Strength assurance for stress-induced polarization-holding fibers

A new method of assuring strength for stress-induced polarization-holding fibers has been clarified on the basis of prooftesting. A simple equation considering the residual stress in a fiber is derived. Design diagrams for strength assurance of a polarization-holding fiber are shown. Using the diagrams, allowable applied stress and proof-testing conditions can be determined for a given failure rate and lifetime. The residual stress value and the strength parameter representing the strength distribution of inner cracks are quantitatively evaluated.