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This article provides examples that illustrate the search for different two-layer metamaterials that provide rotation of the polarization plane (“optical activity”). Selected objects show a twenty-year history of the search for a new principle of creation of polarization rotators based on planar metamaterials that were implemented in the form of thin-layered periodic structures. The manifestation of optical activity, presence or absence of satisfactory or perfect matching, the possibility of a multiband phenomena, the role of high spatial harmonics in “electromagnetics” of this effect are explained by the features of the eigen-oscillations that are excited in the gap of the multilayer structure.

We numerically investigate the resonance properties of the reflective metasurface, which is a planar, two-direction lattice of pairs of dielectric bars placed on a metal substrate. The structure is designed in such a way and with such sizes that in its subwavelength mode the first few lowest frequency resonances fall within the far infrared wavelength range. To study the physical processes in the metasurface, spectral characteristics, 3D vector plots and maps for electromagnetic fields in the structure are presented.

The most interesting examples of various double-layer metamaterials that provide “optical activity” are presented to reveal the motivation of use of different cell topologies. The phenomena of the giant “optical activity”, existence or lack of perfect matching, multi-band phenomena, the role of higher space harmonics, and influence of space spectrum rarefying are considered and explained based on the spectral theory of opened structures.

We report on recent developments of the conception of all-dielectric planar metamaterials that are capable to support high-Q trapped-mode resonant excitations. A set of new designs of metamaterials are proposed and configurations of the unit cell allowing trapped-mode resonances are discussed. Advantages of the proposed designs to manifest high-Q resonant regime providing a concision choice of the degree of structural asymmetry within the unit cell are revealed.

The dispersion relation for propagation and attenuation constants of electromagnetic waves which are supported by a metal film placed on a substrate and covered by a thin dielectric layer is studied numerically in visible and infrared wavelength ranges.

We demonstrate for the first time a nanostructured planar photonic metamaterial transmitting light differently in forward and backward directions.

We show that in the visible to near-IR part of the spectrum, normal incidence transmission of circularly polarized light through a nanostructured anisotropic planar chiral metamaterial is asymmetric in the opposite directions. The new effect is fundamentally different from the conventional gyrotropy of bulk chiral media and the Faraday effect. It has a resonance nature associated with a new type of excitation in the metal nanostructure: the enantiomerically sensitive plasmon.

An analytical model of reflection and transmission of plane waves in double regular arrays of bianisotropic particles is developed. A method to correct approximate values of the particle polarizabilities so that the energy conservation requirements are exactly satisfied is proposed. Double arrays of planar omega particles are studied in detail, and it is shown that very sharp Bragg resonances exist in such arrays. The theory is verified by comparison with numerical simulations based on the method of moments.

Numerical solution of electromagnetic wave diffraction by a two-periodic grating of wavy metal strips placed on a dielectric substrate is obtained. The solution is verified for a particular case of straight strips by comparison with the rigorous solution. Analytical expressions for the reflection coefficients from wavy gratings in free space are obtained in the low frequency range. Frequency dependencies of the reflection coefficients are analyzed. Differences in reflection from classical one-periodic gratings of straight strips are discussed.

Results of research of resonant phenomena in planar periodic structures consisted of dielectric elements are presented. An existence of high Q-factor trapped mode resonances is revealed in structure which a periodic cell is composed of two dielectric bars with different lengths or width. Besides higher Q-factor essential difference of studied structures in contrast to the planar structure with a single dielectric bar in the unit cell is appearing of a great red shift of a trapped mode resonant wavelength. This property is very attractive to design a new type high-Q dielectric metamaterials for THz and Infrared.

We report on a bistable light transmission through two-layered structure which consists of two gratings of planar perfectly conducting infinite strips placed on the both sides of a dielectric slab. It is demonstrated that a switching may be achieved nearly the frequency of the high-quality-factor Fano-shape trapped-mode resonance excitation.

We report on a bistable light transmission through a planar metamaterial consisted of a metal pattern of weakly asymmetric elements placed on a nonlinear substrate which enables sharp resonance response by excitation of a trapped mode. A feedback required for bistability is provided by the coupling between strong trapped mode resonance antiphased currents exited on the metal elements and an intensity of inner field in the nonlinear substrate.

The problem of infra red light diffraction on a planar 2-D periodic metal-dielectric or dielectric structures with square periodic cell has been solved. The periodic cell includes either two complex-shaped asymmetric metal elements or two dielectric bars with different lengths. The existence of a high order trapped mode resonance was shown for metal-dielectric structure and its properties were studied. For the first time, the existence of a trapped mode resonance in a dielectric planar structure was shown. Such resonances demonstrate greater quality factor then usual plasmon-polariton resonances.

One-periodic planar arrays of straight wires or metal strips have a long history of applications as quasi-optical polarizing devices and partially transparent mirrors. Their properties are well known.

The problem of visible and IR light diffraction by planar 2-D periodic metaldielectric structures with a periodic cell consisted of two complex-shaped asymmetric metal elements was solved. The mapped PSTD method and ADE technique with complex-conjugate pole model were used for taking into account the dispersion of metal permittivity. The conditions of light confinement by an excitation of trapped mode resonances of the structures were studied. Existence of high order trapped mode resonance with a greater quality factor than the quality factor of lowest one was shown for the first time.

We present a new type of electromagnetic planar metamaterial that exhibit strong dispersion at a local minimum of losses and is believed to be the first metamaterial analog of electromagnetically induced transparency. We demonstrate that pulses propagating through such metamaterials experience considerable delay, whereas the thickness of the structure along the direction of wave propagation is much smaller than the wavelength, which allows successive stacking of multiple metamaterial slabs. This leads to a significant increase in the band of normal dispersion, as well as in transmission levels.

We show for the first time that a classical analogue of EIT can be realized in “zero thickness” planar metamaterials (meta-surfaces) resulting in substantial delay of propagating electromagnetic pulses.

Paper deals with analysis of the ldquotrapped moderdquo resonance properties in optical planar structures for metamaterials applications. The light diffraction solve algorithm for planar periodic metal-dielectric optical structures combines the mapped PSTD method with analytical transfer matrix method. The wavelength dependencies of reflection coefficients for periodic array with broken c-shaped and circle metal elements are presented.

We provide experimental evidence that an electromagnetic pulse can be significantly delayed with minimum loss and distortion, while propagating through a new type of planar meta-materials that supports modes weakly coupled to free-space radiation ("dark modes"). Although changes in the velocity and shape of light pulses propagating through bulk dispersive media have been studied extensively in the past [1], these effects have recently drawn considerable attention, since the ability to accurately control the velocity of light is essential for the development of optical communication technologies. We show that the pulse velocity can be controlled through appropriate subwavelength patterning of a thin metal film, namely a planar metamaterial. As typical examples of such structures, we consider two metamaterial arrays with a 15x15 mm unit cell lithographically etched on a 1.5 mm thick PCB dielectric substrate. The first structure is a bi-layered "fish-scale" [2] consisting of an array of continuous wavy metallic strips residing on both faces of the substrate (see inset to Fig. 1a), while the second is an array of split ring resonators with asymmetric arc lengths (see inset to Fig. 1b). As it can be seen from the experimental spectra of Fig. 1a and Fig. 1b, both planar metamaterials exhibit strong normal dispersion in a transmission window (~5.5 GHz) as a result of "dark mode" excitation.

We report that resonant response with a very high quality factor can be achieved in a planar metamaterial by introducing symmetry breaking in the shape of its structural elements, which enables excitation of dark modes, i.e. modes that are weakly coupled to free space., 4 pages, 3 figures

We report first results on the development of photonic planar and layered 2D- and 3D- chiral metamaterials with intriguing properties including giant rotary power and asymmetric transmission.

We report that normal incidence transmission of circularly polarized waves through the lossy anisotropic planar chiral structure is asymmetric in the opposite direction. The new effect is fundamentally distinct from conventional gyrotropy of bulk chiral media and the Faraday effect, where the eigenstates are a pair of counterrotating elliptical states, while the eigenstates of the lossy anisotropic planar chiral structure are two corotating elliptical polarizations.

Reflection and transmission properties of planar doubly-periodic gratings of perfectly conducting infinitely long crossed wavy-shaped strips are considered. The diffraction characteristics; of-the gratings were calculated by using the method of moments. The possibility of the using of the control, electron devices is discussed to transform the grating of uninterrupted strips into array of separate gammadion-shaped particles. The comparison of the reflection properties of the doubly-periodic gratings of infinity long crossed strips and gammadion-shaped strip particles is presented

The transmission of electromagnetic wave through a planar chiral structure, loaded with the gyrotropic medium being under an action of the longitudinal magnetic field, is studied. The frequency dependence of the metamaterial resonance and the angle of rotation of the polarization plane are obtained. We demonstrate both theoretically and experimentally a resonant enhancement of the Faraday rotation. The ranges of frequency and magnetic field strength are defined, where the angle of polarization plane rotation for the metamaterial is substantially higher than that one for a single ferrite slab.

We propose to achieve a strong bistable response of a thin layer of a saturable absorption medium by involving a planar metamaterial specially designed to bear a high-Q trapped-mode resonance in the infrared region., Comment: 11 pages, 4 figures

The results of research into resonant phenomena in double-periodic subwavelength planar structures made up of paired dielectric bars are presented. For the first time the existence of high Q-factor trapped mode resonances is revealed in these low-loss entirely dielectric structures. A large red shift of the trapped mode resonance of the structure is observed as compared with the resonant wavelength of the periodic structure with only one dielectric bar per unit cell. This shift of the resonant wavelength is caused by a strong coupling of the electromagnetic fields in the adjacent dielectric bar resonators.

We argue the possibility of realization of a polarization-insensitive all-optical switching in a planar metamaterial composed of a 4-fold periodic array of two concentric metal rings placed on a substrate of nonlinear material. It is demonstrated that a switching may be achieved between essentially different values of transmission near the resonant frequency of the high-quality-factor Fano-shape trapped-mode excitation.

Full wave numerical study of electromagnetic wave reflection from and transmission through an array of thin, perfect conducting, planar strip complex-shaped elements placed on a magnetized ferrite substrate is carried out. Our results show, that the absorption level and the frequency band of the structure, when the ferromagnetic resonance and a metal element resonance are close in frequency, are larger than the corresponding characteristics of the ferrite layer without metal elements. A significant enhancement of the Faraday rotation has frequency shift with respect to the main resonance. Both right-handed and left-handed circular polarized incident waves interact effectively with a metal array placed on ferrite substrate unlike the known resonant interaction when only one kind (right- or left-handed) of circular polarized waves interacts with the ferrite slab without metal elements.

Vectorial relations of field amplitudes are derived from the Lorentz lemma applied to electromagnetic fields at direct and reversed scenarios of a wave diffraction on a doubly-periodic planar array. Biorthogonality of polarization eigenstates of the waves propagating in opposite directions is shown with reference to a wave channel formed by an incident wave and a diffraction order. For a planar chiral array, an essential difference in polarization transformations of propagated waves is ascertained in the direct wave channel and in the reversed one. Numerical data are presented to demonstrate the polarization transformations by both transmitting and reflecting planar chiral arrays. A difference in polarization eigenstates inherent to a planar chiral array and a bulk chiral medium is noticed.

We report that planar chiral structures affect the polarization state of light in a manner similar to three-dimensional chiral (optical active) media. In experiments with artificial metal-on-silicon chiral planar gratings of 442 wallpaper group symmetry, containing millions of chiral elements per square centimeter, we observed rotation of the polarization azimuth in excess of 30 degrees of light diffracted from it. The rotation was found to change its sign for two enantiomeric forms of the media and to have components associated with both the structural arrangement and the chirality of individual structural elements.