光纤通信系统中脉冲传输特性的研究
文献类型：学位论文
| 作者 | 张向阳 |
| 学位类别 | 博士 |
| 答辩日期 | 2004 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 王向朝 |
| 关键词 | 光孤子 双折射效应 三阶色散 偏振模色散 色散管理 |
| 其他题名 | Study on properties of pulse propagation in fiber communication systems |
| 中文摘要 | 随着信息时代的到来，人们对信息的需求量越来越大。光纤通信在信息的传递中起着重要作用，但随着光纤通信的发展，光通信在超长距离、超大容量发展进程中，遇到了光纤损耗和色散的问题，限制其发展空间。光孤子传输不变形的特点决定了它在通信领域的应用前景。全面掌握脉冲在光纤中的传输规律，对于光纤传输系统的优化设计起着十分重要的作用。本文研究光脉冲在光纤中的传输特性。研究内容及取得的创新成果可以概括为如下几点：研究孤子脉冲在双折射光纤零色散点附近的传输特性，分析了三阶色散作用下，双折射非线性系统的调制不稳性。讨论了三阶色散对孤子脉冲传输的影响。假设输入光脉冲为线偏振光，偏振方向和光纤的双折射轴成任意夹角。在输入脉冲两个偏振分量强度相等的情况下，分析发现：三阶色散作为一种很小的微扰，不影响孤子的捕获条件，但脉冲的两偏振分量的演化有显著差别。脉冲的形状、频谱和孤子辐射等在两个偏振分量中都呈现出不对称性。当两偏振分量强度不相等时，分析发现：当输入脉冲的振幅超过一定域值时，光纤中会形成一个或多个孤子脉冲：同时，两个相互捕获的脉冲变得很尖，连续的色散波主要在一个分量中。研究了光脉冲在双折射光纤零色散波长的传输特性。分别在等振幅和不等振幅情况下，从脉冲的频谱移动、形成孤子的位置等参量分析了形成光孤子的物理机制。分析发现：在零色散波长，由于频谱的分裂可以在强色散波的背景上形成相互捕获的孤子脉冲。研究光纤双折射随机变化时光的传输特性。从频谱和系综两方面应用蒙特－卡罗方法，对不同模式藕合条件下的偏振模色散矢量几率分布进行了模拟，并将模拟结果进行了函数拟合。发现在光纤很短时，即没有偏振模藕合时，群时延差的几率分布类似一个Delta函数分布，随藕合次数的增加几率分布逐渐变成麦克斯韦分布。在一定的祸合下，群时延差的几率分布可以是高斯分布。随着祸合次数的增加，偏振模色散矢量的两个方向余弦函数的分布分别从高斯分布和Delta函数分布都演化为均匀分布。研究三阶色散作用下，单模光纤色散管埋系统中脉冲的传输特性，分析了三阶色散作用下色散管理孤子的参量演化的过程。研究色散管理孤子在双折射光纤中的传输特性。应用变分法分析并给出了双折射光纤中色散管理孤子参量演化的常微分方程。数值分析双折射对孤子参量的影响，分析发现在双折射光纤中色散管理孤子的宽度和惆啾量都不再是严格周期性变化。提出了偏振管理的概念，在色散管理的同时进行偏振管理可以消除走离效应对脉冲传输的影响，产生自相似结构的管理孤子。 |
| 英文摘要 | With the advent of the information era, the information quantity becomes increasingly higher. Optical communication plays an important role in modern communication areas. But in the development of the optical communication, there exist two main limitations, fiber loss and dispersion in the ultra-long distance and ultra-high capacity optical transmission. Because optical soliton can propagate over long distances without any distortion of its waveform, it has potential applications in the field of optical communication. For designing the optical fiber transmission system, it is very impantant to comprehend the properties of the pulse propagation in the fibers. Propagation of the optical pulse in the fibers is studied in the dissertation. The constents of the research work and conculsions are described as follow: Propagation of solitons in birefringent single-mode fibers near the zero dispersion wavelength is considered. Under effect of the third-order dispersion, the modulation instability of the nonlinear optical fiber system is analyzed. Effects of the third-order dispersion on the soliton propagation are studied. Initial pulses are assumed to be linearly polarized at an arbitrary angle with respect to the polarization axes. When the amplitudes of the partial pulses are equal, it is found that the third-order dispersion, as a small perturbation, does not affect the threshold of the soliton trapping. The evolution of two partial pulses is in a markedly different manner. The asymmetric oscillation structure is dominantly in one polarization. When the initial amplitudes are unequal, it is found that one or more solitons emerge from the initial pulse above a certain threshold. The two-captured pulses are very sharp and the continuum ends up in one polarization. Propagation of solitons in birefringent single-mode fibers at the zero-dispersion wavelength is considered. For equal and unequal amplitude, emerging process of the soliton pulse is anaylzed from the frequency shift and location of the soliton. It is found that due to the frequency spectra break, the trappiung soliton emerges from the background of dispersion wave at the zero-dispersion wavelength. When the birefringence of the fibers changes randomly, optical propagation is considered. The probability distribution of the differential group delay for different mode-coupling times is simulated with Monte-Carlo method. Fitting the results of the simulation, we obtain probability distribution function for different mode-coupling times. It is found that the probability distribution function of the magnitude of the dispersion changes from a very sharp 5-like function to Maxwellian with increase of coupling times of the two polarization modes. At certain coupling times, the probability distribution function is Gaussian. Two direction cosines of the PMD vector are taken statistics. With increasing of the coupling times, it found that the probability distribution of the direction cosines of the PMD vector changes from a Gassian and a δ-like distribution to a uniform distribution. Considering the third-order dispersion, we discuss dispersion-managed system of the single-mode fibers. We study the process of the parameter evolution of the dispersion-managed soliton. Propagation of dispersion-managed soliton in birefringent optical fibers is considered. A set of ordinary differential equations is obtained by means of approximate variational method. Effects of the birefringence on parameters of the dispersion-managed soliton are analysed numerically. It is found that evolutions of pulse duration and frequency chirp are not periodical due to effects of walk-off. Concept of polarization-managed is put forward. When the walk-off is compensated through rotating the axis of the birefringent by π/2 in the dispersion line, managed soliton can be obtained. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15523]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 张向阳. 光纤通信系统中脉冲传输特性的研究[D]. 中国科学院上海光学精密机械研究所. 2004. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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