Nobody predicted 20 years ago that we would ever run into a fiber capacity crunch, if not quite a crisis, across the whole spectrum of applications from cable access networks through mobile backhaul right to inter-continental submarine cables. Major fiber transmission technology developers have been caught on the hop with solutions to the capacity shortage on the horizon, but not yet commercially available. Even when new technologies do emerge, many of them, including some of the spatial division multiplexing techniques from Nokia and others that we discussed last week, will be confined to greenfield deployments. A major cost of fiber infrastructure is installation, especially for access networks and so upgrading with new cable is often unfeasible. The idea of installing…