Propagation of ionizing short laser pulses in a nonlinear optical medium

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2021-2-15

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Deveci, Atalay

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Using a pseudo-spectral method that is split step Fourier method, obtaining a solutionfor propagation of ionizing short Gaussian pulse would be computationally inexpen-sive and practical. For a solution obtained by using split step Fourier method, themost important parameter to choose is step size. However, using either large or smallstep size may yield different numerical errors in the final result. For a large step size,general evolution of the Gaussian pulse could be predicted well but small changesmight be neglected. for a small step size, small changes could be indicated well butthere would be a prone to error in general pulse evolution. Furthermore, using ageneric method of undetermined coefficients that could be utilized for every differ-ential equation would yield a high accuracy solution in order to check the validity ofsplit-step Fourier method.The aim of this study is to examine the evolution of the ionizing short Gaussian pulselasers in a non-linear medium in both low intensity propagation regime and high in-tensity propagation regime via various methods to solve the propagation equationi.esplit-step Fourier method and method of undetermined coefficients. Similarity of twosolutions arising from split-step Fourier method and method of undetermined coefficients would evolve in a similar trend. Comparison of solutions for both gatheredfrom split-step Fourier method and method of undetermined coefficients with the pre-vious solutions from the literature in the low intensity propagation regime are behavesimilar except some pulse parameters. Difference between in the parameters of theGaussian pulse in low intensity propagation regime and high intensity propagationregime has been shown.Results would be given in terms of the pulse parametersi.espot size, pulse length,intensity, power, electron number density, field amplitude and energy. These resultswould be used for whether split-step Fourier method and method of undeterminedcoefficients match the expectancy. Evolution that could be derived by these two dif-ferent methods fulfill the expectancy, that is expected power loss, expected energyloss and shorter focus length.

Subject Keywords

Gaussian pulse evolution, Nonlinear optics, Physics of plasmas, Ionization by Gaussian pulses in air

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https://hdl.handle.net/11511/89901

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

A. Deveci, “Propagation of ionizing short laser pulses in a nonlinear optical medium,” M.S. - Master of Science, Middle East Technical University, 2021.