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: This paper presents the general formalism that allows calculating the permittivity tensor for intersubband transitions in generic semiconductor heterostructures and studies numerically the specific case of coupling and tuning metamaterials in the thermal infrared through coupling to biased GaAs semiconductor quantum wells.
Abstract: In this paper, we propose a new and versatile mechanism for electrical tuning of planar metamaterials: strong coupling of metamaterial resonances to engineered intersubband transitions that can be tuned through the application of an electrical bias. We present the general formalism that allows calculating the permittivity tensor for intersubband transitions in generic semiconductor heterostructures and we study numerically the specific case of coupling and tuning metamaterials in the thermal infrared through coupling to biased GaAs semiconductor quantum wells. This tuning mechanism can be scaled from the visible to the far infrared by the proper choice of metamaterials and semiconductor heterostructures.
32 citations
TL;DR: In this article, two improved methods in retrieving effective refractive indices, impedances, and material properties, such as permittivity (e) and permeability (μ), of metamaterials are discussed.
Abstract: This paper discusses two improved methods in retrieving effective refractive indices, impedances, and material properties, such as permittivity (e) and permeability (μ), of metamaterials. The first method modified from Kong's retrieval method allows effective constitutive parameters over all frequencies including the anti-resonant band, where imaginary parts of e or μ are negative, to be solved. The second method is based on genetic algorithms and optimization of properly defined goal functions to retrieve parameters of the Drude and Lorentz dispersion models. Equations of effective refractive index and impedance at any reference planes are derived. Split ring resonator-rod based metamaterials operating in terahertz frequencies are designed and investigated with proposed methods. Retrieved material properties and parameters are used to regenerate S-parameters and compared with simulation results generated by cst microwave studio software.
32 citations
TL;DR: In this paper, a comparison of wave dispersion for two-and three-dimensional (3D) metamaterial models and evaluation of the applicability ranges of 2D results is presented.
Abstract: Locally resonant metamaterials (LRMs) controlling low-frequency waves due to resonant scattering are usually characterized by narrow band gaps (BGs) and a poor wave filtering performance. To remedy this shortcoming, multiresonant metamaterial structures with closely located BGs have been proposed and widely studied. However, the analysis is generally limited to two-dimensional (2D) structures neglecting the finite height of any real resonator. The aim of this paper is the comparison of the wave dispersion for two- and three-dimensional (3D) metamaterial models and evaluation of the applicability ranges of 2D results. Numerical study reveals that dual-resonant structures with cylindrical inclusions possess only a single (compared to two in the 2D case) BG for certain height-to-width ratios. In contrast, the wave dispersion in metamaterials with multiple spherical resonators can be accurately evaluated using a 2D approximation, enabling a significant simplification of resource-consuming 3D models.
32 citations
TL;DR: Wang et al. as mentioned in this paper proposed a novel method to design an arbitrarily N-sided polygonal transient thermal cloak with nonsingular and homogenous material parameters, which can be realized with only four kinds of natural bulk materials in bilayer configuration throughout.
32 citations
TL;DR: The nanocluster meetingamaterial represents a practical metamaterial architecture that is compatible with the scalable bottom-up manufacturing process and exhibited Lorentz-like resonance.
Abstract: We experimentally observe magnetic resonance in the visible frequency region from self-assembled silver nanocluster metamaterials. Extensive numerical modeling studies were conducted to find the optimal nanocluster dimensions. Self-assembly of silver nanoparticles coated with nanoscale silica coating was then performed on polymer templates fabricated by laser interference lithography. The nanoclusters supported magnetic resonance in the visible region, and the extracted effective permeability exhibited Lorentz-like resonance. The experimentally observed lowest value for the real part of permeability was 0.06. The nanocluster metamaterial represents a practical metamaterial architecture that is compatible with the scalable bottom-up manufacturing process.
32 citations