On The Propagation Properties Of Gaussian Shaped Pulses In Optical Fibers

In this paper, firstly we make a brief introduction to the origin,development and current research of optical fiber communications, then,based on the MNLS equation, introduce the answer of gaussian-shapedpulse. We use the method of variational principle to deduce the evolutionequations for the parameters [amplitude(A),frequency band width(a),chirp(b),frequency(ω), center position(ξ), phase(Φ))]of gaussian-shapedpulses in common situation, without perturbation, and situation of thesmall dielectric loss, the third-order dispersion, the fifth-order nonlinearityand the influence of the couple-interaction.By these equations, wediscussed the peoperties of the parameters when the distance Z changed,and derived the answers to the evolution equations of the parameters(a,b,ω,ξ) under in the situation of without perturbation, then we mainlydiscussed the perturbation to the width made by the small dielectricloss,the third-order dispersion and the fifth-order nonlinearity, then we gotthe curves of the frequency band width(a),the chirp(b)in thesituation ofwithout perturbation, the third-order dispersion and the fifth-ordernonlinearity.By discussing we think: (1) The effects exist in all cases during the gaussian-shaped pulses transferred in the fiber; (2) The small dielectric loss has effect on Φ; (3) AH of the third-order dispersion, the fifth-order nonlinearity and the couple interaction can bring about chirp wave; (4) The chirp wave brought by the third-order dispersion has direct effect on A, a, b,ω,ξ ,Φ, and make the frequency band width expand; (5) The chirp wave brought by the fifth-order nonlinearity direct influence on Φ, and make the pulses shrink; (6) The chirp wave brought by the coupled interaction also has direct effect on A_m,a_m,b_m, ω_m,ξm, Φ_m, what's more, it despoils the property; (7) The initial chirp make the pulses expand more intensive than the third-order dispersion and the fifth-order nonlinearity.So we should make these harmhul effects as little as possible to ensure the gaussian-shaped pulses be transferred efficiently.