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 paper, a modulation of bi-directional metamaterial absorbers that is thermally switchable at terahertz frequencies was investigated, where the magnetic resonance can be systematically blue-shifted and overlapped with the electric resonance, which is unaffectedly settled at about 0.8
15 citations
TL;DR: In this article, an automated phase correction (APC) algorithm is proposed to properly trace and compensate phase angles of the complex logarithmic function which may experience abrupt phase jumps near the resonant frequency region of the concerned EMMs, and hence the continuity of the effective optical properties of lossy metamaterials is ensured.
Abstract: To retrieve complex-valued effective permittivity and permeability of electromagnetic metamaterials (EMMs) based on resonant effect from scattering parameters using a complex logarithmic function is not inevitable. When complex values are expressed in terms of magnitude and phase, an infinite number of permissible phase angles is permissible due to the multi-valued property of complex logarithmic functions. Special attention needs to be paid to ensure continuity of the effective permittivity and permeability of lossy metamaterials as frequency sweeps. In this paper, an automated phase correction (APC) algorithm is proposed to properly trace and compensate phase angles of the complex logarithmic function which may experience abrupt phase jumps near the resonant frequency region of the concerned EMMs, and hence the continuity of the effective optical properties of lossy metamaterials is ensured. The algorithm is then verified to extract effective optical properties from the simulated scattering parameters of the four different types of metamaterial media: a cut-wire cell array, a split ring resonator (SRR) cell array, an electric-LC (E-LC) resonator cell array, and a combined SRR and wire cell array respectively. The results demonstrate that the proposed algorithm is highly accurate and effective.
14 citations
TL;DR: In this article, a simple and versatile analytical model describing propagation of electro magnetic waves in metamaterials is suggested, based on the secondary averaging procedure in full analogy with the ordinary one accepted for Maxwell equations, where the nanoplasmonic inclusions are considered similarly to natural atoms or molecules.
Abstract: Metamaterials are artificial media that allow tailoring the macroscopic properties of light propagation by a careful choice of nanoplasmonic inclusions it is made of. A simple and versatile analytical model describing propagation of electro magnetic waves in metamaterials is suggested. The model is based on the secondary averaging procedure in full analogy with the ordinary one accepted for Maxwell equations, where the nanoplasmonic inclusions (typically referred to as metaatoms or metamolecules) are considered similarly to natural atoms or molecules. The model turns out to be beneficial improvement in the theoretical description of metamaterials since it contributes to the physical understanding of optical phenomena in metamaterials and provides good quantitative correspondence with the results of rigorous numerical methods, and is able to predict new effects.
14 citations
TL;DR: By drastically decreasing the diamagnetic effect with a thin metallic structure in the unit cell and increasing the effective permittivity through strong capacitive coupling, the crossed I-shaped metallic patches metamaterial with an extremely high refractive index in the dual band terahertz region is designed.
Abstract: By drastically decreasing the diamagnetic effect with a thin metallic structure in the unit cell and increasing the effective permittivity through strong capacitive coupling, we designed the crossed I-shaped metallic patches metamaterial with an extremely high refractive index in the dual band terahertz region. The peak index of refraction of near 80 at about 0.75 THz is predicted, along with another peak index of about 25 at 2.85 THz. Based on the careful analysis of the high index on the dependence of the electric field coupling effect, the magnetic field diamagnetic response, and the geometric parameters in the unit cell, it is found that both of the high index bands respectively correspond to different components in the metamaterial structure. To realize a higher effective refractive index for the second band as well as for the first one, we proposed the triple I-shaped metallic metamaterial structure.
14 citations
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TL;DR: In this paper, the authors apply the transformation-optics approach to the design of a metamaterial radome that can extend the scanning angle of a phased-array antenna.
Abstract: We apply the transformation-optics approach to the design of a metamaterial radome that can extend the scanning angle of a phased-array antenna. For moderate enhancement of the scanning angle, via suitable parameterization and optimization of the coordinate transformation, we obtain a design that admits a technologically viable, robust and potentially broadband implementation in terms of thin-metallic-plate inclusions. Our results, validated via finite-element-based numerical simulations, indicate an alternative route to the design of metamaterial radomes which does not require negative-valued and/or extreme constitutive parameters.
14 citations