Numerical modelling of transoceanic cable systems

The advent of the erbium doped fibre amplifier (EDFA) has revolutionised the options available to submarine cable system planners. In a years it has become possible to extend the range of unrepeatered systems to more than 300 km, thus providing options for cheaper and more reliable systems, for increased route diversity or for the direct interconnection of frontier stations. Here EDFAs have been used at the transmitter to achieve a high launch power, and at the receiver to provide a very sensitive pre-amplified receiver, both contributing to the achievement of a long span. In a second application, EDFAs have enabled the capacity of new transoceanic systems such as TAT 12/13 to be increased to 5 Gbit/s, almost a factor of ten increase over earlier systems such as TAT 8-11. Here the EDFAs have been used to replace the complex electronic 3R regenerators used in the earlier systems with optical amplifiers, thus keeping the signal in the optical domain for the entire transmission path