Research On The Impact Of Chirp On The Soliton Trapping Of Dispersive Wave In Photonic Crystal Fibers

The rise of photonic crystal fiber has opened new horizons for effectively supercontinuum generation mainly because of their “endlessly single-mode” behavior,controllable group velocity dispersion characteristics and high nonlinear properties.The generation of dispersive wave is the one of the main physical mechanism of supercontinuum generation.The dispersive wave generation in photonic crystal fiber is a fundamental problem of nonlinear optics,and is also a very complex nonlinear process,which is affected by many factors.Dispersive wave is emitted due to the energy transfer from soliton to narrow-band resonance in the normal dispersion regime.In recent years,dispersive wave has a wide application in the practical engineering and scientific research.Based on the numerical study,our paper shows that the time-frequency characteristic of dispersive wave and the soliton trapping of dispersive wave.At the same time our paper shows the self-steepening on dispersion wave effectt with photonic crystal fiber of two zero dispersion wavelength,also impact of chirp on soliton trapping of dispersive waves in photonic crystalfiber with two zero dispersive wavelengths.Through our simulation results:Firstly,based on the nonlinear Schr?dinger equation,we studied impact of chirp on dispersive wave generation and its influence factors in photonic crystal fiber by the standard split-step Fourier method.Because of the complexity of dispersive wave generation by the theoretical analysis,the generation and influential factors of dispersive wave in photonic crystal fiber are analyzed by the numerical simulation.In order to clearly display the evolution of impact of chirp on soliton trapping of dispersive waves,the spectrogram of output pulses is observed using cross-correlation frequency-resolved optical gating technique.First of all,we analyzed impact of self steepening of dispersive waves,through our simulation results show that: mechanism of dispersive waves generation is difference,impact of the self-steepening on the red and blue shifts of dispersive waves will be different.When considering the self steepening,red-shifted dispersive wave will be significantly affected,while effect of blue-shifted dispersive wave strength relatively small.Secondly,we studied the main influence factors of high-order soliton propagate in photonic crystal fiber and the dispersive wave generation with different initial chirp.The evolution of different chirped pulse in the time domain is analyzed.The study shows that,compared with zero or negative initial chirp,positive initial chirp canmake high order soliton fission and saturation broadening generated earlier.According to the transmission distance,the pulse can be divided into three stages of evolution : initial broadening stage,dramatic broadening stage and saturation broadening stage.Through the discussion can be found in the evolution of the chirped pulse with difference broadening stage has a different effect,we found that the spectra of the initial broadening and dramatic broadening stage which effect of chirp is more obvious.But in the saturation stage,there is no influence of chirp on the spectrum broadening.We found that from time-frequency spectrum analysis can be drawn,the initial pulse chirp is positive,beneficial to the dispersion wave generation,will produce more flat supercontinuum,capture the soliton is also obvious.We find a fascinating phenomenon that the intensity of blue-shifted dispersive wave and red-shifted dispersive wave will be enhanced with positive chirped.we also found that intensity of dispersive wave depend on the soliton intensity.