IIGHTWAVE SYSTEMS HAVE RAPIDLY BECOME

the preferred way to transport huge quantities of information over long distances. On land, second and third generation terrestrial lightwave systems cross the United States at bit rates up to 1.7 Gbls per fiber pair [I], while under the oceans, undersea lightwave systems link North America with Europe and Asia [2]. Although both terrestrial and undersea lightwave systems transport digital information over long distances, the application determines the design constraints and therefore the technology requirements of each. For undersea systems, the key requirement is system reliability. The rigors ofdeploying lightwave cable and repeaters under the sea, coupled with the revenue loss during the time between outage and repair, dictate a design that assures a minimum of costly atsea repairs over a long (usually twenty-five year) system life. For