Chromatic Dispersion Compensation Algorithms For Coherent Nyquist-WDM System And Applications Of Linecoding For WDM-PON

To meet the increasing demands for bandwidth, both optical backbone and optical access network, are faced with the challenge of expansion and upgrade.Coherent optical communication technology is the key enabler for the long-haul transmission at 400 Gb/s, even 1 Tb/s. In particular, as the coherent optical Nyquist-WDM (wavelength division multiplexing) super channel technology can shorten the spectral interval and maximize the use of communication spectrums, seems to be the most promising candidate. With the expansion of the backbone network, the low-speed access network has become the bottle neck in the development of network bandwidth. Passive optical network (PON) has been put foword and became the most attractive access solution. Smooth upgrade to next generation of PON is an important part of the access network research.In this paper, our research are conducted based on adaptive Chromatic Dispersion (CD) estimation algorithms in coherent WDM-Nyquist system and smooth upgrade of PON system. The performance of the adaptive CD estimation and compensation algorithms in coherent optical system is described. In addition, linecoding used in high speed new PON signal in PON evulation is proposed since it can decrease the low-frequency component of coded signal.The main innovation of the dissertation can be elaborated in two aspects.Fisrtly, the performance deficiencies of the existing adatptive CD compensation algorithms in coherent Nyquist system is studied. Two new algorithms applicable to the Nyquist system are proposed and investigated via simulation.Secondly, with regard to PON network upgrade needs, methodologies are analyzed to linecode the high speed new PON signal in PON smooth and gradual upgrade. In the mean time, to decrease the crosstalk to low speed old PON signal. A simple but effective upgrade PON structure based on linecoding is proposed, and pulse position modulation (PPM) linecode is proved to be feasible via experiment. Meanwhile, the use of PPM to encode the downstream signal asymmetric remoduationed WDM-PON is proposed. In this way, the crosstalk to upstream signal is decreased, then the performance of the proposed system is tested.