Left-handed Media Research Articles

艾里高斯涡旋光束正负交变介质中的光波演变

艾里高斯涡旋光束正负交变介质中的光波演变

Reversed Cherenkov-transition radiation in a waveguide partly filled with a left-handed medium

We analyze the electromagnetic field of a charged particle that moves uniformly in a circular waveguide and crosses a boundary between a vacuum area and an area filled with a left-handed medium exhibiting resonant frequency dispersion. The investigation of the waveguide mode components is performed analytically and numerically. The reversed Cherenkov radiation in the filled area of the waveguide and the reversed Cherenkov-transition radiation (RCTR) in the vacuum area are analyzed. The conditions for the excitation of RCTR are obtained. It is shown that the number of modes of RCTR is always finite; in particular, under certain conditions, the RCTR is composed of the first waveguide mode only. Plots of the typical fields of the excited waveguide mode are presented.

Spatial frequency maps of power flow in metamaterials and photonic crystals: Investigating backward-wave modes across the electromagnetic spectrum

We present spatial frequency maps of power flow in metamaterials and photonic crystals in order to provide insights into their electromagnetic responses and further our understanding of backward power in periodic structures. Since 2001, many different structures across the electromagnetic spectrum have been presented in the literature as exhibiting an isotropic negative effective index. Although these structures all exhibit circular or spherical equifrequency contours that resemble those of left-handed media, here we show through $k$-space diagrams that the distribution of power in the spatial frequency domain can vary considerably across these structures. In particular, we show that backward power arises from high-order right-handed harmonics in photonic crystals, magnetodielectric crystals, and across the layers of coupled-plasmonic-waveguide metamaterials, while arising from left-handed harmonic pairs in split-ring resonator and wire composites, plasmonic crystals, and along the layers of coupled-plasmonic-waveguide metamaterials. We also show that the fishnet structure exhibits the same left-handed harmonic pairs as the latter group. These observations allow us to categorize different metamaterials according to their spatial spectral source of backward power and identify the mechanism behind negative refraction at a given interface. Finally, we discuss how $k$-space maps of power flow can be used to explain the high or low transmittance of power into different metamaterial or photonic crystal structures.

Power drainage and energy dissipation in lossy but perfect lenses

It has recently been shown that passive lens designs can retain perfect lensing despite intrinsic loss in the comprising left-handed materials. Here we show that energy conservation is not at odds with the operation of such lossy perfect lenses: The irreversible transfer of electromagnetic power to the lossy material dictates that a smaller portion of the power emitted by the source arrives at the image, but image fidelity remains absolute. Moreover, the power that does arrive at the perfect image must drain from the system there. This is shown to apply to any layered perfect lens based on left-handed media, including the well-known Veselago lens. Combined with what is known about Maxwell's fisheye lens, our results suggest that power drainage is universal to all perfect lenses and is intrinsic to any perfect image. Properly addressing this unique power dynamics is therefore essential to any successful realization of practical perfect lenses with existing metamaterials.

From solitons to rogue waves in nonlinear left-handed metamaterials.

In the present work, we explore soliton and roguelike wave solutions in the transmission line analog of a nonlinear left-handed metamaterial. The nonlinearity is expressed through a voltage-dependent, symmetric capacitance motivated by recently developed ferroelectric barium strontium titanate thin-film capacitor designs. We develop both the corresponding nonlinear dynamical lattice and its reduction via a multiple scales expansion to a nonlinear Schrödinger (NLS) model for the envelope of a given carrier wave. The reduced model can feature either a focusing or a defocusing nonlinearity depending on the frequency (wave number) of the carrier. We then consider the robustness of different types of solitary waves of the reduced model within the original nonlinear left-handed medium. We find that both bright and dark solitons persist in a suitable parametric regime, where the reduction to the NLS model is valid. Additionally, for suitable initial conditions, we observe a rogue wave type of behavior that differs significantly from the classic Peregrine rogue wave evolution, including most notably the breakup of a single Peregrine-like pattern into solutions with multiple wave peaks. Finally, we touch upon the behavior of generalized members of the family of the Peregrine solitons, namely, Akhmediev breathers and Kuznetsov-Ma solitons, and explore how these evolve in the left-handed transmission line.

Nonlinear Intersubband Optical Absorption Coefficient and Refractive Index Changes in Asymmetric Parabolic Double Quantum Wells

The change in optical absorption coefficients and refractive index in GaAs-AlGaAs asymmetric parabolic double quantum wells (DQWs) with applied electric field are studied in detail. Analytical expressions for the linear, nonlinear and total intersubband absorption coefficient and refractive index changes are obtained by using compact density matrix approach. It is found that the magnitude of the nonlinear part of the change in refractive index and absorption coefficients are larger than the linear part in the given frequency region. The value of the total change in refractive index is negative and the asymmetric DQWs becomes left handed media. This property is of great importance for metamaterials science and can contribute substantially to the present search for simple and inexpensive left handed media. Moreover the negative value of the total change in absorption coefficient may be used for developing optical device such as maser at different frequency regime.

FOCUSING THE VERTICAL ELECTRIC DIPOLE RADIATION BY THE PENDRY LENS

The flat lens conception was considered in the pioneering work of V.G. Veselago, who considered the possibility of electromagnetic waves propagation in media with simultaneously negative permittivity and permeability (according to modern terminology − in the left-handed metamaterials). Later, J.B. Pendry put forward the idea of the so-called "superlens", the resolution of which would exceed the diffraction limit. In view of the prospects for the practical applications it has caused a discussion on the possibility of anti-parallelism of phase and group velocities and the actual super-resolution implementation for the source in the form of a monopole. However, using the ray theory approximation reduced the generality of the results, neglecting losses radically distorted them, and errors in the theoretical analysis led to the wrong physical interpretation. In this paper, we obtained a rigorous solution to the problem of focusing radiation from elementary electric dipole located perpendicularly to the plane layer of finite thickness made of the left-handed metamaterial with absorption. Spatial distribution of the electromagnetic field in the layer, as well as the incident and reflected fields at various heights of the dipole, layer thickness and losses in each medium are numerically simulated. The analysis of the calculated spatial structure of the electromagnetic field confirmed the focusing ability of the interfaces between ordinary and left-handed media, as well as a flat lens.

Revisiting Mie’s scattering theory for the analysis of the plasmonic resonance of metal nanospheres

An alternate correction of Mie scattering theory for the analysis of plasmonics resonance of metal nanospheres is proposed. The analysis is based on the correction of Mie scattering theory originally developed for left-handed media or negative index media, which employs a solution using the Ricatti–Bessel functions in the calculation of Mie coefficients. It provides validation that the Mie solution for negative index media of spherical particles is also valid for resonance metal nanospheres. Therefore, the viewpoint of a time-reversal problem for the scattered fields in previous correction is not a necessary, fundamental correction to the Mie scattering theory for spherical metal particles. Our analytical solution is also verified by using finite element method.

On achieving pure electromagnetic left-handedness through magnetodielectric field compression

The relationship between electromagnetic phase and power flow in metamaterials composed of periodic magnetodielectric inclusions is investigated. The distribution of Poynting vectors in $k$ space across multiple Brillouin zones suggests that backward phase is a result of field compression within the inclusions, and that left-handedness can be achieved without negative electric or magnetic susceptibility (i.e., without out-of-phase dipole moments). This hypothesis is verified by showing that a one-dimensional periodic array of magnetodielectric slabs can be designed to mimic the properties of an ideal (homogeneous) left-handed medium. Furthermore, using exact fields and without any field averaging, it is shown that the structure can be designed such that practically all power is carried in the fundamental left-handed spectral component. In the limit where the fundamental contains all the power, this periodic structure has the same spectral power signature as that of a homogeneous left-handed medium. It is shown that this congruence does not manifest when the inclusions are purely dielectric, nor does it manifest for magnetodielectric inclusions in two or three dimensions.

Metamaterial made of V-type systems from LiH molecules

We build a V-type system from LiH molecule with antiparallel dipole moments by applying a strong laser field to one of the two transitions in the \(\varLambda \)-type system made of the excited vibrational state \(A^{1}\varSigma ^{+} (v=1,\,j=1)\) and the vibrational states of the ground level \(X^{1}\varSigma ^{+} (v=1,\,j=0)\) and \(X^{1}\varSigma ^{+} (v=0,\,j=0)\). This has been called previously by us as V-type system of the second kind. In this system, we have magnetic dipole-allowed transitions in addition to the electric dipole-allowed transitions due to the fact that the obtained dressed states have mixed parities. We find that a medium with V-type systems of the second kind from LiH molecule can have a negative refractive index and/or can be a left-handed medium and therefore can be a metamaterial. We determine the incoherent pumping rate \(\varLambda \), the probe detuning \(\Delta _{p}\) and the relative phase between the probe and coupling field phases \(\phi \), for which our medium of molecular systems achieves a negative refractive index and/or both negative electric permittivity and magnetic permeability.

The effective periodic homogeneous metamaterials for infinite complementary dielectric slab characteristics

A comparison of balanced and unbalanced backward wave dispersion relations and the constitutive electromagnetic effective parameters of dielectric constant, magnetic permeability are obtained. In the balanced case, the initial transmission line lies in left handed (LH) medium and the next to cut-off frequency of higher order regions transmission line becomes in right-handed (RH) medium. In the unbalanced case, there are a tiny reject band displays due to the attenuations. It is also desirable for metamaterial parameters extraction properties should behave in antiresonance behaviour in the band gap regions. The proposed extraction technique shows the suitable results for dual negative magnetic permeability and electric permittivity that match with the theory. To demonstrate the infinite wave investigations, there are four unit cell of complementary split- ring resonators (CSRRs) microstrip implementation is obtained and the equivalent lumped element circuit is analyzed. The theory and experiment result exhibits excellent agreement that ensures minimum loss and electrical small size due to less than wavelength dimensions.

Wave fronts and packets in 1D models of different meta-materials: Graphene, left-handed media and transmission line

A comparative study is made of the propagation of wave packets and fronts in three different meta-media, i.e. graphene, left-handed media (LHM) and transmission lines, using one-dimensional models. It is shown that a potential step in graphene influences only the frequency of the electronic wave, i.e., the particular spectrum branch (electron or hole) to which the wave belongs to, while the envelop function (the wave front or packet form) remains unchanged. Although the model for a vacuum and LHM interface is similar to that of the potential step in graphene, the solutions are quite different due to differences in the chirality of the waves. Comparing the propagation of wave fronts and packets in a standard transmission line and its meta-analog we demonstrate that the propagating packets in the meta-line are much more deformed as compared to the standard one, including broadening, asymmetry and even the appearance of fast moving precursors. This influence is seen not only in the case of packets with steep fronts but in soft Gaussian packets as well.

Application of Symmetric Parabolic Double Quantum Wells as Right and Left Handed Media

Application of Symmetric Parabolic Double Quantum Wells as Right and Left Handed Media

Special Features of Electromagnetic Wave Propagation in a Two-Layered Cylindrical Waveguide with Right- and left-handed media. Part 2

Special Features of Electromagnetic Wave Propagation in a Two-Layered Cylindrical Waveguide with Right- and left-handed media. Part 2

Resonances in Reverse Vavilov-Cherenkov Radiation Produced by Electron Beam Passage over Periodic Interface

Resonances in reverse Vavilov-Cherenkov radiation produced by the charged particles beam passage over periodic boundary of dispersive left-handed medium are found out and studied. Analysis and modeling are performed on the base of rigorous mathematical approaches. For the first time, several physical peculiarities owing to these effects are considered in the conditions of possible resonant scattering of electromagnetic waves.

Radiation field of a charged particle moving in right-handed and left-handed media with resonant dispersion

The radiation field of relativistic charged particles moving in media with resonant dispersion is analyzed using the stationary phase method. Three medium models are considered: a model typical for dielectrics, a model typical for magnetics, and a model typical for the left-handed medium. Equations determining stationary points are obtained, and the conditions for the existence of one or two stationary points are found. A simple analytical expression for stationary points in the case of ultrarelativistic motion in resonant dielectric or magnetic materials is given. In the case of an arbitrary velocity, an algorithm for solving the stationary point equation and for computing the radiation field is developed. The results of this algorithm are compared with those obtained by computation of the field using exact formulae. Typical dependences of the field on distance from the charged particle are presented. It is shown that, for the case of the left-handed medium, the radiation field is formed at larger distances behind the charge compared with the cases of typical dielectric and magnetic materials. It is found that the radiation field can possess beats that are more pronounced in the left-handed medium.

Electric and magnetic dipole allowed transitions of atoms for three-dimensionally isotropic left handedness in a mixed atomic vapor

Since previous negative-index atomic media based on quantum optical approaches are highly lossy, a proposal for realizing a three-dimensionally isotropic left-handed atomic vapor medium is suggeste ...

From slow to fast light in amplified negative refraction using atomic coherence assisted by an incoherent pump

We propose and demonstrate a scheme to realize large negative refraction dispersion when a probe field is amplified by cooperation between a coherent field and an incoherent pump. The probe pulse can propagate either subluminally or superluminally in the left-handed amplification medium by modulating parameters of the coherent and incoherent fields.

A Three-Dimensionally Isotropic and Perfectly Vacuum-Impedance-Matched Negative-Index Material

A new scenario for realizing a gain left-handed atomic vapor medium based on both dressed-state mixed-parity transitions (for simultaneous electric-and magnetic-dipole resonance) and incoherently-p ...

Dynamics of the wave packet in a tunnel-coupled structure consisting of amplifying right-handed and absorbing left-handed media

The dynamics of forward and backward waves in the tunnel-coupled waveguide structure that consists of materials with different signs of real and imaginary parts of refractive indices is analyzed. The expressions for the amplitudes of propagating waves and reflection and transmission coefficients are derived. It is demonstrated that such a structure can be used as a slow-wave structure whose parameters can be controlled using an external magnetic field. The absence of the spontaneous generation of the radiation that propagates in the structure is also demonstrated for the given effective gain, phase mismatch of the interacting modes, and waveguide length.