183 research outputs found
Wave Propagation Retrieval Method For Metamaterials: Unambiguous Restoration Of Effective Parameters
In this article we propose a new direct method of effective parameters
restoration that is based on the wave propagation phenomenon. It retrieves the
effective properties unambiguously, is applicable to thick metamaterial (MTM)
slabs and is easy in implementation. It is validated on the case studies of
fishnet, split cube in carcass, Jerusalem cross and ultrahigh refractive index
MTMs. The constraints of the method are designated.Comment: 14 pages, 10 figures, submitted to Physical Review
Dark-field hyperlens: Super-resolution imaging of weakly scattering objects
We propose and numerically demonstrate a technique for subwavelength imaging
based on a metal-dielectric multilayer hyperlens designed in such a way that
only the large-wavevector waves are transmitted while all propagating waves
from the image area are blocked by the hyperlens. As a result, the image plane
only contains scattered light from subwavelength features of the objects and is
free from background illumination. Similar in spirit to conventional dark-field
microscopy, the proposed dark-field hyperlens is promising for optical imaging
of weakly scattering subwavelength objects, such as optical nanoscopy of
label-free biological objects.Comment: 6 figure
From surface to volume plasmons in hyperbolic metamaterials: General existence conditions for bulk high-k waves in metal-dielectric and graphene-dielectric multilayers
We theoretically investigate general existence conditions for broadband bulk
large-wavevector (high-k) propagating waves (such as volume plasmon polaritons
in hyperbolic metamaterials) in subwavelength periodic multilayer structures.
Describing the elementary excitation in the unit cell of the structure by a
generalized resonance pole of a reflection coefficient, and using Bloch's
theorem, we derive analytical expressions for the band of large-wavevector
propagating solutions. We apply our formalism to determine the high-k band
existence in two important cases: the well-known metal-dielectric, and recently
introduced graphene-dielectric stacks. We confirm that short-range surface
plasmons in thin metal layers can give rise to hyperbolic metamaterial
properties, and demonstrate that long-range surface plasmons cannot. We also
show that graphene-dielectric multilayers tend to support high-k waves and
explore the range of parameters for which this is possible, confirming the
prospects of using graphene for materials with hyperbolic dispersion. The
approach is applicable to a large variety of structures, such as continuous or
structured microwave, terahertz (THz) and optical metamaterials.Comment: 9 pages, 5 figure
Epsilon-Near-Zero Grids for On-chip Quantum Networks
Realization of an on-chip quantum network is a major goal in the field of
integrated quantum photonics. A typical network scalable on-chip demands
optical integration of single photon sources, optical circuitry and detectors
for routing and processing of quantum information. Current solutions either
notoriously experience considerable decoherence or suffer from extended
footprint dimensions limiting their on-chip scaling. Here we propose and
numerically demonstrate a robust on-chip quantum network based on an
epsilon-near-zero (ENZ) material, whose dielectric function has the real part
close to zero. We show that ENZ materials strongly protect quantum information
against decoherence and losses during its propagation in the dense network. As
an example, we model a feasible implementation of an ENZ network and
demonstrate that quantum information can be reliably sent across a titanium
nitride grid with a coherence length of 434 nm, operating at room temperature,
which is more than 40 times larger than state-of-the-art plasmonic analogs. Our
results facilitate practical realization of large multi-node quantum photonic
networks and circuits on-a-chip.Comment: 13 pages, 5 figure
Refraction enhancement in plasmonics by the coherent control of plasmon resonances
A plasmonic nanoantenna probed by a plane-polarized optical field in a medium
with no gain materials can show zero absorption or even amplification, while
exhibiting maximal polarizability. This occurs through coupling to an adjacent
nanoantenna in a specially designed metamolecule, which is pumped by an
orthogonal optical field with phase shift. The introduced scheme is a classical
counterpart of an effect known in quantum optics as enhancement of the index of
refraction (EIR). In contrary to electromagnetically induced transparency
(EIT), where the medium is rendered highly dispersive at the point of zero
susceptibility and minimum absorption, in the EIR the system exhibits large
susceptibility and low dispersion at the point of zero or negative absorption.
The plasmonic analogue of the EIR allows for coherent control over the
polarizability and absorption of plasmonic nanoantennas, offering a novel
approach to all optical switching and coherent control of transmission,
diffraction and polarization conversion properties of plasmonic nanostructures,
as well as propagation properties of surface plasmon polaritons on
metasurfaces. It may also open up the way for lossless or amplifying
propagation of optical waves in zero-index to high refractive index plasmonic
metamaterial
Homogenization of metasurfaces formed by random resonant particles in periodical lattices
In this paper we suggest a simple analytical method for description of
electromagnetic properties of a geometrically regular two-dimensional
subwavelength arrays (metasurfaces) formed by particles with randomly
fluctuating polarizabilities. Such metasurfaces are of topical importance due
to development of mass-scale bottom-up fabrication methods, for which
fluctuations of the particles sizes, shapes, and/or composition are inevitable.
Understanding and prediction of electromagnetic properties of such random
metasurfaces is a challenge. We propose an analytical homogenization method
applicable for normal wave incidence on particles arrays with dominating
electric dipole responses and validate it with numerical point-dipole modeling
using the supercell approach. We demonstrate that fluctuations of particles
polarizabilities lead to increased diffuse scattering despite the subwavelength
lattice constant of the array. The proposed method can be readily extended to
oblique incidence and particles with both electric and magnetic dipole
resonances.Comment: 10 pages, 5 figure
Bismuth ferrite as low-loss switchable material for plasmonic waveguide modulator
We propose new designs of plasmonic modulators, which can be utilized for
dynamic signal switching in photonic integrated circuits. We study performance
of plasmonic waveguide modulator with bismuth ferrite as an active material.
The bismuth ferrite core is sandwiched between metal plates
(metal-insulator-metal configuration), which also serve as electrodes so that
the core changes its refractive index under applied voltage by means of partial
in-plane to out-of-plane reorientation of ferroelectric domains in bismuth
ferrite. This domain switch results in changing of propagation constant and
absorption coefficient, and thus either phase or amplitude control can be
implemented. Efficient modulation performance is achieved because of high field
confinement between the metal layers, as well as the existence of mode cut-offs
for particular values of the core thickness, making it possible to control the
signal with superior modulation depth. For the phase control scheme, {\pi}
phase shift is provided by 0.8-{\mu}m length device having propagation losses
0.29 dB/{\mu}m. For the amplitude control, we predict up to 38 dB/{\mu}m
extinction ratio with 1.2 dB/{\mu}m propagation loss. In contrast to previously
proposed active materials, bismuth ferrite has nearly zero material losses, so
bismuth ferrite based modulators do not bring about additional decay of the
propagating signal
Pseudocanalization regime for magnetic dark-field hyperlens
Hyperbolic metamaterials (HMMs) are the cornerstone of the hyperlens, which
brings the superresolution effect from the near-field to the far-field zone.
For effective application of the hyperlens it should operate in so-called
canalization regime, when the phase advancement of the propagating fields is
maximally supressed, and thus field broadening is minimized. For conventional
hyperlenses it is relatively straightforward to achieve canalization by tuning
the anisotropic permittivity tensor. However, for a dark-field hyperlens
designed to image weak scatterers by filtering out background radiation
(dark-field regime) this approach is not viable, because design requirements
for such filtering and elimination of phase advancement i.e. canalization, are
mutually exclusive. Here we propose the use of magnetic (-positive and
negative) HMMs to achieve phase cancellation at the output equivalent to the
performance of a HMM in the canalized regime. The proposed structure offers
additional flexibility over simple HMMs in tuning light propagation. We show
that in this ``pseudocanalizing'' configuration quality of an image is
comparable to a conventional hyperlens, while the desired filtering of the
incident illumination associated with the dark-field hyperlens is preserved
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