宽带光纤拉曼放大器的优化设计

【作者】 陶在红；

【导师】 张明德；

【作者基本信息】 东南大学 ， 物理电子学， 2004， 硕士

【摘要】 随着信息容量需求的急速增长和WDM技术的快速发展,大大激发了对高性能光放大器的需求。光纤拉曼放大器(FRA) 利用传输光纤本身的非线性效应实现光放大,由于其自身的优良特性,已成为宽带放大器中最有前景的竞争者。本文主要研究平坦增益带宽光纤拉曼放大器的优化设计。首先在第一章简要介绍了FRA的特点及发展情况。接着在第二章中对FRA的理论模型进行了较全面的分析,并讨论了FRA的主要工作特性。在第三章中,采用四阶阿当迭代算法对FRA的主要工作特性进行了数值计算,分析了FRA的增益特性,计算了放大器的噪声系数。求解中不作任何假设近似,综合考虑了泵浦、信号、噪声在传输过程中的相互作用,因此更符合实际情况。比较表明,计算结果与发表的结果符合很好。宽带光纤拉曼放大器的优化设计是本文的重点内容,第四章介绍了一种新颖的宽带光纤拉曼放大器的优化设计方法。通过研究多波长后向泵浦光纤拉曼放大器的传输方程, 分两步来确定各泵浦波的频率及输入功率的大小。首先通过模拟退火算法和遗传算法迭代出满足条件的泵浦波频率, 而后利用平均功率分析方法, 采用四阶阿当迭代方法计算出各泵浦波输入功率的大小, 从而设计出具有较宽平坦增益带宽的光纤拉曼放大器。设计了两个光纤拉曼放大器, 一个采用双波长泵浦, 得到的平坦增益带宽达50nm, 增益不平坦度小于1dB。另一个采用四波长泵浦, 得到的平坦增益带宽达80nm, 增益不平坦度小于1dB。所得结果证明提出的优化设计方法对于设计多波长泵浦平坦增益带宽光纤拉曼放大器是一种有效的方法。更多还原

【Abstract】 All-optical amplifiers with large gain-bandwidth are required extensively because of the increasing of the capacity of optical fiber communication systems and the development of Wavelength Division Multiplexing (WDM) technologies. Fibre Raman Amplifiers (FRAs), which use the intrinsic nonlinear properties of transmission fibers to obtain signal amplification, are the most promising in broadband optical amplifiers owning its unique performances. Flat gain bandwidth is an important requirement in designing the amplifiers. This dissertation studies the optimization of the gain spectrum of FRAs in order to obtain the FRAs with optimal gain-flattened and larger gain-bandwidth performances.The fundamentals and developments of FRAs are firstly introduced in the first chapter. In the second chapter, a theoretical model of FRAs is presented and the main characteristics of FRA are discussed. In the third chapter, the optical gains and noise figures are numerically calculated by making use of the 4-step Adams_Bashforth method. The analysis includes all the interactions among pumps, signals and noise without any approximation. Comparing the calculation results with reported data shows that a good agreement is given. The optimal design of broadband FRAs is the main target in this dissertation. A novel optimal design method for FRAs is presented. The propagation equations of FRAs pumped backward at multiple wavelengths are solved with two steps. First, the simulated annealing algorithm and the genetic algorithm are used to obtain required pump frequencies; Then, by making use of average power analysis method, the 4-step Adams_Bashforth method is adopted to design optimal gain-flatness and gain-bandwidth performances. Two fiber Raman amplifiers are designed with two pumps and four pumps,respectively. The relative gain flatnesses for the two-pump FRA and the four-pump FRA are all less than 1dB within the bandwidths of more than 50nm and 80nm,respectively. The calculational results verify that the proposed method is practicable and useful for designing FRAs with flat gain in broad bandwidth.更多还原