初始啁啾对光纤中光孤立子传输的影响—变分研究

本文用变分法研究了初始啁啾对光纤中光孤立子传输的影响,证明在初始啁啾不超过某一确定值时,光孤立子传输仍可维持,但其幅度和脉宽都在振荡。     

色散管理和非线性管理控制光孤子群的传输

从描述光孤子传输的非线性薛定谔(NLS)方程出发,给出了色散管理和非线性管理的光孤子的传输方程,利用对称分步傅里叶方法对方程进行数值求解,模拟研究了色散管理和非线性管理控制光孤子在光纤中的传输演化特性。结果表明,只有色散管理控制光孤子群在光纤中的传输,随着传输距离增加,孤子间的相互作用逐渐加剧,如色散管理和非线性管理同时控制光孤子群在光纤中的传输,可极大地抑制孤子间的相互作用,且随着距离增加相邻孤子间的作用几乎不变,这一结果可应用于光孤子群远距离的传输。     

光纤放大器中孤子传输的高阶效应

本文求解了含三光子吸收、非线性高阶色散和自感应Raman效应的NLS方程,由此解讨论了光纤放大器的高阶效应对孤子传输的影响.     

光孤子的光流线量子理论研究

运用光流线量子理论研究光纤中的光孤子问题,给出了非线性色散光纤中光孤子传输基本方程。     

光孤子的光流线量子理论研究

运用光流线量子理论研究光纤中的光孤子问题,给出了非线性色散光纤中光孤子传输基本方程。     

孤立波在理想单模光纤中的传播

一、引言 光纤中的孤立波概念最先是由光纤通讯的发展而引进的。由于光信号在光纤传输中发生展宽、畸变,光信号传输速率受到限制。在1973年,Hasegawa和Tappert提出用介质的非线性效应补偿它的色散,二者达到平衡后,便形成稳定非线性波,此即孤立波。稍后,便得到了描述孤立波在理想单模光纤中传播的非线性薛定谔方程。利用逆散射方法可以求解。据现有的文献,已给出N=1、2孤立波的解析表达式,给出了N=1、2、3的孤立波波形图。本文通过求解秩很高的逆散射函数方程     

色散和非线性对异步光码分多址系统的影响

为了研究色散和非线性对异步光码分多址系统性能的影响,基于非线性薛定谔方程,采用数值模拟的方法,取得了异步光码分多址系统误比特率与传输距离的关系曲线和与用户数关系曲线.结果表明,光纤中的群速度色散、3阶色散和非线性效应都会引起异步光码分多址系统性能劣化,其中以群速度色散效应的影响最为严重;系统传输媒质可以采用色散位移光纤...     

色散指数缓变光纤中非线性薛定谔方程的基本孤子解

用守恒量扰动法获得了色散指数缓变光纤中含三阶色激的非线性薛定谔方程的基本孤子解。理论分析了色散指数级变光纤中光孤子的传输特性，发现三阶色散使光孤子产生时间漂移，漂移量与色散变化率有关。     

单模激活光纤中的孤立子

在考虑色散与非线性效应下,本文推导了脉冲在激活光纤中的运动方程;引用激活物质极化的量子理论,揭示出在激活物质极化的一级近似并满足一定条件时,激活光纤中可产生孤立子。计算结果表明,激活光纤中产生孤立子比普通孤子所需光强     

色散缓变光纤中Raman弧子自频移效应的研究

利用绝热优动法研究了色散缓变光纤中Ｒａｍａｎ弧了自频移效应，得到了色散缓变光纤中Ｒａｍａｎ弧子自频移的表达式。结果表明：光纤色散变化率存在一个可以有效抑制弧子自频移的阈值，当光经行色散变化率大于这个阈值时，色散缓变光纤可以抑制弧子自频移，而当光经行色散变化率小于这个阈值时，色散缓变光纤不仅不能抑制弧子自频移，反而加剧弧子自频移。     

OPTICAL FIBER NONLINEAR SOLITON COMMUNICATION

In anormalous dispersion of monomode optical fiber,optical solitons are evolvedfrom optical pulses when the dispersion is balanced by the nonlinearity.Undistorted transmissioncan be realized by using optical solitons,which can offer much greater the transmission capacityand extend the repeater spacing of the fiber communication system.The mechanism of thegeneration of optical solitons is expounded.A few forms of nonlinear transmission equationare obtained by using a concise method.The general complete expression of elementary solitonsolution of the nonlinear transmission equation without loss is given,and the design of the solitontransmission system is discussed.     

高阶色散和非线性效应下三阶孤子对传输的研究

高阶色散及高阶非线性效应是制约光孤子稳定传输的重要因素。基于光孤子传输的非线性薛定谔方程,综合考虑三阶色散和五阶非线性的影响,采用分步傅里叶算法,数值研究了三阶孤子对间的相互作用。结果表明：三阶色散导致三阶孤子对无规则地裂变,裂变后的光脉冲形状发生畸变,脉冲中心位置出现偏移;考虑负五阶非线性作用后,在一定程度上抑制了孤子裂变,但是光脉冲在传播过程中伴有能量转移。而正五阶非线性作用使三阶孤子对传输图形进一步恶化。适当地选取负五阶非线性参数值,可以完全消除三阶孤子对的裂变和相互作用,改善了脉冲中心位置的线性偏移。     

Effect of Soliton Propagation in Fiber Amplifiers

The propagation of optical solitons in fiber amplifiers is discussed by considering a model that includes linear high order dispersion, two-photon absorption, nonlinear high-order dispersion, self-induced Ramam and five-order nonlinear effects.Based on traveling wave method, the solutions of the nonlinear Schrodinger equations, and the influence on soliton propagation as well as high-order effect in the fiber amplifier are discussed in detail.It is found that because of existing five-order nonlinear effect ,the solution is not of secant hyperbola type, but shows high gain state of the fiber amplifier which is very favourable to the propagation of solitons.     

光学孤子在单模光纤中的非线性传输方程

人们熟知,由非线性薛定谔(NLS)方程描述的光学孤子可以在单模光纤中稳定地传输。本文在准单色近似和慢变包络近似条件下,利拥泰勒级数展开推出了这一非线性传输方程。由于推出的方程包含着高阶线性色散和光纤损耗项,因而可以用来研究短光脉冲(皮秒量级)在单模光纤传输过程中相关的非线性光学孤子效应,比如光学孤子分裂和光学孤子损耗等。     

The Micro-Theory of Ultra-Short Pulse Propagating in Nonlinear Fiber

The modified quantum nonlinear Schrodinger equation of ultra-short pulse propagating in fiber is derived using dispersion relation and the Hamiltonian of the transmission system. The derived equation is solved with linearization approximation, and modulation instability is analyzed. The equation is also solved with Hartree approximation. The results indicate that pulse power, loss and self-steeping effect change the critical frequency, the maximum gain and the gain spectrum range, but the third order dispersion has no effect on modulation instability. The expectation value of optical field is average of a set of modified classical solitons, and higher order terms change the amplitude, pulse position and phase of soliton.     

光纤放大器中孤子的量子效应

利用含时Hartree近似法得到光孤子在含光纤损耗、双光子吸收、三阶色散效应的光纤放大器中传输时的量子非线性薛定谔方程,在一定条件下,有量子态的孤子解,并由此方程讨论了经典和量子效应对孤子在光纤放大器中传输时的影响,由此进一步发现,光场算符的量子力学平均值是一系列修正的经典孤子的叠加。     

光纤孤子的“双陷”型非线性管理

为了研究光纤系统中由色散参量和 “双陷”型非线性参量可能导致的孤子现象,通过分步傅里叶数值算法求解了变系数（1+1）维非线性薛定谔方程。结果发现,光纤孤子在两种“双陷”型非线性光学系统中具有一系列有趣的性质,如单孤子脉冲在可变参量背景下由“双陷”型非线性结构诱发的周期性振荡;双孤子脉冲在常参量背景下由“双陷”型非线性结构诱导的走离效应;三个孤子脉冲在两种“双陷”型非线性光学系统中体现的特殊相互作用、融合效应等。     

Ultrashort pulse propagation, pulse breakup, and fundamental soliton formation in a single-mode optical fiber

The propagation of ultrashort (0.83 ps), intense dye laser pulses through a single-mode optical fiber is investigated. The input wavelength is tuned in the vicinity of the zero dispersion wavelength of the fiber. Although the input power is sufficient to generate solitons of up to the tenth order we do not observe the formation of high-order solitons. Instead, the input pulse breaks up temporally and spectrally after an initial stage of narrowing, and an ultrashort Stokes pulse is formed which shifts continuously to lower frequencies with increasing fiber length. The parameters of this pulse closely correspond to those of the fundamental soliton solution of the nonlinear Schroedinger equation. Using fiber lengths from a few meters up to 1 km the resulting pulse durations lie between 55 and 410 fs and the corresponding wavelengths between 1.36 and 1.54 μm. Numerical simulations solving a modified nonlinear Schroedinger equation including higher order dispersion and the Raman effect are in good agreement with the experimental results. It is shown that the principal soliton pulse shaping mechanisms are pulse narrowing and the soliton self-frequency shift.     

Hartree近似法研究色散缓变光纤中孤子的量子效应

利用含时Ｈａｒｔｒｅｅ 近似法得到色散缓变光纤的量子非线性薛定格方程,在一定条件下,有量子态的孤子解,并由此方程讨论经典和量子效应对孤子传输的影响,由此我们进一步发现,光场算符的量子力学的平均值是一系列修正的经典孤子的选加,色散缓解应等效为一个长距离分布参数的光纤放大器,导致非线性效应增加,使孤子受到压缩     

Signal transmission by optical solitons in monomode fiber

A transmission rate of ≃1 Tbits/sec (≃0.1 Tbits/s) per 30 km can be achieved using envelope solitons with peak power of ≃10 W (≃10 mW) in a monomode optical fiber, respectively. Unlike the linear pulse in which the bit rate is limited by the group dispersion, the bit rate of soliton transmission is limited by the fiber loss and the input power. Conditions for achieving optimum transmission rate using solitons are theoretically obtained including the effects of fiber loss and second order group dispersion.