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We consider a physical scheme for the realization of optical lattices that have negative refracting under certain conditions. The lattice is formed by clusters of five-level closed-loop chiral atoms assumed to have a Gaussian density distribution in dipole traps along one or two dimensions. With a suitable combination of strong standing wave control fields, spatial symmetry of atoms is achieved. Besides, the dispersion properties of an atomic lattice can be modified conveniently by adjusting various parameters related to the atoms or the lattice. We show that negative-like refraction is not specific to the atoms themselves, but also emerges due to the periodicity of the lattice. We further reveal that the refraction is negative over specific regions on the lattice and strongly depends on the number of atoms trapped along a particular direction. Our model is effectively controllable remotely and may have applications in negative refraction devices and optical information processing. • Enhancement of negative refraction in one- and two-dimensional chiral atomic lattices. • Negative-like refraction is not specific to the atoms themselves, but also emerges due to the periodicity of the lattice. • The refraction is negative over specific regions on the lattice and strongly depends on the number of atoms. [ABSTRACT FROM AUTHOR]

The aim of this paper is to provide a mathematical theory for understanding the mechanism behind the double-negative refractive index phenomenon in bubbly fluids. The design of double-negative metamaterials generally requires the use of two different kinds of subwavelength resonators, which may limit the applicability of doublenegative metamaterials. Herein we rely on media that consists of only a single type of resonant element, and show how to turn the acoustic metamaterial with a single negative effective property obtained in [SIAM J. Math. Anal., 49 (2017), pp. 3252-3276] into a negative refractive index metamaterial, which refracts waves negatively, hence acting as a superlens. Using bubble dimers made of two identical bubbles, it is proved, under the assumption that their volume fraction is small and their orientation is uniformly distributed, that both the effective mass density and the bulk modulus of the bubbly fluid can be negative at frequencies slightly higher than the dipole hybridized frequency for a single constituent bubble dimer. [ABSTRACT FROM AUTHOR]

We numerically propose a negative refractive index metamaterial structure with a unit cell composed of only one semi H-shaped element. With this structure a very high transmission of −0.65 dB and a low reflection of −16.48 dB can be achieved at 4.725 THz, with the real part of the refractive index equal to −1.9. The FOM of the structure is 89.43, which warrants the quality of the proposed structure for negative refractive index applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Donor-acceptor assemblies were designed using a series of superalkalis as donor and teetotum boron clusters as acceptor. • The electro-optic Pockel's effect and second harmonic generation were evaluated. • In the case of dynamic NLO,the SHG process has a stronger NLO response than EOPE. • The positive and negative nonlinear refractive index enable the modulation of laser intensity. The development of nonlinear optics has revolutionized the photonic and optoelectronic fields in recent years. In this paper, we have designed a new class of donor–acceptor frameworks with enhanced nonlinear optical (NLO) properties using a series of superalkalis including Li 3 O, Li 2 NaO, LiNa 2 O, Li 2 KO, LiK 2 O as donors and three sizes of teetotum boron clusters (B 14 , B 18 , and B 22) as acceptors. A systematic first-principles study has been performed on the electronic, linear, and NLO properties of superalkali@B n assemblies. Besides the static non-linearity, the frequency-dependent electro-optic Pockel's effect (EOPE), second harmonic generation (SHG), and nonlinear refractive index have also been evaluated. In the case of dynamic NLO, the SHG process has a stronger NLO response than EOPE. At the typical experimental frequency of the Nd:YAG laser (ω = 0.04282) a.u., the SHG coefficients are about 2–3 times larger than the corresponding EOPE at this wavelength. Also, the nonlinear refractive index shows a remarkable response at ω = 0.04 a.u. for LiK 2 O@B 14. [ABSTRACT FROM AUTHOR]

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Left-handed materials, which have both negative permittivity and permeability, have been the area of potential research over a decade. This paper elucidates the design of a double-negative group (DNG) THz metamaterial, namely, E-shaped, having negative refraction ranging from 34.5 to 37.5 THz. Rectangular microstrip patch antenna (RMPA) with microstrip feed has been designed using Ansoft HFSS with RT Duroid (ϵr = 2.33) as substrate and having the same frequency range as that of the metamaterial's negative region. Upon incorporation of proposed metamaterial's array inside the antenna substrate, bandwidth of antenna increases by 4 THz and directivity of antenna increases by about 43% with E-shaped metamaterial. [ABSTRACT FROM AUTHOR]

Résumé L’histoire du microscope optique est inséparable de celle de l’optique, science de la vision et de la lumière. Les premiers instruments apparaissent fin XVI e début XVII e siècle, avec le polissage des premières lentilles de verre qui réfractent la lumière selon les lois de l’optique géométrique. Durant le XVIII e siècle, un système de lentilles achromatiques est mis au point. À la fin du XIX e siècle, Carl Zeiss, Ernst Abbe, August Köhler et Otto Schott édifient les bases de la microscopie moderne en produisant un objectif apochromatique qui réduit les aberrations et augmente son ouverture numérique. Abbe décrit l’imagerie du microscope en termes de capture d’ordres de diffraction dont les ordres supérieurs augmentent la résolution sans pouvoir dépasser la limite d’une demi-longueur d’onde. Au début du XX e siècle, l’optique devient calculatoire selon Joseph Fourier, amenant Fritz Zernike à concevoir le contraste de phase puis Georges Nomarski à développer le contraste interférentiel de phase. Puis la lumière devient quantique interagissant avec la matière. Du photon naît la fluorescence et le laser qui mènent au microscope confocal à balayage laser. À la fin du XX e et début XXI e siècle, la microscopie devient « superrésolue » permettant d’observer des objets de dimension sublongueur d’onde en modifiant l’éclairage (SIM, STED), par localisation de molécules uniques (PALM, STORM), détection d’ondes évanescentes (TIRF, hyperlentilles), et/ou d’imager des tissus vivants grâce à la non-linéarité. Le microscope devient aussi capable de microdisséquer les cellules sur une coupe tissulaire ou bien de classer les cellules et trier les lames à observer. Summary The history of optic microscope is non separable from the history of optics that is the science of light and vision. The first microscopes appear at 16, 17 th century with the grinding of lenses that refract light according to geometric optics. During 18 th century an achromatic lens system is successfully construct. During the end of 19 th century Carl Zeiss, Ernst Abbe, August Köhler and Otto Schott put the bases of modern microscope using an apochromatic lens with low aberration and high numerical aperture. Abbe theory describes imaging in terms of captured diffracted orders providing better resolution without breakdown half wavelength limit. At 20 th century optics become calculatory from Joseph Fourier bringing Fritz Zernike to conceive the phase contrast and Nomarsky the differential interference contrast. After light become quantic interacting with matter. Photonic optics led to fluorescence, laser light and confocal scanner laser microscope. The end of 20 th and 21 th century the new superresolution technologies are either based on tailored illumination, precise localisation of single molecules, evanescent waves detection and/or non linear optics. Microscope is also capable of microdissection of cells in tissular sections and automatic cell classification and slides trier. [ABSTRACT FROM AUTHOR]

This work presents the measurements of square split resonant rings and metal wires (MWs) and C split resonant rings and MW samples through a prism refraction experiment. Negative refraction properties are observed in both models, and the cell shapes are found to play an important role in resonant frequency of the metamaterial samples. A new method is proposed to strictly broaden the negative refraction passband through overlapping the bandwidths using mixed split resonant rings and MWs. The broadened negative refraction bandwidth over a range of 8-12 GHz wider than the other models is proved by both simulative and experimental results, and provided a good metamaterial property. [ABSTRACT FROM AUTHOR]

Left handed materials which have both negative permittivity and permeability, have been the area of potential research over a decade. This paper elucidates a Double Negative Group (DNG) Electric SRR, having 19.13THz as resonant frequency and having FR4 (ɛr=4.4) as substrate material. Nicolson Ross Wier (NRW) method has been used to retrieve the material parameters from transmission and reflection coefficient. Upon incorporation of splits in the structure, we find shift in resonance of permeability to a higher frequency at THz as the no. of splits increase. Also, the curve for resonance in permeability gets sharper i.e. less broadened with increase in splits (upto 3) on ESRR metamaterial. [ABSTRACT FROM AUTHOR]

Abstract: We report an alternative method of designing a new metamaterial with left handed (LH) characteristics over multi-band (MB) frequencies at microwave frequency regime. The resultant LH metamaterial (LHM) consisting of a single-sided tree-shaped fractal structure features triple magnetic resonances and one electric resonance apart from the lower metal plasma response, which is responsible for the three bands of negative refraction. The multi-resonant mechanism has been systematically studied to account for all electromagnetic behaviors, and capacitor–inductor circuit models are put forward for quantitative analysis. The LHM is balanced in the fundamental passband when only one layer is utilized, whereas the balanced condition is slightly broken when a collection of sub-wavelength cells are cascaded. The negative-zero-positive refraction of the fundamental LH band and the negative refraction of the higher LH band have been numerically validated by a prism-like LHM. For demonstration, a three-layer LHM slab sample is fabricated and measured. Consistent numerical and experimental results are observed. The method not requiring individual resonant particles and electrically continuous wires paves the way for a new route to compact MB LHM design. [Copyright &y& Elsevier]

Abstract: This paper shows, using both a ray optics approach and in the framework of the generalized Lorenz–Mie theory (GLMT), what happens to the optical forces exerted on a lossless spherical particle with an arbitrary (positive or negative) relative refractive index, allowing the external medium also to be metamaterial. It is shown that the anti-parallelism between the linear momentum p of each photon and the Poynting vector S associated with the propagating wave, observed in negative refractive index media, leads to shifts in the direction of the optical force of a single ray and, consequently, to the total optical force exerted by an arbitrary-shaped laser beam. This extends the possible realizable traps and reveals how arbitrary-shaped laser beams can be used to trap particles with arbitrary refractive indices. [Copyright &y& Elsevier]

Abstract: In this Letter to the Editor, I review briefly a historical background of the research on backward waves carried out in the XX century. I also provide a brief introduction to the isofrequency method of analysis for metamaterials and discuss a few unusual examples of wave phenomena at the interfaces. [Copyright &y& Elsevier]

Abstract: We report a novel utilization of periodic arrays of carbon nanotubes in the realization of diffractive photonic crystal lenses. Carbon nanotube arrays with nanoscale dimensions (lattice constant 400nm and tube radius 50nm) displayed a negative refractive index in the optical regime where the wavelength is of the order of array spacing. A detailed computational analysis of band gaps and optical transmission through the nanotubes based planar, convex and concave shaped lenses was performed. Due to the negative-index these lenses behaved in an opposite fashion compared to their conventional counter parts. A plano-concave lens was established and numerically tested, displaying ultra-small focal length of 1.5μm (∼2.3λ) and a near diffraction-limited spot size of 400nm (∼0.61λ). [Copyright &y& Elsevier]

Abstract: We present a computational approach, allowing for a self-consistent treatment of three-dimensional (3D) fishnet metamaterial operating at 710nm wavelength coupled to a gain material incorporated into the nanostructure. We show numerically that loss-free negative index material is achievable by incorporating gain material inside the fishnet structure. The effective gain coefficient of the combined fishnet-gain system is much larger than its bulk counterpart and the figure-of-merit (FOM=|Re(n)/Im(n)|) increases dramatically with gain. Transmission, reflection, and absorption data, as well as the retrieved effective parameters, are presented for the fishnet structure with and without gain. [Copyright &y& Elsevier]

Abstract: In this paper we report both numerical and experimentally high numerical aperture on a mesostructure based on fishnet-like building blocks. Under the indefinite media framework, we are able to identify a negative refraction never cutoff band (3rd band of the extraordinary transmission metamaterial) with low-losses at millimeter-waves. We relate negative refraction with the diffraction modes of the periodic structure. The work is another step forward in the new but rapidly evolving subfield of negative refraction metamaterials by anisotropy. The breadth and utility of this approach suggests that metamaterials at their meso-scale may circumvent the problem associated to narrowness and losses exhibited by negative refractive index media at their subwavelength domain, while still being away from the wavelength scale of electromagnetic band-gap. [Copyright &y& Elsevier]

Abstract: We present a polarization independent fishnet negative index metamaterial at 40GHz. The structure is investigated theoretically using finite element method simulations and experimentally by measuring the amplitude and phase of the S-parameters. The experimental setup for free space measurements of both transmission and reflection is hereby introduced. The internal properties are thereafter retrieved and show the double-negative behavior of the structure. This negative index metamaterial exhibits very high transmission (−0.13dB), low reflection (−33.1dB) and a high figure of merit (FOM=|Re(n)/Im(n)|=42), where the real part of the refractive index is nearly −1 (Re(n)=−0.93) at 40GHz. [Copyright &y& Elsevier]

Abstract: In this paper, we outline a novel class of materials, called metamaterials, with negative refractive index and a high degree of nonlinearity. A brief summary is given on the basic theory of optics to show how this condition arrives for metamaterials to be designed into an antenna with split-ring-resonator (SRR). An example is given on the modeling of such SRR-based metamaterials. On a continuum Hamiltonian, a Klein-Gordon equation was derived which gave rise to both dark and bright solitons that showed interesting behavior against nondimensional time, even to the extent of revealing bi- and tri-breathers. [Copyright &y& Elsevier]

Nature has its own limits and naturally-occurring materials exhibit restricted electromagnetic properties bound within those limits. However, modern day researchers have developed artificially structured material composites, called 'metamaterials', that possess significant potential to provide electromagnetic properties that are quite unusual and are not found in nature. This article is aimed at giving an introductory review of this class of 'designer materials' and their superior properties that are not present in their constituent components. [ABSTRACT FROM AUTHOR]

Abstract: Magneto-phonon polaritons in a two-dimension photonic crystal (PC) are discussed. This PC is constructed by embedding a periodical square lattice of ionic-crystal cylinders into an antiferromagnet. The two media are dispersive, with their individual resonant frequencies near each other. We first set up an effective-medium method to obtain the effective magnetic permeability and dielectric permittivity of the PC, followed by the dispersion relations of surface and bulk polaritons. There are a number of new surface polaritons, and two new distinctive bulk polariton bands in which the negative refraction and left-handedness can appear. The numerical calculations are based on the example, FeF2/TlBr PC. [Copyright &y& Elsevier]

Abstract: We report on the optical response and, in particular, on the refractive properties of an fcc crystal of metallic nanoshells by means of full-electrodynamic layer-multiple-scattering simulations. Exact numerical calculations of the isofrequency surfaces reveal the existence of two frequency regions where negative refraction occurs. A thorough analysis of the photonic band structure, in conjunction with corresponding transmission diagrams, attributes this behavior to the excitation of collective modes, which stem from dipole particle-plasmon resonances, and shows that only in one of the two frequency regions negative refraction without birefringence can be obtained. In addition, we discuss the effect of absorptive losses, and reveal the existence of narrow bands of slab modes in a finite slab of the crystal that can transfer the evanescent components of an incident wave field. [Copyright &y& Elsevier]

Abstract: We study theoretically the negative refraction of a surface plasmon polariton. The system we consider consists of a vacuum that is in a contact with two metals that each fill a quarter space with a periodic boundary between them. The interface of each of the metals with the vacuum supports a surface plasmon polariton. When a surface plasmon polariton passes through the periodic boundary between the metals it transforms partly into the Bragg beams of the refracted and reflected surface plasmon polaritons and partly into volume waves in the vacuum. A suitable choice of the period can ensure that the only propagating Bragg beams of the refracted surface plasmon polariton are the specular beam and the (−1)-order beam, which is negatively refracted. With a suitable choice for the form of the profile function and its amplitude the specular beam can be made to vanish. [ABSTRACT FROM AUTHOR]

Abstract: We consider such passbands that appear due to excitation of plasmons inside the one-dimensional photonic crystal with elementary cells containing layers of positive and negative permittivities. The corresponding Bloch waves can be regarded as surface plasmon chains that are subsequently excited at the layers’ boundaries. The band structure depends on the elementary cell composition that also determines the plasmon type. The excited plasmons can be similar to surface plasmons that propagate along a dielectric slab “sandwiched” between two semi-spaces with negative permittivity, or to surface plasmons that propagate along a negative permittivity slab sandwiched between two dielectric semi-spaces. It is shown that the existence of negative refraction does not depend on the frequency dispersion of permittivity. The latter fact permits us to distinguish six elementary cell compositions with qualitatively different band structures. The frequency evolution of the band structure of a plasmonic PC with a given frequency dispersion of the permittivity can be considered as a transition between various kinds of band structures. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we numerically demonstrate electromagnetic focusing using a spatially dispersive metamaterial. Based on the phenomenon of broadband all-angle negative refraction by a crossed wire mesh, it is demonstrated that a flat slab of the metamaterial enables partial focusing of p-polarized electromagnetic radiation. The reported results are supported by full wave simulations and by analytical calculations based on homogenization theory. [ABSTRACT FROM AUTHOR]

Abstract: Metamaterial building blocks from microwave to optical range are mainly based on metal-dielectric composites. In almost all structures with true negative index (not coming from losses), two kinds of meta-atoms (electric and magnetic) are mixed to drive simultaneously the effective permittivity and permeability to negative values leading in turn to a negative index of refraction. In this paper, we show that two coupled structures with localized plasmons modes (e.g. cut-wires or split ring resonators) can exhibit negative refractive index by their own, by appropriately controlling the hybridization scheme of the plasmons modes. Because of small metal filling factor and reduced optical losses, the resulting structures may pave the way to realistic applications of metamaterials at optical frequencies. [Copyright &y& Elsevier]

Abstract: We discuss a relationship between the traditional framework of the frequency-dependent dielectric permittivity and magnetic permeability in the electrodynamics of continuous media and the spatial dispersion framework utilizing the dielectric tensor depending both on the frequency and wavevector . For electromagnetic waves, the latter approach includes the former as a specific limiting case for small k within the accuracy. While the dispersion of the transverse electromagnetic waves in this approximation is captured by the phenomenology, the dispersion of the longitudinal electric waves would be missed. The general framework also accommodates more complex situations such as excitonic resonances and additional electromagnetic waves. We also review the well-known Landau–Lifshitz arguments on the physical meaning of at sufficiently high frequencies. In that context, the need is discussed for the effective medium response to include contributions from the spatial dispersion of the electric-dipole polarization and from the electric-quadrupole polarization on an equal footing with contributions from the magnetic-dipole resonances. [Copyright &y& Elsevier]

Abstract: Peculiarities of wave refraction are investigated in periodic structures consisting of alternating layers of ferromagnetic insulator and GaAs–AlGaAs-type semiconductor bilayers. It is shown that in quantum Hall effect conditions, the refractive indices and consequently the refraction angles of the propagating waves are quantized.Two different geometries of the refracting plane are considered: (I) parallel and (II) perpendicular to the quantizing magnetic field. It is shown that in the first case, negative refraction through the lateral surface of the structure is possible. A frequency region is found where the refraction is negative for all angles of incidence and regardless of the sign of permittivity tensor components. Analytical expressions for both phase and group refractive indices are obtained.In the second case, one of the propagating waves (in the birefringent regime) is backward. Despite this, and unlike in the case of non-quantizing magnetic fields, negative refraction is impossible. [Copyright &y& Elsevier]

Abstract: We simulate and discuss novel spatio-temporal propagation effects that relate specifically to pulsed, phase-mismatched second-harmonic generation in a material characterized by simultaneously negative permittivity and permeability, having finite length. Using a generic Lorentz model for the dielectric permittivity and magnetic permeability, the fundamental and second-harmonic frequencies are tuned so that the corresponding indices of refraction are negative for the pump and positive for the second-harmonic signal. A phase-locking mechanism causes part of the second-harmonic signal generated at the entry surface to become trapped and dragged along by the pump and to refract negatively, even though the index of refraction at the second-harmonic frequency is positive. These circumstances culminate in the creation of an anomalous state consisting of a forward-moving second-harmonic wave packet that has negative wave vector and momentum density, which in turn leads to non-specular reflections at intervening material interfaces. The forward-generated second-harmonic signal trapped under the pump pulse propagates forward, but has all the attributes of a reflected pulse, similar to its twin counterpart generated at the surface and freely propagating backward away from the interface. This describes a new state of negative refraction, associated with nonlinear frequency conversion and parametric processes, whereby a beam generated at the interface can refract negatively even though the corresponding index of refraction at that wavelength is positive. [Copyright &y& Elsevier]

Abstract: We develop a covariant criterion for negative phase velocity propagation, one that is robust to coordinate transformations in both space and spacetime, and can be applied to moving media. Conversely, the criterion used widely for static media, namely , is not covariant and can be satisfied by viewing a simple medium (characterized by rest-frame constitutive parameters ) in a frame that moves faster than , the speed of light in the medium’s rest frame. Our covariant criterion also confirms that in the geometric optics limit negative refraction cannot occur in curved vacuum. [Copyright &y& Elsevier]

In this paper we present our investigation of 2D Archimedean lattice photonic crystals with p4g space group symmetry. The structures are made of GaAs both as air holes and dielectric rods in air. In order to analyze the photonic crystal optical properties we performed calculations of the band structures, equi-frequency contours and electromagnetic propagation through the basic structures and waveguides. In addition, we investigated negative refraction and left-handedness in the p4g photonic crystal. [ABSTRACT FROM AUTHOR]

Abstract: We report our experimental results on two-dimensional left-handed metamaterials (LHM) exhibiting negative refraction and subwavelength imaging. Transmission and reflection spectra of LHM are studied and a left-handed transmission band is observed at the frequencies where both dielectric permittivity and magnetic permeability are negative. Impedance matching is verified both with the experiments and simulations. The two-dimensional LHM structure is verified to have a negative refractive index. We employed three different methods to observe negative refraction; refraction through prism-shaped LHM, beam shifting method, and phase shift experiments. We further demonstrated subwavelength imaging and resolution using LHM superlenses. The effect of thickness on the resolving power is investigated experimentally. [Copyright &y& Elsevier]

Abstract: We study the dependence of the retrieval parameters, such as the electric permittivity, , the magnetic permeability, , and the index of refraction, n, on the size of the unit cell of a periodic metamaterial. The convergence of the retrieved parameters on the number of the unit cells is also examined. We have concentrated our studies on the so-called fishnet structure, which is the most promising design to obtain negative n at optical wavelengths. We find that as the size of the unit cell decreases, the magnitude of the retrieved effective parameters increases. The convergence of the effective parameters of the fishnet as the number of the unit cells increases is demonstrated but found to be slower than for regular split ring resonators and wires structures. This is due to a much stronger coupling between the different unit cells in the fishnet structure. [Copyright &y& Elsevier]

Abstract: We present a study of the lensing properties of two-dimensional (2-D) photonic quasicrystal (PQC) slabs made of dielectric cylinders arranged according to a 12-fold-symmetric square-triangle aperiodic tiling. Our full-wave numerical analysis confirms the results recently emerged in the technical literature and, in particular, the possibility of achieving focusing effects within several frequency regions. However, contrary to the original interpretation, such focusing effects turn out to be critically associated to local symmetry points in the PQC slab, and strongly dependent on its thickness and termination. Nevertheless, our study reveals the presence of some peculiar properties, like the ability to focus the light even for slabs with a reduced lateral width, or beaming effects, which render PQC slabs potentially interesting and worth of deeper investigation. [Copyright &y& Elsevier]

Abstract: Negative refractive index materials are known to be able to support a host of surface plasmon states for both polarizations of light. This makes possible unique effects such as a perfect lens. Checkerboards consisting of alternating cells of positive and negative refractive index represent a very singular situation in which the density of modes diverges at the corners. This raises the question as to whether such effects will still be observed in a real dissipative system of finite size. We have considered several aspects of such structures including these and symmetry aspects (rectangular against triangular checkerboards). We have also studied silver checkerboards whose transverse extent is finite. Negative refractive index checkerboards bring new electromagnetic paradigms both through the intriguing possibilities they appear to offer, and the challenges they present to our understanding of the diffraction process. Most intriguing of all is the possibility of a triangular checkerboard lens whose resolution is limited not by wavelength, but only by the losses in the constituent materials, while a ray picture suggests it behaves as a perfect mirror. The resolution of this lens increases without limit as the losses tend to zero as shown by the generalized lens theorem. We finally show that light confinement can be achieved to certain extent using dielectric triangular photonic crystal (PC) checkerboards displaying the all-angle-negative-refraction (AANR) within the Bragg regime in p polarization. Effectively even a single rectangular or triangular PC can act as an open resonator that confines light in its neighborhood. This cloaking effect has been previously observed in PC slabs displaying the AANR effect. We show that the cloaking is enhanced for three triangular PC wedges sharing a vertex and further improved for 12 triangular PC wedges arranged in a checkerboard fashion. [Copyright &y& Elsevier]

Abstract: In this study, we propose guidelines to optimize the transmission and bandwidth of left handed materials (LHM) composed of two-dimensional lattice of metallic wires interleaved with double split ring resonators (SRRs). Several LHM structures are fabricated to test the proposed rules of design and operate between 7 and 14GHz. In a first step, we show that adding extra SRR layers within each period of wire layers (i.e. interleaving the wire lattice with several SRR lattices) increases the transmittance of the material. In a second step, we demonstrate that adding extra SRR layers in a non-equidistant manner (i.e. inserting several SRR lattices shifted one another by different distances) widens the LHM frequency bandwidth. The results of experimental characterization are found to be in excellent agreement with theoretical predictions. A LHM behavior is obtained in a wide frequency band of ∼1GHz around 8.2GHz with a transmission of −1.2dB measured at resonance. The negative refraction of the material is verified from measurements at oblique incidence. [Copyright &y& Elsevier]

Abstract: We investigate numerically the transmission properties of 1D and 2D composite metamaterials (CMM) consisting of periodically arrangements of circular split-ring resonators (SRR) and wires. The theoretical methods used are the commercially available code Microwave Studio for transmission calculations and a retrieval procedure which gives the effective electric permittivity, ɛ, and magnetic permeability, μ, of the system. Our theoretical results are in good agreement with experimental data. [Copyright &y& Elsevier]

Abstract: Possibilities to realize a negative refraction in chiral composites in dual-phase mixtures of chiral and dipole particles are studied. It is shown that because of a strong resonant interaction between chiral particles (helices) and dipoles, there is a stop band in the frequency area where the backward-wave regime is expected. The negative refraction can occur near the resonant frequency of chiral particles. Resonant chiral composites may offer a root to realization of negative-refraction effect and superlenses in the optical region. [Copyright &y& Elsevier]

Abstract: We report the true left-handed transmission of a composite metamaterial (CMM) consisting of periodically stacked split-ring resonator (SRR) and wire elements. The negative permeability (μ <0) gap is demonstrated explicitly by comparing SRR and closed-ring resonator structures. We confirm experimentally that the plasma cut-off frequency of the CMM is determined by the combined dielectric response of SRR and wire elements, and it is much lower than that of the wire-only medium. This is crucial to identify the left-handed transmission bands of the CMM. We further investigate the effect of intralayer and interlayer disorder on the transmission spectrum of CMM arising from misaligned fabrication and stacking of the SRR layers. We found that the intralayer disorder affects the μ <0 gap of SRRs and the left-handed transmission band of CMM significantly, whereas the SRR transmission is rather immune to interlayer disorder. [Copyright &y& Elsevier]

Abstract: The problem of subwavelength imaging via a photonic crystal slab lens made of two-dimensional (2D) square arrays of parallel dielectric cylinders in air is studied and discussed theoretically. The finite-difference time-domain method is employed to investigate the unique features of imaging by such lens. We confirm earlier findings that a photonic crystal slab lens can provide the imaging of a point source. By analysing the transmission properties of the proposed structure, we demonstrate that inside the all-angle negative refraction, there are some favourable directions for waves to travel. We show that the surface termination of the photonic crystal is a key parameter to obtain a good quality image. The super-resolution of two sources separated by a distance less than the wavelength is also considered. It is shown that the achievable resolution is limited by the slab length. [Copyright &y& Elsevier]