Propagation Theory of Nonlinear Optical Waveguides and Simulation of Optical Soliton Propagation

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The results of this research are as follows :1. Higher order effects such as third-order dispersion, shock effect, and soltion self-frequency shift on all-optical logic gates that use asymmetric nonlinear optical fiber couplers were investigated, and it was found that third-order dispersion seriously affects the operations of logic devices. In order to diminish the degradation, the bandwidth limited amplification was introduced. The logic functions can be improved by trapping only the soliton components in the finite gain-bandwidth.2. A three-dimensional beam propagation method was developed for the analysis of nonlinear optical fibers. All-optical logic gates with practical, three-dimensional geometry consisting of optical fibers and a nonlinear film were proposed, and their operations of Boolean arithmetric were demonstrated.3. A wide-angle finite element beam propagation method based on the Fade approximation was developed for both TB and TM waves propagating in nonlinear optical waveguides. In order to avoid nonphysical reflections from computational window edges, the transparent boundary condition and the perfectly matched layer were introduced, and to improve numerical accuracy, the finite element mesh and the reference refractive index were adaptively renewed at each propagation step.