Statistics of electromagnetic propagation and localization.
Item
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Title
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Statistics of electromagnetic propagation and localization.
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Identifier
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AAI3037391
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identifier
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3037391
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Creator
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Chabanov, Andrey Anatolievich.
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Contributor
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Adviser: Azriel Genack
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Date
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2002
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Condensed Matter | Physics, Optics
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Abstract
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A statistical description of wave propagation in random media is necessary to characterize large fluctuations found in these samples. The nature of fluctuations is determined by the closeness to the localization transition. In the absence of inelastic processes, this can be specified, in many circumstances, by a single parameter---the ensemble average of the dimensionless conductance. As a result, the extent of localization can be determined by any of a wide variety of related statistical measurements. Among the quantities that most directly reflect key aspects of localization are the following: (i) the ensemble average of the dimensionless conductance, (ii) the variances of the probability distribution of transmission quantities, such as the intensity, the total transmission, and the dimensionless conductance, and (iii) the ratio of the width to the spacing of modes of an open sample. We show that these quantities are equivalent measures of localization in the absence of absorption.;We find that even in the presence of absorption, the extent of localization can be characterized by a single parameter---the variance of the total transmission normalized by its ensemble average. Measurements of fluctuations in intensity and total transmission of microwave radiation allow us to study photon localization in both weakly and strongly scattering quasi-1D dielectric samples and in periodic metallic wire meshes containing metallic scatterers, while ruling it out in three-dimensional samples of aluminum spheres. We find in low-density collections of alumina spheres contained in a copper tube, at frequencies above the first Mie resonance, the variance of normalized total transmission scales exponentially, once it becomes greater than unity. When this parameter is large, transmission spectra are observed to be a series of Lorentzian lines, with widths that are smaller than the separation between peaks, associated with tunneling through localized states. These spectra have an extraordinarily wide intensity distribution. In addition, the joint resonant behavior of the wave intensity and phase leads to a new type of correlation between the intensity and delay time, which is associated with a profound change in the statistics of dynamics of localized waves as compared to those of extended waves.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
