SUBMARINE SYSTEMS : FROM LABORATORY TO SEABED

Submarine cable systems that incorporate optical amplifiers by use of dense wavelength division multiplexing (DWDM) technology are discussed. The equipment and architecture of modern submarine networks are briefly described. The submarine system family includes: a cable that contains as many as eight optical fiber pairs; submarine repeaters that provide gain to compensate for fiber loss; a branching unit that allows for undersea fiber connect; submarine line terminal equipment (SLTE) that interfaces terrestrial traffic to the submarine transmission line; and power feed equipment (PFE) to "fuel" the submerged plant. All the equipment are monitored and controlled by a submarine management system (SMS). The phases of research and development (R & D), and a contract implementation work plan are also outlined. Today's submarine systems are usually manufactured, laid, installed and commissioned in an 18-month period. Large-scale R & D efforts have made it possible to increase cable capacity and robustness in accordance with market needs. The most significant in this respect are erbium-doped fiber amplifiers and out-of-bound forward error correction (FEC). Hence, these submarine cable systems have become the backbone of intercontinental telecommunication networks.