This letter discusses the importance of the nature of local fields inside a unit cell of optical metamaterials in developing a valid effective medium theory. In particular, we apply the Meier-Wokaun procedure to derive a corrected version of the Maxwell-Garnett formula for the refractive index of a medium composed by metallic rods with subwavelength cross-section. We compare this result with the values obtained using the full mode analysis calculated via numerical simulations and analyze the impact of surface plasmon polaritons in adequately determining the effective refractive index of the medium.
We describe an efficient rigorous model suitable for calculating the properties of finite metamaterial samples, which takes into account the discrete structure of metamaterials based on capacitively loaded ring resonators. We illustrate how this model applies specifically to a metamaterial lens employed in magnetic resonant imaging. We show that the discrete model reveals the effects which can be missed by a continuous model based on effective parameters, and that the results are in close agreement with the experimental data.
We present a metamaterial-based random polarization control plate to produce incoherent laser irradiation by exploiting the ability of metamaterial in local polarization manipulation of beam upon transmission via tuning its local geometry. As a proof-of-principle, we exemplify this idea numerically in a simple optical system using a typical L-shaped plasmonic metamaterial with locally varying geometry, from which the desired polarization distribution can be obtained. The calculating results illustrate that this scheme can effectively suppress the speckle contrast and increase irradiation unifo…
A numerical study of the features of the scattering of incident radiation at a periodically modulated hyperbolic metamaterial boundary was carried out. We have found optimal - sawtooth-shaped profile of the interface which provides minimal reflection. It is shown that at a certain orientation of the optical axes of the metamaterial, a subwave localization of the field occurs at the saw-tooth interface. An approximate analytical expression for the eigenmode was found. A generalization of the numerical method is implemented for calculating fields, based on the application of the Green's second i…
We present an effective-medium model for calculating the frequency-dependent effective permittivity $ε(ω)$ and permeability $μ(ω)$ of metamaterial composites containing spherical particles with arbitrary permittivity and permeability. The model is derived from the zero-scattering condition within the dipole approximation, but does not invoke any additional long-wavelength approximations. As a result, it captures the effects of spatial dispersion and predicts a finite effective refractive index and antiresonances in $ε(ω)$ and $μ(ω)$, in agreement with numerical finite-element calculations.
In this paper, we investigate the role of the current loop in the generation of second and third harmonic signals from magnetic metamaterials. We will show that the fact that the current loop in the magnetic resonance acts as a source for nonlinear effects and it consists of two orthogonal parts, leads to the generation of two harmonic signals in two orthogonal polarizations.
A finite element method (FEM) for solving the complex valued k(ω) vs. ω dispersion curve of a 3D metamaterial/photonic crystal system is presented. This 3D method is a generalization of a previously reported 2D eigenvalue method. This method is particularly convenient for analyzing periodic systems containing dispersive (e.g., plasmonic) materials, for computing isofrequency surfaces in the k-space, and for calculating the decay length of the evanescent waves. Two specific examples are considered: a photonic crystal comprised of dielectric spheres and a plasmonic fishnet structure. Hybridizati…
A robust wedge setup is proposed to unambiguously demonstrate negative refraction for negative index metamaterials. We applied our setup to several optical metamaterials from the literature and distinctly observed the phenomena of negative refraction. This further consolidates the reported negative-index property. It is found there generally exists a lateral shift for the outgoing beam through the wedge. We derived a simple expression for calculating this beam shift and interestingly, it provides us a strategy to quantitatively estimate the loss of the wedge material (Im[n]). Addition- ally, w…
In this paper, we show by experiment that by covering a thin flat nonlinear lens on the sources, the sub-diffraction-limit observation can be achieved by measuring either the near-field distribution or the far-field radiation of the sources at the harmonic frequencies and calculating the inverse Fourier transformation to obtain the sub-wavelength imaging. Especially, the sub-wavelength image calculated from measured far-field data demonstrates very clear resolution. Since metamaterials included with active elements can easily behave strong nonlinearity under very weak incident electromagnetic …
Polaritonic materials, owing to a strong phonon-polariton resonance in the THz and far-infrared parts of the electromagnetic spectrum, offer both high-index dielectric and metallic response in this regime. This complex response makes them suitable candidates for the design of metamaterial-related phenomena and applications. Here we show that one type of polaritonic-material-based structures that are particularly suitable for the achievement of a wide range of metamaterial properties are systems of polaritonic rods. To study the interplay between the material and the structural resonances in su…
Light absorption plays an important role in many research areas. Here, we propose and demonstrate a thin ultra-broadband strong light absorber consisting of periodic taper arrays on a gold substrate.
Electromagnetic localization and existence of gap solitons in nonlinear metamaterials, which exhibit a stop band in their linear spectral response, is theoretically investigated. For a self-focusing Kerr nonlinearity, the equation for the electric field envelope with carrier frequency in the stop band - where the magnetic permeability $μ(ω)$ is positive and the dielectric permittivity $ε(ω)$ is negative - is described by a nonlinear Klein-Gordon equation with a dispersive nonlinear term. A family of standing and moving localized waves for both electric and magnetic fields is found, and the rol…
Toroidal dipole, first described by Ia. B. Zeldovich [Sov. Phys. JETP 33, 1184 (1957)], is a distinct electromagnetic excitation that differs both from the electric and the magnetic dipoles. It has a number of intriguing properties: static toroidal nuclear dipole is responsible for parity violation in atomic spectra; interactions between static toroidal dipole and oscillating magnetic dipole are claimed to violate Newton's Third Law while non-stationary charge-current configurations involving toroidal multipoles have been predicted to produce vector potential in the absence of electromagnetic …
Light propagation in all-dielectric rod-type metamaterials is studied theoretically. The electric and magnetic dipole moments of the rods are derived analytically in the long-wavelength limit. The effective permittivity and permeability of a square lattice of rods are calculated by homogenizing the corresponding array of dipoles. The role of dipole resonances in the optical properties of the rod array is interpreted. This structure is found to exhibit a true left-handed behavior, confirming previous experiments [L. Peng \textit{et al.}, Phys. Rev. Lett. \textbf{98}, 157403 (2007)]. A scaling a…
Near-field coupling is a fundamental physical effect, which plays an important role in the establishment of classical analog of electromagnetically induced transparency (EIT). However, in a normal environment the coupling length between the bright and dark artificial atoms is very short and far less than one wavelength, owing to the exponentially decaying property of near fields. In this work, we report the realization of a long range EIT, by using a hyperbolic metamaterial (HMM) which can convert the near fields into high-k propagating waves to overcome the problem of weak coupling at long di…
Balancing the complexity and the simplicity has played an important role in the development of many fields in science and engineering. As Albert Einstein was once quoted to say: 'Everything must be made as simple as possible, but not one bit simpler'. The simplicity of an idea brings versatility of that idea into a broader domain, while its complexity describes the foundation upon which the idea stands. One of the well-known and powerful examples of such balance is in the Boolean algebra and its impact on the birth of digital electronics and digital information age. The simplicity of using onl…
In this Letter, we develop an electrostatic theory for designing bulk composites with effective lossless negative permittivities. The theory and associated design procedure are validated by comparing their predictions with those of rigorous full-wave simulations. It is demonstrated that the excitation of the Frohlich mode (the first-order surface mode) of the constitutive nanoparticles plays a key role in achieving negative permittivities with compensated losses.
The possibility of compensating absorption in negative-index metatamterials (NIMs) doped by resonant nonlinear-optical centers is shown. The role of quantum interference and extraordinary properties of four-wave parametric amplification of counter-propagating electromagnetic waves in NIMs are discussed.
We consider spin angular momentum density in inhomogeneous acoustic fields: evanescent waves and surface waves at interfaces with negative-density metamaterials. Despite being purely longitudinal (curl-free), acoustic waves possess intrinsic vector properties described by the velocity field. Motivated by the recent description and observation of the spin properties in elastic and acoustic waves, we compare these properties with their well-known electromagnetic counterparts. Surprisingly, both the transverse spin of evanescent waves and the parameters of surface waves are very similar in electr…
One of the most important goals of condensed matter physics is materials by design, i.e. the ability to reliably predict and design materials with a set of desired properties. A striking example is the deterministic enhancement of the superconducting properties of materials. Recent experiments have demonstrated that the metamaterial approach is capable of achieving this goal, such as tripling the critical temperature Tc in Al-Al2O3 epsilon near zero (ENZ) core-shell metamaterial superconductors. However, transport properties of such metamaterials remained much worse compared to conventional su…
Sub-wavelength confinement of light in nonlinear hyperbolic metamaterials due to formation of spatial solitons has attracted much recent attention because of its seemingly counter-intuitive behavior. In order to achieve self-focusing in a hyperbolic wire medium, a nonlinear self-defocusing Kerr medium must be used as a dielectric host. Here we demonstrate that this behavior finds natural explanation in terms of analogue gravity. Wave equation describing propagation of extraordinary light inside hyperbolic metamaterials exhibits 2+1 dimensional Lorentz symmetry. The role of time in the correspo…
We propose herein a method of material-structure integrated design for broadband absorption of dielectric metamaterial, which is achieved by combination of genetic algorithm and simulation platform. A multi-layered metamaterial absorber with an ultra-broadband absorption from 5.3 to 18 GHz (a relative bandwidth of as high as 109%) is realized numerically and experimentally. In addition, simulated results demonstrate the proposed metamaterial exhibits good incident angle and polarization tolerance, which also are significant criteria for practical applications. By investigating the working prin…
Lattices of topological defects, such as Abrikosov lattices and domain wall lattices often arise as metastable ground states in higher-dimensional field theoretical models. We demonstrate that such lattice states may be described as extra-dimensional metamaterials via higher-dimensional effective medium theory. A 4+1 dimensional extension of Maxwell electrodynamics with a compactified time-like dimension has been considered as an example. It is demonstrated that from the point of view of macroscopic electrodynamics an Abrikosov lattice state in such a 4+1 dimensional spacetime may be described…
The discovery of photonic crystals thirty years ago, in conjunction with research advances in plasmonics and metamaterials, has inspired the concept of decameter scale metasurfaces, coined seismic metamaterials, for an enhanced control of surface (Love and Rayleigh) and bulk (shear and pressure) elastodynamic waves. The powerful mathematical tools of coordinate transforms, effective medium and Floquet-Bloch theories, which have revolutionized nanophotonics, can be translated in the language of civil engineering and geophysics. Experiments on seismic metamaterials made of buried elements in the…
Advanced photonic nanostructures have enabled the maximization of synthetic chiroptic activities. The unique structuring of these building blocks has empowered chiral selective interactions with electromagnetic waves in plasmonic structures and dielectric media. Given the repertoire of optimized chiral surfaces in the literature and the ubiquity of chirality in the organic realm, the natural direction to consider is the operation of these devices in larger optical systems much like their chiral organic counterparts. In this review, we recapitulate advances in active and nonlinear chiral metama…
Ultrafast excitation of Bloch plasmon polaritons in hyperbolic metamaterials with an extreme ultra-violet transient grating
Umeå University（于默奥大学）；Elettra Sincrotrone Trieste（的里雅斯特同步辐射中心）；CIC nanoGUNE BRTA（nanoGUNE研究中心）；Ikerbasque, Basque Foundation for Science（伊卡巴斯克，巴斯克科学基金会）；Università degli Studi di Modena e Reggio Emilia（摩德纳和雷焦艾米利亚大学）；Wallenberg Initiative Materials Science for Sustainability（瓦伦堡可持续材料科学倡议）
As demonstrated by Chernodub, vacuum in a strong magnetic field behaves as a periodic Abrikosov vortex lattice in a type-II superconductor. We investigate electromagnetic behavior of vacuum in this state. Since superconductivity is realized along the axis of magnetic field only, strong anisotropy of the vacuum dielectric tensor is observed. The diagonal components of the tensor are positive in the x and y directions perpendicular to the magnetic field, and negative in the z direction along the field. As a result, vacuum behaves as a hyperbolic metamaterial medium. If the magnetic field is cons…
We report on the optical and physical characterization of metallic nanowire (NW) metamaterials fabricated by electrodeposition of ~30 nm diameter gold nanowires in nano-porous anodic aluminum oxide. We observe a uniaxial anisotropic dielectric response for the NW metamaterials that displays both epsilon-near-zero (ENZ) and epsilon-near-pole (ENP) resonances. We show that a fundamental difference in the behavior of NW-metamaterials from metal-dielectric multilayer (ML) metamaterials is the differing directions of the epsilon-near-zero (ENZ) and epsilon-near-pole (ENP) dielectric responses relat…
In this review, we take an extensive look at the role that the principles of causality and passivity have played in various areas of physics and engineering, including in the modern field of metamaterials. The aim is not to provide a comprehensive list of references as that number would be in the thousands, but to review the major results and contributions which have animated these areas and to provide a unified framework from which to understand the developments in different fields. Towards these goals, we chart the early history of the field through its dual beginnings in the analysis of the…
Metamaterials possess artificial bulk and surface electromagnetic states. Tamed dispersion properties of surface waves allow one to achieve controllable super-Planckian radiative heat transfer (RHT) process between two closely spaced objects. We numerically demonstrate enhanced RHT between two 2D grooved metal plates by a full-wave scattering approach. The enhancement originates from both transverse magnetic spoof surface plasmon polaritons and a series of transverse electric bonding- and anti-bonding waveguide modes at surfaces. The RHT spectrum is frequency-selective, and highly geometricall…
We introduce a formalism that describes the interaction of light with bifacial optical nanomaterials. They are artificial noncentrosymmetric materials in which counter-propagating waves behave differently. We derive electromagnetic material parameters for uniaxial crystalline media in terms of the complex transmission and reflection coefficients of a single layer of the constituent nanoscatterers, which makes the numerical evaluation of these parameters very efficient. In addition, we present generalized Fresnel coefficients for such bifacial nanomaterials and investigate the fundamental role …
As a basic building block, optical resonant cavities (ORCs) are widely used in light manipulation; they can confine electromagnetic waves and improve the interaction between light and matter, which also plays an important role in cavity quantum electrodynamics, nonlinear optics and quantum optics. Especially in recent years, the rise of metamaterials, artificial materials composed of subwavelength unit cells, greatly enriches the design and function of ORCs. Here, we review zero-index and hyperbolic metamaterials for constructing the novel ORCs. Firstly, this paper introduces the classificatio…
We study the guided modes in the wire medium slab taking into account both the nonlocality and losses in the structure. We show that due to the fact that the wire medium is an extremeley spatially dispersive metamaterial, the effect of nonlocality plays a critical role since it results in coupling between the otherwise orthogonal guided modes. We observe both the effects of strong and weak coupling, depending on the level of losses in the system.
CONTEXT.Large field-of-view imaging/polarimetry instruments operating at millimeter and submm wavelengths are fundamental tools to understand the role of magnetic fields (MF) in channeling filament material into prestellar cores providing a unique insight in the physics of galactic star-forming regions. Among other topics, at extra-galactic scales, polarization observations of AGNs will allow us to constrain the possible physical conditions of the emitting plasma from the jets and/or exploring the physics of dust inside supernova remnants. The kilo-pixel NIKA2 camera, installed at the IRAM 30-…
The Rashba interaction induced when inversion symmetry is broken in solids is a key interaction connecting spin and charge for realizing novel magnetoelectric cross-correlation effects. Here, we theoretically explore the optical properties of a bulk Rashba conductor by calculating the transport coefficients at finite frequencies. It is demonstrated that the combination of direct and inverse Edelstein effects leads to a softening of the plasma frequency for the electric field perpendicular to the Rashba field, resulting in a hyperbolic electromagnetic metamaterial. In the presence of magnetizat…
