Research On Nonlinear Effect Control In Optical Fiber Based On Phase Shaping Technology

With the further development of fiber preparation technology,a variety of nonlinear optical fibers have been successfully prepared,prompting the continuous development of this field of nonlinear fiber optics.The regulation of nonlinear effects in optical fibers is one of the research hotspots in the field of nonlinear fiber optics in recent years.When the pulse propagates in the optical fiber,it is inevitable that it will be disturbed by higher-order linear and nonlinear effects,resulting in nonlinear phenomena such as Raman soliton self-frequency shift,third harmonic generation,four-wave mixing,and dispersion wave radiation.This nonlinear phenomena provide new perspectives for applications such as nonlinear frequency conversion,supercontinuum generation,and digital-to-analog conversion.Optical pulse shaping technology can adjust ultrashort pulses into complex waveforms to meet actual needs.The spectral phase modulation method can adjust the time domain waveform of the pulse without affecting the spectral distribution,which provides new possibilities for adjusting and controlling the nonlinear effects in the fiber.In this paper,the nonlinear phase effects in the optical fiber are investigated by spectral phase modulation of the initial input pulse,numerical simulation and theoretical analysis.First,we studied the influence of the Raman scattering effect in the fiber on the interaction between Airy pulse and the soliton.We found that Airy-solitons will fuse together after interaction,and the position of the fusion point can be controlled by changing Airy tailing direction.This control allows us to generate Airy solitons with different decelerations.Unlike the interaction between the two solitons,when the current edge soliton is replaced by an accelerated Airy pulse,the Raman-induced soliton self-frequency shift is significantly enhanced,while the decelerated Airy pulse is slightly suppressed.These characteristics are attributed to the adjustable oscillation direction of the tail of the asymmetric Airy pulse.We clearly reveal these processes through cross-correlation frequency resolution gate technology.We also studied the effect of the chirp on the Raman-induced soliton self-frequency shift when the Airy pulse contains an initial chirp.Our results not only provide a new method for manipulating the Raman-induced soliton self-frequency shift,but may also help to improve the control of soliton fusion events during the generation of supercontinuum,as well as optical strange waves and giant dispersion waves.Subsequently,we studied the law of the spectral phase modulation shaping pulse to study the dispersion wave.We found that the dispersion wave excited when the pulse is transmitted in the optical fiber can be controlled by adjusting the spectral phase of the initial input pulse.At the same time,using the tunable asymmetric oscillation pulses obtained by the second-and third-order spectral phase modulation,we realized a multiple excitation process,which greatly increased the energy of the dispersive wave.In the continuous collision between multiple peaks of an asymmetric pulse and a soliton,we give the dispersion wave frequency derived by the corresponding phase matching conditions,and we can find that the theoretical and numerical experiments are in good agreement.Our results provide a new method for controlling the dispersion wave emission in optical fibers,which may be a new strategy for developing new light sources(broadband supercontinuum generation or infrared frequency comb)for spectroscopy applications.