48 research outputs found
Vector circuit theory for spatially dispersive uniaxial magneto-dielectric slabs
We present a general dyadic vector circuit formalism, applicable for uniaxial
magneto-dielectric slabs, with strong spatial dispersion explicitly taken into
account. This formalism extends the vector circuit theory, previously
introduced only for isotropic and chiral slabs. Here we assume that the problem
geometry imposes strong spatial dispersion only in the plane, parallel to the
slab interfaces. The difference arising from taking into account spatial
dispersion along the normal to the interface is briefly discussed. We derive
general dyadic impedance and admittance matrices, and calculate corresponding
transmission and reflection coefficients for arbitrary plane wave incidence. As
a practical example, we consider a metamaterial slab built of conducting wires
and split-ring resonators, and show that neglecting spatial dispersion and
uniaxial nature in this structure leads to dramatic errors in calculation of
transmission characteristics.Comment: 11 pages, 6 figures, submitted to Journal of Electromagnetic Waves
and Application
Structural tunability in metamaterials
We propose a novel approach for efficient tuning of the transmission
characteristics of metamaterials through a continuous adjustment of the lattice
structure, and confirm it experimentally in the microwave range. The concept is
rather general and applicable to various metamaterials as long as the effective
medium description is valid. The demonstrated continuous tuning of metamaterial
response is highly desirable for a number of emerging applications of
metamaterials including sensors, filters, switches, realizable in a wide
frequency range
Nonlocal homogenization for nonlinear metamaterials
We present a consistent theoretical approach for calculating effective
nonlinear susceptibilities of metamaterials taking into account both frequency
and spatial dispersion. Employing the discrete dipole model, we demonstrate
that effects of spatial dispersion become especially pronounced in the vicinity
of effective permittivity resonance where nonlinear susceptibilities reach
their maxima. In that case spatial dispersion may enable simultaneous
generation of two harmonic signals with the same frequency and polarization but
different wave vectors. We also prove that the derived expressions for
nonlinear susceptibilities transform into the known form when spatial
dispersion effects are negligible. In addition to revealing new physical
phenomena, our results provide useful theoretical tools for analysing resonant
nonlinear metamaterials
Self-oscillations in nonlinear torsional metamaterials
We study the nonlinear dynamics of torsional meta-molecules - sub-wavelength resonators with strong coupling between electromagnetic excitation and rotational deformation - and show that such structures may undergo self-oscillations. We develop a semi-an
Realistic metamaterial lenses: Limitations imposed by discrete structure
We study the peculiarities of a metamaterial "superlens," caused by its discrete structure and finite size. We show that precise modeling of the lens provides remarkable distinctions from continuous medium approximation. In particular, we address the problem of highest resolution that can be achieved with a realistic electrically thin metamaterial lens. We conclude that discrete structure imposes essential limitations on the resolution and that the resolution cannot be improved by decreasing dissipation in the system. Further implications related to effective medium description of discrete structures are discussed.Ministerio de Educaci贸n y Ciencia TEC2007-65376 y TEC2007-68013-C02- 01Uni贸n Europea FEDER CSD2008-00066Junta de Andaluc铆a TIC-25
Broadband isotropic 渭-near-zero metamaterials
Natural diamagnetism, while being a common phenomenon, is limited to permeability values close
to unity. Artificial diamagnetics, to the contrary, can be engineered to provide much lower values
and may even possess an effective permeability close to zero. In this letter, we provide an
experimental confirmation of the possibility to obtain extremely low permeability values by
manufacturing an isotropic metamaterial composed of conducting cubes. We show that the
practical assembly is quite sensitive to fabrication tolerances and demonstrate that permeability of
about 渭=0.15 is realisable.This work was supported by the Ministry
of Education and Science of Russian Federation (Project
11.G34.31.0020), Dynasty Foundation (Russia), grant of the
President of Russian Federation, and by the Australian
Research Council (CUDOS Centre of Excellence
CE110001018)