非均匀光纤中暗孤子传输特性研究

由于变系数非线性Schrödinger方程的增益、色散和非线性项都是变化的, 根据方程这一特点可以研究光脉冲在非均匀光纤中的传输特性. 本文利用Hirota方法, 得到非线性Schrödinger方程的解析暗孤子解. 然后根据暗孤子解对暗孤子的传输特性进行讨论, 并且分析各个物理参量对暗孤子传输的影响. 经研究发现, 通过调节光纤的损耗、色散和非线性效应都能有效的控制暗孤子的传输, 从而提高非均匀光纤中的光脉冲传输质量. 此外, 本文还得到了所求解方程的解析双暗孤子解, 最后对两个暗孤子相互作用进行了探讨. 本文得到的结论有利于研究非均匀光纤中的孤子控制技术.     

周期集总放大系统中暗孤子的传输和相互作用

本文研究了暗孤子在周期集总放大色散渐减光纤系统中的传输和相互作用。解析得到了包含周期集总放大的变系数非线性薛定谔方程的精确1-暗孤子和2-暗孤子解。基于精确的1-暗孤子解,研究了色散渐减周期集总放大系统中暗孤子的传输和放大;基于精确的2-暗孤子解,研究了两个暗孤子之间的碰撞、排斥和平行传输三种相互作用。研究发现,当周期集总放大器的参数、光纤的损耗和色散参数相互平衡时,通过色散渐减光纤可以实现暗孤子的放大和恢复;选择合适的孤子参数,可以控制色散渐减周期集总放大光纤系统中暗孤子间的相互作用。该研究结果对有关暗孤子的放大和传输可提供一定的理论指导。     

孤子色散管理传输及其在常规光纤通信中的可行性研究

从描述光纤中孤子脉冲传输的非线性薛定谔（NLS）方程出发，利用对称分步傅里叶方法对方程进行数值求解．研究了色散管理孤子（DMS）在常规光纤中的传输演化特性，分析了色散管理孤子在常规光纤通信系统中的可行性．结果表明，孤子在通过密集周期性搭配具有相反色散系数的光纤中传输，可以降低孤子间的相互作用，使得孤子的传输演化特性得到改善．利用色散管理来对常规光纤中光孤子脉冲之间的相互作用加以抑制，从而提高信息传输的比特率，但必须具有特殊的光纤制造工艺．     

单模光纤中四阶色散控制的孤子族

研究了单模光纤中最小群速度色散波长附近的孤子传输,利用最小作用量原理得到了由四阶色散控制的一族孤子解,在这族孤子解中包含了原来文献中报道的精确解且解析解与数值模拟结果一致.     

色散渐减光纤链中孤子的周期集总放大和恢复EI北大核心CSCD

基于包含渐减色散和周期集总放大的变系数非线性薛定谔方程,通过一种简单变换,解析出其精确孤子解,并研究了色散渐减周期集总放大(DDPLA)光纤链路中孤子的传输、放大和恢复。研究结果表明,当光纤色散、损耗和放大器增益相互平衡时,色散渐减光纤链路中可实现孤子的周期放大和恢复;而且可根据光纤损耗和放大周期来设置放大器的增益,或根据光纤损耗和放大器增益来设置放大周期,从而实现孤子的周期性放大或恢复。另外,采用数值计算的方法讨论了孤子的稳定性和相邻孤子间的相互作用。研究结果对实际的色散渐减周期集总光纤链中孤子的传输及周期放大链路的精确配置具有一定的理论指导意义。     

色散渐减光纤链中孤子的周期集总放大和恢复

基于包含渐减色散和周期集总放大的变系数非线性薛定谔方程,通过一种简单变换,解析出其精确孤子解,并研究了色散渐减周期集总放大(DDPLA)光纤链路中孤子的传输、放大和恢复。研究结果表明,当光纤色散、损耗和放大器增益相互平衡时,色散渐减光纤链路中可实现孤子的周期放大和恢复;而且可根据光纤损耗和放大周期来设置放大器的增益,或根据光纤损耗和放大器增益来设置放大周期,从而实现孤子的周期性放大或恢复。另外,采用数值计算的方法讨论了孤子的稳定性和相邻孤子间的相互作用。研究结果对实际的色散渐减周期集总光纤链中孤子的传输及周期放大链路的精确配置具有一定的理论指导意义。     

单模光纤中四阶色散控制的孤子族

研究了单模光纤中最小群速度色散波长附近的孤子传输，利用最小作用量原理得到了由四阶色散控制的一族孤子解，在这族孤子解中包含了原来文献中报道的精确解且解析解与数值模拟结果一致．     

色散缓减光纤的模面积对孤子传输的影响

本文求解了色散缓减光纤的NLS方程,由其孤子解讨论了色散缓减光纤模面积对孤子传输的影响。     

超短光脉冲在光纤中传输计算机模拟计算的研究

本文提出了一种研究超短光脉冲在介质中传输特性的简单的计算机计算方法.用该方法得到了正色散光纤中的频率调制、频谱加宽和方波自成形,以及负色散光纤中的一、二、三阶孤子传输.其数值计算结果与解非线性薛定谔方程的数值结果完全一致.     

光传输、通信理论

当皮秒孤子在群色散沿长度方向指数衰减的色散渐变光纤(DDF)中传输时,孤子的群色散和自相位调制保持局域平衡.宽度可以保持不变,用于孤子光通信有其特殊的优越性。但群色散分布满足要求的色散渐变光纤制造难度较大。文章提供了用群色散分段均匀的光纤(称其为阶梯色散渐变光纤)来加以替代的可能性。模拟结果表明,孤子可以在由这样的光纤及滑频滤波器     

Optical solitons for the decoupled nonlinear Schrödinger equation using Jacobi elliptic approach

Most of the important aspects of soliton propagation through optical fibers for transcontinental and transoceanic long distances can best be described using the nonlinear Schrödinger equation. Optical solitons are electromagnetic waves that span in nonlinear dispersive media and permit the stress and intensity to stay unaltered as a result of the delicate balance between dispersion and nonlinearity effects. However, this study exploited the Jacobi elliptic method and obtained different soliton solutions of the decoupled nonlinear Schrödinger equation with ease. Discussions about the obtained solutions were made with the aid of some 3D graphs.     

Bright and dark solitons in the normal dispersion regime of inhomogeneous optical fibers: Soliton interaction and soliton control

Symbolically investigated in this paper is a nonlinear Schrödinger equation with the varying dispersion and nonlinearity for the propagation of optical pulses in the normal dispersion regime of inhomogeneous optical fibers. With the aid of the Hirota method, analytic one- and two-soliton solutions are obtained. Relevant properties of physical and optical interest are illustrated. Different from the previous results, both the bright and dark solitons are hereby derived in the normal dispersion regime of the inhomogeneous optical fibers. Moreover, different dispersion profiles of the dispersion-decreasing fibers can be used to realize the soliton control. Finally, soliton interaction is discussed with the soliton control confirmed to have no influence on the interaction. The results might be of certain value for the study of the signal generator and soliton control.     

Darboux Transformation and Soliton Solutions for InhomogeneousCoupled Nonlinear Schrödinger Equations with Symbolic Computation

With the aid of computation, we consider the variable-coefficient coupled nonlinear Schrödinger equations with the effects of group-velocity dispersion, self-phase modulation and cross-phase modulation, which have potential applications in the long-distance communication of two-pulse propagation in inhomogeneous optical fibers. Based on the obtained nonisospectral linear eigenvalue problems (i.e. Lax pair), we construct the Darboux transformation for such a model to derive the optical soliton solutions. In addition, through the one- and two-soliton-like solutions, we graphically discuss the features ofpicosecond solitons in inhomogeneous optical fibers.     

Controllable Optical Solitons in Optical Fiber System with Distributed Coefficients

We present how to control the dynamics of optical solitons in optical fibers under nonlinearity and dispersion management, together with the fiber loss or gain. We obtain a family of exact solutions for the nonlinear Schrödinger equation, which describes the propagation of optical pulses in optical fibers, and investigate the dynamical features of solitons by analyzing the exact analytical solutions in different physical situations. The results show that under the appropriate condition, not only the group velocity dispersion and the nonlinearity, but also the loss/gain can be used to manipulate the light pulse.     

Multi-Solitons and Combined Solitons with Self-Similar Behaviors in a Birefringent Fiber with Higher-Order Effects

A coupled variable-coefficient higher-order nonlinear Schr(o|¨)dinger equation in biretringent fiber is studied,and analytical multi-soliton,combined bright and dark soliton,W-shaped and M-shaped soliton solutions are obtained.Nonlinear tunnelling of these combined solitons in dispersion barrier and dispersion well on an exponential background is discussed,and the decaying or increasing,even lossless tunnelling behaviors of combined solitons are decided by the decaying or increasing parameter.     

Some types of dark soliton interactions in inhomogeneous optical fibers

Dark solitons are the subject of intense theoretical and experimental studies in nonlinear optics due to their unique characteristics compared with bright solitons. In this paper, the variable coefficient high-order nonlinear Schrödinger equation in the inhomogeneous optical fiber is investigated. Via the Hirota bilinear method and symbolic computation, the analytic dark two-soliton solutions are obtained. With the suitable choices of functions and coefficients for the obtained dark two-soliton solutions, some new phenomena are presented for the first time. The influences on phases and amplitudes of soliton interactions are detailed analyzed. Moreover, sets of double-triangle structures and methods of changing the propagation direction of dark solitons are introduced. Finally, by choosing suitable functions of the fourth-order dispersion parameter, the arch-structure and M-structure interactions are revealed. Results may be potentially useful in designing all-optical switches and optical fibers.     

Dark Bound Solitons and Soliton Chains for the Higher-Order Nonlinear Schrödinger Equation

Dark bound solitons and soliton chains without interactions are investigated for the higher-order nonlinear Schrödinger (HNLS) equation, which can model the propagation of the femtosecond optical pulse under some physical situations in nonlinear fiber optics. Via the modulation of parameters for the analytic solutions, different types of dark bound solitons and soliton chains can be derived for the HNLS equation. In addition, stabilities of those structures are checked through numerical simulations. Our discussions are expected to be helpful in interpreting those new structures, and applied to the long-distance transmission of the femtosecond pulses in optical fibers.