: We present the theory, design, and realization of a polarization-insensitive metamaterial absorber for terahertz frequencies. Effective-medium theory is used to describe the absorptive properties of the metamaterial in terms of optical constants---a description that has been thus far lacking. From our theoretical approach, we construct a device that yields over 95% absorption in simulation. Our fabricated design consists of a planar single unit-cell layer of metamaterial and reaches an absorptivity of 77% at 1.145 THz.

690 citations


"Effect of Position Randomness on Ab..." refers background in this paper

  • ...considerations such as four-fold symmetric structures [17], use of multi-scale structuring [3] etc....

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Journal ArticleDOI
06 Dec 2012-Nature
TL;DR: It is shown that the film-coupled nanocubes provide a reflectance spectrum that can be tailored by varying the geometry (the size of the cubes and/or the thickness of the spacer) and can be controlled at scales out of reach of lithographic approaches that are otherwise required to manipulate matter on the nanoscale.
Abstract: Efficient and tunable absorption is essential for a variety of applications, such as designing controlled-emissivity surfaces for thermophotovoltaic devices, tailoring an infrared spectrum for controlled thermal dissipation and producing detector elements for imaging. Metamaterials based on metallic elements are particularly efficient as absorbing media, because both the electrical and the magnetic properties of a metamaterial can be tuned by structured design. So far, metamaterial absorbers in the infrared or visible range have been fabricated using lithographically patterned metallic structures, making them inherently difficult to produce over large areas and hence reducing their applicability. Here we demonstrate a simple method to create a metamaterial absorber by randomly adsorbing chemically synthesized silver nanocubes onto a nanoscale-thick polymer spacer layer on a gold film, making no effort to control the spatial arrangement of the cubes on the film. We show that the film-coupled nanocubes provide a reflectance spectrum that can be tailored by varying the geometry (the size of the cubes and/or the thickness of the spacer). Each nanocube is the optical analogue of a grounded patch antenna, with a nearly identical local field structure that is modified by the plasmonic response of the metal's dielectric function, and with an anomalously large absorption efficiency that can be partly attributed to an interferometric effect. The absorptivity of large surface areas can be controlled using this method, at scales out of reach of lithographic approaches (such as electron-beam lithography) that are otherwise required to manipulate matter on the nanoscale.

658 citations


"Effect of Position Randomness on Ab..." refers background in this paper

  • ...Studies have also reported field enhancement of several orders in random structures compared to their periodic counterparts [14], [15]....

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Journal ArticleDOI
TL;DR: In this paper, the authors show that equivalent circuits offer a qualitative and even quantitative simple explanation for the behavior of various types of left-handed (or negative-index) metamaterials and apply this unifying circuit approach in accounting for the features and in optimizing the structure employing parallel metallic bars on the two sides of a dielectric film.
Abstract: We show that equivalent circuits offer a qualitative and even quantitative simple explanation for the behavior of various types of left-handed (or negative-index) metamaterials. This allows us to optimize design features and parameters while avoiding trial and error simulations or fabrications. In particular, we apply this unifying circuit approach in accounting for the features and in optimizing the structure employing parallel metallic bars on the two sides of a dielectric film.

354 citations

Journal ArticleDOI
TL;DR: In this paper, a polarization-independent ultrawideband metamaterial absorber is proposed for X-band applications, which is achieved by the combination of an artificial impedance surface (AIS) and a resistor-capacitor (RC) layer.
Abstract: A polarization-independent ultrawideband metamaterial absorber is proposed for X-band applications. High absorptivity over an ultrawide spectrum is achieved by the combination of an artificial impedance surface (AIS) and a resistor-capacitor (RC) layer. In addition, the unique hexagonal shape of an AIS and RC layer enables polarization insensitivity. A circuit analysis is introduced based on a transmission-line model and shows good agreement with the full-wave analysis. Fabrication tolerance issues are considered with parametric studies in the electromagnetic simulation. The proposed absorber is fabricated on low-cost FR4 substrates, and its absorption performance is experimentally demonstrated at different angles and polarizations of incident electric fields.

196 citations


"Effect of Position Randomness on Ab..." refers background in this paper

  • ...Several new structural design techniques such as multilayer [2], multi-scale [3], lumped-component loaded [4] etc....

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