Fiber optic cable having extended contraction window and associated

Abstract

A fiber optic cable according to the present invention includes at least one lengthwise extending channel surrounding an elongate central support member with each channel defining a channel axis. At least one optical fiber is positioned within each channel and has an average position offset in a direction generally radially inward from the channel axis toward the central support member at about room temperature. In one embodiment, the at least one channel is defined by one or more buffer tubes stranded about the central support member. In another embodiment, the at least one channel is defined by core having one or more lengthwise extending slots. The fiber optic cable may also include a protective jacket surrounding the central support member and the channel defining means. The optical fibers typically have a coefficient of thermal expansion less than the respective coefficient of thermal expansion of at least one of the protective jacket, the channel defining means and central support member. Thus, by offsetting the average position of the optical fibers at about room temperature in a direction extending generally radially inward from the channel axis, the thermal contraction window of the fiber optic cable is thereby increased. The fiber optical cable of the present invention thus provides consistent optical signal transmission performance over a predetermined range of temperatures and as the cable is placed under tensile loads up to a predetermined maximum load due to the optimized elongation and contraction windows.