Topic
Transformation optics
About: Transformation optics is a research topic. Over the lifetime, 2687 publications have been published within this topic receiving 102378 citations.
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TL;DR: In this article, low-loss, negative-index of refraction metamaterials were designed and tested for X, Ku, and K microwave frequency bands and an S-shaped, split-ring resonator was used as a unit cell to design homogeneous slabs of negative index metammaterials.
Abstract: Low-loss, negative-index of refraction metamaterials were designed and tested for X, Ku, and K microwave frequency bands. An S-shaped, split-ring resonator was used as a unit cell to design homogeneous slabs of negative-index metamaterials. Then, the slabs of metamaterials were cut unto prisms to measure experimentally the negative index of refraction of a plane electromagnetic wave. Theoretical simulations using High-Frequency Structural Simulator, a finite element equation solver, were in good agreement with experimental measurements. The negative index of refraction was retrieved from the angle- and frequency-dependence of the transmitted intensity of the microwave beam through the metamaterial prism and compared well to simulations; in addition, near-field electromagnetic intensity mapping was conducted with an infrared camera, and there was also a good match with the simulations for expected frequency ranges for the negative index of refraction.
10 citations
TL;DR: In this paper, a meta-atom was proposed for creating metamaterials with giant nonlinear optical activity but vanishing linear optical activity in a wide frequency range, which is called pure nonlinear activity.
Abstract: We demonstrate a type of meta-atom for creating metamaterials with giant nonlinear optical activity but vanishing linear optical activity in a wide frequency range. Such properties are not found in any natural materials, and we call this regime as pure nonlinear optical activity. We further extend our design concept and show that the metamaterial can be tuned dynamically to exhibit either positive or negative polarization rotation.
10 citations
TL;DR: In this article, a graded-index all-dielectric lens was proposed to enhance the directivity of an H-plane horn antenna by modifying the physical space shape of the lens to eliminate singular index values and rescaling the optical path inside the lens.
Abstract: Conformal transformation optics is employed to enhance an H-plane horn’s directivity by designing a graded-index all-dielectric lens. The transformation is applied so that the phase error at the aperture is gradually eliminated inside the lens, leading to a low-profile high-gain lens antenna. The physical space shape is modified such that singular index values are avoided, and the optical path inside the lens is rescaled to eliminate superluminal regions. A prototype of the lens is fabricated using three-dimensional printing. The measurement results show that the realized gain of an H-plane horn antenna can be improved by 1.5–2.4 dB compared to a reference H-plane horn.
10 citations
01 Apr 2010
TL;DR: In this article, the material parameters for cylindrical transparent devices with arbitrary cross-sections were developed based on the coordinate transformation and the results of the simulation showed that although the incident waves are distorted in the transformation region apparently, they return to the original wavefronts when passing through the device.
Abstract: Electromagnetic transparent device is very important for antenna protection. In this paper, the material parameters for the cylindrical transparent devices with arbitrary cross section are developed based on the coordinate transformation. The equivalent two-dimensional (2D) transparent devices under TE plane and cylindrical wave irradiation is designed and studied by full-wave simulation, respectively. It shows that although the incident waves are distorted in the transformation region apparently, they return to the original wavefronts when passing through the device. All theoretical and numerical results validate the material parameters for the cylindrical transparent devices with arbitrary cross section we developed.
10 citations
TL;DR: This work design and simulate a spherical cloak which takes into account the dispersive nature of relative permittivity and permeability tensors realized by plasma-like metamaterials and works over a broad frequency-band even though these materials are of a highly dispersion nature.
Abstract: Electromagnetic cloaking, as challenging as it may be to the physicist and the engineer has become a topical subject over the past decade. Thanks to the transformations optics (TO) invisibility devices are in sight even though quite drastic limitations remain yet to be lifted. The extreme material properties which are deduced from TO can be achieved in practice using dispersive metamaterials. However, the bandwidth over which a metamaterial cloak is efficient is drastically limited. We design and simulate a spherical cloak which takes into account the dispersive nature of relative permittivity and permeability tensors realized by plasma-like metamaterials. This spherical cloak works over a broad frequency-band even though these materials are of a highly dispersive nature. We establish two equations of state that link the eigenvalues of the permittivity and permeability tensors in every spherical cloak regardless of the geometrical transformation. Frequency dispersive properties do not disrupt cloaking as long as the equations of states are satisfied in the metamaterial cloak.
10 citations