Chiral Nihility Metamaterial Research Articles

Nonlinear effects in chiral nihility metamaterial

In this paper, the characteristics of chiral nihility nonlinearities have been investigated theoretically. In the case of this medium, permittivity and permeability are equal to zero, regardless of the existence of nonlinear effects, which is due to the presence of cross-susceptibilities in chiral medium. We have made a study of hyperbolic secant (sech) pulse to define the influence of nonlinear chiral parameter on the propagation of an electromagnetic wave in chiral nihility media. Numerical results are given and discussed to confirm the characteristics investigated theoretically.

Effects on reflected and transmitted powers of planar stratified structures involving chiral nihility metamaterials

Behavior of different planar multilayer periodic structures due to plane wave excitation has been studied using the transfer matrix method. Multilayer structure is composed of odd number of slabs and the layers at odd locations have same characteristics and layers at even locations have same characteristics. For each structure, layers at odd locations are of chiral nihility metamaterial whereas three different cases are considered for layers at even locations, i.e., dielectric, chiral and chiral nihility. Effects of polarization rotation due to the optical activity of material's chirality is studied with respect angle of incidence and frequency in THz region. Chiral nihility adds property of transparency to the structure for normal incidence. Chiral nihility-chiral nihility structure for normal incidence yields transparency whereas same structure for oblique incidence yields total rejection at higher frequencies.

Fields in fractional dual DB', D'B and D'B' waveguides containing chiral nihility medium

In electromagnetics, a set of boundary conditions requiring vanishing of the normal components of the flux densities D and B (DB boundary) or their normal derivatives (DBboundary) have assumed great importance, recently. In the present study, we employ DB � , DBand DB boundary conditions to investigate the fields in a three layered fractional dual planar waveguide. Middle layer of the waveguide is filled with air and other two layers are filled with chiral nihility metamaterial. Fractional dual solutions for the waveguide are obtained using a fractional curl operator with a parameter ' α ' defining the fractional order of the operator. For limiting values of the parameter, i.e., α =0 and α =1 , the solutions to the Maxwell's equations correspond to the original and dual to the original solutions, respectively. Whereas, in general (0 <α< 1) , so called intermediate solutions are obtained. It has been noted that fields do exist in chiral nihility material backed by DB � , DBor DB boundary, and a circular wave behaviour of the fields is observed in the core of the waveguide. In this sense DB � ,DBa nd DB � chiral nihility waveguides behave identical to their DB counterpart.

FOCUSING, POWER TUNNELING AND REJECTION FROM CHIRAL AND/OR CHIRAL NIHILITY/NIHILITY METAMATERIALS LAYERS

Focusing of electromagnetic plane wave from a large paraboloidal re∞ector, composed of layers of chiral and/or chiral nihility metamaterials, has been studied using Maslov's method. As a flrst step, the transmission and re∞ection of electromagnetic plane wave from two parallel layers of chiral and/or chiral nihility metamaterials are investigated using transfer matrix method. The efiects of change of angle of incidence, chirality parameters and impedances of layers are noted and discussed. Special cases by taking extreme values of permittivity of second layer, while assuming value of corresponding chirality equal to zero, are also obtained for validating the methodology. These special cases are equivalent to re∞ection from a perfect electric conductor backed chiral layer and nihility backed chiral layer, respectively. Results of re∞ection from parallel layers have been utilized to study focusing from a large paraboloidal re∞ector. The present study, on focusing from a paraboloidal re∞ector, not only unifles already published work by various researchers but also provides better understanding of the problem.

Fields in fractional dual DB waveguides containing chiral nihility metamaterials

A fractional curl operator is used to derive fields for guided waves in a three-layered fractional dual planar waveguide with DB boundary, i.e. the normal components of electric flux density D and magnetic flux density B become zero at the interface. The middle layer of the waveguide is filled with air and the other two layers are filled by chiral nihility metamaterial. For the purpose of solution, a general wave propagating inside the waveguide is assumed and decomposed into transverse electric and transverse magnetic modes. It is noted that fields do exist in chiral nihility material backed by DB. Moreover, it is noted that only co-polarized wave is reflected back from DB interface of the waveguide. In the core of DB waveguide, filled with air, we get circular wave behavior of fields.

ELECTROMAGNETIC FIELDS IN A CIRCULAR WAVEGUIDE CONTAINING CHIRAL NIHILITY METAMATERIAL

Propagation of electromagnetic flelds and power in a circular waveguide containing chiral nihility metamaterial is studied. Space inside the waveguide is divided into two circular regions. One region contains chiral nihility metamaterial while other region is of free space. Two cases of the waveguide, in this regard, are considered for analysis. For the case of perfect electric conductor (PEC) waveguide, there is no net electric fleld and power propagation in chiral nihility region of the guide whereas both flelds and power exist in non- nihility region (which is free space in our cases) of the guide. For perfect electromagnetic conductor (PEMC) waveguide, both electric and magnetic flelds exist in the chiral nihility and non-nihility regions.

PLANAR DB BOUNDARY PLACED IN A CHIRAL AND CHIRAL NIHILITY METAMATERIAL

Re∞ection from a planar DB interface placed in chiral and chiral nihility medium is studied. No difierence between the two cases, regarding re∞ection chracteristics, is noted. No re∞ected backward wave is produced for DB interface placed in chiral nihility metamaterial. In this regard, DB interface may be considered as flrst known perfect re∞ector interface which yields non zero power when placed in chiral nihility medium.

ELECTROMAGNETIC RESPONSE OF A CIRCULAR DB CYLINDER IN THE PRESENCE OF CHIRAL AND CHIRAL NIHILITY METAMATERIALS

Scattering of electromagnetic plane wave from an inflnitely long circular DB cylinder placed in chiral and chiral nihility metamaterials is studied, and the results are compared with that of scattering from DB cylinder placed in free space. The discussion is further extended by considering coating of DB cylinder with chiral/chiral nihility metamaterial. For DB cylinder placed in unbounded free space/chiral/chiral nihility metamterial, only co- polarized scattered flelds are obtained, whereas, for chiral/chiral nihility metamaterial coated case, both co- and cross-polarized scattered flelds are noted. Numerical results are presented for difierent values of chirality parameter.

Radiation Characteristics of Elementary Sources Located in Unbounded Chiral Nihility Metamaterial

Radiation characteristics of an electric dipole located in unbounded chiral nihility metamaterial are studied. For this purpose, expressions for radiated electric and magnetic fields due to electric dipole are derived in terms of cylindrical wave functions using the vector potentials. It is noted that electric dipole radiates no electric field whereas there is nonzero radiated magnetic field in the chiral nihility medium.

Waves in Fractional Dual Planar Waveguides Containing Chiral Nihility Metamaterial

Field expressions for guided waves in three-layered fractional dual planar waveguides are derived by virtue of fractional curl operator. Fractional dual waveguides may be regarded as intermediate steps of the two waveguides which are related through principle of duality. All layers are parallel to the walls of the guide. Middle layer of the waveguide is filled with air however other two layers are filled with chiral nihility metamaterial. Parameter α describes the order of the fractional curl operator. No electric field exists in the chiral nihility layers of the waveguide for α = 0, whereas no magnetic field exists in the chiral nihility layers for α = 1. That is, power flow is confined to only air region of the waveguide for integer values of fractional parameter and corresponding situations have been previously discussed in a published work. In present work, it is noted that, for 0 < α < 1, neither electric field and nor magnetic field is zero inside chiral nihility layers of the fractional dual waveguides. By varying the values of order of the fractional curl operator, one can observe how situation dealing with no electric field changes to situation dealing with no magnetic field. Behavior of fields and power flow in different regions of the fractional waveguides is discussed. It is concluded that, even for fractional dual waveguides, real part of power flow is zero in chiral nihility regions of the waveguides.

Surface polaritons in planar chiral nihility meta-material waveguides

Chiral nihility meta-material is a special case of chiral medium, in which both the permittivity and permeability are equal to zero. The feature of surface wave modes (or surface polaritons) in the planar chiral nihility waveguides which the core or cladding consist of chiral nihility meta-materials is investigated. The dispersion curves, electromagnetic fields, energy flow distribution and the power of surface wave modes in the planar chiral nihility waveguides are presented for typical parameters. Some novel peculiarities such as anomalous dispersion curves, the power flows opposite to the wave vector propagation direction in the planar chiral nihility waveguides have been found.

CHARACTERISTICS OF GUIDED MODES IN PLANAR CHIRAL NIHILITY META-MATERIAL WAVEGUIDES

The characteristics of guided modes in the planar waveguides which the core or cladding consists of chiral nihility meta-materials are studied theoretically. The dispersion curves, electromagnetic fields, energy flow distribution and the power of several low-order guided modes in the chiral nihility waveguides are presented. Some novel features such as anomalous dispersion curves, the power flows opposite to the wave vector propagation direction in the chiral nihility waveguides have been found.

Waves in planar waveguide containing chiral nihility metamaterial

We investigate the guided waves in a three-layered planar waveguide, with one layer filled with air and the other two filled with the chiral nihility material. We have shown that no electric field exists in the chiral layers. However, the magnetic fields are nonzero within the chiral regions due to the decoupling between electric and magnetic fields. The disappearance of the electric field is caused by the negative reflections for two egienwaves in the chiral nihility at the boundaries of the planar waveguide. The electromagnetic energies can only be guided away from the source in the air layer. Simulation results have validated our theoretical analysis.