Investigation Of High-precision Chromatic Dispersion Management Technology For Ultra-high Speed Optical Transmission System

With the development of ultra-fast, ultra-long haul, and large-capacity for the optical transmission system, fiber chromatic dispersion effects on the transmission system is growing. For the same modulation format of optical transmission systems, the dispersion tolerance for 100 Gbit/s system is only 1% of that for 10 Gbit/s system. This requires a high accuracy of compensation for the transmission fiber dispersion. In order to achieve an accurate compensation, we firstly need an accurate measurement of fiber dispersion. Herein, in the perspective of nonlinear suppression, we analyze how accurate dispersion management technology enhances the performance of system. We also discuss relevant technologies on in-line dispersion compensation in optical transmission link and tunable dispersion compensation at receiver. In addition, based on current dispersion measurement technique, we suggest a rapid method for dispersion measurement and this method is demonstrated by simulation.At the beginning of this thesis, the physical damage to the fiber is theoretically analyzed, including dispersion, PMD and a variety of nonlinear effects. The topic originates from the production of a variety of physical injuries, giving their impacts on the transmission system performance. This provides a theoretical basis for in-depth study and discussion in the subsequent chapters.In this thesis, we analyze the improvement on system performance by employing high accurate dispersion management technology. We firstly investigate the intra-channel cross-phase modulation (IXPM) and intra-channel four-wavelength-mixing (IFWM) effect in high speed optical transmission system and then explain how to suppress these two nonlinear effects by optimizing dispersion map design. The difference between high precision dispersion management map and the dispersion map of existing fiber links is compared. We compare the effect of non-linearity suppression by using these two maps. The results show that the system performance can be improved by using high precision dispersion management map.We also analyze dispersion compensation technique on existing optical transmission link. At first, by comparing current dispersion compensation methods, we pointout the advantages of dispersion compensation fiber (DCF) with trip-cladding structure employed in the optical fiber link. Based on the criterion for trip-cladding structure on the properties of dispersion compensation module, this thesis proposes a systematic criterion:by determining the amount of nonlinear phase shift and the dispersion curve of DCF, we conclude that when the figure of merit of dispersion compensation fiber is greater or the dispersion compensation coefficient is greater, the nonlinear phase shift caused by dispersion compensation module is smaller. However, with an increase in dispersion compensation coefficient, the dispersion compensation curve will not match that of the transmission fiber, and it will thus affect the dispersion compensation accuracy and cause nonlinear impairments. Therefore, in the selection of dispersion compensation module, we need to consider several factors including FOM, dispersion compensation coefficient and dispersion curve. In addition, we analyze the post dispersion compensation for residual dispersion and propose a method using the extracted clock signal power with incorporation of a tunable dispersion compensation device. This method can optimize the residual dispersion by monitoring the clock signal power. This is proven by simulation results.High precision dispersion compensation requires accurate dispersion measurement. The thesis lastly analyses relevant techniques on dispersion measurement. First, we conduct a comprehensive analysis and summarize the advantages and disadvantages on existing dispersion measurement techniques and commercial measurement equipments. In need of real-time and fast dispersion measurement for future optical networks, we suggest a fast dispersion measurement apparatus. Analysis of the principle as well as its simulation results show that this method is rapid, accurate, simple, low cost, and it can provide a large dispersion measurable range.