Towards photonic networking: Experimental demonstration of a reconfigurable survivable WDM ring network

A novel highly-flexible optical add/drop multiplexer (OADM) architecture suitable for evolution of point-to-point WDM systems towards an optical network layer has been presented. Three rack-mounted OADM nodes based on this architecture have been built with off-the-shelf components. These nodes were then assembled in a 10-Gbit/s 4-wavelength self-healing (2-fibre) unidirectional ring network. Each node performs basic functionalities like "Add", "Drop" and "Transit". Broadcast and efficient self-healing protection were also demonstrated. The experimental results show very good cascadability of the nodes with negligible power penalty (0.3 dB after 1080 km transmission with 12 signal regenerations). A path over 2000 km across a multi-layer transport network was experimentally simulated by recirculations carried out with this ring network testbed. Already, these demonstrations, together with system studies in routing, dimensioning and network architecture, show the short-term feasibility of flexible WDM ring network architectures, which is identified as an important step in the implementation of photonic networking.