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A new metamaterial with negative permeability is presented in this study. Negative permeability metamaterials are called mu-negative (MNG) metamaterial as well. The transmission co-efficient of this metamaterial shows resonance at a certain frequency in the C-band of microwave frequency range for the z-axis wave propagation. It also exhibits the characteristics of a mu-negative (MNG) metamaterial there. In the basic construction, the unit cell was formed by joining two metal split square resonator by a copper link on FR-4 substrate material. The measured result is presented and it shows good conformity with the simulated result. Keywords— cloak; c-band; metamaterials

In this paper, common metamaterial parameter retrieval techniques, that is, S-parameter retrieval, Field averaging, Transfer Matrix and Snell's law are reviewed. Their general principles are discussed and, for each method, an analysis of their relative strengths and weaknesses is performed. The paper concludes with a highlight of other recently developed techniques.

Tailoring electrodynamical phenomena of radiation, emission, and scattering with auxiliary surrounding structuring is one of primary objectives of fundamental and applied investigations nowadays. Resent interests in optical frequency range are partially related to engineering of light-matter interaction dynamics with applications to invisibility cloaking, quantum information devices, optical interconnects and others. Many of frontier proposals, however, are still at the proof of concept stage and require reliable verifications. While performing and analyzing results of optical experiments are sometimes challenging due to their involved complexity related to nano-scale structuring, experimental platform and fabrication of radio waves devices is relatively straightforward. Being able to emulate a span of optical phenomena with GHz frequencies, we demonstrate the way of tailoring scattering characteristics of objects, embedded in wire metamaterial. Regimes of scattering suppression and super-scattering were investigated and the relations to optical effects were discussed. Furthermore, emulation experiments on other effects, among them the near-field interference, causing directional excitation of waves propagating in hyperbolic metamaterials and invisibility cloaking will be reviewed. The ability to detect both near and far fields at the GHz range opens vast opportunities for emulation experiments of different kinds.

The control of electromagnetic radiation in transformation optical metamaterials brings the development of vast variety of optical devices. Of a particular importance is the possibility to control the propagation of light with light. In this work, we use a structured planar cavity to enhance the thermo-optic effect in a transformation optical waveguide. In the process, a control laser produces apparent inhomogeneous refractive index change inside the waveguides. The trajectory of a second probe laser beam is then continuously tuned in the experiment. The experimental results agree well with the developed theory. The reported method can provide a new approach toward development of transformation optical devices where active all-optical control of the impinging light can be achieved.

Plasmonic metamaterial composites are often considered to be promising building blocks for a number of applications that include subwavelength light manipulation, imaging, and quantum optics engineering. These applications often rely on effective medium response of metamaterial composites and require metamaterial to operate in exotic (hyperbolic, or epsilon-near-zero) regimes. However, the behaviour of metamaterials is often different from the predictions of effective medium. In this work we aim to understand the implications of composite nature of metamaterials on their optical properties. Plasmonic nanowire metamaterials are a convenient metamaterial platform that is capable of realization of ENZ, hyperbolic, and elliptic responses depending on light frequency and metamaterial geometry. In this work we show that the response of metamaterial in elliptical regime may be strongly affected by the additional electromagnetic wave that represents collective excitation of cylindrical surface plasmons in nanowire arrays. We present an analytical description of optical properties of additional wave and analyse the effect of this mode on quantum emitters inside nanorod metamaterials.

Existing discrete electromagnetic cloaks are often limited to circular shape and always based on one dimensional discretization of radius variable in cylindrical coordinates. In this paper, we proposed a two dimensional (2D) discrete square invisible cloak which really does not require any continuous constitutive material parameters. The discrete square cloak consists of several homogeneous blocks, and they are discretized from the original transform medium whose material parameters are often continuous spatial functions of both x and y variables in Cartesian coordinates. With proper design of numbers of blocks, we demonstrated the scattering properties of the proposed cloaking structure through rigorous analysis of the scattered electromagnetic fields. The proposed cloaking structure could be possibly realized, therefore may lead to a practical path to an experimental demonstration of electromagnetic cloaking.

Anomalous field enhancement accompanied by resonant absorption phenomenon was originally discussed in the context of plasma physics and in applications related to radio-communications between the ground and spacecraft returning to Earth. Indeed, there is a critical period of time when all communications are lost due to the reflection/absorption of electromagnetic waves by the sheath of plasma created by a high speed vehicle re-entering the atmosphere. While detailed experimental studies of these phenomena in space are challenging, the emergence of electromagnetic metamaterials enables researchers exceptional flexibility to study them in the laboratory environment. Here, we experimentally demonstrated the strong localized field enhancement of magnetic field for an electromagnetic wave propagating in Mie-resonance-based inhomogeneous metamaterials with magnetic permeability gradually changing from positive to negative values. Although these experiments were performed in the microwave frequency range, the proposed all-dielectric approach to transition metamaterials can be extended to terahertz, infrared and visible frequencies. We anticipate that these results, besides most basic science aspects, hold the potential for numerous applications, including low-intensity nonlinear transformation optics, topological photonics and the broader area of surface and interface science.

This paper discusses the coupling of two dimensional and one dimensional nano-materials to electromagnetic waves across the spectrum, from RF to light wave.

Nearly perfect concealing of arbitrary objects in ENZ metamaterial acting as an alignment-free cloak is proposed. The scattering suppression relies on the combination of normal and additional modes simultaneously existing in a spatially dispersive material.

This work proposes to study the behavior of different wavelengths of light in the visible spectrum when they are incident on a two-dimensional cylindrical structure that appears to be invisible or undetectable due to what is known as a ‘cloak’ formed around the actual object. This is achieved by modifying an existing Finite Difference Time-Domain model for such a structure in the Gigahertz range to function in the optical frequency region by changing different parameters such as the inner and outer radii of the cloak, the cell size and the number of time steps that affect the permeability, permittivity and hence refractive index of the structure. Results suggest that certain colors of light can be cloaked more effectively than the others.

MEMS based metamaterials are an ideal architecture to provide dynamic electromagnetic properties in the infrared range of the electromagnetic spectrum. We detail several realizations of infrared MEMS metamaterials and discuss potential applications.

Our recent efforts suggest that there exists strong electromagnetic field enhancement in our recently proposed metallic metamaterial. Of particular importance here is the potential for the realization of compact terahertz free-electron lasers (THz-FELs) using this structure. We present the capability of controlling electromagnetic field enhancement, which must be one of the main issues in developing the compact THz-FELs. Moreover, switching and sensing abilities of this structure could also be investigated for other metal-based THz applications. The numerical and experimental works will be presented in the conference.

Since its inception in 2006, transformation optics has become an established tool to understand and design electromagnetic systems. It provides a geometrical perspective into the properties of light waves without the need for a ray approximation. Most studies have focused on modifying the trajectories of light rays, e.g. beam benders, lenses, invisibility cloaks, etc. In this contribution, we explore transformation optics beyond the manipulation of light trajectories. With a few well-chosen examples, we demonstrate that transformation optics can be used to manipulate electromagnetic fields up to an unprecedented level. In the first example, we introduce an electromagnetic cavity that allows for deep subwavelength confinement of light. The cavity is designed with transformation optics even though the concept of trajectory ceases to have any meaning in a structure as small as this cavity. In the second example, we show that the properties of Cherenkov light emitted in a transformation-optical material can be understood and modified from simple geometric considerations. Finally, we show that optical forces—a quadratic function of the fields—follow the rules of transformation optics too. By applying a folded coordinate transformation to a pair of waveguides, optical forces can be enhanced just as if the waveguides were closer together. With these examples, we open up an entirely new spectrum of devices that can be conceived using transformation optics.

The electromagnetic backscattering from a dispersive metamaterial coated conducting sphere with an intervening air gap is presented in this article. The boundary-value technique is used to obtain the backscattering cross section. The results indicate that it is possible to achieve low radar echo width over a broad range of frequencies for certain cases. This opens possibilities for devices such as spherical antennas with low observability.

Plasmonic waveguide metamaterials are some of the most promising structures for achieving a negative index of refraction at optical frequencies. In this paper, we analyze one such structure through a three-dimensional Fourier decomposition of electromagnetic fields into plane-wave components with purely real wave vectors. The visual depiction of the Poynting vector associated with each plane wave component in real-k space provides intuitive insights into the electromagnetic response of this medium.

Metamaterials have great potential for the practical applications of stealth technology. Therefore, it is important to understand effect of their geometrical parameters on the electromagnetic wave absorption. In this paper, dependence of the absorption on certain geometrical parameters of a metamaterial absorber is numerically investigated.

We propose and demonstrate ultra-broadband three dimensional carpet cloaking for full polarization. A non-resonant metamaterial, which exhibits broadband magnetic and electric anisotropy with little dispersion, is used as a main building block in the cloak design. Nearly perfect cloaking performance is confirmed over a broad bandwidth with frequency scanning measurement. In particular, the experimental result shows that phase is well preserved by the cloak.

We present experimental results on angle-dependent microwave response of the double negative microwave metamaterials. Polarization and angle-dependent transmission spectra of two microwave negative index metamaterials were measured. Two sets of S-shape single unit cells were designed for the 12.5 GHz and 20 GHz frequency ranges. Transmission spectra were measured as a function of polarization and incidence angles of the incoming electromagnetic waves.

Microwave negative index metamaterials have been recently characterized by using primarily far-field transmission of flat slabs and wedges to determine transmission losses and index of refraction, respectively. Although these methods are adequate for most purposes, a more complete characterization of spatial transmission is useful to analyze metamaterials in 3-D, for examples, to characterize irregular forms of metamaterials, such as gradients, prisms, and conformal surfaces. We report here the infrared imaging of the transmitted intensity of microwave electromagnetic waves through a prism of the negative index metamaterials.

Chiral metamaterials are such materials that cannot be found in the nature and show exotic properties as negative refraction index. One of the most important properties of chiral metamaterials is to show optical activity by changing the polarization of the electromagnetic wave. In this way, an electromagnetic wave can be directed and can be controlled. Furthermore, cross coupling is created between electric field and magnetic field in the chiral medium In this study, focusing gain and effects on the antenna applications are searched. Since chiral metamaterials have exotic properties, they have advantages in antennas, gain, bandwidth and designing small material dimensions. 1 GHz bandwidth is obtained in this study.

Recent years have seen a growing interest in the development of novel electromagnetic media, such as metamaterials. Unlike conventional materials, metamaterials derive their properties from their structure rather than their composition. These artificial, periodic, materials can be engineered to give a specific response to an electromagnetic wave and mediate novel particle wave interactions.

Dielectric properties of fluids are of interest in modern radio physics and medicine. The dispersion characteristics of fluids in the GHz frequency range are required to characterize properties of metamaterials with fluid-filled unit cells. The same dispersion properties also play an important role in such important medical applications as diagnosis of the state of a biological object. This work is devoted to study of electromagnetic properties of liquids in the ultra-high frequency range (UHF).

Cloaking devices enabling to hide objects from external observers have numerous potential applications but still face challenges in realization, especially in the visible spectral range. In particular, inherent losses and extreme parameters of metamaterials required for the cloaking are the limiting factors. Here, we propose and demonstrate numerically nearly perfect concealing of objects in ENZ-meta-materials (homogeneous and layered realizations) acting alignment-free scattering suppression covers. The suppression of visibility relies on the reconstruction of a plane wavefront after scattering of light by an object placed inside an anisotropic metamaterial with vanishing permittivity along one of the major crystallographic directions (uniaxial ENZ meta-material). We also consider a realistic realization of the metamaterial as a metal-dielectric multilayer and demonstrate the cloaking in forward and backward directions with perfectly preserved wavefronts and less than 10% absolute intensity change.

Modified metallic metamaterials are known to provide external radiation from Cerenkov-like modes which can be excited using an electron bunch. Extremely strong electromagnetic field enhancement could be formed for compact, efficient free-electron lasers with open metallic structures. The numerical and experimental works will be presented in detail.

The control of electromagnetic radiation in transformation optical metamaterials brings the development of vast variety of optical devices. Of a particular importance is the possibility to control the propagation of light with light. In this work, we use a structured planar cavity to enhance the thermo-optic effect in a transformation optical waveguide. In the process, a control laser produces apparent inhomogeneous refractive index change inside the waveguides. The trajectory of a second probe laser beam is then continuously tuned in the experiment. The experimental results agree well with the developed theory. The reported method can provide a new approach toward development of transformation optical devices where active all-optical control of the impinging light can be achieved.

Metamaterials are man-made artificial periodic structures composed by sub wavelength electromagnetic resonant or non-resonant structures, which can be characterized by effective medium parameters. The potential applications of such materials have attracted a great deal of interest within the scientific communities, like the negative refraction lens and invisible cloaks. In this paper, we will introduce some examples of microwave lens and low scattering surfaces based on metamaterials. We believe that these designs are good candidates to replace traditional devices in microwave and optical engineering.

A recently published theory has suggested that a cloak of invisibility is in principle possible, at least over a narrow frequency band. We describe here the first practical realization of such a cloak; in our demonstration, a copper cylinder was “hidden” inside a cloak constructed according to the previous theoretical prescription. The cloak was constructed with the use of artificially structured metamaterials, designed for operation over a band of microwave frequencies. The cloak decreased scattering from the hidden object while at the same time reducing its shadow, so that the cloak and object combined began to resemble empty space.

The use of Cherenkov radiation in the optical and microwave ranges for measuring the accelerator beam energy and the energy spectrum is described. Suggested methods are based on a dependence of the radiation intensity on the phase velocity of electromagnetic waves in the Cherenkov radiator medium. Mathematical procedure of extraction of the energy spectrum from the measured intensity is given in detail.

An invisibility device should guide light around an object as if nothing were there, regardless of where the light comes from. Ideal invisibility devices are impossible, owing to the wave nature of light. This study develops a general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics. The imperfections of invisibility can be made arbitrarily small to hide objects that are much larger than the wavelength. With the use of modern metamaterials, practical demonstrations of such devices may be possible. The method developed here can also be applied to escape detection by other electromagnetic waves or sound.

This paper addresses the 2D and 3D micro- and nanofabrication of ElectroMagnetic MetaMaterials (EM3) for the terahertz range. EM3 refers to artifbial composite materials which consist of a collection of repeated metal elements designed to have a strong response to applied electromagnetic felds, so that near resonance both the effective permittivity and magnetic permeability µ become simultaneously negative. This unusual situation leads to exotic consequences such as a negative index of refraction and an inverse Doppler and Cerenkov effect. EM3 fabricated so far have been mostly two-dimensional and in this respect are highly anisotropic. By anisotropic, it is inferred that the response of the system depends on the direction of illumination. The anisotropic nature of the metamaterials impedes eventual real-life applications of the negative media as it places constraints on the impinging electromagnetic waves. Ways of producing three-dimensional (3D) or more isotropic EM3 by means of tilted x-ray exposures will be introduced. Basic geometry tells us that if the structures are inclined at 30-45°, this would lead to an improvement of the coupling of the vector by 50-70%

The main directions of studies of materials with negative index of refraction, also called left-handed or metamaterials, are reviewed. First, the physics of the phenomenon of negative refraction and the history of this scientific branch are outlined. Then recent results of studies of photonic crystals that exhibit negative refraction are discussed. In the third part numerical methods for the simulation of negative index material configurations and of metamaterials that exhibit negative index properties are presented. The advantages and the shortages of existing computer packages are analyzed. Finally, details of the fabrication of different kinds of metamaterials are given. This includes composite metamaterials, photonic crystals, and transmission line metamaterials for different wavelengths namely radio frequencies, microwaves, terahertz, infrared, and visible light. Furthermore, some examples of practical applications of metamaterials are presented.

In this paper, we summarize some recent activities in the field of metamaterial research at the National University of Singapore (NUS). Integral equations are applied for electromagnetic modelling of supernatural materials. Some special characteristics of the metamaterials are shown. Moreover, quasi-static Lorentz theory and numerical method (i.e., the method of moments for solving the electric field integral equation) and the transmission line theory are both presented to obtain the effective constitutive relations of metamaterials, respectively. Finally, feasibility of fabricating metamaterials based on analysis of equivalent transmission line model in the microwave spectrum and even higher is also shown and correspondingly some broad-bandwidth and low-loss metamaterial structures are designed and synthesized.

Cataloged from PDF version of article. We report free space transmission and the first reflection measurements of a composite double negative (DNG) metamaterial, also known as a left-handed material (LHM). The metamaterial composes of the split-ring-resonators and discontinuous thin wires. Very high transmission values of the metamaterial are observed within a frequency range for which both effective permeability and permittivity are expected to be negative.

Limitation of the cloak-size reduction is investigated numerically by a finite-difference time-domain (FDTD) method. A metallic pole that imitates an antenna is cloaked with an anisotropic and parameter-gradient medium against electromagnetic-wave propagation in microwave range. The cloaking structure is a metamaterial submerged in a plasma confined in a vacuum chamber made of glass. The smooth-permittivity plasma can be compressed in the radial direction, which enables us to decrease the size of the cloak. Theoretical analysis is performed numerically by comparing scattering waves in various cases; there exists a high reduction of the scattering wave when the radius of the cloak is larger than a quarter of one wavelength. This result indicates that the required size of the cloaking layer is more than an object scale in the Rayleigh scattering regime.

We propose a post-processing approach for tuning terahertz metamaterials by modifying the coupling between two metamaterial layers. We demonstrate that this method allows the metamaterial resonance to be shifted by 31% of the central frequency.

Duhem overviews the experimental results of W. Weber and G. Kirchhoff on the speed of light, as well as the research of B. Riemann, C. Neumann, and L. Lorenz. He then discusses the fundamental hypothesis of Maxwell and his electromagnetic theory of light.

The composite nature of metamaterial structures, made up of metallic and dielectric parts, repeated and modulated in a certain order in the space, increases the numerical complexity of electromagnetic analysis: homogenizing such structures with a continuous dielectric model that achieves the same global electromagnetic response could be challenging, but it could give more information about the physical mechanism of wave propagation through it. The idea developed in this paper is to associate an equivalent permittivity to a novel metamaterial architecture (i.e. the microstrip-line-based metamaterial), solving an Inverse Scattering Problem (ISP). The expected global electromagnetic response involves the cloaking effect, artificially created by the radiation of surface waves propagating around the periodic structure. In the proposed Inverse Scattering Homogenization method (ISHM), the equivalent permittivity results exhibit values between zero and one, further tested in a Forward Scattering Problem (FSP), in order to establish a one-to-one correspondance between heterogeneous (physical) and homogeneous (mathematical) model.

We analyze, analytically and computationally, light emission in nonlocal plasmonic nanowire metamaterials and analyze the contribution of longitudinal wave to the density of optical states in the system.

Metamaterials are designed to achieve unprecedented light-matter interactions. Here we demonstrate a novel viable and scalable assembly route to optical metamaterials with structures dictated by their own light-matter interactions.

This tutorial shows how the geometrical-optics expression for the field reflected from a surface can be derived directly from the general first-order stationary-phase solution of the associated radiation integral. It will improve the understanding of how these two techniques are related to one another. The material presented is ideally suited for post-graduate courses on high-frequency electromagnetics techniques.

Electromagnetic metamaterials offer great flexibility for wave manipulation and enable exceptional functionality design, ranging from negative refraction, anomalous reflection, super-resolution imaging, transformation optics to cloaking, etc. However, demonstration of metamaterials with unprecedented functionalities is still challenging and costly due to the structural complexity or special material properties. Here, we demonstrate for the first time the versatile fluidic radio frequency metamaterials with negative refraction using a water-embedded and metal-coated 3D architecture. Effective medium analysis confirms that metallic frames create an evanescent environment while simultaneously water cylinders produce negative permeability under Mie resonance. The water-metal coupled 3D architectures and the accessory devices for measurement are fabricated by 3D printing with post electroless deposition. Our study also reveals the great potential of fluidic metamaterials and versatility of the 3D printing proc...

Herein, it is shown that under conditions of total internal reflection of plane homogeneous electromagnetic waves at the interface of a hyperbolic metamaterial (HMM) and an ordinary isotropic medium, special inhomogeneous electromagnetic waves are excited in certain circumstances near the surface of the metamaterial and their amplitude changes with distance according to the non-exponential law. The existence conditions for such waves are established for the case when the optical axis is located within the interface plane and forms an angle with the plane of incidence. The energy flux and density of energy of special inhomogeneous waves in a HMM are determined.

The frequency spectrum of free-electron laser pumped by electromagnetic wave with magnetized and unmagnetized background plasma is analyzed by the theory of three-wave interaction and PIC simulation, respectively. The frequencies of PIC simulation are in agreement with the results of the three-wave interaction theory. The results show that the frequency spectrum is very plentiful.

Electromagnetic metamaterials consist of two or three dimensional arrays of tailored metallic and/or dielectric inclusions and provide unprecedented sub-wavelength control over light–matter interactions. Metamaterials are fashioned to yield a specific response to the electric and magnetic components of light and may be treated as effective media, described by effective optical constants and , and have realized a multitude of exotic properties difficult to achieve with natural materials. An inductive-capacitive unit cell geometry provides enhanced values of optical constants, as well as the ability to dynamically control the novel responses exhibited by electromagnetic metamaterials. The ability of metamaterials to achieve real-time dynamic properties has realized novel applications and has made them relevant for the next revolution in advanced materials and related devices.

Near-field plates and their potential uses were theoretically and experimentally investigated under this grant. Near-field plates are subwavelength-textured surfaces that can focus electromagnetic fields to deep subwavelength resolutions. Their operation was theoretically explained, design methodologies were formulated, and several prototypes developed at microwave frequencies. This research effort also included a second objective. The second objective was rather broad: to arbitrarily control electromagnetic fields within a 2D region of space using anisotropic and inhomogeneous metamaterials. This effort involved the development of circuit-based metamaterials that exhibit tensorial effective material parameters, and the implementation of electromagnetic devices using such metamaterials. It also involved the development of synthesis methods for anisotropic and inhomogeneous two dimentional (2D) metamaterials.

In this work, an outline of the seminal work done by Professor Mario Sorolla at the Universidad Publica de Navarra will be described. Different types of artificial electromagnetic media, from 1D to volumetric configuration, exploiting EBG/ET and Metamaterial phenomena, spanning from RF to THz frequency ranges will be presented.