Study On Propagation Of High-peak Pulses In Nonliear Dispersion-Decreasing Fiber

Rogue wave(abbreviated RW) is a single high-peak pulse,which was firstly found in the ocean. Because it has extremely high-amplitude and exceedingly strong power of destroy, which pops up without any sign and suddenly appears or disappears, rogue wave have attracted domestic and international scholars’ extensive attention on them.Now, rogue waves are found in many fields, such as systems of ultra-cold atoms, atmospheric environment, finance and so on. After a long time of studying and exploring, people have already a preliminary understanding of rogue waves, but the research works are still in initial stage. Because the theoretical model of deep water wave mechanics and the dynamic model of optical wave transmission in nonlinear optical system are exactly similar, the concept of rogue waves in the ocean is introduced into optical fields naturally. In the optics system, rogue waves have very high peak values, thus they can be used as an important application on the aspect of high peak power pulses generation. So, in this dissertation, we mainly study the excitation and propagation of high-peak pulses in nonlinear dispersion-decreasing fiber based on variable-coefficient nonlinear Schr?dinger equation.The specific contents are mainly four aspects as follow:(1) Introduce the concept of rogue waves on the ocean and the optics, the factors of generation as well as the research progress and methods.(2) From the Maxwell equation, we deduce the variable-coefficient nonlinear Schr?dinger equation which is the general theoretical model of optical pulses propagating in inhomogeneous optical fibers. On this basis, the soliton solutions on continuous wave background of this equation are introduced, which include Peregrine soliton,Kuznetsov-Ma soliton and Akhmediev breathers. Also, the numerical simulation method of optical pulses transmission is presented: the split-step Fourier method.(3) Because the Peregrine soliton is often used to describe the rogue wave in theory, we discuss in detail the Peregrine soliton transmission in nonlinear dispersion-decreasing fibers based on the Peregrine soliton solution. Moreover, by inputting different localized pulses on continuous-wave background, we study the excitation and propagation of high-peak pulses in nonlinear dispersion-decreasing fiber.(4) In addition, the propagation of the continuous wave loaded by Gaussiantype, Hyperbolic secant-type and Cosine type perturbation in nonlinear dispersion-decreasing fibers are discussed. We study the amplitude and width of three disturbance pulses as well as initial chirp parameter are affect on transmission characteristic of high-peak pulses inspired by these three initial condition. It can provide theoretical basis to study the transmitting and controlling of the high-peak pulses in optical fibers.