Soliton ultrafast all-optical mesh networks

Abstract

Channel transmission error arguments show how the size of an all-optical multihop network employing deflection routing is limited for a given optical bit rate. These limits are quantified for nonregenerative all-optical mesh networks such as Manhattan Street network and ShumeNet employing solitons. It is found that the node-to-node fibre span cannot exceed a few kilometres for network sizes up to 400 nodes when the optical bit rate is as high as 100 Gbit/s if the packet error rate is to be bounded below 1 Introduction All-optical networks and ultrahigh bit ratesThe ever-growing need for faster communication speed is leading towards all-optical packet-switching fibre networks, as optical components progressively replace their slower electronic counterparts. As a first step towards higher transmission rates, optical fibres replaced copper wires as network links between nodes. The switching nodes, however, remained electronic, and the optical signal had to be down-converted to electronics for switching, buffering and routing, and then remodulated onto an optical carrier for retransmission. As a next step, in all-optical networks even the switching process will be completely optical. This will allow even higher transmission rates, since the switching can be done much faster than allowed by standard electronic switches, and more flexibility, as the switch is completely transparent to the optical packet, which can thus support any bit rate in the payload. Only the header will need to have a fixed rate since it is the only part of the packet that needs to be read at every intermediate node to correctly route the packet.Multihop mesh networks [l, 23 are attractive in this perspective since they break down the computational complexity of the control of the switching process, which increases exponentially with the number of users, by evenly distributing it among all nodes. In two-connected networks, for instance, each node has only two optical inputs and two optical outputs, and the routing and This proved to be even more attractive in all-optical networks, where one of the technological limitations is the lack of very fast access, flexible, simple optical memories. The limited-time buffering strategy of deflection routing is perfectly suited to be implemented with simple recirculating fibre delay loops, with no need of optical amplification in the loop. Both multihop distributed networks (as opposed to single-hop, centralised networks) and deflection routing (as opposed to store-and-forward (S&F) routing) are solutions which trade efficiency for a much simpler hardware implementation. If ultrahigh bit rates can be sustained by these distributed structures using deflection routing, a net gain in throughput can effectively be achieved.Generation, multiplexing and demultiplexing of optical packets at ultrahigh bit rates is made possible by recent technological breakthoughs in nonlinear optics. Mode-locked semiconductor lasers in the 1.55 pm wavelength region are today capable of producing trains of pulses of widt...