During the last thirty years or so it has been widely recognised in the research community that the key transmission medium seeming capable of serving both the ever-growing demand for bandwidth and the unceasing need for new services, is optical fibre. In this context, Wavelength Division Multiplexing (WDM) is the most popular technique for introducing concurrency among multiple user transmissions into the network and, thus, exploiting the huge amount of fibre bandwidth available under the...
