Numerical Research Of Interaction Between Femtosecond Optical Solitory Waves

In the dissertation, the nonlinear Schrodinger equation(NLSE) which describes the transmission of picosecond optical pulses in the optical fiber and the higher-order nonlinear Schrodinger equation which describes the transmission of femtosecond optical pulses in the optical fiber were introduced firstly. On the basis of summaring the reported research results, we investigate the interaction of optical dark solitons and obtain some useful results by means of numerical method. Those provide the theoretical basis for increasing the capacity of optical soliton communication system and raising the bit rate.The numerical results show that the interaction between femtosecond bright solitons is different from that between picosecond bright solitons. The latter is repulsive and attractive periodically, but the former keeps repulsive after the first collision. The interaction between femtosecond dark solitons is similar to that of the picosecond dark solitons. They are more stable than the bright solitons and have only little repulsive force between them. Furthermore, the numerical results show that the interaction of femtosecond dark solitons agree with the empirical expression of picosecond dark solitons for the separation of two solitons as a function of initial separation and traveling distance in a certain range. But it is also found that the smaller the initial separation between two dark solitons is, the larger the difference between numerical simulation results and formula calculation results is. The numerical results also show that it is effective to choose appropriate proportion of amplitude for restraining the interaction of bright solitons. Finally, we introduce the influence of optical source chirp on the interaction of femtosecond bright solitons and investigatethe influence of optical source chirp on the interaction of femtosecond dark solitons. The results show that optical source chirp can increase the interaction between femtosecond bright solitons and affect the femtosecond dark solitons seriously.