Physical design of the SL repeater

SL undersea fiber-optic cable allows for the installation of multiple pairs of fibers in the same cable. Using the same high-pressure repeater housing as used in previous undersea systems (and thereby accruing the benefits of no tooling costs and proven handling methods), we are able to mount six optical regenerators. This group of regenerators will dissipate approximately 30 W in service. Previous undersea repeaters dissipated approximately 8 W and achieved a maximum internal temperature of 5°C above the repeater ambient. That might imply a temperature of 20°C above ambient for the SL repeater, which would be intolerably high for reliable undersea performance and longevity. The main thrust of the SL design was to lower this temperature rise. We have achieved a design which is capable of dissipating 30 W with only 4° C temperature rise. This paper describes the design steps necessary to achieve this result and examines the overall repeater structure showing its special design features for accommodating fiber sealing and jointing.