Research On The Generation And Characteristics Of Dispersive Wave In Photonic Crystal Fibers

Photonic crystal fiber(PCF)has been widely used in the field of optical fiber communication for its good characteristics,also make it possible for many more in-depth research in nonlinear optical field.The dispersive wave(DW)generation in the photonic crystal fiber is a very complicated nonlinear process,and the DW generation can greatly broadening the output spectrum of the input pulse.Specifically,when the input high-order soliton pulse transporting in nonlinear media,it's not stable and will be affected by the dispersion and nonlinear effect.consequently,the high-order soliton can break into its fundamental components,this phenomenon known as soliton fission.The emission of a phase-matched DW across the zero-dispersion wavelength is currently believed to play an important role in the supercontinuum generation.Based on the generalized nonlinear Schrodinger equation,we utilize the method of numerical simulation to study the DW generation and the relationship with dispersion slope in PCF with different zero dispersion wavelengths(ZDW),the interaction between dispersive waves and solitons has also been studied.The main research contents are listed below:Firstly,based on the generalized nonlinear Schrodinger equation,we utilize the standard split-step Fourier method to study the DW generation and it's characteristics in PCF.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(XFROG),the time and frequency characteristics of the DW can be observed simultaneously,and the trapping of DW by solitons along with the transmission has also been studied.Secondly,we disclose the physical mechanism for DW generation and the impact of dispersive slope on DW generation.Both positive dispersion slope and negative dispersion slope for pump wavelength have been studied.It is demonstrated that the wavelength of the dispersive wave can be blue-shifted or red-shifted relative to the center wavelength of the soliton,depending on the dispersion slope of the pump wavelength.For the positive dispersion slope,the generated blue-shifted DW(B-DW)is at the blue side of output spectrum,while the generated red-shifted DW(R-DW)is at the red side of output spectrum when the dispersion slope is negetive.We discussed the interaction between dispersive waves and solitons,namely the soliton capturing phenomenon.Making use of the X-FORG technology we numerical simulate the soliton trapping phenomenon in PCF with single zero dispersion wavelength.Thirdly,we numerically studied the generation of DW and its interaction with solitons in PCFs with different dispersion wavelength,we systematically analysis the influence of different dispersion slope on DW generation in PCFs with different ZDWs range from one to three.It is demonstrated that we can simultaneously obtain both blue-shift dispersion wave(B-DW)and red-shift dispersion wave(R-DW)in PCF with two ZDW,the interaction between R-DW and soliton helps to expand the spectrum to longer wavelength direction;As for the PCF with three ZDW,we can obtain B-DW near the first ZDW when the dispersive slope is positive while R-DW is generated near the second ZDW when the dispersive slope is negative.In addition,we can also obtain the soliton-like radiation in the second anomalous dispersion regime,which conversed most of the energy of the DW in the first normal dispersion regime,the generated spectrum is more smoothness and extends to longer wavelength of the spectrum.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.