A broadcast-and-select OADM optical network with dedicated optical-channel protection

A metro-area optical-ring network based on a novel optical add-drop multiplexer (OADM) architecture using a wavelength blocker is proposed. We demonstrate experimentally the performance of the OADM and capability of optical channel dedicated protection in a two-fiber ring network with 24×10 Gb/s dense wavelength division multiplexing traffic capacity. The channel-by-channel optical protection of the network is enabled by using a liquid crystal-based wavelength-selective switch as the protection switch and erbium-doped fiber amplifiers (EDFAs) with fast transient-gain control. The bit-error rate performance of the network is studied for the normal operation and for the transition to the protection state from a failure. The network protection for all channels is provided within 5 ms on a cable-cut failure. Importance of transient-gain control during protection switching to reduce the network transients is also discussed.