True surface waves guided by metamaterials

The dispersion properties of surface waves propagating along the interface between a resonant metamaterial and vacuum have been studied. It is shown that such an interface can support both forward and backward waves. The case of degeneracy, where an infinite number of waves with arbitrary retardation correspond to one frequency, has been investigated.     

Peculiarities of propagation of electroinductive waves in magnetic metamaterials

The coupling of doubly split ring resonators in the GHz range has been experimentally, analytically, and numerically studied in order to design a metamaterial with dominant electrical coupling as a model of nanoscale metamaterials. An example of propagation of GHz electroinductive waves in a metamaterial is demonstrated.     

Hysteresis of switching waves and dissipative solitons in nonlinear magnetic metamaterials

Localized structures forming in the bistable regimes in a chain of weakly coupled split ring resonators, which are the building blocks of a nonlinear magnetic metamaterial, where electric current is generated by external electromagnetic radiation, have been studied analytically and numerically. The hysteresis of the velocity of switching waves (fronts) has been revealed and discrete dissipative solitons have been found.     

Surface electromagnetic waves on magnetic media

We assume complex magnetic and dielectric properties of two adjacent, isotropic, semi-infinite media and examine surface electromagnetic waves (SEW) at their plane interface. The dispersion curves and non-radiative conditions are derived and compared with other results. Comments are made about which materials will allow surface electromagnetic waves. The importances of the dielectric constants of the sample and the overlayer materials are emphasized with an example, Si and NiO.     

Periodic waves in nonlinear metamaterials

Periodic waves are presented in this Letter. With symbolic computation, equations for monochromatic waves are studied, and analytic periodic waves are obtained. Factors affecting properties of periodic waves are analyzed. Nonlinear metamaterials, with the continuous distribution of the dielectric permittivity obtained, are different from the ones with the discrete distribution.     

Surface spin waves in anisotropic magnetic multilayers

The spectrum of magnetostatic surface spin waves of a stack of magnetic and nonmagnetic layers is investigated theoretically. The calculation treats a very general case: each layer is allowed to be of different thickness, magnetization and magnetocrystalline anisotropy. Some interesting spezial cases are discussed in detail.     

Nonlinear waves guided by graded-index films

We derive both the dispersion relation and the power flow for waves guided by a linear graded-index film in contact with an arbitrary nonlinear cladding. For an exponential-like graded-index profile and a Kerr-like nonlinearity we present numerical results and compare them with those familar from the step-index profile.     

Dyakonov surface waves in photonic metamaterials

We show that suitable photonic metamaterial structures can support lossless surface waves of the form envisaged by Dyakonov. The idea we put forward is based on the birefringent properties of photonic crystals in the long-wavelength limit, and uses the metamaterial anisotropy of the structures to meet the resonance conditions at which Dyakonov surface waves exist. Implementation of this concept can lead to the first experimental observation of Dyakonov waves, and might open the door to the realization of widely tunable sensing devices based on the unique properties of such waves.     

Enhancing magnetic dipole emission with magnetic metamaterials

Magnetic dipole(MD) transitions are important for a range of technologies from quantum light sources and displays to lasers and bio-probes. However, the typical MD transitions are much weaker than their electric counterparts and are usually neglected in practical applications. Herein, we experimentally demonstrate that the MD transitions can be significantly enhanced by the well-developed magnetic metamaterials in the visible optical range. The magnetic metamaterials consist of silver nanostrips and a thick silver film, which are separated with an Eu~(3+):polymethyl methacrylate(PMMA) film. By controlling the thickness of the Eu~(3+):PMMA film, the magnetic resonance has been tuned to match the emission wavelength of MDs. Consequently,the intensity of MD emission has been significantly increased by around 30 times at the magnetic resonance wavelength, whereas the intensity of electric dipole emission is well-preserved. The corresponding numerical calculations reveal that the enhancement is directly generated by the magnetic resonance, which strongly increases the magnetic local density of states around the MD emitter and can efficiently radiate the MD emission into the far field. This is the first demonstration, to the best of our knowledge, that MD transitions can be improved by an additional degree of magnetic freedom, and we believe this research shall pave a new route towards bright magnetic emitters and their potential applications.     

Surface waves in ferrofluids under vertical magnetic field

We present here new experimental results about the waves at the horizontal free surface of a magnetic fluid submitted to a normal magnetic field. The waves are generated by a small modulation at frequency of the vertical field . Using a shadowgraph method, we are able to measure the wavevector k of the 2D waves for a given value of and . The dispersion relation of the surface waves is established experimentally. On the other hand, we propose a theoretical derivation of the dispersion equation which includes a more complete treatment of the magnetic term than the previous works. Finally, we conclude that a linear and inviscid analysis is sufficient to fit well the experimental data, except in the vicinity of the critical field where a surface instability occurs. Received 11 May 1998     

Surface waves in cholesterics in a magnetic field

Propagating waves on the free surface of a cholesteric liquid crystal in a vertical magnetic field are considered for the case when the anisotropy of the magnetic susceptibility is negative. Surface fluctuations distort the helical structure and the dispersion relation and penetration depth are shown to depend on three possible restoring forces: the surface tension, the twist elastic forces associated with the helix, and the magnetic field.     

Nonlinear waves guided by a dielectric slab

We consider dispersion relations and field structure of TE-polarized guided waves travelling along an asymmetric dielectric slab surrounded by two different nonlinear media. For a given configuration there are four types of guided waves. Three of this four types possess at least one field maximum outside the slab region and have no counterpart in linear waveguide optics. The solutions of the dispersion relations depend now on an additional parameter making them more flexible with respect to the linear limit.     

Nonlinear waves guided by a dielectric slab

An exact solution of Maxwell's equations is found for TM-polarized nonlinear guided waves which are guided by a linear dielectric slab embedded between two nonlinear uniaxial media. Additional waves in comparison with the linear case arise. Some of these waves have no counterpart in linear systems. Similarities and differences with respect to TE-polarized nonlinear guided waves are pointed out.     

Optical hollow-core waves in nonlinear Epsilon-Near-Zero metamaterials

We investigate non-diffracting hollow-core nonlinear optical waves propagating in a layered nanoscaled metal-dielectric structure characterized by a very small average linear dielectric permittivity (Nonlinear Epsilon-Near-Zero metamaterial). We analytically show that hollow-core waves have a power flow exactly vanishing at a central region and exhibiting a sharp sloped profile at the edges of the regions surrounding the core. Physically, the absence of power flow at the core region is due to the vanishing of the transverse component of the electric displacement field, a condition that can be satisfied by the full compensation between the nonlinear and linear dielectric contributions.     

Enhanced transmission of electromagnetic waves through metamaterials

This paper reviews our recent experimental and simulation results regarding the electromagnetic wave transmission through three configurations of sandwiching structures of metamaterials: a metallic mesh sandwiched between two identical layers composed of split rings, metallic fractals, and fractal slits, respectively. We observed the enhanced transmission of the waves through these three types of sandwiching composites with respect to the opaque metallic mesh. The locations of the transmission peaks in the spectrum are associated closely with the band characteristics of the sandwiching layer by appearing either on the left- or the right-hand side of its band. PACS 41.20.Jb; 42.70.Qs; 78.20.-e; 42.25.Bs; 47.53.+n     

Controlling flexural waves in thin plates by using transformation acoustic metamaterials

In this study, we design periodic grille structures on a single homogenous thin plate to achieve anisotropic acoustic metamaterials that can control flexural waves. The metamaterials can achieve the bending control of flexural waves in a thin plate at will by designing only one dimension in the thickness direction, which makes it easier to use this metamaterial to design transformation acoustic devices. The numerical simulation results show that the metamaterials can accurately control the bending waves over a wide frequency range. The experimental results verify the validity of the theoretical analysis. This research provides a more practical theoretical method of controlling flexural waves in thin-plate structures.     

Surface and guided magnetic polaritons in a film with perpendicular uniaxial magnetic anisotropy

The dispersion relations of surface and guided polaritons in a ferromagnetic film are obtained for perpendicular magnetic anisotropy in the Voigt geometry. A new frequency window for guided modes is predicted for small external magnetic field. The frequency of surface-guided mode decreases at first as a function of intensity of the external magnetic field applied parallel to the film surface, then goes through a minimum and finally increases with the field intensity. The calculations are carried out for physical parameters now available in substituted iron garnet films.     

Knotted solitons in nonlinear magnetic metamaterials

We demonstrate that nonlinear magnetic metamaterials comprised of a lattice of weakly coupled split-ring resonators driven by an external electromagnetic field may support entirely new classes of spatially localized modes--knotted solitons, which are stable self-localized dissipative structures in the form of closed knotted chains. We demonstrate different topological types of stable knots for the subcritical coupling between resonators and instability-induced breaking of the chains for the supercritical coupling.     

Diffraction of surface waves in metals and metamaterials

The diffraction of pulsed electromagnetic beams propagating along the interface between a dielectric and a metal or a metamaterial is investigated. The equation for slowly varying amplitudes of confined surface waves with a finite cross section size and duration is derived and solved. The dynamics of the diffractive-dispersive broadening of pulsed beams are examined. The conditions of surface dark soliton existence in media with Kerr nonlinearity are obtained.