Materials Aspects of the SL Lightguide Undersea Cable Design: 1988 MRS Spring Meeting Plenary Addres
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1988 MRS Spring Meeting Plenary Address Raymond D. Tuminaro AT&T Bell Laboratories
Undersea optical fiber cables employ a large number of materials, ranging from silica and its dopants in the fibers, to polymeric and metallic materials in the cable fibers. Because undersea optical Systems are designed to carry a large volume of telecommunication traffic, and because the social and economic impacts of a system System failure are so severe in terms of communication disruption, lost revenues, repair costs, and loss of user confidence, an extremely high premium is placed on ultra reliable performance of the cable and the repeaters that comprise the undersea portion of the system. The focus of Raymond D. Tuminaro's Plenary Address given at the 1988 MRS Spring Meeting in Reno and reprinted here was on the fiber and cable materials of an undersea optical system developed by AT&T Bell Laboratories. He reviewed the materials in terms of their requirements and functions. He also discussed the principal impairments to long-term reliable performance and reviewed methodologies for assuring acceptable materials performance for a projected 25-year Service life. Tuminaro, who received BS and MS degrees in electrical engineering from New York University, has worked at AT&T Bell Laboratories in New Jersey since 1966. His assignments have included the modeling of nuclear electromagnetic pulse effects on the functioning of telecommunication facilities, and the design of various transmission media and Systems for long-distance Communications. Prior to joining AT&T, he was employed at Wheeler Laboratories and Lockheed Electronics, where his responsibilities involved microwave technologies and military radar.
Introduction Starting in the 1950s, AT&T has been involved in the design, installation, and Operation of undersea coaxial cable Systems to provide international and interisland t e l e c o m m u n i c a t i o n Services. These Systems are analog transmission Systems, utilizing frequency division 14
multiplexing to simultaneously transmit multiple Channels over a Single cable. 1 W i t h t h e p a s s a g e of t i m e , a n d in response to an ever growing demand for Services, the frequency bandwidths of s u c c e s s i v e S y s t e m s h a v e b e e n increased to accommodate the need for increased traffic density. The increases
in bandwidth have been accompanied by increases in copper ohmic losses, brought about by the skin effect phen o m e n o n , 2 m a n d a t i n g ever s h o r t e r spacing between repeaters, and consequently larger numbers of repeaters for a given system length. The reliability outlook for extending coaxial cable technology b e y o n d its p r e s e n t capacity, with a decrease in repeater spacing below the current value of about 9 km, is not favorable. Fortunately, we now have available optical fibers for transmission media. Unlike coaxial cable, the fiber medium is not limited by t h e skin effect p h e nomenon. Using fiber technology, we can transmit large a m o u n t s of traffic through a very small
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