The Transmission Of Combined Soliton In Fiber Laser

Fiber laser has many advantages,such as small size,light weight,good gain feature,high conversion efficiency,low threshold,high output beam quality,and compatibility with fiber-optic communication system.It has also some potential applications,like laser processing,optical communication,medical equipment,military,and so on.With the rapid development of ultrafast optical field,a great many researchers have been focusing on mode-locked fiber laser recently.To date,different kinds of pulses,such as soliton–similariton pulse evolution,femtosecond pulse,square pulse,stable bound soliton,noiselike pulse,dissipative soliton,and multiwavelength pulse,have been experimentally observed in passively mode locked fiber lasers.The traditional soliton is formed by the balance between linear and nonlinear effect.Because of its high information capacity,long transmission distance,high transmission rate,low error rate,good secrecy and strong anti-interference ability,it has been widely studied by scholars.However,in the study of many solitons,the numerical study on the transmission characteristics of the bright-dark soliton pair,the dipole soliton and other combined soliton have less in the fiber laser.Based on the simplified fiber laser model,the transmission characteristicsof the bright-dark soliton pair and the dipole soliton in the fiber laser are numerically studied by the MATLAB using the split-step Fourier transform algorithm.Specific content includes:(1)This paper introduces the concepts and classification of soliton,the research progress of soliton at home and abroad,and the application prospect of soliton.Introduce the principle of the generation of soliton in fiber laser,the significance and the research status at home and abroad.(2)The establishment of the model.Based on the simplified model of fiber laser,the average transmission equation model of optical pulse in fiber laser is established.In addition,considering the interaction between solitons,the coupled nonlinear schrodinger equation in the optical fiber laser is obtained.(3)Firstly,based on the average transmission equation model of optical pulse in fiber laser,distribution Fourier method is used to study the transmission characteristics of bright-dark soliton pair in fiber laser.Secondly,Based on the modified coupled nonlinear schrodinger equation model,analyzing the changes of the bright-dark soliton pair affected by the gain,saturation energy,pulse width,and polarization angle during the fiber laser transmission.The results show that the stable existence of the bright-dark soliton pair is related to the group velocity dispersion in the fiber laser.The bright-dark soliton pair can be stable transmitted in the zero dispersion region.At the same time,the bright-dark soliton pair is influenced by the small signal gain coefficient,saturated energy,initial pulse width and polarization angle in fiber laser.Thelarger the small signal gain coefficient or the saturation energy,the peak intensity of the bright-dark soliton pair is greater with the width narrower.To a certain degree,the bright-dark soliton pair is split.The polarization controller can control the output of the bright-dark soliton pair.(4)Based on the modified average nonlinear Schrodinger equation in the fiber laser,the transmission of dipole soliton in fiber laser is studied numerically.The results show that when the dispersion is zero and the small signal gain coefficient is zero,the dipole soliton is stable in the fiber laser.At the same time,with the change of dispersion,gain and pulse width in the fiber laser,the transmission of dipole soliton is affected.