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In this study, a novel tunable metasurface is designed in order to filter the electromagnetic waves. The single-frequency window-shaped structure is enhanced to have dualfrequency by loading a gap in order to filter the electromagnetic waves. An epsilon-negative (ENG) unit cell is designed to form the metasurface. The parameter retrieval for the effective permittivity and permeability is performed using a version of the Nicholson-Ross-Weir (NRW) algorithm, which is improved by implementing the Kramers-Kronig relationship. The parametric analyses are also performed as regards the geometrical and material properties. The simulations are conducted via CST Microwave Studio, which is based on Finite Integration Method (FIM).

The analytically realization of electromagnetic wave frequency conversion in a time-varying medium was shown by the two methods. The first method considers the optical analog of the electromagnetic wave redshift in the expanding universe using the transformation optics mathematical approach. The second one describes the transient process of pulse electromagnetic wave interaction with the time-varying medium using method of the second order Volterra integral equation. The frequency conversion was shown for several types of commercial laser wavelengths.

International audience; We propose a broadband measurement method for measuring the electromagnetic (EM) properties of metamaterials in the 1-6 GHz frequency range. For this experimental technique, an original adjustable height strip transmission-line was developed that makes it possible to characterize metamaterials with different volumes and different numbers of unit cells. Therefore, it was possible to assess the influence of the number of unit cells in a sample on the measured constitutive parameters (complex permittivity and permeability). This study enabled us to define the criterion of the representative elementary number of cells. This criterion must be satisfied in practice in order to determine the microwave behavior for the sample under test in as close as possible to an infinite medium, whose EM properties can only be determined from simulations. Experimental and theoretical results for split ring resonator-type metamaterials are presented, compared, and discussed.

Functional optical metamaterials usually consist of absorbing, anisotropic and often non-centrosymmetric structures of a size that is only a few times smaller than the wavelength of visible light. If the structures would be substantially smaller, excitation of higher-order electromagnetic multipoles in them, including magnetic dipoles, would be inefficient. As a result, the material would act as an ordinary electric-dipole material. The required non-negligible size of metamolecules, however, makes the material spatially dispersive, so that its optical characteristics depend on light propagation direction. This phenomenon significantly complicates the description of metamaterials in terms of conventional electric permittivity and magnetic permeability tensors. In this work, we present a simple semianalytical method to describe such spatially dispersive metamaterials, which are also allowed to be optically anisotropic and non-centrosymmetric. Applying the method, we show that a strong spatial dispersion, combined with absorption and optical anisotropy, can be used to efficiently control propagational characteristics of optical beams.

We present results of modeling of waveguides modes propagation coefficients in cylindrical tree-layer waveguide in this work. Intermediate layer is LHM (Left-Handed-Medium) metamaterial with negative index of refraction. The outer and inner layers are conventional materials with positive index of refraction RHM (Right-Handed-Medium). Our results indicate that in such waveguides exist complex waves and waves with a significant slowdown of phase.

The new concept of metatronics is merging with graphene metamaterials. Our approach to “graphene metamaterials” includes “metamaterial treatment” of beams of electrons (BE) (see also electron density lenses) with a wide range of control of wave characteristics; means of influencing the BE characteristics in dielectric-graphene (DG) and carbon nano-tube-graphene-dielectric structures through the electron waves; and, finally, using advantages of effectively controllable BE as such, for creation of “solid-state graphene metamaterial electron optics (GMEO)”. GMEO can involve applications of such elements as “positive-negative phase” waveguides, lenses, diffraction gratings etc. and such electron devices as spin filters, electron collimators, modulators, beam splitters etc.

Metamaterials and transformation optics have enormously enriched human's ability to control electromagnetic waves and light, leading to novel applications such as cloaking, exotic lens, illusion optics, etc.. In previous designs of transformation optics devices, local media with special parameters such as negative values and suitable anisotropy have been widely used. The parameters of these local media are often required to have complex spatial distribution, but are usually assumed to be independent of the wave vector. These parameters are di-cult to achieve, usually involving both resonances in permittivity and permeability. However, transformation optics can also be achieved by using nonlocal photonic media with parameters not only dependent on frequency and position, but also on the wave vector. We theoretically and experimentally demonstrate realization of nonlocal photonic media with suitable k-dependence, so as to achieve interesting applications such as wide-angle Brewster's angle and transformation optics devices (1). Our work shows the possibility of nonlocal photonic media in controlling electromagnetic waves and light in unprecedented manner.

We studied theoretically electromagnetic surface waves that propagate along an interface between air and magnetic metamaterials. The metamaterials comprise coupled split-ring resonators. We found two types of waves. Waves of the first type propagate due to interaction of the electromagnetic wave with individual rings, which leads to negative magnetic permeability. They are analogous to the well-known surface plasmons. Waves of the second type, however, are of a different nature and propagate when near-field coupling between the rings exists in the transverse direction. Interaction between the two types leads to complex dispersion characteristics, whose properties can be tailored by changing the inter-element coupling.

Recent developments in the field of metamaterials have revealed unparalleled opportunities for "tailoring" space for light propagation, opening a new paradigm in spin- and quantum-related phenomena in optical physics. We show that unique optical properties of metamaterials open unlimited prospects to "tailor" light itself.

We study epsilon-near-zero (ENZ) metamaterials with balanced loss and gain characterized by parity-time (PT ) symmetry. Through the example of a wave tunneling phenomenon, we show that the ENZ regime is particularly suited for PT -symmetry-based phenomena, since it enhances the effects of feasibly small levels of gain (and loss). Overall, the combination of the ENZ and PT -symmetry concepts may pave the way to novel, and otherwise unattainable, propagation effects and anomalous light-matter interactions.

In the homogenization of metamaterials, one of the important challenges yet to be fully resolved resides in the proper modeling of the influence of higher-order multipolar terms describing the basic constituent inclusions. As an important step in this direction, we consider here a metamaterial composed of a three-dimensional cubic array of purely quadrupolar inclusions, with zero electric and magnetic dipole moments, so that the leading term in their multipole expansion is the electric quadrupole moment. Applying a first-principle homogenization approach similar to (A. Alu, Phys. Rev. B, 84, 075153, 2011) the spatially dispersive permittivity of such an array in the long-wavelength limit is derived. This tensorial permittivity is a quadratic function of the propagation constant in the medium and it is shown to depend on the propagation direction, as a symptom of strong spatial dispersion.

— We discuss the change in the magnetic flux profile by introducing a negative refractive index material (metamaterial) in between the source and receiver. The environment parameters, e and μ , has a significant effect on the propagation of electromagnetic wave. The behavior of Transverse Magnetic (TM) wave when the medium in the path of propagation is changed to negative permittivity and permeability is simulated and discussed. The effect of size, shape and anisotrophy of the metamaterials, for near-field regions, on the magnetic flux density has been studied using finite element analysis. An enhancement in the magnetic flux density when a metamaterial is introduced in between the source and receiver was observed. The results show that the static and quasi-static behavior of the system is same. Keywords—metamaterials, quasi static, magnetic flux transverse magnetic I. I NTRODUCTION The idea of charging on the go is an exciting option for various high power applications like Electric Vehicle. Wireless power charging can be done by radiative or non-radiative processes. Use of microwave and optical frequencies falls into the radiative category while non-radiative process refers to the near-field domain. This concept was put forward by Nikola Tesla when he invented an apparatus for transmitting electrical energy wirelessly [1]. Later, with the advent of microwave transmission technology in 1960’s researchers dreamed power transfer from satellite space station to earth [2]. For short distances inductive coupling is very convenient [3-4]. The enhancement in coupling efficiency is obtained by replacing coils with resonators [5-7]. The efficiency can further be improved by introducing a negative refractive index material between the source and the receiver [8-12]. The negative refractive index material or metamaterial has the unique property of enhancing the evanescent as well as non-evanescent waves [10]. In this paper we present the magnetic flux density variations for quasi-static scenarios when a metamaterial is introduced in between the source and the receiver. The model used for simulation is a 2-dimensional one as we are interested only in the profile in that direction which is in the direction of propagation. II. T

In this paper, an electromagnetic millimeter wave is incident upon periodic chiral-chiral metamaterial structure, embedded in fractional dimension space. An exact solution for reflectance and transmittance in D dimension space is obtained using transfer matrix method. The results computed for fractional dimension are compared with integer dimensional for both the cases of normal and oblique incidences. Numerical results are presented for analyses in this paper. This study explores ways for investigating the electromagnetic waves propagation in stratified structures at fractional boundaries.

We investigate the electromagnetic response of a novel class of multi-layered metamaterials exhibiting one-dimensional mirror asymmetry. In the quasi-homogenized, we prove that the effect of mirror asymmetry yields a specific electromagnetic chiral response.

The paper proposes a new metamaterial unit cell structure that shows resonance in the microwave S-Band frequency range. It also shows negative permittivity and positive permeability at that frequency, which has characterized the material as single negative material. In this design two separate split ring resonator have been used. Commercially available CST Microwave Studio simulation software has been used to get the reflection and transmission parameters for this unit cell.

Metamaterial with negative refractive index is the key phenomenon behind the concept of a cloaking device to hide an object from light in visible spectrum. Metamaterials made of two and three dimensional lattices of periodically placed electromagnetic resonant cells can achieve absorption and propagation of incident electromagnetic radiation as confined electromagnetic fields confined to a waveguide as surface plasmon polaritons, which can be used for shielding an object from in-tune electromagnetic radiation. The periodicity and dimensions of resonant cavity determine the frequency, which are very small as compared to the wavelength of incident light. Till now the phenomena have been demonstrated only for lights in near infrared spectrum. Recent advancements in fabrication techniques have made it possible to fabricate array of three dimensional nanostructures with cross-sections as small as 25 nm that are required for negative refractive index for wavelengths in visible light spectrum of 400-700 nm and for wider view angle. Two types of metamaterial designs, three dimensional concentric split ring and fishnet, are considered. Three dimensional structures consisted of metal-dielectric-metal stacks. The metal is silver and dielectric is yttrium oxide, other than conventional materials such as FR4 and Duroid. High κ dielectric and high refractive index as well as large crystal symmetry of Yttrium oxide has been investigated as encapsulating medium. Dependence of refractive index on wavelength and bandwidth of negative refractive index region are analyzed for application towards cloaking from light in visible spectrum.

We present an overview of results from our recent and ongoing research in the field of metamaterials. In particular, we focus on the recently emerged concepts of parity-time-symmetric metamaterials, metamaterial analog computing, and transformation multiphysics.

A method for arbitrarily controlling the phase progression and power flow of electromagnetic fields within a region of space is introduced. Specifically, the method describes how to design a 2D inhomogeneous, anisotropic medium that supports prescribed spatial distributions of the wave vector and Poynting vector direction. Plane-wave relations in anisotropic media are used in conjunction with an impedance matching process to find the required material parameters.

In this paper, we theoretically study optical responses of tightly-coupled terahertz metamaterial. Unlike loosely-coupled one, tightly-coupled metamaterials exhibit resonant optical responses that are highly dependent on the interaction between each unit resonators. In order to predict optical response and spectral behavior of effective parameters of the metamaterials, a model based on coupled-mode theory is applied. Resonant optical response is shown to be highly dependent on the gap-size between the resonators which relates to the inter-unit coupling, and we show that this dependency implies the possibility of miniaturized metamaterials .

The purpose of this paper is to introduce transformation optics and general relativity with metamaterials to design optical devices. To show how useful the transformation optics is, we propose photonic metamaterials or photonic crystal waveguide with the structure of honeycomb lattice to slow light. We also show that general relativity gives the theoretical tools for designing optical devices made of such exotic properties and man-made materials. The media with a desired device function facilitate space-time transformations and include negative refractive index. One of the applications of slow light is to design single photon source.

Recently metamaterials have been employed to construct electromagnetic (EM) wave absorbers [1]. The idea of metamaterial absorber is to adjust the effective permittivity and permeability independently by varying the dimensions of electric and magnetic resonant components in the unit cell so as to match the effective impedance of the absorber to free space and achieve a large resonant dissipation at the meantime. Thus, wave transmission and reflection are minimized simultaneously and absorption is maximized. Although metamaterial absorber has relatively narrow bandwidth, it possesses many advantages such as high absorption, low density, and thin electric thickness. Moreover, the frequency response can be tailored or scaled from microwave to terahertz and infrared regimes through carefully designing the constituent resonant structures. Since the EM performance of the metamaterial absorber is entirely determined by the resonant structure in the unit cell, it is possible to change or control the absorber performance by incorporating active elements into the resonant unit cell [2-3].

By exploring the relationship between the propagation of electromagnetic waves in a gravitational field and the light propagation in a refractive medium, it is shown that, in the presence of a positive cosmological constant, the velocity of light will be smaller than its special relativity value. Then, restricting again to the domain of validity of geometrical optics, the same result is obtained in the context of wave optics. It is argued that this phenomenon and the anisotropy in the velocity of light in a gravitational field are produced by the same mechanism.

The energy distribution of a thermal electromagnetic field in a cavity with a finite (but big) Q-factor is derived on the basis of the Rytov–Lifshitz theory of equilibrium electromagnetic fluctuations.

We study the electromagnetic field radiated by high-frequency electric currents in infinite conducting cylinders, with longitudinal or solenoidal flows. We show that the behavior of the radiated fields is very different for radiofrequencies and for higher frequencies. When ωa/c is large (where a is the cylinder radius), the radiated power varies very rapidly as a function of the frequency and is almost zero for certain values.

We show that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu//sub eff/, which can be tuned to values not accessible in naturally occurring materials, including large imaginary components of /spl mu//sub eff/. The microstructure is on a scale much less than the wavelength of radiation, is not resolved by incident microwaves, and uses a very low density of metal so that structures can be extremely lightweight. Most of the structures are resonant due to internal capacitance and inductance, and resonant enhancement combined with compression of electrical energy into a very small volume greatly enhances the energy density at critical locations in the structure, easily by factors of a million and possibly by much more. Weakly nonlinear materials placed at these critical locations will show greatly enhanced effects raising the possibility of manufacturing active structures whose properties can be switched at will between many states.

Resonance (frequency 1.4 cm(−1) changes induced in the four-photon optical spectrum of water by a millimeter-wave electromagnetic field are observed experimentally. Comparison with the spectrum of ice in the range 0‒2 cm(1 shows that the action of such a field is of a structure-forming character.

Transformation Optics (TO) is a systematic approach that makes use of coordinate transformations to design devices capable of controlling the propagation of electromagnetic waves [1]. This control is achieved on the basis of macroscopic equivalent constitutive tensors of a volumetric anisotropic material. In practice, TO-based devices can be implemented by using metamaterials, which can be engineered to achieve electromagnetic behaviors which can not be found in nature [2]. Metamaterials can be realized by periodically arranging many small inclusions in a dielectric host environment and their use offers promising opportunities for the practical implementation of TO-based devices; there are, however, technological difficulties in controlling the variation of the macroscopic constitutive tensors of volumetric metamaterials, as well as in realizing anisotropic and extreme parameters. A significant technological simplification can be obtained by using metasurfaces (MTS) [3] instead of volumetric metamaterials. MTSs are thin metamaterial layers constituted by a periodic lattice of sub-wavelength elements. Due to the small periodicity in terms of a wavelength, they can be characterized in terms of an equivalent impedance providing the relationship between the average tangential components of the electric and magnetic fields. Indeed, effects similar to addressing waves in volumetric media may be obtained by modulating the properties of an impedance surface supporting surface waves (SW) [4-6].

We present an ultra-broadband metamaterial absorber worked in mid-infrared regime by using the graded permittivity waveguide structure. The light was dissipated for the excitation of the slow light mode and the localized electromagnetic resonance.

29th URSI General Assembly and Scientific Symposium (URSI GASS), Beijing, PEOPLES R CHINA, AUG 16-23, 2014; International audience; Transformation optics offers an unconventional approach for the design of novel radiating devices. Here we propose an electromagnetic metamaterial able to split an isotropic radiation into multiple directive beams. By applying transformations that modify distance and angles, we show how the multiple directive beams can be steered at will. We describe transformation of the metric space and the calculation of the material parameters. Full wave simulations are performed to validate the proposed approach. The idea paves the way to interesting applications in various domains in microwave and optical regimes.

Metamaterials are composite structures which permit unprecedented control over light matter interactions. Here we show use of metamaterials as spatial light modulators permitting single pixel compressive imaging at terahertz frequencies.

WOS:000347171300050 (Nº de Acesso Web of Science) One of the intriguing potentials of metamaterials is the possibility to realize a nonlocal electromagnetic reaction, such that the effective medium response at a given point is fundamentally entangled with the macroscopic field distribution at long distances. Here, it is experimentally and numerically verified that a microwave nonlocal metamaterial formed by crossed metallic wires enables a low-loss broadband anomalous material response such that the refractive index decreases with frequency. Notably, it is shown that an electromagnetic beam refracted by our metamaterial prism creates a reversed microwave rainbow.

Transmission and reflection properties, anisotropy, chirality, optical nonlinearity and luminescent of metamaterials can be controlled at will using dynamic nanostructures reconfigurable with electromagnetic forces or by exploiting structured illumination with coherent light.

In this work we theoretically study light propagation in magnetized epsilon-near-zero (ENZ) metamaterials. We reveal novel regimes of propagation, including optical isolation of circularly polarized waves and back-scattering immune surface wave propagation.

Metamaterials are new artificial materials with unusual electromagnetic properties that are not found in naturally occurring materials. All "natural" materials such as glass, diamond and such have positive electrical permittivity, magnetic permeability and an index of refraction. In these new artificially fabricated materials - termed as negative index materials (NIM) or double negative (ONG) media or left handed (LH) materials or backward wave (BW) media - all these material parameters are negative. With these unusual material parameters, new kinds of miniaturized antennas and microwave components/devices can be created for the wireless communications and the defense industries. The electrical permittivity and the magnetic permeability are the main determinants of a material's response to electromagnetic (EM) waves. In metamaterials, both these material parameters are negative. Correspondingly, the refractive index of the metamaterials is also negative. Another strange property of metamaterials is its reverse Doppler effect.

Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment-all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, 'space-coiling' metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials ('meta-liquids'), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks.

We introduce a microwave cloak composed of smart metamaterials whose electromagnetic properties can be effectively changed by mechanical deformation. Against mechanical deformations, our smart metamaterials self-adjust own flexible elasto-electromagnetic crystal structure for obeying transformation optics rules. With this idea, we built microwave cloak made of flexible silicone rubber tube array and experimentally demonstrated self-adjustable carpet cloak in broadband ranges (8-12GHz) with variable deformations.

Two different expressions are used in this paper to extract bulk electromagnetic properties matching to effective permeability and permittivity, which characterize metamaterials. These parameters have been determined by calculation of S-parameters. We use global approaches with these different analytical methods of calculation. This choice of global approaches is justified by the fact that negative refraction index metamaterials belongs to particular category where the limits of validity of the effective medium theories are not defined. For designing and testing the studied structure, we use HFSS software as a computational approach based on finite element method.

We present a remarkably simple exact analytical solution for the electromagnetic field distribution across an infinite metamaterial composite with an arbitrary graded variation of complex effective permittivity and permeability for the case of constant impedance across the structure. Arbitrary temporal dispersion and losses are allowed and the model is generally applicable to different inhomogeneous and anisotropic media simultaneously containing positive and negative refractive index constituents, as long as the effective medium approximation remains valid. The analytical solution is validated by a dispersive numerical model of lossy metamaterials that uses a transmission line matrix method based on Z-transforms, where a close agreement between the analytic and numerical results is obtained.

International audience; We propose a broadband measurement method for measuring the electromagnetic properties of metamaterials in the frequency range (1-6 GHz). In this experimental technique, an original adjustable height strip transmission-line was developed, which allows characterizing several layers of metamaterial. Therefore, the influence on the measured constitutive parameters (complex permittivity and permeability) of the number of unit cells in the sample to be characterized has been studied. This study enables us to define the criterion of the representative elementary number of cells. This criterion must be satisfied in practice in order to determine a microwave behavior for the sample under test very close to that of the infinite medium. Experimental and simulated results are presented and discussed.

In this paper, the effect of loss on the performance of the two-dimensional cylindrical wave expander is studied. The variations of the normalized distributions of the constitutive parameters are analyzed in detail with the minification factor and the relative thickness respectively. The work above can provide some guidance and suggestions for the practical implementations.

We propose a novel numerical method for extracting the effective medium parameters of metamaterial structures. The reference scattering parameters of a metamaterial structure are provided as the target goal of a nonlinear optimization algorithm. The algorithm internally executes electromagnetic simulations of a homogeneous medium for identical excitations, and varies the relative permittivity and permeability values until the scattering parameters of that medium match the reference scattering values. A specific example for homogenizing a row of silver nanorods in visible wavelengths is presented, which highlights the limitations of relying solely on the scattering parameters.