Optical Soliton Communication Systems, Transmission Characteristics And Polarization Mode Dispersion

Known for its perspective advantages of high speed, long distance, high capacity, high security and etc., optical communication systems stand high in people's favors and have become one of principle parts of modern communication. Optical soliton communication is a kind of new ultrahigh-speed, high-capacity, ultra-long haul nonlinear all optical communication technology. It is based on nonlinear fiber optics; it reduces or overcomes the limitations of fiber dispersion on optical pulses; its communication distance can be up to several ten thousand kilometers; it adapts to WDM and OTDM high-speed long-haul optical communication; and it is considered the perfect communication mode to further increase optical communication capacity. The purpose of this thesis is to study the propagation characteristics of optical solitons in single-mode optical fibers and the influence of high-order nonlinear effects and polarization mode dispersion (PMD) to soliton propagation and their suppression in optical soliton communication systems. Based on the analysis of basic principles and characteristics of optical soliton, a number of aspects of optical soliton communication systems are examined in this thesis and the impacts of one of high-order nonlinear effects, Raman self-frequency shift, and PMD to soliton propagation and the interactions between neighboring solitons and their suppressions are investigated intensively.The basic concepts of optical soliton communication and the major factors impacting the propagation characteristics and transmission capacity are firstly introduced and analyzed, and the latest research developments and its perspectives in optical soliton communication are reviewed. Secondly, based on .the Nonlinear Schrodinger equations and high-order Nonlinear Schrodinger equations, which describe the pulse propagation in single mode optical fibers, the formation of optical solitons is elucidated by simulation the optical pulse evolution using Symmetrical Split-step Fourier Method and the propagation characteristics of optical solitons arediscussed. Subsequently, as a comparison, soliton interactions are analyzed with difference initial relative phase difference and relative amplitude without consideration of high-order nonlinear effects at first. And then under the influence of intrapulse Raman scattering, the interactions between in-phase and out-phase optical basic and high order neighboring solitons are investigated by numerical simulation in detail, and the impacts of soliton interactions to timing jitter and the impacts of Raman effects to soliton frequency shift are analyzed, respectively. And it is proposed and proved that a nonlinear gain can be used to effectively suppress the soliton interactions under the influence of intrapulse Raman scattering. Furthermore, based on the coupled Nonlinear Schrddinger Equations, which describe the pulse propagation in birefringent optical fibers, the evolution of optical soliton pairs is simulated in both time and frequency domain using split step Fourier method and the interactions between in-phase and orthogonal solitons are investigated. Simultaneously, the effects of relative amplitude, initial power and polarization-mode dispersion to the interactions of in-phase and orthogonal solitons are discussed. At last, according to Manakov equations, the multiple soliton interactions in a polarization-division multiplexing system are numerically studied in this dissertation and the impacts of soliton interactions to timing jitter are analyzed. As a countermeasure, a nonlinear gain is proposed to effectively suppress the soliton interactions in a polarization-division multiplexing system and stabilize the soliton propagation.At the last part of this thesis, a relative detail summary and prospects are proposed. Based on the known theoretical basis and previous research results, some further efforts should be paid in the following topics, but are not limited, such as other high-order nonlinear effects and their combination effects, PMD, the impacts of soliton interactions to the so...