Label-Controlled Optical Switching Nodes Label-Controlled Optical Switching Nodes

NUR 959 Trefw.: optische telecommunicatie / nietlineaire optica / optische signaalverwerking. Subject headings: optical fibre communication / nonlinear optics / optical information processing. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means without the prior written consent of the author. Summary Optical networks are evolving from initially static optical circuits and subsequently optical circuit switching towards optical packet switching in order to take advantage of the high transport capacity made available by WDM systems in a more flexible and efficient way. Optically labeling of packets and routing the packets's payload optically under control of its label allows the network nodes to route and forward IP data without having to process the payload, thus keeping it in the optical domain; this is a promising solution to avoid electronic bottlenecks in routers. All-optical label switching can therefore be used to route and forward packets independent of their length and payload bitrate. Several optical signal labeling techniques have been proposed in previous research reported in literature; orthogonal labeling and time-serial labeling have been studied in this thesis. This thesis studies two orthogonal modulation labeling techniques: one based on FSK labels with an IM payload, and another one on SCM labeling for a DPSK modulated payload. A time-serial labeling method based on IM labels with IM or DPSK payload is also presented and studied. The first two techniques assume electronic processing of the labels in the node, and hence assume that labels can be transmitted at a much lower bitrate than the payload data rate. The third technique assumes all-optical signal processing in the nodes, capable of handling a label at the same bitrate or slightly lower than the payload data. Labels at low bitrate in comparison with the payload bitrate are desirable in systems where the label processing will be conducted in the electrical domain, while labels at the same bitrate as the payload can be used in systems where the processing is conducted in the optical domain, exploiting all-optical processing techniques. These three techniques have been chosen because they are compatible with the existing networks, since the modulation format, bitrates, transmission properties, and other features of the signals are similar to the ones used for commercially available applications. Thus, they can be considered important candidates for migration scenarios from optical circuit switching towards optical burst switching networking. vi Orthogonal …