852 research outputs found

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

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    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

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    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

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    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

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    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

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    By a computer simulation approach we study the scattering of pp- or ss-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)C^{(1)} and C(10)C^{(10)} for the Scattering of S-Polarized Light from a One-Dimensional Randomly Rough Dielectric Surface

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    We calculate the short-range contributions C(1)C^{(1)} and C(10)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)C^{(1)} a nd C(10)C^{(10)} to the angular intensity correlation function. The contribution C(1)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)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

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    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

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    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

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    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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