Studies On Key Technologies Of Optical Packet-Switched Networks

The widespread use of the Internet and the availability of high-bandwidth services necessitate a fundamental shift of the network-bottleneck from transporting to switching. However, nowadays wavelength switching is actually connection-oriented circuit switching (CS) with huge granularity, which proves significantly capacity-wasted and fundamentally mismatched with the needs of the fastest-growing sector of telecommunications—the Internet. Optical packet switching (OPS) exploits the bandwidth statistically and represents the most promising solution for future intelligent optical networks, providing efficient way to satisfy the increasing demand for bandwidth requirement and network flexibility. Always use packet switching in lowest layer for efficiency. That explains the motivation of our efforts into the research. This dissertation aims to tackle several tough system-level issues of OPS, such as switching architectures①, optical buffering strategies②, ultra-fast wavelength conversion③and all-optical logic devices④. It first presents a survey of the current state of the art in optical packet switching. The performance of typical switching architectures is examined in terms of homo-wavelength crosstalk. Corresponding analytical models are developed by introducing the effective crosstalk-coefficient for each interfering channel. It is shown that the tree-like node structure (as in the broadcast-and-select node) performs better than the other ones. ①Optical output buffering strategies are studied, for OPS with variable packet length and for prioritized optical burst switching. In particular, a prioritized scheme of optical feedback buffering in OPS node is proposed. Related Vacation Queuing Model is established with Binomial Gated Multi-Service discipline. Furthermore, numerical analysis and network simulations are conducted to validate the model and examine the performance. ②Ultra-fast wavelength conversion based on nonlinear-optical-loop-mirror is investigated, involving the effects of walk-off and group velocity dispersion. Two-phase-shifted Bragg gratings are introduced, serving as a narrow band-pass filter to improve the system performance. Numerical simulations show that the pulses out of the modified implementation are compressed and reshaped. ③Two types of ultra-fast all-optical XOR gates, using semiconductor-optical-amplifier-based Mach-Zehnder interferometer (SOA-MZI), are studied through analytical method and numerical simulations, in searching of the optimal parameters and the suitable operation condition. Consequently, several rules and limits on the parameter design have been drawn. In further investigation, a novel packet-level self-synchronization scheme for slotted optical packet networks is proposed to perform address recognition, payload delineation or ultra-fast optical sampling. Through numerical simulations, this scheme operating at 40Gb/s is validated and its performance is examined. ④...