Towards transparent optical networks: still some challenges ahead

Optical transparency is widely recognized to potentially offer significant cost savings as a result of the elimination of OEO regenerators in optical nodes (either based on optical cross-connects or optical add-drop) but this is obtained at the expense of new constraints/challenges on the physical layer. Technical solutions are available and currently being assessed from an industrial viewpoint. However, the actual impact of their implementation in optical networks is still to be fully assessed in terms of complexity and cost. The degree of actual transparency reached by next-generation optical networks and their commercial and operational availability will clearly be conditioned by this last point.