THz wave emission in the cavity which contains the graphene-multilayer asymmetric hyperbolic metamaterials is investigated numerically using transfer matrix method. In was assumed that the gain saturation appears as the decrease of imaginary part of effective dielectric permittivity. Gain –loss balance predicts the intensity of THz lasing.
The investigation of hyperbolic metamaterials, shows that metal layers that are part of graphene structures, and also types I and II layered systems, are readily controlled. Since graphene is a nicely conducting sheet it can be easily managed. The literature only reveals a, limited, systematic, approach to the onset of nonlinearity, especially for the methodology based around the famous nonlinear Schrödinger equation [NLSE]. This presentation reveals nonlinear outcomes involving solitons sustained by the popular, and more straightforward to fabricate, type II hyperbolic metamaterials. The NLSE for type II metatamaterials is developed and nonlinear, non-stationary diffraction and dispersion in such important, and active, planar hyperbolic metamaterials is developed. For rogue waves in metamaterials only a few recent numerical studies exist. The basic model assumes a uniform background to which is added a time-evolving perturbation in order to witness the growth of nonlinear waves out of nowhere. This is discussed here using a new NLSE appropriate to hyperbolic metamaterials that would normally produce temporal solitons. The main conclusion is that new pathways for rogue waves can emerge in the form of Peregrine solitons (and near-Peregrines) within a nonlinear hyperbolic metamaterial, based upon double negative guidelines, and where, potentially, magnetooptic control could be practically exerted.
Electromagnetic waves propagation in the complex cavity with anisotropic hyperbolic metamaterial are investigated using direct calculation of modal field and dispersion equation. The transfer matrix method was adopted for arbitrary orientation of optical axis according to slab boundary. Increasing of the density of states in the cavity have show.
Electromagnetic radiation in the complex cavity with anisotropic hyperbolic metamaterial are investigated using direct calculation of modal field and dispersion equation. Anisotropy of the hyperbolic media slab was taken into account. The 4x4 Berreman matrix method was adopted for arbitrary orientation of optical axis according to slab boundary.
The dispersion characteristics characteristic of the hyperbolic metamaterial consists of graphene and semiconductor layers titled according to outer boundary are presented. The graphene – SiC structure seems promising due to realistic technology condition for its manufacturing. Possibility of control of the light propagating through such structure will be discussed.
Metamaterials, made in form of periodically arranged metal and dielectric cylindrical inclusions, have been investigated
on the basis of the integral equation method, based on periodic Green's function. Metal rods are described in terms of
complex permittivity [see manuscript]. Along the rods terahertz and infrared waves propagate substantially with the speed of
light c and small losses weakly depending on the transverse wave number, whereas in the optical range, in particular in
the shortwave part of a spectrum, they turn into the slow -waves of a dielectric waveguide.
We are carefully analyzing the properties of the eigenwaves of 2D-structure with regularly ordered metal nanorods in
lossless dielectric. Plane-wave-decomposition was used in numerical calculations. New “hyperbolic” solutions were
A concept of a family of unique backward-wave photonic devices, such as frequency up and down converting nonlinear-optical mirrors, sensors, modulators, filters and amplifiers is proposed. Novel materials are considered, which support coexistence of ordinary and backward waves and thus enable enhanced nonlinear-optical frequency conversion processes. Particular properties of short-pulse regime are investigated.
Model of terahertz radiation sources was developed in this work. This model based on the nanopeapod: carbon nanotube
(10, 10) with incapsulated chains of the fullerene C60. Simulation of the nanoemitter action was carried out by means of
the molecular-mechanical model. The length of the considered nanotube is equals to 10.3 nm, and radius of this tube is
equals to 1.35 nm. It was found that to generate the radiation in terahertz range it is necessary to apply the external field
with strength of 1⋅106 V / cm to our system. The moving fullerene C60 has a charge of +3е, and the nanotube has a charge
of -3е. It was established that the field emission process from the surface of the nanotube is not observed in this case.
The submitter model of nanoemitter works with a frequency 0.36 THz at a field strength of 1⋅106 V / cm.
The properties of new optical waveguides with nanosize cross-section made of noble metals and glasses are described.
As was found, this waveguide supports propagation of modes with unusual propagation properties. For estimation of the
field localization, losses, propagation length, velocity and others characteristics the numerical simulations by FEM
method has been used. The set of advanced structures are studied: a conventional coaxial; a coaxial waveguide with
periodically arrange metal tubes for reducing the metal part in the structure; the coaxial waveguides with elliptic-type
central rod and two cross ellipses. The effects of the asymmetry of the central part those structures have been estimated.
The comparison of the results of this investigation by wavelength deviation has been performed. A combination of noble
metal plus active glasses has been estimated towards minimization of losses. The power flow distribution for different
types of modes is investigated. The best characteristics can be achieved for the dipole-like modes which can be excited
by an external dipole.
In this paper we propose new optical waveguides, made of glasses and noble metals. Such waveguides are like coaxial
cables where inner metal rods are replaced by thin metal annuluses filled with a glass inside. Numerical simulations
demonstrate that the proposed waveguide, having nanosize cross-section, supports propagation of modes, which phase
velocity is close to the speed of light and which field is localized outside the metal. These modes are dipole-like modes
and are characterized by comparatively low losses.
The technique of nanoparticles dynamics studies based on selective plane illumination microscopy and statistical particle
tracking velocimetry has been developed. It allows for the visualization of water suspended gold nanoparticles dynamics.
Distribution of particles temperature and velocity of their ordered motion could be obtained with spatial resolution of
several micrometers. The proposed technique could be used for the studies of photothermal and photophorethic effects
induced by laser irradiation in colloidal systems.
Novel approach to cloaking, which allows to realize directly the idea of wave guiding and to eliminate the reflection
from the cloaked structure, is proposed. Cloaking structure is composed of metal wires guiding TEM modes
around the object. In high conductive metal wires at microwave frequencies, the TEM modes are dispersionless
and the energy propagates along the wires. A plane wave incident onto a wire medium (WM) under any angle,
excites both TEM and TM modes, which have similar polarizations. The TEM modes provide full transmission
through the cloaking structure if the total length of wires equals a number of half-wavelengths. The TM mode
attenuates in WM at frequencies below the plasma frequency of WM and does not contribute to reflection if the
WM is dense enough. The angle between WM and the propagation direction of the incoming wave is chosen
so that the difference in paths of waves in WM and free space outside the cloak is a multiple of wavelengths in
order to eliminate distortion of the phase front. In the infrared range quasi-TEM modes, supporting propagation
of plasmons, play role of TEM modes. Parameters of WM are chosen so that the quasi-TEM modes have
low dispersion and their phase velocity is slightly less than the speed of light. Results of HFSS simulations
demonstrate considerable cloaking effect.
In recent years a lot of attention has been paid to metal nanoscale structures because of new phenomena and
potential applications in waveguide and antenna techniques. Especially in the optical region new effects arise
based on plasmon resonances. It is known that in the optical region some noble metals behave like free-electron
plasma with low losses. In this study field propagation in nanoporous metal structures is considered. We consider
propagation in regular arrays of pores in metal in the presence of an interface. Although the field is decaying
outside the pores, these inclusions are so close to each other that there is interaction with the neighboring pores.
In addition the metal-insulator interface causes coupling. Near the plasmonic resonance these interactions are
strong enough, and there exist guided wave modes along the array. Properties of these modes are investigated.
The allowed frequency range where the guided modes exist depends on the geometry, i.e., on the size of the pores
and on the distance between them. In such structures there exist three propagating modes, two transversely and
one longitudinally polarized. The transversely polarized fields propagate as forward waves and the longitudinally
polarized fields form a backward wave. When the chain of pores is far from the interface, the two transversely
polarized modes become decoupled and have the same dispersion due to degeneracy.
The original microscopic system has been developed for the investigation of nanoparticles moving in the electromagnetic field of laser beam. In our scheme nanoparticles could be observed in the direction perpendicular to the incident laser beam in the dark-field mode. In this work a flow of nanoparticles, induced by light pressure forces in laser beam is investigated using the particle image velocimetry technique. Laser manipulation of nanoparticles with wide laser beam was experimentally demonstrated.
Electromagnetic wave diffraction on a cylindrical dielectric grating is considered. The problem is reduced to integral equation. Logarithm singularity of the integral equation kernel is extracted in explicit form that allows to solve integral equation changing integral by the high-precision quadrature formulae. Such analytical transformations result in high convergence of the algorithm. Angular and spectral dependencies of E-polarized wave through the dielectric grating are analyzed for different kinds of polygonal cross-section.
The gain in one-dimensional photonic band gap structure, containing active layers, is studied. Nonlinearity of the material, caused by Kerr effect, is taken into account. Nonlinear problem of wave transmission through nonlinear multilayered structure is solved using perturbation method. It is shown, that the gain in photonic band gap structure can be essentially enhanced at the photonic band gap edge in comparison with a bulk material having the same optical thickness.
The inclusion of radiation polarization considerably extends the sensitivity and the potentials of optical coherence tomography. The recorded signals are however skewed by using wide-band light sources and polarization sensitive elements, as well as by frequency dispersion of the objects under study. It is essential for such layered system with spatial anisotropy as eye cornea and sclera.
Some peculiarities of the electromagnetic waves propagation in photonic band gap structures are considered. The wave phenomena at the edge of band gaps of 1D structures stimulating the nonlinear processes are described. Some examples of unusual optics laws in 2D structures are given.
Cornea anisotropic properties have been investigated experimentally by Mueller matrix technique. The system of the plane anisotropic layers has been used as an optical model of the cornea. In this model we consider every layer to be a closely packed system of long cylinders. Jones's transmission matrices of the above mentioned multilayer anisotropic system were calculated using transfer matrix 4 X 4 method. The multilayer systems with different ordering of layer's optical axis were analyzed. We have obtained spectral dependencies of limit values of linear and circular dichroism and birefringence from cornea fiber orientation. Mueller matrices of rabbit cornea were measured experimentally. Then we turn from the experimental Mueller matrix to Jones matrix to reveal clearly the cornea anisotropy. This transition is correct for the depolarization-free objects. Analyzing the cornea experimental Muller matrices by the depolarization criterion method we conclude that cornea has a negligible depolarization. Theoretical and experimental results appear to be in good agreement.