Drawing influence on the lifetime of optical fibres

Strength and lifetime measurements carried out on optical fibers with different residual tensile stress at the surface are discussed. This stress was optically measured and included in the theory of fiber strength and lifetime. The strength results were compared with measurements done on pure silica fibers without residual stress. In lifetime predictions, this residual tensile stress in the outside region of the fiber has to be taken into account. However, the decrease in intrinsic strength was much larger than the increase in residual stress in the outside region of the fiber. This phenomenon, which is not well understood, depends on drawing conditions