Research On The Impact Of Self-steepening Effect On The Soliton Trapping In Photonic Crystal Fibers

Contrasted with these conventional fibers,photonic crystal fiber(PCF)has been widely used in the field of optical fiber communication for its good characteristics,for instance,controllable group velocity dispersion characteristics,high nonlinear properties,endlessly single-mode characteristic and so on,so its characteristics make it possible for many more in-depth research in nonlinear optical field.The high-order soliton is affected by dispersion and high-order nonlinear effect,then it breaks into fundamental solitons,simultaneously the dispersive wave(DW)is emitted.The DW generation in the photonic crystal fiber is a very complicated nonlinear process,and it can greatly broaden the output spectrum of the input pulse.The emission of a phase-matched DW across the zero-dispersion wavelength is currently believed to play an important role in the supercontinuum generation.On the basis of the generalized nonlinear Schrodinger equation,we utilize the method of numerical simulation to study the DW generation and the relationship with self-steepening effect in PCF with two zero dispersion wavelengths(ZDWs),the interaction between the trapped DWs and self-steepening effect has also been studied.The main research contents are listed below:First,on the basis of the generalized nonlinear Schrodinger equation,we utilize the standard split-step Fourier method to study the DW generation and how self-steepening(SS)effect to affect the DW generation.Considering the fact that the generation of DW in the photonic crystal fiber is a very complicated nonlinear process,we use the windowed Fourier transform methods to simulate the cross-correlation frequency-resolved optical gating technique(X-FROG),the time and frequency characteristics of the DW can be observed simultaneously.We numerically studied the physical mechanism for DW generation and the impact of self-steepening effect on DW generation.Due to the different generation mechanism between the red-shifted dispersive waves(R-DWs)and blue-shifted dispersive waves(B-DWs),the SS effect will have different effect on them.It's demonstrated that with the increase of SS coefficient,the power ratio of R-DWs is weakened greatly whereas the power ratio of B-DWs is enhanced,which means that self-steepening effect leads to the energy redistribution between solitons and DWs,Secondly,we disclose the impact of self-steepening effect on soliton trapping.In our simulation,when we take the SS effect into account,we adjust the input pulse width to change the SS coefficient.Trapping of R-DWs is restrained obviously,while the trapped B-DWs is affected slightly.These phenomena indicate that we can obtain a smoother and broader SC or blue-extended SC just by choosing appropriate SS coefficients.The numerical results is of great significance in the optimizing of continuous spectrum light source as well as in the controlling of continuous spectral width and flatness.