We show how guided electromagnetic waves propagating along an adiabatically tapered negative-refractive-index metamaterial heterostructure can be brought to a complete halt. It is analytically shown that, in principle, this method simultaneously allows for broad bandwidth operation (since it does not rely on group index resonances), large delay-bandwidth products (since a wave packet can be completely stopped and buffered indefinitely) and high, almost 100%, in/out-coupling efficiencies. By nature, the presented scheme invokes solid-state materials and, as such, is not subject to low-temperature or atomic coherence limitations. A wave analysis, which demonstrates the halting of a monochromatic field component travelling along the heterostructure, is followed by a pertinent ray analysis, which unmistakably illustrates the trapping of the associated light-ray and the formation of a double light-ray cone ('optical clepsydra') at the point where the ray is trapped. This method for trapping photons conceivably opens the way to a multitude of hybrid optoelectronic devices to be used in 'quantum information' processing, communication networks and signal processors and may herald a new realm of combined metamaterials and slow light research.

We review the recent experimental work done in our group on left-handed metamaterials (LHMs). The metamaterial structure is composed of periodic arrays of split-ring resonators and wire meshes and exhibits a left-handed propagation band at frequencies of negative permittivity and negative permeability. The verification of negative refraction is made by using prism shaped LHM and also by beam-shifting method. We have achieved subwavelength focusing of a point source with a resolution of 0.13λ through a flat LHM superlens.

Recently there has been a number of studies of single-layer and double-layer arrays of small resonant particles made of a noble metal. The intense interest to these structures is caused by their promising properties for near-field enhancement and subwavelength imaging applications, especially in the optical range. They have substantial advantages over the structures containing DNG (double negative) materials as they are easier in fabrication and may mitigate the problem of losses. So far the super-resolution properties were theoretically investigated only for the arrays of a finite extent. In this work we consider single-layer and multilayer infinite arrays. This formulation allows to build a highly effective algorithm and to consider both the problem of excitation of a periodic structure by a single dipole and the modal properties of the structure. The field produced by a single dipole source is effectively described by using the array scanning method, accelerated by the Ewald method. Each subwavelength sphere is represented as an electric dipole scatterer. Special attention is given to the investigation of the number of layers influence on local field enhancement and to the study of the field distribution between the layers.

Interest in optical devices that image with superresolution and inherent optical parallelism continues. Recently, the concept of superresolution is pursued along the lines of negative refraction and transparent multilayer, metallo-dielectric photonic band gap structures. Flat superlenses image from the near-field to the near- or far-field with resolution beyond the diffraction limit. There is a need for characterization methods which allow measurement of the point spread function of such devices. Scanning near-field microscopes (SNOMs) measure the field intensity in the vicinity of objects as close as 5 nm due to shear-force technique. Improvement of transversal resolution up to λ/20 may be possible due to considerable improvement of energy throughput of SNOM probes. To this aim we propose to corrugate the dielectric core-metal coating interface of SNOM probes. The corrugations facilitate the excitation of surface plasmons, which enhance the transport of energy to the probe aperture.

We theoretically investigate a periodic multistack made of alternating layers of positive and negative refractive index. Under normal incidence, its transfer function exhibits spectral resonances highly reminiscent of the Airy function of a classical Fabry-Perot resonator. We use Transfer Matrix Formalism and Coupled-Mode Theory to rigorously establish that analogy, which stems from a deep, although hidden, identity between the two structures.

The main concepts dealing with negative refraction are clarified in order to understand if a high conductive metal layer thinner than the wavelength can really be considered as a metamaterial with a negative refraction index. The theoretical method to find the direction of phase velocity is clearly explained. The use of the causality principle is presented. We discuss why the negative refractive metamaterial has to be regarded as a dispersive one. Discussions are illustrated by means of FDTD simulations. The superlens application is presented. We explain why it is not obvious to consider a thin metal layer as a negative refractive material.

Cavity solitons are controllable two-dimensional transverse Localized Structures (LS) in dissipative optical cavities. Such LS have been suggested for use in optical data storage and information processing. Typically, diffraction constrains the size of these light spots to be of the order of the square root of the diffraction coefficient of the system. Due to recent advances in the development of metamaterials, the diffraction strength in a cavity could be controlled by adding a left-handed material layer in a Fabry-Perot resonator together with a traditional nonlinear material. This system thus potentially allows for LS beyond the size limit imposed by natural diffraction. However, when the diffraction strength becomes smaller, the non-local response of the left-handed metamaterial starts to dominate the nonlinear spatiotemporal dynamics. Considering a typical linear non-local response, we develop a mean-field model describing the spatiotemporal evolution of LS. First, the influence of this non-local response on the minimal attainable width of the LS is studied [Gelens et al., Phys. Rev. A 75, 063812 (2007)]. Secondly, we elaborate on the different possible mechanisms that can destabilize the LS, leading to stable oscillations, expanding patterns, or making the LS disappear. Furthermore, we also show multiple routes towards excitability present in the system. We demonstrate that these different regions admitting stationary, oscillating or excitable LS unfold from two Takens-Bogdanov codimension-2 points [Gelens et al., Phys. Rev. A 77 (2008)].

Since the event of metamaterials, a considerable effort has been performed to fabricate them in the infrared and optical regimes. However, apart from the experimental demonstration and observation of H. J. Lezec et al based on surface plasma polariton, direct visualisation of negative refraction based on metal-dielectric resonances have not been performed experimentally so far in the infrared or visible regime (photonic crystals with periodicity on the order of the wavelength are not considered here). Very often only simulations have given the needed phase information for the retrieval methods in optical experiments. In this paper, a metamaterial composed of SRR (Split Ring Resonators) and a continuous wire is considered. We extract the phase information from the transmission and the reflection measurements through a diffraction grating made of the metamaterial to be characterized and silicon or gold. This retrieval allows a unambiguous retrieval of the effective parameters under conditions discussed in the paper at IR and visible wavelengths.

Two-dimensional imaging through a layered metallic flat lens involves coupling of the TE and TM polarisations that appear at the same time in the 2D spatial spectrum of the incident image. In effect the modulation transfer function and the impulse response that characterise 2D imaging through a metallic multilayer both have a matrix form and cross-polarisation coupling is observed for most spatially modulated beams with a linear or circular incident polarisation. Our present analysis is focused on these 2D cross-polarisation effects. In particular we investigate the role of singularities in the MTF and their relation to the regularisation problems for the respective 2D point spread functions. The analysis is based on transfer matrix method without the quasi-static approximation or scalar field approximation.

The question of whether stable, active metamaterials can be created is addressed, both through a discussion of absolute instability and an analysis of a transmission-line that produces dispersion analogous to that of the familiar split-ring resonator/wire-based metamaterial. Gain is introduced using negative conductance diodes, and it is shown that the frequency bandwidth controls the window of stable gain. The diodes are located as lumped elements in the unit cell. It is demonstrated that the production of a stable, active, negative phase frequency window is possible.

This paper is focused on the control of the electrical characteristics of resonant type metamaterial transmission lines, that is, transmission lines loaded with complementary split ring resonators (CSRRs). The key parameters of metamaterial transmission lines for microwave and millimetre wave circuit design are the characteristic impedance and the phase constant (rather than the effective magnetic permeability or dielectric permittivity). Thanks to the presence of reactive elements loading the host line, metamaterial transmission lines exhibit a major design flexibility that can be useful for circuit design purposes. Specifically, we can tailor the dispersion diagram and the characteristic impedance to some extent. By virtue of this, it is possible the design of microwave and millimetre wave components with superior performance in terms of bandwidth, or the design of multi-band components, both of interest in modern wireless communication systems. Thanks to the small electrical size of the unit cell of such lines, the resulting metamaterial-based components are also very small and fully compatible with planar technology (that is, no lumped elements are used). Different examples are provided to illustrate the possibilities of resonant type metamaterial transmission lines. This includes hybrid couplers, power dividers and phase shifters, among others. The paper includes also the theoretical foundations of the approach.

Although a lot of progress has been made in the field of integrated photonics, the integration density of photonic integrated circuits remains much lower than their electronic counterparts, mainly limited by an inherent wavelength condition on the size of their constituents. Only recently, researchers have tried to overcome this wavelength condition, e.g., by the use of plasmonics and left-handed materials. In this contribution, we want to present a waveguide - an essential component in photonic circuits - that has the possibility of confining light in a waveguide with sub-wavelength diameter [P. Tassin et al., to be published in Appl. Phys. Lett.]. This waveguide uses a left-handed material in order to control the phase evolution of an optical mode during propagation through the waveguide. We calculate the contributions to this phase shift from the optical path length and from the reflections at the cladding interface and we show that the control of this phase shift by a left-handed material allows for tailoring the properties of the optical modes. From the calculated mode profile and dispersion relation, we show that the proposed geometry allows for waveguides with a thickness that is at least one order of magnitude smaller than the optical wavelength. The proposed miniaturization scheme does not inversely affect the confinement properties of the propagating modes, i.e., the optical mode diameter remains comparable to the waveguide thickness and the light does not extend far into the cladding.

Impedance matching in negative index 2D air hole array was addressed by the retrieval of the effective parameters. By solving the eigenvalues problem, we first stress the major difference between an electromagnetic confinement in air for the ground right handed branch and in the host matrix for the left handed one. We then calculate the complex transmission and reflection coefficients for a finite slab from which the effective refractive index and impedance are deduced by using a Fresnel inversion technique. The criterion n = -1 was found incompatible with the impedance matching condition z = 1. Also, the relevance of the dispersion characteristics was assessed by a technique based on spatial Fourier transform.

We theoretically investigate second harmonic generation that originates from the nonlinear, magnetic Lorentz force term from single and multiple apertures carved on thick, opaque metal substrates. The linear transmission properties of apertures on metal substrates have been previously studied in the context of the extraordinary transmission of light. The transmission process is driven by a number of physical mechanisms, whose characteristics and relative importance depend on the thickness of the metallic substrate, slit size, and slit separation. In this work we show that a combination of cavity effects and surface plasmon generation gives rise to enhanced second harmonic generation in the regime of extraordinary transmittance of the pump field. We have studied both forward and backward second harmonic generation conversion efficiencies as functions of the geometrical parameters, and how they relate to pump transmission efficiency. The resonance phenomenon is evident in the generated second harmonic signal, as conversion efficiency depends on the duration of incident pump pulse, and hence its bandwidth. Our results show that the excitation of tightly confined modes as well as the combination of enhanced transmission and nonlinear processes can lead to several potential new applications such as photo-lithography, scanning microscopy, and high-density optical data storage devices.

In recent years a lot of attention has been paid to metal nanoscale structures because of new phenomena and potential applications in waveguide and antenna techniques. Especially in the optical region new effects arise based on plasmon resonances. It is known that in the optical region some noble metals behave like free-electron plasma with low losses. In this study field propagation in nanoporous metal structures is considered. We consider propagation in regular arrays of pores in metal in the presence of an interface. Although the field is decaying outside the pores, these inclusions are so close to each other that there is interaction with the neighboring pores. In addition the metal-insulator interface causes coupling. Near the plasmonic resonance these interactions are strong enough, and there exist guided wave modes along the array. Properties of these modes are investigated. The allowed frequency range where the guided modes exist depends on the geometry, i.e., on the size of the pores and on the distance between them. In such structures there exist three propagating modes, two transversely and one longitudinally polarized. The transversely polarized fields propagate as forward waves and the longitudinally polarized fields form a backward wave. When the chain of pores is far from the interface, the two transversely polarized modes become decoupled and have the same dispersion due to degeneracy.

Terahertz biosensors are used for sensing chemical and biochemical material. In order to sense small material quantities, such as DNA strands, sensors with a high sensitivity are needed. Our recent approach applies asymmetric double-split ring resonators (aDSR) in a two-dimensional array. Interaction of resonances within the structure results in a steep flank in the frequency response which is sensitively shifted by small amounts of biomolecules loaded on the sensor surface. Additionally a high E-field concentration connected to the split ring resonances is used to maximize the frequency shift induced by biomaterial covering only a small fraction of the sensor area. Minutes amounts of biomaterial can therefore be detected. In this presentation, the approach is analyzed with numerical simulation. We demonstrate the functionality and optimization of the aDSR array structures, and the capability to detect submicrometer layers of dielectric material with a spatially selective deposition on the resonant structures. A measurement of the complementary structure is presented as proof of principle.

Nonreciprocal properties of magnetoplasmons in the imperfect magnetised semiconductor films sandwiched between the dielectric layers have been explored. It is demonstrated that losses qualitatively alter the eigenwave spectrum and the properties of magnetoplasmons. The effect of the structure parameters is analysed, and it is shown that strongly nonreciprocal attenuation of the eigenmodes in asymmetric structures may result in the unidirectional propagation of magnetoplasmonic modes. The competing effects of the reciprocal and nonreciprocal field displacement, and the impact of the field and power flux distributions on the mechanisms of nonreciprocal and unidirectional magnetoplasmon propagation in the imperfect semiconductor films are discussed.

The optical near field of subwavelength grooves milled in metal surfaces is investigated and channel plasmon polariton nanoantennas are analyzed with a Spectral Boundary Integral Equation approach. Due to an extensive use of semi-analytical meshless procedures the numerical simulation tool guaranties the solution with high accuracy and reduced complexity. The results indicate a strong field enhancement inside the groove and a pronounced dependence of the antenna characteristics on the groove geometry.

We study surface plasmon polariton (SPP) guiding structures, which are a modification of the Metal-Insulator-Metal (MIM) waveguide. The designs are constructed by introducing a periodic modulation in a MIM waveguide, with a glass core and silver claddings. This periodic modulation is created either by causing periodic indentations in the silver slabs encompassing the glass core, or by increasing the glass spacer material in certain periodic locations. Our objective is to achieve long range sub-wavelength waveguiding with vast dispersion engineering capabilities. We employ the Finite Difference Time Domain Method (FDTD) with the Auxiliary Differential Equation method (ADE) for the calculation of the dispersion relation of the guided modes, as well as the real time propagation suggests that the guiding mechnism in the examined structures is based on the electromagnetic (EM) couping between the slit plasmon modes. These - depending on the design - exist in the grooves between the silver plates or in the larger areas of the glass core spacer. Put it different, the guiding mechanism in the examined SPP waveguide designs is analogous to the EM energy transfer along metallic nanoparticle chains.

The field of plasmonics has historically been a playground exclusively for the optics community. Primarily this is because the response of metals becomes dominated by their large conductivities at much lower frequencies, making it difficult to exploit the unique properties of surface plasmon (SP) modes. Indeed SPs on flat, perfectly conducting substrates are better described as simple surface currents or grazing photons. However the realization that one can form metal-dielectric composites to support surface waves with plasmon-like properties has opened the field of plasmonics to the terahertz and microwave domains. Pendry et al. [Science, 305, 847 (2004)] were among the first to speculate about an extension of plasmonics into long wavelength regimes. They demonstrated that the perforated surface of a perfect conductor can support a SP-like mode whose behavior is determined purely by the geometry of the substrate. Beginning with our initial experimental verification of these SP-like modes excited via grating-coupling, we present an overview of some of our recent microwave studies. We progress to study the classical method of prism coupling and also consider the enhanced transmission phenomenon (mediated by plasmon-like surface modes) through hole arrays. Finally the first experimental evidence of coupled SP-like modes between two such perforated metal substrates placed in close proximity will be presented.

We have measured the angle and wavelength dependent transmission of index matched metal hole arrays, and of arrays with a dielectric pillar in each hole. Index matching enhances the transmission, but also broadens the resonances due to an enhanced coupling between plasmon and radiation modes. Hole arrays that are covered with glass or have a glass pillar in each hole are created using an imprinting technique. We observe additional waveguide modes in the transmission spectra of these arrays and discuss the avoided crossing that we observe for the hybrid structure with dielectric pillars in the holes.

We numerically study the optical properties of metal lattices made from periodically arranged plasmonic molecules, i.e., coupled gold nanowire pairs. It is shown that the interaction between the metallic wires, which is directly controlled by the specific lattice geometry, leads to the formation of collective surface plasmon modes. Surface plasmon hybridization is discussed and the direct influence of near- and far-field interaction are highlighted. In particular, it is shown that the common hybridization schema can be reversed by tuning the wire-wire interaction. Moreover, optical activity of higher order modes is demonstrated in case of symmetry breaking. An additional degree of freedom is introduced by inserting a homogeneous metal film, i.e., taking into account wire-image coupling.

Black holes are like space-time rivers: their geometry can be viewed as if space were a moving medium rushing towards their singularities. Horizons are formed when the flow speed exceeds the speed of light such that nothing can escape anymore. Realizing this idea with ultrashort pulses in microstructured optical fibers, we performed the first experimental demonstration of an artificial event horizon in optics.

The fundamental approach to a slowly varying amplitude formulation for nonlinear waves in metamaterials will be established. The weakly nonlinear slowly varying amplitude approach will be critically examined and some misunderstandings in the literature will be fully addressed. The extent to which negative phase behaviour has a fundamental influence upon soliton behaviour will be addressed and will include non-paraxiality, self-steepening and nonlinear diffraction. A Lagrangian approach will be presented as a way of developing a clear picture of dynamical behaviour. Exciting examples, involving waveguide and polarization coupling and interferometer systems will illustrate the extent to which non-paraxiality, self-steepening and nonlinear diffraction will be required as part of the soliton behaviour patterns, including coupler systems. In addition, a strongly nonlinear approach will be taken that seeks exact solutions to the nonlinear equations for a metamaterial. The investigations will embrace "optical needles", or autosolitons. A boundary field amplitude approach will be developed that leads to useful and elegant eigenvalue equations that expose in a very clear manner the dependence of wave number upon the optical power density. All the work will be beautifully illustrated with dramatic color-coded outcomes that will also embrace the soliton lens.

Metamaterials based on single-layer metallic Split Ring Resonators (SRR) and Wires have been demonstrated to have a resonant response in the near infra-red wavelength range. The use of semiconductor substrates gives the potential for control of the resonant properties of split-ring resonator (SRR) structures by means of active changes in the carrier concentration obtained using either electrical injection or photo-excitation. We examine the influence of extended wires that are either parallel or perpendicular to the gap of the SRRs and report on an equivalent circuit model that provides an accurate method of determining the polarisation dependent resonant response for incident light perpendicular to the surface. Good agreement is obtained for the substantial shift observed in the position of the resonances when the planar metalisation is changed from gold to aluminium.

An original all-dielectric design that performs cloaking at terahertz frequencies is demonstrated. The cloak consists of radially positioned discretized micrometer-sized cylindrical elements. Based on Mie theory and under adequate excitation conditions (H along the rod axis), high-κ cylinders exhibit a strong magnetic resonance dependent on the cylinder radii and material properties. Full-wave simulations coupled with a field-summation retrieval technique were employed to adjust the electromagnetic response of individual ferroelectrics rods (Ba_0.5Sr_0.5TiO₃; ε = 200 - tan δ = 2.10^-2). The rods magnetic plasma frequency was engineered such that the full cloak displays a progressive variation in its permeability radial component; hence satisfying, for this polarization, the reduced equations derived from the conformal transformation theory. The cloaking performance was assessed by modelling the complete micro-structured device. Results unambiguously show that cloaking of any wavelength scaled objects located inside the cloak is achieved above the Mie resonance frequency at 0.58 THz for the present device. In particular, the phase fronts of the electric field behind the device are well reconstructed with a high value in transmission of the incident plane wave. This also means that the absorption losses are small within the cloak in comparison with the metallic systems originally proposed. Although cloaking is observed in a narrow band, this all-dielectric configuration provides an attractive route for designing cloaking devices at microwave and terahertz frequencies.

In this contribution a three-dimensional left-handed metamaterial is presented which is shown to be a physical implementation of the rotated TLM scheme. The key characteristics of the metamaterial in terms of dispersion relation and Bloch impedance as well as composite right/left-handed response are analysed. An implementation of the 3D metamaterial is presented and measurements provided showing very good agreement. Different computational approaches to the analysis of the structure aperiodic arrangements are discussed.

The properties of metamaterials made of an increasing number of discrete functional layers are analyzed. Convergence of the effective properties towards their bulk counterparts is observed if the light propagation in the metamaterial is dominated by a single eigenmode. The effective properties of the finite structure will be compared to the properties of the infinite structure for which an effective refractive index can be derived from the dispersion relation. The dispersion relation is furthermore shown to be useful in deriving angle dependent effective material parameters. They are compared to the effective properties obtained from a finite slab by applying a dedicated retrieval procedure.

An analytical description for plane wave propagation in metamaterials (MM) is presented. It follows the usual approach for describing light propagation in homogenous media on the basis of Maxwell's equations, though applied to a medium composed of metallic nanostructures. Here, as an example, these nanostructures are double (or cut) wires. In the present approach the multipole expansion technique is used to account for the electric and magnetic dipole as well as the electric quadrupole moments of the carrier distribution within the nanostructure where a model of coupled oscillators is used for the description of the internal charge density dynamics. It is shown how expressions for the effective permittivity and permeability can be derived from analytical expressions for the dispersion relation, the magnetization and the electric displacement field. Results of the analytical model are compared with rigorous simulations of Maxwell's equations yielding the limitations and applicability of the proposed model.

Fabry-Perot cavities are perhaps the best known of the optical transmission resonators, with cavity field enhancement accomplished by two parallel and partially reflecting planes. Recently it has been shown that arrays of narrow slits cut into a metal substrate are similarly able to exhibit resonant transmission modes. Here, the transmission of normally incident plane wave microwaves through a single stepped sub-wavelength slit in a thick metal plate is explored. The presence of the step substantially increases the radiation wavelength, which may be resonantly transmitted to well beyond twice the plate thickness. Insight into the resonant behaviour of the stepped slit is provided through the analysis of the field solutions produced by a finite element model. This model also predicts resonant transmission which is in excellent agreement with the experimental results.

Stress effect on the behavior of optical waveguide sensor consists of dielectric slab inserted between metamaterial (MTM) cladding and substrate is investigated by using numerical calculations. Several MTMs with different values of ε and μ with ε μ = 4 are chosen in order to clarify the variation of stress effect with respect to the material constants. Numerical calculations of the effective index for both transverse electric modes (TE) and transverse magnetic modes (TM) as a function of stress and slab thickness have been performed. It is found that stress affects the performance of the waveguide sensor.

The vast parameter space associated with bianisotropic mediums supports a host of complex electromagnetic behaviours. Planewave propagation in a bianisotropic medium is generally characterized by four independent wavevectors. We considered planewave propagation in a Faraday chiral medium (FCM), which is a particular bianisotropic medium that combines natural optical activity with Faraday rotation. FCMs may be theoretically conceptualized as metamaterials arising from the homogenization of isotropic chiral mediums with either magnetically biased ferrites or magnetically biased plasmas. Provided that the magnetoelectric coupling is sufficiently large, there are enhanced possibilities for negative-phase-velocity propagation and therefore negative refraction in FCMs. They can also give rise to the phenomenon of negative reflection. That is, an incident plane wave with positive phase velocity can result in a negatively reflected plane wave with negative phase velocity, as well as a positively reflected plane wave with positive phase velocity. Also, an incident plane wave with negative phase velocity can result in a negatively reflected plane wave with positive phase velocity, as well as a positively reflected plane wave with negative phase velocity.

We study the traversal times of electromagnetic pulses across dispersive media with negative dielectric permittivity (ε) and magnetic permeability (μ) parameters. First we investigate the transport of optical pulses through an electrical plasma and a negative refractive index medium (NRM) of infinite and semi-infinite extents where no resonant effects come into play. The total delay time of the pulse constitutes of the group delay time and the reshaping delay time as analyzed by Peatross et al.1 For evanescent waves, even with broadband width, the total delay time is negative for an infinite medium whereas it is positive for the semi-infinite case. Evidence of the Hartman effect is seen for small propagation distance compared to the free space pulse length. The reshaping delay mostly dominates the total delay time in NRM whereas it vanishes when ε(ω) = μ(ω). Next we present results on the propagation times through a dispersive slab. While both large bandwidth and large dissipation have similar effects in smoothening out the resonant features that appear due to Fabry-Perot resonances, large dissipation can result in very small or even negative traversal times near the resonant frequencies. We investigate the traversal and the Wigner delay times for obliquely incident pulses. The coupling of evanescent waves to slab plasmon polariton modes results in large traversal times at the resonant conditions. We also find that the group velocity mainly contributes to the delay time for pulse propagating across a slab with refractive index (n) = -1. The traversal times are positive and subluminal for pulses with sufficiently large bandwidths.

Metamaterials have attracted much interest since their realization by Smith et al. [2]. A few research teams all other the world are making them a reality in the infrared and optical regime. Following the theoretical study of C. Rockstuhl et al. [4], we have fabricated various metamaterial structures derived from the combination of SRR (Split Ring Resonators) and nano-continuous wires by diminishing the size of the legs of the SRR perpendicular to the gap. This geometrical transformation shown in the SEM (scanning electron microscope) pictures of figure 1 allows an experimental understanding of the origin of resonances in metamaterials under normal incidence. The fabrication was performed by e-beam lithography, gold on silicon. Simulations were performed using a Drude model of the electromagnetic permittivity of gold. Both measurement and simulation results lead to an accurate analyze of the plasmonic resonances of the metamaterial and open the way to their control in infrared metamaterials under normal to plane propagation.

The focus of this report is the peculiarities of electromagnetic wave propagation in magnetic metamaterials with a periodic array of two-dimensional (2D) electronic gas layers. A model system is considered which consists of alternating layers of a magnetic insulator and nanoscale metallic layers or GaAs-AlGaAs-type semiconductor bilayers with 2D electronic plasma. In the presence of a strong external magnetic field perpendicular to the plane of the layers, the Landau quantization of the electron motion and confinement of the electrons within 2D layers lead to the realization of the integer quantum Hall effect. Assuming that a unit cell dimension of the structure is much smaller than the wavelength of interest and using expressions for the effective permittivity and permeability tensors of the system, the dispersion relations and behavior of refracted electromagnetic waves are studied at an arbitrary angle of incidence with respect to the magnetic field. It is shown that when the wave is incident on the top surface of the structure, the negative refraction is impossible. Despite of that, the medium exhibits a propagation of a backward wave with wavefront normal directed toward the refracting interface. In addition, the frequency regions of existence for the backward waves can be tuned by applied magnetic field. The effects of the quantization of 2D electron dynamics are examined

We present the results of rigorous numerical calculations of the dependence of the reflection coefficient of a semi-infinite two-dimensional photonic crystal on the angle of incidence of the incoming plane wave. We show that, contrary to some results published earlier, this coefficient is not strictly real even outside the crystal bandgaps. We also propose a definition of the effective permittivity and permeability μ of a truncated photonic crystal and specify the symmetry conditions to be satisfied by the truncation plane and the dominant crystal eigenmode to assure continuity of ε and μ when the mode character changes from propagating to evanescent. The value of the reflection coefficient obtained by treating the crystal as a homogeneous medium with ε and μ defined in the proposed way is shown to be a good approximation to the rigorous value in a wide range of angles of incidence, extending beyond that corresponding to propagating crystal modes.

In this paper we present a numerical analysis of a planar or sub-structured metallic flat lens for mode coupling between a pair of waveguides. The analysis of periodically sub-structured silver coupler is based on the finite element model of the device. The uniform and infinite double layered silver coupler is also considered, and is modelled with the transfer matrix method. The study is focused on minimising propagation losses and optimising the coupling coefficient, which is calculated from the transfer properties of the lens for a Gaussian distribution of the modal fields. The analysis reveals the importance of the periodic nanostructure of the silver layers for reaching a coupling efficiency which is higher than could be obtained with uniform layers or with air.

Novel approach to cloaking, which allows to realize directly the idea of wave guiding and to eliminate the reflection from the cloaked structure, is proposed. Cloaking structure is composed of metal wires guiding TEM modes around the object. In high conductive metal wires at microwave frequencies, the TEM modes are dispersionless and the energy propagates along the wires. A plane wave incident onto a wire medium (WM) under any angle, excites both TEM and TM modes, which have similar polarizations. The TEM modes provide full transmission through the cloaking structure if the total length of wires equals a number of half-wavelengths. The TM mode attenuates in WM at frequencies below the plasma frequency of WM and does not contribute to reflection if the WM is dense enough. The angle between WM and the propagation direction of the incoming wave is chosen so that the difference in paths of waves in WM and free space outside the cloak is a multiple of wavelengths in order to eliminate distortion of the phase front. In the infrared range quasi-TEM modes, supporting propagation of plasmons, play role of TEM modes. Parameters of WM are chosen so that the quasi-TEM modes have low dispersion and their phase velocity is slightly less than the speed of light. Results of HFSS simulations demonstrate considerable cloaking effect.

Optical waveguide isolators are vital integrated optic modules in advanced optical fiber communication systems. This study demonstrates an integrated optical isolator which has simple structure consisting of three layers. The thin magnetic garnet film is sandwiched between linear dielectric cover and metamaterial (MTM) substrate. The effective refractive indexes for both forward and backward fields are analytically calculated by deriving the dispersion equation of the TM fields. The difference Δβ between the phase constant for forward and backward propagation is calculated numerically for different values of MTMs permittivity (ε_s) and permeability (μ_s). In all the calculations, the value of ε_sμ_s is kept equal to 4. Δβ is also plotted as a function of the film thickness. Results show that the value of Δβ changes with the parameters of MTMs and the film thickness. This helps in selecting the optimal design for the isolator at which Δβ approaches zero. The results are encouraging to propose an optical isolator.