Studies On Several Key Technologies In Switching Nodes For Optical Packet Networks

As the packet data rates increase, all-optical techniques are expected to assist in releasing the network from undesirable latencies related to O/E/O conversions at the switching nodes, especially assuming that transmission line rates will continue to increase beyond 10 Gb/s. In order to transmit packets from source to destination all-optically, it is crucial to be able to generate local clock signals for processing, as well as to be able to separate and recognize the address information embedded in a packet. jFirst of all, when optical packet enter the switching node it will processed by self-synchronization module, by the aid of which, local access node on the network, releasing the necessity of clock recovery, can select a single pulse from incoming packet streams, which is then utilized as a seed pulse to generate various local bit patterns to perform address recognition, ultra-fast optical sampling, or payload delineation.This dissertation mainly covers the following topics, Optical packet self-synchronization; Optical packet header extraction; Optical header payload separation; Switching nodes contention resolution. The original points consist of: Proposed in the second chapter this dissertation is a novel scheme of packet-level self-synchronization with semiconductor-optical-amplifier-assisted asymmetric Mach-Zehnder interferometer (SOA-MZI). The effect of cross-phase modulation (XPM) and cross-gain modulation (XGM) in SOAs coupled with the interfering characteristics of MZI are employed to make the proposal simple, fast and integrable, with no special treatment of the marker pulses. Through numerical simulation, with the system parameters designed properly, an intensity contrast ratio of more than 13dB at 100G/s can be achieved. And the second packet-level self-synchronization scheme is based on semiconductor optical amplifier (SOA), also included in the second chapter. The effect of fast gain saturation and relatively slow gain recovery in SOA are employed to make the proposal simple, fast and integrable, with no special treatment of the marker pulses.