Abstract

Kilometer lengths of fiber consist mostly of very-high-strength pristine fiber, but occasional extrinsic defects limit the overall strength. Traditionally, the spontaneous failure of these weak defects is thought to control mechanical reliability of the fiber, but it has recently been recognized that the strong fiber between the extrinsic defects also poses a reliability problem; its strength can degrade in aggressive environments, even in the absence of an applied stress, to the point that it cannot be handled for splicing and connectorizing. The strength degradation appears as an abrupt loss of strength, or knee, in the zero-stress aging behavior, but when a stress is applied it also causes a knee in the fatigue behavior; beyond the knee the failure time is much shorter than predicted from data before the knee. This confounds any lifetime predictions for fiber under stress.

© 1994 Optical Society of America