Abstract

All mechanical-reliability assessments of silica optical fibers are based on the assumptions that the strength-controlling flaws are sharp (i.e., c ≫ a, where c is the flaw length and a is its half-width) and that the rate-limiting step leading to catastrophic failure is slow crack growth. Since the estimated flaw length is pristine silica (~20 Å) suggests a flaw opening smaller than the typical end radius of conventional surface-detection probes, the strength-controlling flaw has not been characterized. The crack-growth rate is defined as

© 1994 Optical Society of America