Generation Of High-Power Breathing Pulses Based On The Suppression Of Peregrine Soliton Background Waves

The study of rogue waves in optics has a history of more than ten years,which has become a research hotspot to physicists.The optical rogue wave was proposed firstly by Soli et al.in their study of supercontinuum in optical fibers.The realization of optical rogue waves on the optical platform provides convenience for studying the generation mechanism of rogue waves.At present,the generation mechanisms of rogue waves are mainly divided into two types.From the linear theory,a large number of crossovers occur locally with appropriate phase and amplitude,eventually forming strange waves.Another explanation is the nonlinear process,the generation of rogue waves is closely related to the modulation instability in nonlinear effects.In mathematics,the modulation instability can be described by the soliton solutions on finite background waves of the nonlinear Schr(?)dinger equation.Among them,Peregrine soliton solution has been commonly used to describe rogue waves in optics.Peregrine soliton is a single pulse localized in time and space.Due to its high peak power,it has potential applications in the generation of ultrashort pulse.Ultrashort pulse has important application value in the fields of optical fiber communication,optical information storage,optical fiber sensing,nonlinear optical fiber and so on.The research content of this thesis is the generation of high-power breathing pulses from Peregrine solitons based on the nonlinear Schr(?)dinger equation numerically.And the transmission characteristics of breathing pulses are studied.The research results can provide a certain theoretical basis for the generation of high-power breathing pulses from Peregrine solitons.The details are as follows:(1)The thesis introduces the origin and concept of rogue waves,analyzes the generation mechanism and research status of rogue waves,and summarizes the research progress of Peregrine solitons and the generation of high-power pulses based on Peregrine solitons.(2)From Maxwell equations,the transmission equation of optical pulse in the optical fiber ring cavity is introduced.The principle of saturable absorber is introduced,which lays a theoretical foundation for the generation of breathing pulse based on Peregrine soliton in the next step.The split-step Fourier method and numerical simulation process are briefly described.(3)Based on Peregrine soliton,an erbium-doped fiber ring cavity is proposed to generate high-power breathing pulse.Peregrine solitons cannot transmit stably in optical fibers due to the existence of background waves.The erbium-doped fiber ring cavity can be used to eliminate the effect of background wave.The erbium-doped fiber ring cavity is composed of single-mode fiber,erbium-doped fiber and optical couplers.By controlling the lengths of the single-mode fiber and the erbium-doped fiber in the ring,the intra-cavity dispersion can reach nearly zero dispersion,and the dispersion management can be realized.In order to obtain the high peak power breathing pulse,the pulse of Peregrine soliton at the maximum excitation position is selected as the initial input of the optical fiber ring.Under the action of the fiber ring cavity,the high-power breathing pulses can be obtained and transmitted for long distance in the erbium-doped fiber ring cavity.And the background waves on both sides of the PS gradually evolve into small side lobes.The transmission characteristics of breathing pulse are related to dispersion,nonlinearity and small signal gain.As the nonlinear coefficient increases,the peak intensity of breathing pulses increases,and the amplitude and frequency of oscillation increase.When the nonlinear coefficient increases to a certain extent,the local breathing pulse gradually forms.With the increase of the small signal gain,the peak intensity of breathing pulses increases,but the amplitude and frequency of oscillation have a little change.(4)Based on Peregrine soliton,a saturable absorber is proposed to eliminate the background wave and generate high-power breathing pulse.According to the filtering properties of the saturable absorber,we can use it to remove the background wave of the Peregrine soliton.The results show that the high-power breathing pulse with periodic oscillation can be achieved from Peregrine soliton by the saturable absorber with appropriate modulation depth.And the high-power breathing pulses can be transmitted long-distance in the optical fiber.The peak powers of breathing pulses are controlled by the location of saturable absorber and the length of gain fiber.And the breathing pulse has strong anti-noise ability.When two adjacent breathing pulses are in the same phase,the pulses attract each other,and this effect decreases with the increase of the initial interval.In the out-of-phase case,the pulses repel each other and split as the initial interval increases.