Studies On Self-Synchronization Clock Extraction Technology In Optical Packet Switching Network

Long as the diversity of the telecommunication service, the optical fiber network developed fast as a fundamental network which supports it. The bandwidth was greatly widened and the record has already reached T-byte level. The achievements of optical transportation raised new demand of the process capacity of the switching node. But nowadays the process is completed in electronic domain, limiting the increase of network bandwidth. So the research emphasis of the optical network has shifted from transporting to switching. Optical packet switching (OPS) network becomes the orient of future optical communicationIt is necessary to process kinds of signals from optical packets at the nodes of OPS network. All optical signal processing is unavoidable especially in communication system whose speed exceeds 40Gbit/s. All optical self-synchronization is just one of the all optical signal processing at the switching nodes. The optical pulse denoting the beginning of each optical packet named marker pulse is extracted to be the local address clock.Recent years, the self-synchronization technology based on SOA has raised great research interest. The SOAs in such schemes act as intensity discriminators thanks to their fast gain saturation under short and strong pulse so there is no need of special treatment at wavelengths, polarization, intensity, or bit-period of the marker pulse, avoiding some nonlinear effect in transporting. Nowadays the research in this field advances towards making the system more compact, integral and less consumption of energies. This paper aims to analyze all optical self-synchronization schemes based on SOA, emphasizing on the influence of ASE noise and the problem of the performance relying on the coding ways of the input pulses:The first chapter briefly introduces the OPS network, describing the key technologies and the current researches. The emphasis is at the all optical self-synchronization technology.The second chapter introduces the characteristic of SOA in the self-synchronization schemes, impressing on its dynamic gain and numerical model. It also gives the numerical simulation steps in self-synchronization schemes.All optical self-synchronization clock extraction based on SOA is one of the most important functions of the advanced optical network nodes, but ASE noise produced by SOA will influence the capability of self-synchronization scheme which makes the analysis of noise in need. The impact of ASE noise on the SOA-DI synchronization clock extraction scheme is discussed by introducing a method of equivalent noise source, giving a theoretical model and doing numerical simulation in the third chapter. The simulation result shows that compared with the situation of excluding the impact of ASE, if other parameters are fixed, when the postpone of DI diminishes to certain value, CR descends rapidly instead of increasing. On the basis of the result, the system performance could be improved by optimizing the parameters to counteract the noise.Proposed in last chapter is a self-synchronization scheme based on the XGM effect of the SOA. If the input pulses have long successive "0", the saturated gain of SOA may recover and the error recognition will occur. This scheme attempts to solve this problem by introducing more delay control pulses and its performance is examined by numerical simulation under condition of some parameters.