Migration of broadcast-and-select optical crossconnects from semi-static to dynamic reconfiguration and their physical layer modeling

Abstract

Optical Crossconnects (OXC) are indispensable for the proliferation of broadband services. Next generation OXCs should be dynamically reconfigurable, to render the optical layer flexible and agile, cost competitive, in order to be a viable alternative to fully electronic solutions and multi-service, i.e. to be able to handle both optical circuits and packets equally well. In this work, an evolutionary migration scenario from semi-static to dynamically reconfigurable broadcast-and-select OXCs is presented. The cornerstone of this approach is modularity in both the node architecture and the corresponding functionality, since these two are inextricably linked. Here, the three evolutionary steps of a modular broadcast-and-select architecture are presented, their principle of operation is explained and their complexity is analyzed. The key building-blocks to implement these OXCs are optical switching elements operating in a gated mode and tunable wavelength converters. Concerning the physical performance of these architectures, an important consideration is that node capacity is traded for higher node cascadeability. This trade-off is studied extensively considering a combination of different switching technologies and optical components. Moreover, the 2R regenerative properties of the all-optical and optoelectronic wavelength converters play a key role in the node cascadeability assessment which is otherwise compromised by OSNR limitations. For this reason, analytical models providing an insight on how certain physical mechanisms are leading to performance degradation are used. The final assessment is made using a commercial simulation tool, allowing the derivation of conclusions for the size of the transparent islands.