Self-phase modulation and self-steepening in cubic and fifth-order dispersionless media with nonzero relaxation time.
Item
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Title
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Self-phase modulation and self-steepening in cubic and fifth-order dispersionless media with nonzero relaxation time.
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Identifier
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AAI9029964
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identifier
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9029964
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Creator
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Mustafa, Mustafa Aref.
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Contributor
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Adviser: Jamal T. Manassah
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Date
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1990
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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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Engineering, Electronics and Electrical
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Abstract
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The research presented here deals with some analytical solutions for self-phase modulation (SPM) and induced-phase modulation (IPM). In solving the electromagnetic wave equations, the method of multiple-scales is utilized. New sets of quasi-linear partial differential equations to describe the pulse shape and the phase associated with the propagation of an ultrashort intense pulse through a cubic nonlinear {dollar}\chi\sp{lcub}(3){rcub}{dollar} and a fifth-order nonlinear {dollar}\chi\sp{lcub}(5){rcub}{dollar}- media, are summarized. The treatment neglects group velocity dispersion and therefore is valid for thin medium.;The solution of the quasi-linear differential equations show that the pulse shape is skewed towards the trailing edge, and that this asymmetry can give rise to optical shock deformation unless balanced by dispersion. The intensity and medium thickness required for the pulse amplitude and phase to steepen are analysed. The pulse phase is shown to be asymmetric and its maximum is shifted from the maximum corresponding to the amplitude. The spectral distribution of the pulse is computed for different pulse intensities. We find that the anti-Stokes extent of the spectrum is larger that the Stokes side. With nonzero relaxation time, additional asymmetry and downshift towards the Stokes side of the spectrum appear.;We also show that the interference patterns produced by an SPM ultrafast pulse have their fringe positions shifted with respect to that of a plane wave due to the existence of the amplitude-phase maxima time shift. Further discussions center on the Fourier transform of the Young interferometric intensity distribution. We show that its range is determined by the same parameters as those of the spectral extents.;We then analyse the effect of an amplitude filter on the outgoing pulse shape (i.e., width, amplitude, and position of its maximum). Our research specifies the conditions under which the amplitude filter can be used to compress pulses.;The effects of strong pump signal on a weak second harmonic probe signal propagating simultaneously into a nonlinear medium (IPM) is examined. The superbroadening of the spectrum of a weak probe signal and the deformation of its pulse shape are investigated analytically. Finally a numerical method is used to determine the amplitude and phase of the pump signal and probe, when the probe signal is of comparable magnitude to that of the pump.
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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.
