Subthreshold flaws and their failure prediction in long-distance optical fiber cables

A study of surface defects and static fatigue data is presented to support the view that subthreshold surface defects are responsible for failure in proof-tested optical fibers. For this type of defect, crack initiation, as opposed to crack growth, is the rate-limiting step. Classical crack propagation theory does not describe this process sufficiently well for lifetime production, but semiempirical techniques indicate that this popular treatment may be pessimistic. A more conventional reliability treatment, similar to that used for other system components, appears to offer the best available approach to the task of failure lifetime prediction in proof-tested fibers