Study On Transmission And Control Of Femtosecond Dark Solitons And Similaritons

Optical solitons,as the excellent carrier of information transmission,can transmit steadily over long distance in optical fiber.However,the interaction between solitons will directly affect the quality of information during transmission and lead to high bit error rate.The study of the propagation and the interaction between solitons has become a hot topic in the field of soliton research.In this paper,based on the variable-coefficient higher-order nonlinear Schr(?)dinger equation and the cubic-quintic nonlinear Schr(?)dinger equation including Raman effect,external harmonic potential,the exact femtosecond dark soliton solutions,bright and dark similaritons solutions are presented by means of the Hirota method and the self-similar transformation,respectively.Furthermore,the propagation and interaction of femtosecond dark solitons are investigated in several typical inhomogeneous fiber systems.The interaction control and the tunneling effects of bright and dark similaritons in inhomogeneous fiber systems are investigated,respectively.The main contents of the study are as follows:(1)Chapter one,we introduce the research background of solitons,and the status of the transmission and control of optical solitons and self-similar waves,respectively.(2)Chapter two,we present the exact femtosecond one-dark soliton solution and two-dark soliton solutions for a higher-order variable-coefficient nonlinear Schr(?)dinger equation via modified Hirota method.Based on these exact solutions,we investigate the propagation properties of femtosecond one-dark solitons and the interaction between femtosecond dark solitons in the parametric systems with Gaussian distribution and exponential periodic distribution.It is found that in these two kinds of inhomogeneous optical fiber systems,the two femtosecond solitons can achieve parallel transmission by choosing the appropriate distributed parameters and soliton parameters to control the velocity of soliton.The presented results are expected to provide a theoretical basis for the control of femtosecond dark soliton interaction.(3)Chapter three,we obtain exact one-and two-bright and dark similaritons solutions for a variable-coefficient cubic-quintic nonlinear Schr(?)dinger equation with an externalharmonic potential and the Raman effect via similarity transformation and Hirota method.The compression,propagation and control of the interaction between the bright and dark similaritons in exponential decreasing periodic systems are investigated,respectively.In addition,based on the obtained solutions,the tunneling effects of bright and dark similaritons are further studied.It is found that in exponential decreasing periodic system,the compression and amplification of the similaritons,the control of the parallel transmission,the elastic collision and the inelastic collision can be realized by adjusting the parameters of the system and the related parameters of the similaritons.It is also found that bright and dark similaritons are different when passing through dispersion barrier(well)or nonlinear potential barrier(well),but the state of the similaritons do not change after it passes through the dispersion barrier(well)or the nonlinear barrier(well).(4)Chapter four,the full contents are summarized,and the next work is prospected...