Lightpath Establishment in Wavelength-Routed WDM Optical Networks

Wavelength-division multiplexing (WDM) technology has been improving steadily in recent years, with existing systems capable of providing huge amounts of bandwidth on a single fiber link. WDM systems are currently being deployed in long-distance telecommunication networks on a point-to-point basis, with the optical signals being converted back to electronics at each node. The electronic switching and processing costs at the nodes can potentially be very high, leading to severe performance bottlenecks and limiting the delivery of optical link bandwidth to the end users. Emerging wavelength-routed WDM systems, which utilize photonic crossconnects (PXCs), are capable of switching data entirely in the optical domain. Configuring these optical devices across a network enables one to establish all-optical connections, or lightpaths [1], between source nodes and destination nodes (Fig. 1). Data carried on these lightpaths avoid electronic conversion and processing at intermediate nodes, thereby alleviating the electronic bottleneck.