The Generation Of High-power Pulse Trains Based On The Second-order Akhmediev Breathers

With the continuous development of optical fiber communication technology,ultrashort pulses with high peak power and narrow pulse widths have become a hot spot in scientific research.Ultrashort pulses have important application in the fields of optical fiber sensing,optical fiber communication,optical information storage,and nonlinear optics.The transmission of optical pulses in optical fibers can be described by the nonlinear Schrodinger equation.Theoretical research proves that the soliton solution on a finite background can be obtained by using the nonlinear Schrodinger equation.Usually the soliton solutions on a finite background include the Peregrine soliton solution,the Kuznetsov-Ma soliton solution,and the Akhmediev breathers solution,Among them,the Akhmediev breathers can be used to generate ultra-short pulse trains.This paper is mainly based on the numerical study of the second-order Akhmediev breathers on the generation and transmission characteristics of the high-power pulse train in the optical fiber.The research results can provide a certain theoretical basis for the generation of pulse train based on the Akhmediev breathers in the optical fiber experiment.The main contents of this paper are as follows:(1)Based on the introduction of the concept of soliton,the classification of soliton solution and the application of optical soliton in optical fiber communication,the paper summarized the research progress of Akhmediev breathers and Akhmediev breathers generating ultrashort pulse train.(2)From Maxwell's equation,the transmission equation of optical pulse in single-mode fiber and the exact solution of the Akhmediev breathers in the nonlinear Schrodinger equation are introduced.It provides a theoretical premise for the next step in the study of pulse trains generated by Akhmediev breathers,and the split-step Fourier numerical simulation method is briefly introduced.(3)Based on the first-order Akhmediev breathers,the transmission characteristics of the pulse trains generated in the optical fiber are numerically studied.Theoretically,the background wave is a key factor that affects the transmission of pulse trains generated by Akhmediev breathers in the optical fiber.Three different methods of eliminating background waves to generate pulse trains are compared and discussed.The pulse train obtained by using the phase superposition method to eliminate the background wave can effectively increase its duty cycle,but the peak power of the pulse decrease significantly with the increase of the pulse duty cycle,and it is stably transmitted in the optical fiber.The interference superposition method is used to eliminate the background wave.Although the pulse period does not change,the pulse intensity increases significantly,and the stable transmission distance becomes shorter.The optical chopping method is used to eliminate the background wave,the peak power and duty cycle of the pulse train do not change,and stable transmission distance increases as breathers period increases.(4)Based on the second-order Akhmediev breathers,the transmission characteristics of the high-power pulse train in the optical fiber are numerically studied.The second-order Akhmediev breathers can be regarded as the collision and superposition of two first-order Akhmediev breathers.Due to the existence of background waves,the pulse sequence of the second-order Akhmediev breathers cannot be directly transmitted in the optical fiber for stable long-distance transmission.Here we mainly use the optical chopping method to eliminate the background wave to generate high peak power pulse trains.The research results show that the peak power and duty cycle of the extracted pulse train remain unchanged and can be transmitted stably over long distances in the optical fiber.However,the transmission distance is affected by the number and period of the pulse sequence.The anti-interference ability of high-power pulses has been proven to be good.We simulate the evolution of the second-order Akhmediev breathers in the fiber through the superposition of two periodic disturbances.The chopping process is carried out at the excited position,and it can also transmit stably in the optical fiber.