Influence Of The Oscillating Parameter On Gain Sidebands In Dispersion Oscillating Fiber

Recently,optical fiber communications have developed in the direction of ultra-high speed,ultra-long distance,and high-bit.Dispersion,nonlinearity,and loss are factors that affect the stable transmission of optical pulses in fiber.With the improvement of optical fiber connection technology and the use of erbium-doped fiber amplifiers(EDFA),fiber loss is no longer a major factor limiting the development of optical fiber communications.In general,the dispersion effect causes pulse broadening in the time domain.The nonlinear effect broadens the pulse spectrum,and the interaction between the dispersion and the nonlinear effects leads to modulation instability.Modulation instability can produce a series of gain sidebands,which are usually observed in the anomalous dispersion region.However,in this paper,we study the characteristics of multiple sets of symmetry gain sidebands in the normal dispersion region and dispersion oscillation fiber.Influence of the average dispersion,the period and amplitude of the dispersion oscillation and gain or loss on the output sidebands of the quasi-continuous pump wave induced by modulation instability in dispersion oscillating fiber is investigated.Analytic and numerical calculations were used to study the comparison.The main contents are as follows:(1)The nonlinear Schrodinger equation governing the evolution of optical fields in nonlinear medium is derived from the Maxwell's equations.At the same time,we briefly describe Split-Step Fourier method and the method of linear stability analysis.(2)Based on the normalized nonlinear Schrodinger equation,the analytical solution of the gain spectrum of the modulation instability in the dispersion management system is obtained by using the linear stability analysis method,which provides a theoretical basis for the subsequent numerical simulation and the comparison of the analytical results.Secondly,the effect of the shape of the initial Gaussian quasi-continuous wave on the gain sideband is studied.It is found that multiple sets of gain sidebands can be obtained when the half-width is relatively large.(3)In dispersive oscillating fibers,the effects of average dispersion,dispersion oscillation period and dispersion oscillation amplitude,and gain/loss alignment modulation pumping wave output modulation instability gain sideband are investigated.With the increase of the average dispersion and dispersion oscillation period,the center frequency of each sideband moves towards the center frequency of the spectrum,and the corresponding gain value gradually decreases.When the amplitude of dispersion oscillation increases,sideband splitting occurs and the strong dispersion oscillation occurs.Considering the influence of the gain/loss on the output sideband spectrum,it was found that the inner and outer sidebands of the splitting were suppressed to different extents.