Topic
Transformation optics
About: Transformation optics is a research topic. Over the lifetime, 2687 publications have been published within this topic receiving 102378 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this article, a geometrically flat hyperlens that can still magnify and transfer sub-wavelength objects to the far-field is presented, which has great potential for practical application by solving many problems of conventional curvilinear hyperlenses.
Abstract: Here, we present a geometrically flat hyperlens that can still magnify and transfer sub-wavelength objects to the far-field. The flat hyperlens is designed using the transformation optics approach, which transforms the virtual space of the cylindrical coordinate into the physical space of the trapezoidal coordinate. We also suggest the possible design of two alternating multilayers by using an effective medium approximation. The sub-wavelength magnification using the designed flat hyperlens is numerically demonstrated. Such a flat hyperlens has great potential for practical application by solving many problems of conventional curvilinear hyperlenses arisen from their geometries.
22 citations
TL;DR: This work uses the Schwarz-Christoffel transformation as a versatile tool to produce perfect conformal mapping of coordinates between the virtual and flat reflectors, thereby avoiding the need to monitor the anisotropy of the material that results when employing quasi-conformal methods.
Abstract: A flat reflector capable of scanning over wide angles is designed using a transformation optics approach. This reflector is derived from its virtual parabolic counterpart using a conformal coordinate transformation that determines the permittivity profile of the flat reflector. By changing the permittivity profile, the flat reflector is then capable of scanning up to 47° away from broadside while maintaining good beam characteristics across a wide frequency range. Moreover, its directivity is comparable to that of the virtual parabolic reflector, even at high scan angles. We use the Schwarz-Christoffel transformation as a versatile tool to produce perfect conformal mapping of coordinates between the virtual and flat reflectors, thereby avoiding the need to monitor the anisotropy of the material that results when employing quasi-conformal methods.
22 citations
TL;DR: In this article, a scattering (S-) parameter retrieval method for anisotropic elastic metamaterials is presented. But the method cannot directly determine the diagonal components in effective tensor property, and the conventional methods simply use the analytic inversion formulae for the material characterization.
Abstract: In this paper, the scattering (S-) parameter retrieval method is presented specifically for anisotropic elastic metamaterials; so far, no retrieval has been accomplished when elastic metamaterials exhibit fully anisotropic behavior. Complex constitutive property and intrinsic scattering behavior of elastic metamaterials make their characterization far more complicated than that for acoustic and electromagnetic metamaterials. In particular, elastic metamaterials generally exhibit anisotropic scattering behavior due to higher scattering modes associated with shear deformation. They also exhibit nonlocal responses to some degrees, which originate from strong multiple scattering interactions even in the long wavelength limit. Accordingly, the conventional S-parameter retrieval methods cannot be directly used for elastic metamaterials, because they determine only the diagonal components in effective tensor property. Also, the conventional methods simply use the analytic inversion formulae for the material characterization so that inherent nonlocality cannot be taken into account. To establish a retrieval method applicable to anisotropic elastic metamaterials, we propose an alternative S-parameter method to deal with full anisotropy of elastic metamaterials. To retrieve the whole effective anisotropic parameter, we utilize not only normal but also oblique wave incidences. For the retrieval, we first retrieve the ratio of the effective stiffness tensor to effective density and then determine the effective density. The proposed retrieval method is validated by characterizing the effective material parameters of various types of non-resonant anisotropic metamaterials. It is found that the whole effective parameters are retrieved consistently regardless of used retrieval conditions in spite of inherent nonlocality.
22 citations
TL;DR: In this paper, the authors numerically investigate the Fano-type resonance in complex metamaterials, and demonstrate the presence of Fano−Feshbach resonances due to the interaction between two Fano type resonances in the overlapping region, implemented by breaking and tuning the symmetric properties of the resonant metallic element.
Abstract: Metamaterials support optically excitable dark-plasmon modes featured by antisymmetric surface current oscillations, which can be explained by Fano-type resonance and can be tailored by controlling the embedded structural geometry. In this article, we numerically investigate the Fano-type resonance in complex metamaterials, and demonstrate the presence of Fano–Feshbach resonances due to the interaction between two Fano-type resonances in the overlapping region, implemented by breaking and tuning the symmetric properties of the resonant metallic element. Features of the resonance are discussed. This work shows that the domain of dark-plasmon mode based metamaterial system supports rich physics and can lead to various potential applications.
22 citations
22 citations