Residual stress relaxation in cleaved fibers

The relaxation of intrinsic stress, in particular, the frozen-in stress in the vicinity of the cleaved end of optical fibers is studied. Stress distribution is measured at many cross sections along the fiber using a conventional polariscopic stress measurement technique. Fibers drawn with different tensions are used to study the dependence of stress release on the draw tension. From the measured frozen-in stress, the frozen-in viscoelastic stress is studied through the calculation of mean axial stress. The dependence of the release of viscoelastic stress on the draw tension is established. Though the presence of residual stress shows a sudden decline as a consequence of cleaving, it is not completely released at the cleaved end and is explained by the frozen-in viscoelastic stress in the optical fiber. The study shows that the relaxation of frozen-in viscoelastic stress near the cleaved fiber end is only a fraction of the amount of total residual stress in the optical fiber.