Design and Implementation of Wavelength Flexible Nodes

We present an experimental and analytic study of a photonic (all-optical) crossconnect with wavelength flexibility. The crossconnect is designed to scale efficiently with increasing traffic volumes and bit rates on dense wavelength division multiplexed optical networks. At the heart of the crossconnect is a MEMS-based photonic switch fabric capable of switching between hundreds of input and output ports. Complementing the switch is an all-optical wavelength converter, provisioned on the output ports of the switch to avoid wavelength blocking and allow efficient use of network capacity. In an alternate configuration, a small number of converter/amplifier pairs may be provisioned in a loop-back mode to create a shareable converter pool. The crossconnect was successfully tested in both configurations with error-free transmission at a bit rate of 10 Gb/s. We also consider the blocking performance of such a crossconnect under a dynamic, random model for lightpath requests. Analysis and simulations under this model show that wavelength flexibility greatly increases the ability of a node to accommodate random lightpath requests. In many cases, even a relatively few wavelength converters have a significant impact.