二阶分布式拉曼放大器特性的研究

发布时间：2018-04-25 03:20

本文选题：二阶分布式拉曼放大器 + 拉曼散射效应　；参考：《武汉邮电科学研究院》2017年硕士论文

【摘要】：光纤通信技术的不断进步使信息社会快速发展,当前大容量、长距离、高速率的密集波分复用技术(DWDM)的使用把光纤通信推向一个崭新的高度,同时急剧增大的通信业务和高质量要求的光通信系统促使光放大器性能不断增强。传统的掺铒光纤放大器(EDFA)由于带宽受到限制以及较低的噪声性能等原因无法完全满足光通信系统的要求,而拉曼光纤放大器(FRA)具有带宽大、增益高、低噪声等优点,在光放大器的家族中有重要地位。分布式拉曼放大器(DRA)不仅更可以充分展露FRA的带宽大的优势特征,还能有效的减小其他非线性效应的影响。但是一阶光纤拉曼放大器的作用依然有限,为满足更高通信质量的要求,二阶DRA及更高阶DRA成为研究热点。二阶DRA有更高的增益,能显著的优化系统的信噪比,采用二阶泵浦的方案可以有效提高RFA的性能,使其更适用于无中继长距离传输系统。本论文以二阶分布式拉曼放大器为研究对象,主要分析了二阶DRA的增益平坦优化方法以及噪声特性与二阶泵浦占比的关系,主要内容可归纳如下:(1)首先介绍了拉曼放大器相关背景知识,引出研究二阶拉曼放大器的意义,然后概括了国内外对这个课题的研究状况。(2)在给出拉曼散射的概念后,先使用量子理论的方法进行解释,后面又从经典理论加以说明,简述了二阶拉曼的泵浦技术和结构方案,由上述理论知识推导了二阶拉曼的传输方程,给出了不同条件下拉曼方程的求解方法,为二阶拉曼放大器增益特性和噪声特性的分析奠定理论计算基础。(3)介绍了影响拉曼增益的几种因素,通过对拉曼增益谱简单分析,得出拉曼增益平坦优化的必需性,于是又介绍了遗传算法,进一步给出了应用于二阶DRA的二步优化算法。(4)给出了二阶DRA的噪声来源,进而解释了描述分布式拉曼放大器噪声大小的等效噪声指数的概念,而后实验研究了二阶泵浦功率在泵浦总功率的占比情况对系统等效噪声指数的影响,并在理论求解拉曼传输方程的基础上对实验结果进行了分析验证。(5)总结和展望部分对整篇文章作了简要的概述整理,对课题研究的发展进行了预测。
[Abstract]:With the continuous progress of optical fiber communication technology, the rapid development of the information society, the current large capacity, long distance, high speed dense wavelength division multiplexing (DWDM) technology, the use of optical fiber communication to a new height, At the same time, the rapid increase of communication services and high quality of optical communication systems promote the performance of optical amplifiers. Because of the limited bandwidth and low noise performance, the traditional EDFAs can not fully meet the requirements of optical communication systems, while the Raman fiber amplifiers (FRAs) have the advantages of large bandwidth, high gain, low noise and so on. It plays an important role in the family of optical amplifiers. Distributed Raman amplifiers (DRAs) can not only fully reveal the advantages of large bandwidth of FRA, but also effectively reduce the influence of other nonlinear effects. However, the first order fiber Raman amplifier still has a limited function. In order to meet the requirement of higher communication quality, the second order DRA and higher order DRA become the research focus. The second order DRA has higher gain and can significantly optimize the signal-to-noise ratio of the system. The second order pumping scheme can effectively improve the performance of the RFA and make it more suitable for the non-secondary long distance transmission system. In this paper, the second order distributed Raman amplifier is studied. The gain flatness optimization method of the second order DRA and the relationship between the noise characteristics and the second order pump duty ratio are analyzed. The main contents can be summarized as follows: firstly, the background knowledge of Raman amplifier is introduced, and the significance of studying second-order Raman amplifier is introduced. Then, the research status of this subject at home and abroad is summarized. (2) after giving the concept of Raman scattering, The second order Raman pumping technique and structure scheme are briefly described by means of quantum theory and then explained by classical theory. The transport equation of second order Raman is derived from the above theoretical knowledge. The method of solving Raman equation under different conditions is given, which lays a theoretical calculation foundation for the analysis of gain and noise characteristics of second-order Raman amplifiers. Several factors affecting Raman gain are introduced. The Raman gain spectrum is analyzed simply. The necessity of Raman gain flattening optimization is obtained, and then genetic algorithm is introduced. Furthermore, the two-step optimization algorithm for second-order DRA is given, and the noise source of second-order DRA is given. Then the concept of equivalent noise index describing the noise level of distributed Raman amplifiers is explained. Then the effect of the second order pump power on the system equivalent noise exponent is studied experimentally in the case of the ratio of the second order pump power to the total pump power. Based on the theoretical solution of Raman transport equation, the experimental results are analyzed and verified. (5) in the part of summary and prospect, the whole paper is briefly summarized and arranged, and the development of the research is forecasted.
【学位授予单位】：武汉邮电科学研究院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN722

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