Theoretical Investigation Of Control Of Optical Pulse In Inhomogenous Optical Transmission Systems

By using the combination of analytical (the similarity reduced method) and numerical(dicrete-step fast Fourier transform algorithm) methods, the influence of spatial diffraction,spatiotemporal coupling, higher-order dispersion and nonlinearity to amplitude, phase,chirp and width of self-similar pulse or beam is annalytically and numerically investigatedbased on the variable-coefficient of nonlinear Schr dinger equation in an inhomogenuousoptical fiber. The control behaviours of rogue wave including annihilation, sustainmen,postponement, recurrence and quick excitation are studied. The generation and interactionof self-similar multi-soliton and rogue wave are discussed emphatically, and the feasibilityfor avoidance and application of rogue wave is presented. These results provide theoreticalfoundation for parameter modulation and dynamical control of optical pulse in theinhomogenous optical fiber, and have potential applications for the solitary waves ofmatter and plasma in the dynamics of various physical systems. The main contents are asfollows.1. Dynamical control of1+1dimensional temperal and spatial self-similar solitons.By means of the similarity reduced method, the propagation and control of1+1dimensional temperal and spatial self-similar solitons with exact balance of dispersion ordiffraction and nonlinearity are investigated. The modulation and control for the velocity,amplitude, phase, central position of bright, dark and flat-top self-similar pulses are firstlyrealized by choosing different dispersion or diffraction and nonlinearity functions. Theseresults may provide feasible schemes and design of optical fibers and theoretical basis in the application of similaritons and solitons in extra-huge volume optical communications.2. Dynamical control of2+1dimensional spatial self-similar solitons andmodulated spatial beam.Starting from2+1dimensional variable-coefficient nonlinear Schr dinger equaiton,the dynamical control of self-similar multi-solitons with and without continuous wavebackground and modulated spatial beams in the cubic-quintic nonlinear medium is firstlyinvestigated. The parameter control and dynamical behaviour of self-similar and ordinarysoliton are compared. The influence of self-similar solitons in continuous wavebackground is studied. With the help of numerical method, we analyze the stability of thesesolitons with the white noise. These results are useful to experimental observation.3. Parameter control and dynamical behaviour of3+1dimensional self-similar multi-solitons.The expressions of3+1dimensional self-similar multi-solitons in the inhomogenousdispersion, diffraction, nonlinearity and gain or loss medium are analytically derived. Theexistence condition of bright and dark similaritons and solitons are obtained. The controlbehaviours of3+1dimensional spatiotemporal self-similar soliton pair is studied. Theparameter control and dynamical behaviour of self-similar and ordinary spatiotemporalsolitons are compared. These peoperties may have theoretical importance to increase thebit-rate and reduce bit error rate in optical communication.4. Parameter control and dynamical behaviour of pico-and femto-second rogue waves.The propagation behaviours of picosecond of rogue wave triplets and femtosecond ofone-and two-rogue waves, including annihilation, sustainmen, postponement, recurrence, quick excitation and longitudinal control are studied. The controllable behaviours of one-and two-rogue waves propagating through a dispersion barrier or dispersion well in anexponential background are discussed. These results may have potential importance for thegeneration and sustainment of exceptionally high-amplitude optical pulses-optical roguewaves, and provide theoretical foundation for preventing the disadvantage of rogue waves,or even for controlling and making use of it.