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Here, we study the electromagnetic response of asymmetric mushroom-type metamaterials loaded with nonlinear elements. It is shown that near a Fano resonance, these structures may have a strong tunable, bistable, and switchable response and enable giant nonlinear effects. By using an effective medium theory and full wave simulations, it is proven that the nonlinear elements may allow the reflection and transmission coefficients to follow hysteresis loops, and to switch the metamaterial between "go" and "no-go" states similar to an ideal electromagnetic switch. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the impact of bending a multi-wire endoscope in the context of subwavelength imaging and near-field transport. To this end, we study the reflection and transmission by a "bent" wire medium in different configurations and demonstrate that the structure can be quite robust to the effect of bending provided the total length of the bent wires satisfies the Fabry-Pérot condition. The study is carried out relying on an analytical homogenization theory and using two additional boundary conditions obtained with physical arguments. It is proven that a structure formed by two connected sets of tilted metallic wires can allow for the near field transport with a deeply subwavelength resolution. To illustrate the applications and potentials of the results, the performance of bent multi-wire endoscopes is characterized using full wave numerical simulations. [ABSTRACT FROM AUTHOR]

In recent years, the confinement of light in open systems with no radiation leakage has raised great interest in the scientific community both due to its peculiar and intriguing physics and due to its important technological applications. In particular, materials with near-zero permittivity offer a unique opportunity for light localization, as they enable the formation of embedded eigenstates in core-shell systems with suppressed radiation loss. For all the solutions presented thus far in the literature, the exact suppression of the radiation leakage can occur only when the size of the resonator is delicately tuned. Surprisingly, here, it is shown that the tuning of the resonator radius may be unnecessary, and nonlocal metal spherical nanospheres of any size may support multiple embedded eigenstates with monopole-type symmetry. [ABSTRACT FROM AUTHOR]

The electric drift-current bias was recently introduced as a new paradigm to break the Lorentz reciprocity in graphene. Here, we study the impact of the nonreciprocal response in the energy extracted from a beam of swift charges traveling in the vicinity of a graphene sheet with drifting electrons. It is demonstrated that the drift bias leads to an asymmetric electron-energy-loss spectrum that depends on the sign of the charge velocity. It is found that when the drift and electron beam velocities have comparable values but opposite signs, the energy loss is boosted resulting in a noncontact friction-type effect. In contrast, when the drift and electron beam velocities have the same sign, the energy loss is negligible. Furthermore, it is shown that different theoretical models of the drift-biased graphene conductivity yield distinct peaks for the energy-loss spectrum, and thereby electron beam spectroscopy can be used to test the validity of the different theories. [ABSTRACT FROM AUTHOR]

Following our recent idea of using plasmonic and nonplasmonic nanoparticles as nanoinductors and nanocapacitors in the infrared and optical domains [N. Engheta et al., Phys. Rev. Letts. 95, 095504 (2005)], in this work we analyze in detail some complex circuit configurations involving series and parallel combinations of these lumped nanocircuit elements at optical frequencies. Using numerical simulations, it is demonstrated that, after a proper design, the behavior of these nanoelements may closely mimic that of their lower-frequency [i.e., radio frequency (rf) and microwave] counterparts, even in relatively complex configurations. In addition, we analyze here in detail the concepts of nanoinsulators and nanoconnectors in the optical domain, demonstrating how these components may be crucial in minimizing the coupling between adjacent optical nanocircuit elements and in properly connecting different branches of the nanocircuit. The unit nanomodules for lumped nanoelements are introduced as building blocks for more complex nanocircuits at optical frequencies. Numerical simulations of some complex circuit scenarios considering the frequency response of these nanocircuits are presented and discussed in detail, showing how practical applications of such optical nanocircuit concepts may indeed be feasible within the current limits of nanotechnology. [ABSTRACT FROM AUTHOR]

It is theoretically and numerically demonstrated that a mixture of two topologically distinct material phases is characterized by an anomalous "transparency window" in a spectral range wherein the individual material phases are strongly reflecting. In particular, it is shown that a metamaterial formed by a metallic wire grid embedded in a magnetized plasma may support the propagation of waves with long wavelengths, notwithstanding the components, when taken separately, completely block the electromagnetic radiation. The effect is explained in terms of topological properties of the magnetoplasmon. Furthermore, it is highlighted that some naturally available materials may be regarded as a mixture of two topologically distinct phases, and hence may be characterized by a similar anomalous transparency effect as well. [ABSTRACT FROM AUTHOR]

Here, we formally develop theoretical methods to topologically classify a wide class of bianisotropic continuous media. It is shown that for continuous media, the underlying wave vector space may be regarded as the Riemann sphere. We derive sufficient conditions that ensure that the pseudo-Hamiltonian that describes the electrodynamics of the continuous material is well behaved so that the Chern numbers are integers. Our theory brings the powerful ideas of topological photonics to a wide range of electromagnetic waveguides and platforms with no intrinsic periodicity and sheds light over the emergence of edge states at the interfaces between topologically inequivalent continuous media. [ABSTRACT FROM AUTHOR]

Here we theoretically predict and experimentally verify that permeability μ-near-zero (MNZ) materials give the opportunity to supercouple waveguides with highly mismatched cross sections. Rather distinct from the supercoupling provided by permittivity-near-zero materials we discovered several years ago, the MNZ supercoupling can take place when the transition channel cross section is much wider than that of the input and output waveguides. We develop a simple analytical model that captures the physical mechanisms that enable this remarkable effect. The MNZ supercoupling effect is experimentally verified with rectangular waveguide technology by mimicking the μ-near-zero response with the help of cylindrical split ring resonators. [ABSTRACT FROM AUTHOR]

We propose a first-principles effective medium formalism to study the propagation of electron waves in semiconductor heterostructures with a zero band gap. Our theory confirms that near the K point the dynamics of a two-dimensional electron gas modulated by an external electrostatic potential with honeycomb symmetry is described by the same pseudospinor formalism and Dirac massless equation as a graphene monolayer. Furthermore, we highlight that even though other superlattices based on semiconductors with a zincblende-type structure can have a zero band-gap and a linear energy-momentum dispersion, the corresponding effective medium Hamiltonian is rather different from that of graphene, and can be based on a single-component wave function. [ABSTRACT FROM AUTHOR]

We show that the non-local susceptibility  (r, r′) for a non-translationally invariant homogenized wire medium is, modulo a constant, given by a simple Green function related to the material geometry. We also show that two previous methods for solving wave interaction problems for bounded wire media (wave expansion method and transport equation) are equivalent to each other, and to a third method involving particle reflection at the boundary. We discuss the importance of the dead layer or virtual interface, and find it to be analogous to the excitonic semiconductor case. Several examples are provided to clarify the material. [ABSTRACT FROM AUTHOR]

Photonic topological materials with a broken time-reversal symmetry are characterized by nontrivial topological phases, such that they do not support propagation in the bulk region but forcibly support a nontrivial net number of unidirectional edge-states when enclosed by an opaque-type boundary, e.g., an electric wall. The Haldane model played a central role in the development of topological methods in condensed-matter systems, as it unveiled that a broken time-reversal symmetry is the essential ingredient to have a quantized electronic Hall phase. Recently, it was proved that the magnetic field of the Haldane model can be imitated in photonics with a spatially varying pseudo-Tellegen coupling. Here, we use Green's function method to determine from "first principles" the band diagram and the topological invariants of the photonic Haldane model, implemented as a Tellegen photonic crystal. Furthermore, the topological phase diagram of the system is found, and it is shown with first principles calculations that the granular structure of the photonic crystal can create nontrivial phase transitions controlled by the amplitude of the pseudo-Tellegen parameter. [ABSTRACT FROM AUTHOR]

We consider the effect of quantum friction at zero absolute temperature resulting from polaritonic interactions in closely positioned two-dimensional arrays of polarizable atoms (e.g., graphene sheets) or thin dielectric sheets modeled as such arrays. The arrays move one with respect to another with a nonrelativistic velocity v«c. We confirm that quantum friction is inevitably related to material dispersion, and that such friction vanishes in nondispersive media. In addition, we consider a classical analog of the quantum friction which allows us to establish a link between the phenomena of quantum friction and classical parametric generation. In particular, we demonstrate how the quasiparticle generation rate typically obtained from the quantum Fermi golden rule can be calculated classically. [ABSTRACT FROM AUTHOR]

I characterize the spatial optical solitons supported by arrays of metallic nanowires embedded in Kerr-type material. The array of nanowires is described using an effective medium model and is regarded as a continuous medium. I show that the conditions necessary for the formation of spatial solitons are radically different in presence of the nanowires. In particular, within the effective medium model, spatial solitons are allowed in the nanowire material only when the host material is a "self-defocusing" material. It is proven that the characteristic soliton beamwidth is related to the degree of hyperbolicity of the isofrequency surfaces of the photonic states and that a sufficiently strong electric field amplitude may enable subwavelength solitary waves. [ABSTRACT FROM AUTHOR]

We derive an effective medium model to characterize the macroscopic electromagnetic response of metallic nanowire arrays embedded in a host dielectric with a Kerr-type nonlinear permittivity function. It is shown that the macroscopic electromagnetic fields are coupled to the conduction current in the nanowires and to an additional quasistatic potential through a system of nonlinear equations. We prove that a weak nonlinearity leads to an electromagnetic response closer to that of an indefinite medium, and to isofrequency contours with increased hyperbolicity. For high field intensities the negative refraction of electromagnetic waves at an air-nanowire material interface is enhanced when the nanowires are embedded in a self-focusing Kerr medium. [ABSTRACT FROM AUTHOR]

Based on an analogy with electromagnetic metamaterials, we develop an effective medium description for the propagation of electron matter waves in bulk semiconductors with a zinc-blende structure. It is formally demonstrated that even though departing from a different starting point, our theory gives results for the energy stationary states consistent with Bastard's envelope-function approximation in the long-wavelength limit. Using the proposed approach, we discuss the time evolution of a wave packet in a bulk semiconductor with a zero-gap and linear energy-momentum dispersion. [ABSTRACT FROM AUTHOR]

The speed of integrated circuits is ultimately limited by the mobility of electrons or holes, which depend on the effective mass in a semiconductor. Here, building on an analogy with electromagnetic metamaterials and transformation optics, we describe a transport regime in a semiconductor superlattice characterized by extreme anisotropy of the effective mass and a low intrinsic resistance to movement--with zero effective mass--along some preferred direction of electron motion. We theoretically demonstrate that such a regime may permit an ultrafast, extremely strong electron response, and significantly high conductivity, which, notably, may be weakly dependent on the temperature at low temperatures. These ideas may pave the way for faster electronic devices and detectors and functional materials with a strong electrical response in the infrared regime. [ABSTRACT FROM AUTHOR]

We investigate the radiation properties of two types of elementary sources embedded in a uniaxial wire medium: a short dipole parallel to the wires and a lumped voltage source connected across a gap in a generic metallic wire. It is demonstrated that the radiation pattern of these elementary sources may have quite anomalous and unusual properties. Specifically, the radiation pattern of a short vertical dipole resembles that of an isotropic radiator close to the effective plasma frequency of the wire medium, whereas the radiation from the lumped voltage generator is characterized by an infinite directivity and a nondiffractive far-field distribution. [ABSTRACT FROM AUTHOR]

Most metamaterial designs are based on the resonant response of either high permittivity or metallic particles embedded in a dielectric host (e.g. an array of metallic particles standing in air). As a consequence, the response of the material is typically narrowband, and this holds back many interesting applications. Here, we show that the key to achieve a broadband isotropic response may lie on a low-permittivity host with a plasmonic-type response. In particular, we demonstrate that a host medium with such characteristics may enable an effective permittivity εeff and permeability μeff simultaneously negative in a frequency range that may be quite broad as compared to typical designs based on metallic particles standing in a dielectric host. It is shown that the proposed configuration is largely insensitive to disorder and that a slab of the metamaterial may mimic to some extent the Veselago-Pendry's superlens, enabling negative refraction and imaging with super-resolution. [ABSTRACT FROM AUTHOR]

Metamaterials are characterized by counterintuitive phenomena, which have been debated since their first practical realization. Due to their anomalous backward power flow, it has been recently discussed whether even the classic definition of the Poynting vector, defining the power flux per unit surface, should be modified when dealing with metamaterials with exotic properties. Here, we settle this issue and fully clarify the physics of negative refraction, showing that the Poynting vector and other power relations in artificial materials may be unambiguously defined consistently with classic formulas for homogeneous media. [ABSTRACT FROM AUTHOR]

We critically analyze the anomalies in the frequency dispersion of the magnetic permeability, showing that it may be sometimes-without contradicting causality-inconsistent with the Kramers-Kronig relations for passive materials, as formulated by Landau and Lifshitz, even at extremely low frequencies where the permeability has definitely a very precise physical meaning. This suggests that in general the permeability may not satisfy the Kramers-Kronig formulas for passive materials, and an alternative set of relations to link the real and imaginary parts of the permeability in the frequency region where the permeability retains its physical meaning is proposed. [ABSTRACT FROM AUTHOR]

We propose a simple, robust, and versatile time domain approach to homogenize metamaterials, taking into account both frequency and spatial dispersion. The macroscopic electromagnetic response of optical metamaterials, such as the fishnet structure and plasmonic metamaterials with near zero parameters, is characterized in terms of local effective parameters ε and μ, under the assumption that the effects of spatial dispersion are weak. [ABSTRACT FROM AUTHOR]

Continuing our recent work (2008 New J. Phys. 10 053011), we demonstrate that due to strong nonlocal effects additional boundary conditions (ABCs) are essential to characterize the reflection of electromagnetic waves by nonconnected wire arrays using homogenization methods. Based on simple physical considerations, we derive the ABCs for circumstances where the wire medium is adjacent either to a dielectric or to a conducting material, and demonstrate that in the lossless case such boundary conditions ensure the conservation of the power flow. It is shown that the number of ABCs is related to the number of metallic wires in a unit cell. We illustrate the application of the novel boundary conditions to several configurations with practical interest. [ABSTRACT FROM AUTHOR]

In this paper, a nonlocal homogenization model is proposed for the analysis of the spectrum of natural modes on sub-wavelength mushroom-type high-impedance surfaces composed of a capacitive grid connected to a grounded wire-medium (WM) slab. Modal characteristics of mushroom structures are studied in conjunction with the surface-wave and leaky-wave propagation on WM slabs based on local and nonlocal homogenization models, showing the importance of spatial dispersion (SD) in WM. It is shown that mushroom structures support proper real (bound) forward and backward modes, whose dispersion determines the stopband properties of the mushroom structure, and proper (exponentially decaying from the surface) and improper (exponentially growing from the surface) complex leaky-wave modes related to the backward and forward radiation, respectively. Results obtained by different homogenization models are compared leading to important conclusions. Specifically, an interesting observation concerns the mushroom structures with short vias, wherein the SD of the WM slab is significantly reduced, and the results of local and nonlocal homogenization models are in excellent agreement. [ABSTRACT FROM AUTHOR]

In this work, we investigate the possibility of near-field transport using an array of tilted metallic wires. It is demonstrated that consistent with the results reported in Belov et al (2006 Phys. Rev. B 73 033108), which describes subwavelength imaging by an array of metallic wires normal to the interface, the setup considered here may enable the transport of the subwavelength details of a given source through an oblique projection. The array of tilted wires permits the transfer of the electric field component parallel to the wires at the image plane, even when there is no electric field normal to interface, and thus the manipulation of other near-field components (i.e. other wave polarizations) that are not accessible with the usual setup of wires normal to the interface. The emergence of negative refraction due to the extreme anisotropy of structured material is also demonstrated. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate that the interaction of electromagnetic waves with a microstructured material formed by metallic wires connected to a metallic surface can be described using homogenization methods provided an additional boundary condition (ABC) is considered. The ABC is derived by taking into account the specific microstructure of the wire medium. To illustrate the application of the result, we characterize a substrate formed by an array of tilted metallic wires connected to a ground plane, demonstrating that in such a configuration the wire medium behaves essentially as a material with extreme optical anisotropy and that in some circumstances the substrate can be seen as an impedance surface. [ABSTRACT FROM AUTHOR]

In this work, we study the realization of realistic polarization transformers formed by long metallic helices. To this end, we propose a new homogenization model to characterize the propagation of electromagnetic waves in a medium formed by infinitely long helices. We derive approximate analytical expressions for the effective permittivity, effective permeability and the magnetoelectric tensor of the composite material, taking into account the effects of spatial dispersion. We apply the new homogenization model to characterize novel linear-to-circular polarization transformers. Our results show that the metamaterial screen may be designed in such a way that an incoming linearly polarized wave may be transformed into a circularly polarized transmitted wave, and that the transmission efficiency of such polarization transformer may be as high as 95%. [ABSTRACT FROM AUTHOR]

In this paper, it is proved that the continuity of the tangential components of the average electric and magnetic fields is insufficient to describe the reflection of plane waves by a set of thin parallel wires embedded in a dielectric host using a homogenization approach. Based on physical arguments a new boundary condition is proposed to characterize the scattering of waves by the homogenized wire medium. In order to further support the proposed theory, the problem of reflection of a plane wave by a set of semi-infinite parallel wires is solved analytically within the thin-wire approximation. Extensive numerical simulations demonstrate that when the additional boundary condition is considered the agreement between full wave results and homogenization theory is very good even for wavelengths comparable with the lattice constant. [ABSTRACT FROM AUTHOR]

The homogenization of composite structures made of long thin metallic wires is an important problem in electromagnetics because they are one of the basic components of the double-negative medium. In this paper, we propose a new analytical model to characterize the effective pennittivity of the three-dimensional- wire medium in the long wavelength limit. We study two different topologies for the wire medium. The first structure consists of a lattice of connected wires, whereas the second one consists of a lattice in which the wires are not connected. Our results show that the propagation of electromagnetic waves in the two metamaterials is very different. While one of the structures exhibits strong spatial dispersion, the other one seems to be a good candidate for important metamaterial applications. We also found that, for extremely low frequencies, one of the structures supports modes with hyperbolic wave normal contours, originating negative refraction at an interface with air. We validated our theoretical results with numerical simulations. [ABSTRACT FROM AUTHOR]

In this paper we propose a new approach to compute the dynamic potential (Green function) from two- and three-dimensional periodic arrays of point sources in a three-dimensional space. The method has at least exponential convergence rate (in some cases it has Gaussian convergence rate). The convergence rate is independent of the position of the observation point in the unit cell. The proposed approach can also be used to calculate the derivatives of the Green function very efficiently. [ABSTRACT FROM AUTHOR]

The objective of this paper is to discuss the differences between the homogenization of a bulk metamaterial and the homogenization of a thin metamaterial slab (complex surface). To this end, we study the canonical problem of propagation of electro-magnetic waves in a mesh of crossed metallic wires embedded in a dielectric slab. We prove that it may not be appropriate to characterize the complex surface with the same effective parameters as the bulk metamaterial and the usual boundary conditions. We develop a modified homogenization procedure that is suitable to homogenize the complex surface using the bulk material effective parameters. The results of our analytical model are compared with full wave numerical results, yielding an excellent agreement for long wavelengths. Our formulation is valid for slabs of arbitrary thickness. We hope that this work may contribute to a more profound understanding of the interaction of electromagnetic waves with the emerging metamaterials. [ABSTRACT FROM AUTHOR]

In this paper, we propose a periodic Green's function-based method for computing the static effective permittivity of metallic crystals. The method is valid for arbitrary lattice structures and inclusion shapes. We show that the homogenization problem can be reduced to an integral equation over the boundary of a generic metallic inclusion. The kernel of the integral equation is a periodic Green's function. This Green's function corresponds to the static potential from a three-dimensional array of point charges plus a uniform density of charge. Different representations of the Green's function are presented and discussed. We apply the developed formalism to characterize the effective permittivity of a three-dimensional array of thin metallic wires. [ABSTRACT FROM AUTHOR]

In this paper, we present a new hybrid method that makes the calculation of the band structure of artificial materials with cylindrical metallic inclusions very efficient. We derive an auxiliary problem whose band structure is that of the metallic crystal along with several dispersionless bands. The eigenfunctions of the auxiliary problem have continuous derivatives up to order 2. Thus, the spectrum of the auxiliary problem can be efficiently computed using the plane-wave method. The band structure of the metallic crystal is then obtained by extracting from the computed results the dispersionless bands. [ABSTRACT FROM AUTHOR]

Dispersion forces between neutral material bodies are due to fluctuations of the polarization of the bodies. For bodies in equilibrium these forces are often referred to as Casimir–Lifshitz forces. For bodies in relative motion, in addition to the Casimir–Lifshitz force, a lateral frictional force ("quantum friction", in the zero temperature limit) comes into play. The widely accepted theory of the fluctuation-induced forces is based on the "fluctuational electrodynamics", when the Maxwell equations are supplemented by random current sources responsible for the fluctuations of the medium polarization. The first part of our paper touches on some conceptual issues of the theory, such as the dissipation-less limit and the link between Rytov's approach and quantum electrodynamics. We point out the problems with the dissipation-less plasma model (with its unphysical double pole at zero frequency) which still appears in the literature. The second part of the paper is devoted to "quantum friction", in a broad sense, and it contains some novel material. In particular, it is pointed out that in weakly dissipative systems the friction force may not be a stationary process. It is shown, using an "exact" (nonperturbative) quantum treatment, that under appropriate conditions, an instability can occur when the kinetic energy (due to the relative motion between the bodies) is transformed into coherent radiation, exponentially growing in intensity (the instability gets eventually limited by nonlinear effects). We also discuss a setup when the two bodies are at rest but a constant electric current is flowing in one of the bodies. One may say that only the electron component of one body is dragged with respect to the other body, unlike the usual setup when the two bodies are in relative motion. Clearly, there are differences in the frictional forces between the two setups. [ABSTRACT FROM AUTHOR]

Topological photonic systems have recently emerged as an exciting new paradigm to guide light without back-reflections. The Chern topological numbers of a photonic platform are usually written in terms of the Berry curvature, which depends on the normal modes of the system. Here, we use a gauge invariant Green's function method to determine from first principles the topological invariants of photonic crystals. The proposed formalism does not require the calculation of the photonic band-structure, and can be easily implemented using the operators obtained with a standard plane-wave expansion. Furthermore, it is shown that the theory can be readily applied to the classification of topological phases of non-Hermitian photonic crystals with lossy or gainy materials, e.g., parity-time symmetric photonic crystals. The calculation of the topological invariants of non-Hermitian systems typically relies on the natural modes of the system. Here, an alternative method is presented which does not require the knowledge of the band structure, based on the Green's function. [ABSTRACT FROM AUTHOR]

Following our recent theoretical studies [M. G. Silveirinha and C. A. Fernandes, Phys. Rev. B 78, 033108 (2008)], it is experimentally verified that an array of crossed metallic wires may behave as a nonresonant material with extremely large index of refraction at microwaves and may enable the realization of ultrasubwavelength waveguides. [ABSTRACT FROM AUTHOR]

Here, I discuss some implications of the time-reversal invariance of lossless radiating systems. I highlight that time-reversal symmetry provides a rather intuitive explanation for the conditions of polarization and impedance matching of a receiving antenna. Furthermore, I describe a solution to generate the time-reversed electromagnetic field through the illumination of a matched receiving antenna with a Herglotz wave. [ABSTRACT FROM AUTHOR]

For long wavelengths, three-dimensional connected metallic wire meshes are impenetrable by light and have an electromagnetic response similar to that of an electron gas below the plasma frequency. Surprisingly, here it is shown that when two opaque metallic meshes are spatially interlaced, the combined structure enables an anomalous light tunneling in the long wavelength regime. The effect is due to the destructive interference of the waves scattered by the two wire meshes, which leads to a Fano-type resonance. The Fano resonance occurs when the longitudinal (plasmon) mode satisfies the Fabry-Pérot condition. [ABSTRACT FROM AUTHOR]

We theoretically demonstrate that a system formed by two coupled graphene sheets enables a negative damping regime wherein graphene plasmons are pumped by a direct current. This effect is triggered by electrons drifting through one of the graphene sheets and leads to wave instabilities and a spontaneous light emission (spasing) in the midinfrared range. It is shown that there is a deep link between the drift-induced instabilities and wave instabilities in moving media, as both result from the hybridization of oscillators with oppositely signed frequencies. With a thickness of a few nanometers and wide spectral tunability, the proposed structure may find interesting applications in nanophotonic circuitry as an on-chip light source. [ABSTRACT FROM AUTHOR]

Here, we present an overview of a first principles homogenization theory of periodic metamaterials. It is shown that in a rather general context it is possible to formally introduce effective parameters that describe the time evolution of macroscopic (slowly-varying in space) initial states of the electromagnetic field using an effective medium formalism. The theory is applied to different types of “wire metamaterials” characterized by a strong spatial dispersion in the long wavelength limit. It is highlighted that the spatial dispersion may tailor in unique ways the wave phenomena in wire metamaterials leading to exotic tunneling effects and broadband lossless anomalous dispersion. [ABSTRACT FROM AUTHOR]

In this paper, it is shown that bulk metamaterials formed by multilayered mushroom-type structures enable broadband negative refraction. The metamaterial configurations are modeled using homogenization methods developed for a uniaxial wire medium loaded with periodic metallic elements (for example, patch arrays). It is shown that the phase of the transmission coefficient decreases with the increasing incidence angle, resulting in the negative spatial shift of the transmitted wave. The homogenization model results are obtained with the uniform plane-wave incidence, and the full-wave results are generated with a Gaussian beam excitation, showing a strong negative refraction in a significant frequency band. Having in mind a possible experimental verification of our findings, we investigate the effect of introducing air gaps in between the metamaterial layers, showing that even in such simple configuration the negative refraction phenomenon is quite robust. [ABSTRACT FROM AUTHOR]

We study the role of topological edge states of light in the transport of thermally generated radiation in a closed cavity at a thermodynamic equilibrium. It is shown that even in the zero temperature limit--when the field fluctuations are purely quantum mechanical--there is a persistent flow of electromagnetic momentum in the cavity in closed orbits, deeply rooted in the emergence of spatially separated unidirectional edge state channels. It is highlighted that the electromagnetic orbital angular momentum of the system is nontrivial, and that the energy circulation is towards the same direction as that determined by incomplete cyclotron orbits near the cavity walls. Our findings open inroads in topological photonics and suggest that topological states of light can determine novel paradigms in the context of radiative heat transport. [ABSTRACT FROM AUTHOR]

In time-reversal invariant electronic systems the scattering matrix is antisymmetric. This property enables a spin-Hall effect, designated here as "scattering anomaly", such that the electron transport does not suffer from back reflections independent of the specific geometry of the propagation path or the presence of time-reversal invariant defects. In contrast, for a generic time-reversal invariant photonic system, the scattering matrix is symmetric and there is no similar anomaly. Here, it is theoretically proven that despite these fundamental differences there is a wide class of photonic platforms--in some cases formed only by time-reversal invariant media--in which a scattering anomaly can occur. It is shown that an optical system invariant under the action of the composition of the parity, time-reversal, and duality operators (P·T·D) is characterized by an antisymmetric scattering matrix. Specific examples of photonic platforms wherein the scattering anomaly occurs are given, and it is demonstrated with full wave numerical simulations that the proposed systems enable bidirectional waveguiding immune to arbitrary deformations of the propagation path. Importantly, our theory unveils a new class of fully three-dimensional structures wherein the transport of light is fully protected against reflections and uncovers unsuspected links between the electrodynamics of reciprocal and nonreciprocal materials. [ABSTRACT FROM AUTHOR]