852 research outputs found

### Near field and far field scattering of surface plasmon polaritons by one-dimensional surface defects

A rigorous formulation for the scattering of surface plasmon polaritons (SPP)
from a one-dimensional surface defect of any shape that yields the
electromagnetic field in the vacuum half-space above the vacuum-metal interface
is developed by the use of an impedance boundary condition. The electric and
magnetic near fields, the angular distribution of the far-field radiation into
vacuum due to SPP-photon coupling, and the SPP reflection and transmission
coefficients are calculated by numerically solving the k-space integral
equation upon which the formulation is based. In particular, we consider
Gaussian-shaped defects and study the dependence of the above mentioned
physical quantities on their 1/e half-width a and height h. SPP reflection is
significant for narrow defects; maximum reflection (plasmon mirrors) is
achieved for a~lambda/10. For increasing defect widths, protuberances and
indentations behave differently. The former give rise to a monotonic increase
of radiation at the expense of SPP transmission for increasing defect
half-width. Indentations exhibit a significant increase of radiation (decrease
of SPP transmission) for half-widths of the order of or smaller than the
wavelength, but tend to total SPP transmission in an oscillatory manner upon
further increasing the half-width. Light-emitters might thus be associated with
either wide indentations, or protuberances with widths that are of the order of
or smaller than the wavelength.Comment: REVTeX 3.1, 10 pages with 9 EPS figures (epsf macro

### Random Surfaces that Suppress Single Scattering

We present a method for generating numerically a one-dimensional random
surface, defined by the equation x_3 = \zx, that suppresses single-scattering
processes in the scattering of light from it within a specified range of
scattering angles. Rigorous numerical calculations of the scattering of light
from surfaces generated by this approach show that the single-scattering
contribution to the mean scattered intensity is indeed suppressed within that
range of angles.Comment: 3 pagers (Latex), 3 figure

### Beer's law in semiconductor quantum dots

The propagation of a coherent optical linear wave in an ensemble of
semiconductor quantum dots is considered. It is shown that a distribution of
transition dipole moments of the quantum dots changes significantly the
polarization and Beer's absorption length of the ensemble of quantum dots.
Explicit analytical expressions for these quantities are presented

### Replacement of ensemble averaging by the use of a broadband source in scattering of light from a one-dimensional randomly rough interface between two dielectric media

By the use of phase perturbation theory we show that if a single realization
of a one-dimensional randomly rough interface between two dielectric media is
illuminated at normal incidence from either medium by a broadband Gaussian
beam, it produces a scattered field whose differential reflection coefficient
closely matches the result produced by averaging the differential reflection
coefficient produced by a monochromatic incident beam over the ensemble of
realizations of the interface profile function.Comment: 10 pages, 7 figure

### The Scattering of Electromagnetic Waves from Two-Dimensional Randomly Rough Perfectly Conducting Surfaces: The Full Angular Intensity Distribution

By a computer simulation approach we study the scattering of $p$- or
$s$-polarized light from a two-dimensional, randomly rough, perfectly
conducting surface. The pair of coupled inhomogeneous integral equations for
two independent tangential components of the magnetic field on the surface are
converted into matrix equations by the method of moments, which are then solved
by the biconjugate gradient stabilized method. The solutions are used to
calculate the mean differential reflection coefficient for given angles of
incidence and specified polarizations of the incident and scattered fields. The
full angular distribution of the intensity of the scattered light is obtained
for strongly randomly rough surfaces by a rigorous computer simulation
approach.Comment: 15 pages (RevTeX

### The Angular Intensity Correlation Functions $C^{(1)}$ and $C^{(10)}$ for the Scattering of S-Polarized Light from a One-Dimensional Randomly Rough Dielectric Surface

We calculate the short-range contributions $C^{(1)}$ and $C^{(10)}$ to the
angular intensity correlation function for the scattering of s-polarized light
from a one-dimensional random interface between two dielectric media. The
calculations are carried out on the basis of a new approach that separates out
explicitly the contributions $C^{(1)}$ a nd $C^{(10)}$ to the angular intensity
correlation function. The contribution $C^{(1)}$ displays peaks associated with
the memory effect and the reciprocal memory effect. In the case of a
dielectric-dielectric interface, which does not support surface electromagnetic
surface waves, these peaks arise from the co herent interference of
multiply-scattered lateral waves supported by the in terface. The contribution
$C^{(10)}$ is a structureless function of its arguments.Comment: LaTeX, 14 pages including 5 figures. To appear SPIE publicatio

### Intrinsic Mean Square Displacements in Proteins

The thermal mean square displacement (MSD) of hydrogen in proteins and its
associated hydration water is measured by neutron scattering experiments and
used an indicator of protein function. The observed MSD as currently determined
depends on the energy resolution width of the neutron scattering instrument
employed. We propose a method for obtaining the intrinsic MSD of H in the
proteins, one that is independent of the instrument resolution width. The
intrinsic MSD is defined as the infinite time value of that appears in
the Debye-Waller factor. The method consists of fitting a model to the
resolution broadened elastic incoherent structure factor or to the resolution
dependent MSD. The model contains the intrinsic MSD, the instrument resolution
width and a rate constant characterizing the motions of H in the protein. The
method is illustrated by obtaining the intrinsic MSD of heparan sulphate
(HS-0.4), Ribonuclease A and Staphysloccal Nuclase (SNase) from data in the
literature

### The Design of Random Surfaces with Specified Scattering Properties: Surfaces that Suppress Leakage

We present a method for generating a one-dimensional random metal surface of
finite length L that suppresses leakage, i.e. the roughness-induced conversion
of a surface plasmon polariton propagating on it into volume electromagnetic
waves in the vacuum above the surface. Perturbative and numerical simulation
calculations carried out for surfaces generated in this way show that they
indeed suppress leakage.Comment: Revtex 6 pages (including 4 figures

### Nanogroove array on thin metallic film as planar lens with tunable focusing

Numerical results for the distributions of light transmitted through metallic
planar lenses composed of symmetric nanogroove arrays on the surfaces of a gold
film are presented and explained. Both the near- and far-field distributions of
the intensity of light transmitted are calculated by using a Green's function
formalism. Results for an optimal transverse focus based on a quadratic
variation of groove width are obtained. Meanwhile, a significant dependence of
the focal length on the wavelength of light incident from the air side through
the gold film into a dielectric substrate is found for this detector
configuration.Comment: 14 pages, 6 figure

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