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We propose to synthesize a parametric metasurface whose transmission properties are modified by illuminating a control electromagnetic wave on the structure, in the same way the channel conductance of a transistor is controlled by a gate signal. We present a general solution of the problem that yields analytical expressions for the synthesized metasurface susceptibilities. It turns out that such a...
The excellent photoluminescent properties of graphene quantum dots (GQDs) makes them suitable candidates for biomedical applications, but their corrosion resistance has not been extensively studied. Here we report a detailed and systematic study of the luminescence and electrochemical behavior of GQDs. In the measured photoluminescence (PL) spectra, the emission peak is shown to be at ����455 nm....
We report on the role of the coupling of the modes of Mie resonances in an all-dielectric metamaterial so as to achieve negative index at terahertz frequencies. We studied this role according to the lattice spacing and according to the frequency overlapping of the modes of resonance. We show that negative effective index requires sufficiently high mode coupling.
Loading an electrically small antenna (ESA) with non-Foster active matching networks (MN) is an interesting way to obtain broad impedance bandwidth. Locating one of these active networks in the antenna structure itself can be advantageous especially when the application requires a compact design. The introduction of the so called sensitivity (Sens) parameter allows finding a suitable placement for...
We propose a novel mechanism for designing quantum hyperbolic metamaterials with use of semiconductor Bragg mirrors containing periodically arranged quantum wells. The hyperbolic dispersion of exciton-polariton modes is realized near the top of the first allowed photonic miniband in such structure. We predict formation of low amplitude spatially localized oscillatory structures: oscillons described...
Here we study the effect of realistic metal properties on the emergence of magnetic localized surface plasmons. These are subwavelength magnetic dipole modes supported by metallic particles that are corrugated with very long, curved grooves. By means of numerical simulations, we show that, despite the presence of losses in the metal, the concept of magnetic localized surface plasmons is general and...
We report on the influence of the layer eccentricity on the resonant properties of active coated nano-particles made of a silver core and gain impregnated silica shell illuminated by a near-by magnetic line source. For a fixed over-all size of the particle, designs with small and large cores are analyzed in terms of their far- and near-fields, as well as power flow properties. They demonstrate that...
Bianisotropic media besides permittivity and permeability possess additional material parameters describing bianisotropic coupling. Here we consider the scenario when bian-isotropic parameters are non-zero, while the permittivity and permeability tend to zero. Only a special case of reciprocal bianisotropic nihility was studied in the literature. In this work we generalize the concept of bianisotropic...
In this contribution, we present the design of a power-selectivity horn filtenna based on the use of a nonlinear Split Ring Resonator (SRR). In particular, in order to obtain a nonlinear behavior of the SRR, we load its external gap with a pair of Schottky diodes, which require a not negligible power level to be activated. Inserting the resulting nonlinear resonator inside the throat of a horn antenna,...
Measurements of the negative optical phase shifts of Ag/TiO2 and Ag/SiO2 bilayer films have been carried out with the modified walk-off interferometer. Appearance and monotonic rise of the phase shift anisotropy for p- and s-polarization by increasing incidence angle has been revealed experimentally. The results of measurements have shown rather good coincidence with theoretical calculations.
The construction is proposed of the hyperbolic metamaterial for an optical spectral range with the expanded working range of wavelength due to periodic system of nanorods in a definite range of diameters and heights. The construction is fulfilled on aluminum-oxide ceramics with the periodic system of nanoholes with the diameters from 30 up to 50 nm filled with particles of noble metal, which forms...
Transparent conducting oxides have received significant attention in recent years for their tunability. Here, we study the tunability in the static optical properties of TCO films and nanostructures, as well as their dynamic properties under optical pumping. Combined with their low-temperature and CMOS-compatible processing techniques, TCOs are shown to be key materials for future dynamic nanophotonic...
We present our recent advances in nanoscale lasing action enabled by plasmonic resonances. First, we study lasing action in plasmonic crystals incorporating optically pumped four-level gain media. We show that the excitation of dark plasmonic resonances (via the gain medium) enables accessing the optimal lasing characteristics of this class of systems. Second, we analyze the conditions for the emergence...
The Thomson Reuters Web of Science™ lists more than 1500 journal articles related to metamaterial antennas from 2001 to 2015; this paper overviews some major objectives of such antennas.
A new approach to design a metamaterial surface (meta-surface) with the objective of reducing the waveguide's cutoff frequency of the fundamental mode is proposed. From an analytical study of the dispersion diagrams of waveguides with anisotropic walls, a hypothesis for the surface impedances is set up. By means of this new hypothesis, the design of a unit-cell is optimized. Finally, the periodically...
This paper presents simulation results of two different subwavelength metamaterial-based antireflection coatings operating at millimeter waves. The first design minimizes the reflection from a slab of acrylic and the second design minimizes the reflection from a slab of human tissue comprising skin-blood-skin layers. These designs achieve a relative reduction in the reflected power by 99.5% (23 dB)...
Discontinuities in the geometry of a beam pipe can represent serious issues for the stability of the beam in a particle accelerator. Many devices installed along the machine introduce parasitic cavities which are undesired and give rise to wake fields and resonances, which on turn contribute in destabilizing the beam. These resonances are often damped using dispersive or resistive materials placed...
When a particle beam travels through an accelerator structure like the LHC, energy is lost to the structure itself. This phenomenon is described through the beam-coupling impedance and is ideally reduced to improve beam quality and energy efficiency. In this paper, the use of metamaterials with negative permeability is investigated as a method of reducing impedance. A fast and cost-effective way of...
We study the hybridization of two graphene based one dimensional edge surface plasmon polaritons (1DSPP). We discuss normal and anomalous coupling between 1DSPP and we exploit the sensitivity of these devices to the carrier concentration on graphene sheets to propose metamaterials dynamically tunable by means of an electrical gate.
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