Jisha, C P; Dr.Kuriakose, V C(Cochin University of Science & Technology, March , 2008)
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Abstract:
This thesis deals with the study of light beam propagation through different
nonlinear media. Analytical and numerical methods are used to
show the formation of solitonS in these media. Basic experiments have
also been performed to show the formation of a self-written waveguide in a
photopolymer. The variational method is used for the analytical analysis
throughout the thesis. Numerical method based on the finite-difference forms of the original partial differential equation is used for the numerical
analysis.In Chapter 2, we have studied two kinds of solitons, the (2 + 1) D
spatial solitons and the (3 + l)D spatio-temporal solitons in a cubic-quintic
medium in the presence of multiphoton ionization.In Chapter 3, we have studied the evolution of light beam through a
different kind of nonlinear media, the photorcfractive polymer. We study
modulational instability and beam propagation through a photorefractive
polymer in the presence of absorption losses. The one dimensional beam
propagation through the nonlinear medium is studied using variational and
numerical methods. Stable soliton propagation is observed both analytically
and numerically.Chapter 4 deals with the study of modulational instability in a photorefractive
crystal in the presence of wave mixing effects. Modulational
instability in a photorefractive medium is studied in the presence of two
wave mixing. We then propose and derive a model for forward four wave
mixing in the photorefractive medium and investigate the modulational
instability induced by four wave mixing effects. By using the standard
linear stability analysis the instability gain is obtained.Chapter 5 deals with the study of self-written waveguides. Besides
the usual analytical analysis, basic experiments were done showing the
formation of self-written waveguide in a photopolymer system.
The formation of a directional coupler in a photopolymer system is
studied theoretically in Chapter 6. We propose and study, using the
variational approximation as well as numerical simulation, the evolution
of a probe beam through a directional coupler formed in a photopolymer system.
Description:
Department of Physics,
Cochin University of Science and Technology