Research On The Manipulation Of Optical Rogue Wave By Induced Modulational Instability In Optical Fiber

The terminology of rogue wave(rogue soliton)is originally used to describe a type of destructive ocean waves with largest trough-to-crest height and energy highly centered,but it's short-lived.In recent years,optical rogue soliton(RS)in fiber systems raises people's interest,it's formed in the processes of“long pulse”(e,g.,picosecond,nanosecond or even a continuous wave)pumped supercontinuum(SC)generation,and the modulation instability plays an important role.RS generated in the condition of spontaneous modulation instability is unpredictable,so it's difficult to harness.In general,it can be filtered by the filters to improve the SC's smoothness and stabilization.However,the SC and RS generated by induced modulation instability have some novel characteristics,in this paper,on the basis of the generalized nonlinear Schrodinger equation,a detailed study of the manipulation of RS during SC generation by induced modulation instability has been made by utilizing the standard split-step Fourier method.A standard single-mode PCF is used,The main research contents are listed below:Firstly,modulation instability gain spectrum is explored by taking the Raman response function and high-order dispersion into account,it provides us the theoretical basis to choose an appropriate seed pulse.Then,utilize a modulated sub-picosecond pulse to study the mechanisms behind the SC and RS formation.The windowed Fourier transform methods is used to simulate the cross-correlation frequency-resolved optical gating technique(X-FROG),so the time and frequency characteristics of the SC spectrum components can be observed simultaneously.Secondly,based on the numerical simulation results,we make a detailed analysis about the SC and RS generation under different modulation frequencies and depths.When the modulation frequency is very small or seeding in the tail of the modulation instability gain spectrum,the seed is almost not work;seeding in the vicinity of the peak of modulation instability gain tends to generate RS more efficiently,but it can significantly degrades the smoothness of the SC;modulation depth also have a great effect on the RS generation,very weak modulation or large values of modulation depths are beneficial to the RS generation,and we analyze the different physical mechanisms for the two cases.Under the conditions of RS can be stably transmitted,one can manipulate the RS generation in a wide range of modulation depths when seeding at the appropriate modulation frequencies and obtain a wavelength tunable RS;And the shortest fiber length for a RS rejected can also be manipulated.Under proper pump conditions,the input noise can be suppressed by the seed pulse,the generated RS is controllable,stable,and useful.Considering the fact that the RS gathers a great deal of energy,it can be used in the generation of high power,high energy ratio Mid-Infrared SC.In addition,the tunable RS in our case can guide tailoring the SC and generating new specific frequency components at some specific wavelength.