260 research outputs found
Propagation of Surface Plasmons in Ordered and Disordered Chains of Metal Nanospheres
We report a numerical investigation of surface plasmon (SP) propagation in
ordered and disordered linear chains of metal nanospheres. In our simulations,
SPs are excited at one end of a chain by a near-field tip. We then find
numerically the SP amplitude as a function of propagation distance. Two types
of SPs are discovered. The first SP, which we call the ordinary or quasistatic,
is mediated by short-range, near-field electromagnetic interaction in the
chain. This excitation is strongly affected by Ohmic losses in the metal and by
disorder in the chain. These two effects result in spatial decay of the
quasistatic SP by means of absorptive and radiative losses, respectively. The
second SP is mediated by longer range, far-field interaction of nanospheres. We
refer to this SP as the extraordinary or non-quasistatic. The non-quasistatic
SP can not be effectively excited by a near-field probe due to the small
integral weight of the associated spectral line. Because of that, at small
propagation distances, this SP is dominated by the quasistatic SP. However, the
non-quasistatic SP is affected by Ohmic and radiative losses to a much smaller
extent than the quasistatic one. Because of that, the non-quasistatic SP
becomes dominant sufficiently far from the exciting tip and can propagate with
little further losses of energy to remarkable distances. The unique physical
properties of the non-quasistatic SP can be utilized in all-optical integrated
photonic systems
Circuit elements at optical frequencies: nano-inductors, nano-capacitors and nano-resistors
We present some ideas for synthesizing nanocircuit elements in the optical
domain using plasmonic and non-plasmonic nanoparticles. Three basic circuit
elements, i.e., nano-inductors, nano-capacitors, and nano-resistors, are
discussed in terms of small nanostructures with different material properties.
Coupled nanocircuits and parallel and series combinations are also envisioned,
which may provide road maps for the synthesis of more complex nanocircuits in
the IR and visible bands. Ideas for the optical implementation of right-handed
and left-handed nano-transmission lines are also forecasted.Comment: 14 pages, 5 figures, submitted to Physical Review Letter
Orthoclinostatic test as one of the methods for evaluating the human functional state
The possible use of different methods to evaluate the autonomic regulation in hygienic studies were examined. The simplest and most objective tests were selected. It is shown that the use of the optimized standards not only makes it possible to detect earlier unfavorables shifts, but also permits a quantitative characterization of the degree of impairment in the state of the organism. Precise interpretation of the observed shifts is possible. Results indicate that the standards can serve as one of the criteria for evaluating the state and can be widely used in hygienic practice
Technology of ultrasonic control of gas-shielded welding process
A new approach to implementation of electrode metal transfer control under MAG, MIG welding is suggested. The process ensures control of thermal and crystallization processes, stabilizes the time of electrode metal drop formation. The results of the research allow formulating the basic criteria of electrode metal transfer control via ultrasonic exposure, determining the conditions of producing a more equilibrium structure of deposit metal
Dynamical Theory of Artificial Optical Magnetism Produced by Rings of Plasmonic Nanoparticles
We present a detailed analytical theory for the plasmonic nanoring
configuration first proposed in [A. Alu, A. Salandrino, N. Engheta, Opt. Expr.
14, 1557 (2006)], which is shown to provide negative magnetic permeability and
negative index of refraction at infrared and optical frequencies. We show
analytically how the nanoring configuration may provide superior performance
when compared to some other solutions for optical negative index materials,
offering a more 'pure' magnetic response at these high frequencies, which is
necessary for lowering the effects of radiation losses and absorption.
Sensitivity to losses and the bandwidth of operation of this magnetic inclusion
are also investigated in details and compared with other available setups.Comment: 34 pages, 3 figure
Transport and optical response of molecular junctions driven by surface plasmon-polaritons
We consider a biased molecular junction subjected to external time-dependent
electromagnetic field. The field for two typical junction geometries (bowtie
antennas and metal nanospheres) is calculated within finite-difference
time-domain technique. Time-dependent transport and optical response of the
junctions is calculated within non-equilibrium Green's function approach
expressed in a form convenient for description of multi-level systems. We
present numerical results for a two-level (HOMO-LUMO) model, and discuss
influence of localized surface plasmon polariton modes on transport.Comment: 9 pages, 6 figure
Magnetoresistance of Three-Constituent Composites: Percolation Near a Critical Line
Scaling theory, duality symmetry, and numerical simulations of a random
network model are used to study the magnetoresistance of a
metal/insulator/perfect conductor composite with a disordered columnar
microstructure. The phase diagram is found to have a critical line which
separates regions of saturating and non-saturating magnetoresistance. The
percolation problem which describes this line is a generalization of
anisotropic percolation. We locate the percolation threshold and determine the
t = s = 1.30 +- 0.02, nu = 4/3 +- 0.02, which are the same as in
two-constituent 2D isotropic percolation. We also determine the exponents which
characterize the critical dependence on magnetic field, and confirm numerically
that nu is independent of anisotropy. We propose and test a complete scaling
description of the magnetoresistance in the vicinity of the critical line.Comment: Substantially revised version; description of behavior in finite
magnetic fields added. 7 pages, 7 figures, submitted to PR
Vanishing Loss Effect on the Effective ac Conductivity behavior for 2D Composite Metal-Dielectric Films At The Percolation Threshold
We study the imaginary part of the effective conductivity as well as its
distribution probability for vanishing losses in 2D composites. This
investigation showed that the effective medium theory provides only
informations about the average conductivity, while its fluctuations which
correspond to the field energy in this limit are neglected by this theory.Comment: 6 pages, 2 figures, submitted to Phys.Rev.
INFORMATION SYSTEMS IN EDUCATIONAL PROCESS OF DEPARTMENT OF THE EXPERIMENTAL PHYSICS
Рассмотрено аппаратное и программное обеспечение, применяемое в образовательном процессе по информационным технологиям на кафедре экспериментальной физикиThe hardware and software systems used in educational process on information technologies on department of the experimental physics are described in the pape
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