Invisible Gateway by Superscattering Effect of Metamaterials.
TL;DR: In this article, a superscatterer with a double negative metamaterial and an invisible gateway was demonstrated to stop electromagnetic waves in an air channel with a width much larger than the cutoff width of the corresponding rectangular waveguide.
Abstract: Illusion devices, such as superscatterer and invisible gateway, have been theoretically studied under the theory of transformation optics and folded geometry transformations. The realization of these devices needs building blocks of metamaterials with negative permittivities and permeabilities. However, superscattering effects, such as stopping wave propagation in an air channel, have not been verified from illusion devices physically because of the challenge of metamaterial design, fabrication, and material loss. In this Letter, we implement a big metamaterial superscatterer, and experimentally demonstrate its superscattering effect at microwave frequencies by field-mapping technology. We confirm that superscattering is originated from the excitation of surface plasmons. Integrated with superscatterer, we experimentally display that an invisible gateway could stop electromagnetic waves in an air channel with a width much larger than the cutoff width of the corresponding rectangular waveguide. Our results provide a first direct observation of superscattering effect of double negative metamaterials and invisible gateway for electromagnetic waves. It builds up an ideal platform for future designs of other illusion devices.
Citations
More filters
TL;DR: In this paper , the recent progress of ceramic-based dielectric metamaterials in electromagnetic applications, energy applications, non-Hermitian systems, and natural materials with near-zero or negative refraction are summarized.
Abstract: Dielectric metamaterials based on ceramics have attracted considerable interest in the past few years owing to their low dielectric loss, simple structure, excellent multifield tunability, and good environmental adaptability. They are considered to be promising alternative to metal‐based metamaterials and can lead to a new strategy for the development of passive devices. In this review, the recent progress of ceramic‐based dielectric metamaterials in electromagnetic applications, energy applications, non‐Hermitian systems, and natural materials with near‐zero or negative refraction are summarized. The design principle and mechanism, as well as manufacturing technologies, are also introduced, and the current development trend of ceramic‐based dielectric metamaterials are proposed.
30 citations
TL;DR: In this paper , a W-shaped metasurface consisting of resonators was proposed to realize broadband reflective linear and circular polarization conversions. But the authors did not consider the impact of the angle of incident waves on the conversion performance.
Abstract: We present a metasurface consisting of W-shaped resonators to realize broadband reflective linear and circular polarization conversions. We find that the cross polarization conversion ratio for normal incidence is over 0.95 from 9.2 to 18.7 GHz, covering 68.1% of the central frequency. We also show that, the conversion performance is almost insensitive to the angle of incident waves. Furthermore, by simply adjusting the geometrical parameters of the W-shaped metasurface, the broadband circular polarization conversion is also achieved. We emphasize that the bandwidth of axis ratio less than 3.0 dB covers from 10.1 to 17.7 GHz, equivalent to 54.7% relative bandwidth. Due to these broadband and high-efficiency polarization conversion features, our proposal may have a wide application prospect.
3 citations
TL;DR: In this paper , the authors proposed a contactless and non-closed strategy to mitigate the sound radiated from an underwater source, which is formulated as the interaction of the source with different cross-sectional shapes and the acoustic superscatterer treated as a concentric cylindrical structure.
Abstract: We propose a contactless and non-closed strategy to mitigate the sound radiated from an underwater source. The problem is formulated as the interaction of the source with different cross-sectional shapes (including ideal zero-cross-section sources, circular-cross-section rods, and rectangular-cross-section rods) and the acoustic superscatterer treated as a concentric cylindrical structure. The acoustic superscatterer consisting of an internal core and a coating made of the double-negative acoustic metamaterial with specific constitutive parameters relies on the coating to virtually magnify its internal core, thus yielding intense multiple scattering with the source. According to the transformation media theory and the method of images, the complete landscape has been presented theoretically and numerically of the remote mitigation of underwater source radiation via an acoustic superscatterer. We demonstrate that by appropriately placing the acoustic superscatterer nearby the source, it can achieve the omnidirectional radiation mitigation stemming from the coherent extinction mechanism. A possible scheme for the practical realization of the acoustic superscatterer is also discussed. This work may facilitate the design and application of remotely placed meta-devices for the manipulation of underwater acoustic waves.
2 citations
TL;DR: In this article , a water-based metamaterial particle for transmission enhancement at a specific frequency is designed, and the influence of the design parameters on the enhanced transmission characteristics is discussed.
Abstract: A realization form of the Mie resonance with adjustable characteristics based on a water-based metamaterial is proposed. A novel local electromagnetic field coupling mechanism based on a water-based metamaterial is established, which is used for transmission enhancement through the sub-wavelength aperture for the first time. The water-based metamaterial particle for transmission enhancement at a specific frequency is designed. By designing the microfluidic control system to control the water filling (i.e., height) of the metamaterial particle, the adjustable transmission enhancement characteristics are realized. The influence of bilateral symmetry and flexible deformation of the metamaterial particle on the transmission characteristics is analyzed. The influence of the design parameters on the enhanced transmission characteristics is discussed.
References
More filters
TL;DR: This work shows how electromagnetic fields can be redirected at will and proposes a design strategy that has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.
Abstract: Using the freedom of design that metamaterials provide, we show how electromagnetic fields can be redirected at will and propose a design strategy. The conserved fields-electric displacement field D, magnetic induction field B, and Poynting vector B-are all displaced in a consistent manner. A simple illustration is given of the cloaking of a proscribed volume of space to exclude completely all electromagnetic fields. Our work has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.
7,811 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 general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics is developed, which can be applied to escape detection by other electromagnetic waves or sound.
Abstract: An invisibility device should guide light around an object as if nothing were there, regardless of where the light comes from. Ideal invisibility devices are impossible, owing to the wave nature of light. This study develops a general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics. The imperfections of invisibility can be made arbitrarily small to hide objects that are much larger than the wavelength. With the use of modern metamaterials, practical demonstrations of such devices may be possible. The method developed here can also be applied to escape detection by other electromagnetic waves or sound.
3,850 citations
TL;DR: This Review presents a broad outline of the whole range of electromagnetic effects observed using all-dielectric metamaterials: high-refractive-index nanoresonators, metasurfaces, zero-index met amaterials and anisotropic metammaterials, and discusses current challenges and future goals for the field at the intersection with quantum, thermal and silicon photonics.
Abstract: The ideal material for nanophotonic applications will have a large refractive index at optical frequencies, respond to both the electric and magnetic fields of light, support large optical chirality and anisotropy, confine and guide light at the nanoscale, and be able to modify the phase and amplitude of incoming radiation in a fraction of a wavelength. Artificial electromagnetic media, or metamaterials, based on metallic or polar dielectric nanostructures can provide many of these properties by coupling light to free electrons (plasmons) or phonons (phonon polaritons), respectively, but at the inevitable cost of significant energy dissipation and reduced device efficiency. Recently, however, there has been a shift in the approach to nanophotonics. Low-loss electromagnetic responses covering all four quadrants of possible permittivities and permeabilities have been achieved using completely transparent and high-refractive-index dielectric building blocks. Moreover, an emerging class of all-dielectric metamaterials consisting of anisotropic crystals has been shown to support large refractive index contrast between orthogonal polarizations of light. These advances have revived the exciting prospect of integrating exotic electromagnetic effects in practical photonic devices, to achieve, for example, ultrathin and efficient optical elements, and realize the long-standing goal of subdiffraction confinement and guiding of light without metals. In this Review, we present a broad outline of the whole range of electromagnetic effects observed using all-dielectric metamaterials: high-refractive-index nanoresonators, metasurfaces, zero-index metamaterials and anisotropic metamaterials. Finally, we discuss current challenges and future goals for the field at the intersection with quantum, thermal and silicon photonics, as well as biomimetic metasurfaces.
1,634 citations
TL;DR: A new type of cloak is discussed: one that gives all cloaked objects the appearance of a flat conducting sheet that has the advantage that none of the parameters of the cloak is singular and can in fact be made isotropic.
Abstract: A new type of cloak is discussed: one that gives all cloaked objects the appearance of a flat conducting sheet. It has the advantage that none of the parameters of the cloak is singular and can in fact be made isotropic. It makes broadband cloaking in the optical frequencies one step closer.
1,419 citations