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: A synthetic paradigm with strictly full parameters and omnidirectionality is reported simultaneously to address this long-held issue for molding heat flow and experimentally demonstrate a series of noncentrosymmetric thermal metadevices that may open a new avenue to manipulating the Laplacian and wave-dynamic fields in ways previously inconceivable.
Abstract: Since the advent of transformation optics and scattering cancelling technology, a plethora of unprecedented metamaterials, especially invisibility cloaks, have been successfully demonstrated in various communities, e.g., optics, acoustics, elastic mechanics, dc electric field, dc magnetic field, and thermotics. A long-held captivation is that transformation-optic metamaterials of anisotropic or noncentrosymmetric geometry (e.g., ellipsoids) commonly come along with parameter approximation/simplification or directional functions. Here, a synthetic paradigm with strictly full parameters and omnidirectionality is reported simultaneously to address this long-held issue for molding heat flow and experimentally demonstrate a series of noncentrosymmetric thermal metadevices. It changes the usual perception that transformation thermotic/dc/acoustic metamaterials are just a direct and simplified derivatives of the transformation-optic counterpart. Instead, the proposed methodology solves an intriguingly important and challenging problem that is not possibly achievable for transformation-optic metamaterials. The approach is rigorous, exact, robust, and yet elegantly facile, which may open a new avenue to manipulating the Laplacian and wave-dynamic fields in ways previously inconceivable.
78 citations
TL;DR: To extract the plasmonic modes of the structure into the far field, two types of 1D grating with triangular and rectangular profile are implemented, obtaining a 10-fold radiative enhancement at visible frequencies.
Abstract: Hyperbolic metamaterials can enhance spontaneous emission, but the radiation-matter coupling is not optimized if the light source is placed outside such media. We demonstrate a 3-fold improvement of the Purcell factor over its outer value and a significant enlargement in bandwidth by including the emitter within a Si/Ag periodic multilayer metamaterial. To extract the plasmonic modes of the structure into the far field we implement two types of 1D grating with triangular and rectangular profile, obtaining a 10-fold radiative enhancement at visible frequencies.
78 citations
TL;DR: In this paper, the causal direction of wavevectors of modes in optical metamaterials is determined, and the signs of refractive index and impedance are determined as a function of real and imaginary parts of dielectric permittivity and magnetic permeability.
Abstract: We derive an approach to determine the causal direction of wavevectors of modes in optical metamaterials, which, in turn, determines signs of refractive index and impedance as a function of real and imaginary parts of dielectric permittivity and magnetic permeability. We use the developed technique to demonstrate that the interplay between resonant response of constituents of metamaterials can be used to achieve efficient dispersion management. Finally, we demonstrate broadband dispersionless index and impedance matching in active nanowire-based negative index materials. Our work has a potential to open new practical applications of negative index composites for broadband lensing, imaging, and pulse routing.
77 citations
TL;DR: In this paper, a steady method was proposed to extract the effective constitutive parameters of a slab of bianisotropic split-ring resonator metamaterial from reflection and transmission coefficients.
Abstract: We propose a steady method to extract the effective constitutive parameters of a slab of bianisotropic split-ring resonator metamaterial from reflection and transmission coefficients. The effective permittivity, permeability and magnetoelectric coupling coefficient of bianisotropic metamaterial can be simply retrieved by our derived analytical inversion equations. In our retrieval method, the transmission and reflection coefficients in only one direction of wave propagation were applied. The method was verified by the retrieval constitutive parameters for different metamaterials, among which one is isotropic structure and the other one is bianisotropic metamaterial. The intrinsic difference between the normal isotropic metamaterial and the bianisotropic metamaterial was evidently revealed. The resonant characteristic of the split ring resonator metamaterial including electric coupling to magnetic resonance was verified by the extracted effective constitutive parameters. The proposed method can be effectively applied in investigation of bianisotropic performance of metamaterials.
77 citations
TL;DR: Nanoscale slot waveguides of hyperbolic metamaterials are proposed and demonstrated for achieving large optical field enhancement and the electric field enhancement effects are verified with the realistic metal-dielectric multilayer waveguide structure.
Abstract: Nanoscale slot waveguides of hyperbolic metamaterials are proposed and demonstrated for achieving large optical field enhancement. The dependence of the enhanced electric field within the air slot on waveguide mode coupling and permittivity tensors of hyperbolic metamaterials is analyzed both numerically and analytically. Optical intensity in the metamaterial slot waveguide can be more than 25 times stronger than that in a conventional silicon slot waveguide, due to tight optical mode confinement enabled by the ultrahigh refractive indices supported in hyperbolic metamaterials. The electric field enhancement effects are also verified with the realistic metal-dielectric multilayer waveguide structure.
76 citations