毕业设计基于FPGAchirp通信系统调制解调技术.doc

编号： 毕业设计(论文)外文翻译 （原文） 学 院： 信息与通信学院 专 业： 通信工程 学生姓名： 李忠斌 学 号： 1000210219 指导教师单位： 信息与通信系 姓 名： 樊孝明 职 称： 讲师 2015年 6 月 8 日 Investigation of modulator chirp and extinction ratio in different RZ- and NRZ duo-binary transmitter modules for performance optimization Abstract - In this work we present a comparative investigation of modulator chirp and extinction ratio in different transmitter modules for 10Gbps, 20Gbps and 40Gbps RZ- and NRZ duo-binary transmission. For comparative analysis three types of transmission modules have been considered viz. push–pull configuration based on dual arm MZIM, delay-and-add circuit based single arm MZIM and a duo-binary filter followed by single arm MZIM. For each case, the modulator chirp has been optimized with an extinction ratio of 20 dB. Investigation has been carried out to find extinction ratio of single arm MZIM used for RZ- and NRZ duo-binary transmission that offers system performance comparable to dual arm MZIM at 10, 20 and 40Gbps. The results help choosing the best suitable transmitter module with optimized modulator chirp and extinction ratio. INTRODUCTION In high speed optical communication systems duo-binary modulation is an effective solution that provides a better spectral efficiency and reduces the performance degradation owing to dispersion and nonlinear effects [1?3]. In the 1980s and the early 1990s, direct modulation of semiconductor laser was the mostly used technique. However, direct modulation has several limiting factors like it induces unwanted chirps which results in spectra broadening of the signal, hence causing severe dispersion penalties [4]. Directly-modulated optical signals experience fluctuations in intensity due to Relative Intensity Noise (RIN) of the semiconductor laser. Nonzero line width of laser sources introduces laser phase noise thus for high speed trans