Wave scattering and splitting by magnetic metamaterials
TL;DR: A range of novel phenomena including partial focusing and splitting into multiple transmitted beams are observed and it is demonstrated that while some of these experimentally observed effects can be described within the approximation of an effective medium, a deeper understanding of the experimental results requires a rigorous study of internal eigenmodes of the lattice of resonators.
Abstract: We study experimentally propagation of electromagnetic waves through a slab of uniaxial magnetic metamaterial. We observe a range of novel phenomena including partial focusing and splitting into multiple transmitted beams. We demonstrate that while some of these experimentally observed effects can be described within the approximation of an effective medium, a deeper understanding of the experimental results requires a rigorous study of internal eigenmodes of the lattice of resonators.
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TL;DR: In this paper, a review of recent developments in magnetic plasmonics arising from the coupling effect in metamaterials is given, where it is shown that the coupling between these units produces multiple discrete resonance modes due to hybridization.
Abstract: Magnetic metamaterials consist of magnetic resonators smaller in size than their excitation wavelengths. Their unique electromagnetic properties were characterized by the effective media theory at the early stage. However, the effective media model does not take into account the interactions between magnetic elements; thus, the effective properties of bulk metamaterials are the result of the “averaged effect” of many uncoupled resonators. In recent years, it has been shown that the interaction between magnetic resonators could lead to some novel phenomena and interesting applications that do not exist in conventional uncoupled metamaterials. In this paper, we will give a review of recent developments in magnetic plasmonics arising from the coupling effect in metamaterials. For the system composed of several identical magnetic resonators, the coupling between these units produces multiple discrete resonance modes due to hybridization. In the case of a system comprising an infinite number of magnetic elements, these multiple discrete resonances can be extended to form a continuous frequency band by strong coupling. This kind of broadband and tunable magnetic metamaterial may have interesting applications. Many novel metamaterials and nanophotonic devices could be developed from coupled resonator systems in the future. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
71 citations
TL;DR: In this article, the role played by the longitudinal and transverse coupling effects in the electromagnetic properties of stacked split ring resonator (SRR) arrays operating at microwave frequencies was investigated.
Abstract: We report on free space transmission experiments carried out on stacked split ring resonator (SRRs) arrays operating at microwave frequencies. We start from the case of a single frequency selective surface which exhibits a rejection at the SRR resonance frequency. By stacking SRR arrays in the propagation direction, we then show experimentally the possibility to induce a transmission band just below this resonance frequency. Full wave analysis shows the role played by the longitudinal and transverse coupling efiects in the electromagnetic properties of such bulk metamaterials, with the appearance of a transmission band resulting from an artiflcial magnetic activity.
18 citations
TL;DR: In this article, localized structures forming in the bistable regimes in a chain of weakly coupled split ring resonators, which are the building blocks of a nonlinear magnetic metamaterial, where electric current is generated by external electromagnetic radiation, have been studied analytically and numerically.
Abstract: Localized structures forming in the bistable regimes in a chain of weakly coupled split ring resonators, which are the building blocks of a nonlinear magnetic metamaterial, where electric current is generated by external electromagnetic radiation, have been studied analytically and numerically. The hysteresis of the velocity of switching waves (fronts) has been revealed and discrete dissipative solitons have been found.
17 citations
TL;DR: In this paper, a review of the recent developments in coupled metamaterials is presented, where the authors show that the coupling effect is not negligible and will have a substantial effect on the metammaterials' properties, especially when the elements are very close.
Abstract: Although the invention of the metamaterials has stimulated the interest of many researchers and possesses many important applications, the basic design idea is very simple: composing effective media from many small structured elements and controlling its artificial EM properties. According to the effective-media model, the coupling interactions between the elements in metamaterials are somewhat ignored; therefore, the effective properties of metamaterials can be viewed as the "averaged effect" of the resonance property of the individual elements. However, the coupling interaction between elements should always exist when they are arranged into metamaterials. Sometimes, especially when the elements are very close, this coupling effect is not negligible and will have a substantial effect on the metamaterials' properties. In recent years, it has been shown that the interaction between resonance elements in metamaterials could lead to some novel phenomena and interesting applications that do not exist in conventional uncoupled metamaterials. In this paper, we will give a review of these recent developments in coupled metamaterials. For the "meta-molecule" composed of several identical resonators, the coupling between these units produces multiple discrete resonance modes due to hybridization. In the case of a "meta-crystal" comprising an infinite number of resonators, these multiple discrete resonances can be extended to form a continuous frequency band by strong coupling. This kind of broadband and tunable coupled metamaterial may have interesting applications. Many novel metamaterials and nanophotonic devices could be developed from coupled resonator systems in the future.
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References
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TL;DR: A composite medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous wires, that exhibits a frequency region in the microwave regime with simultaneously negative values of effective permeability and permittivity varepsilon(eff)(omega).
Abstract: We demonstrate a composite medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous wires, that exhibits a frequency region in the microwave regime with
8,057 citations
TL;DR: This work describes here the first practical realization of a cloak of invisibility, constructed with the use of artificially structured metamaterials, designed for operation over a band of microwave frequencies.
Abstract: A recently published theory has suggested that a cloak of invisibility is in principle possible, at least over a narrow frequency band. We describe here the first practical realization of such a cloak; in our demonstration, a copper cylinder was "hidden" inside a cloak constructed according to the previous theoretical prescription. The cloak was constructed with the use of artificially structured metamaterials, designed for operation over a band of microwave frequencies. The cloak decreased scattering from the hidden object while at the same time reducing its shadow, so that the cloak and object combined began to resemble empty space.
6,830 citations
TL;DR: A bilayer of materials for which not all of the principal elements of the permeability and permittivity tensors have the same sign can transfer a field distribution from one side to the other, including near fields, without requiring internal exponentially growing waves.
Abstract: The range of available electromagnetic material properties has been broadened by recent developments in structured media, notably photonic band gap materials and metamaterials. These media have allowed the realization of solutions to Maxwell’s equations not available in naturally occurring materials, fueling the discovery of new physical phenomena and the development of devices. Photonic crystal effects typically occur when the wavelength is on the same order or smaller than the lattice constant of the crystal. Metamaterials, on the other hand, have unit cell dimensions much smaller than the wavelength of interest. A homogenization process, not unlike
987 citations
TL;DR: 2D measurements of collimated microwave beams transmitted through composite wire and split-ring resonator prisms demonstrate that transmission obeys Snell's law with a negative index, confirming the refractive nature of this signal and refuting alternatives posed in the criticisms.
Abstract: We measure two-dimensional profiles of collimated microwave beams transmitted through composite wire and split-ring resonator prisms. Prior experiments suggest these structures have a negative index of refraction, though these claims have been questioned. Our 2D measurements demonstrate that transmission obeys Snell's law with a negative index, confirming the refractive nature of this signal and refuting alternatives posed in the criticisms. In addition, we present preliminary evidence that a flat rectangular slab of this material can focus power from a point source.
663 citations
TL;DR: In this article, the propagation of magneto-inductive (MI) waves supported by capacitively loaded loops is investigated using a circuit model in which each loop is coupled magnetically to a number of other loops.
Abstract: The propagation of waves supported by capacitively loaded loops is investigated using a circuit model in which each loop is coupled magnetically to a number of other loops. Since the coupling is due to induced voltages the waves are referred to as magnetoinductive (MI) waves. The mathematical formulations are mostly analytical thanks to long standing previous work on the magnetic and electric fields generated by currents flowing in loops. Retardation is neglected, i.e., dimensions of the structure are assumed to be small relative to the free space wavelength. The dispersion relations, derived in the most general case for a tetragonal three-dimensional structure, exhibit both forward and backward waves within a pass band. It is shown that for reproducing the salient features of the waves it is sufficient to take nearest neighbor coupling into account but coupling between loops further away must also be considered if higher accuracy is required. The investigations include that of resonances, conditions for the existence of traveling waves, tolerances, and streamlines of the Poynting vector. Waveguide components, like bends, power dividers and couplers are considered due to the potential applications of the MI waves as magnetic guides. Generality of the results, their possible implications for transverse electromagnetic wave propagation, previous work on similar waves, including the possibility of phase conjugation, are discussed in a separate section.
349 citations