Effect of polymeric coatings on the static fatigue of double-coated optical fibers

Abstract

The effect of polymeric coatings on the static fatigue of double-coated optical fibers is investigated. A closed form solution of the tensile stress in the glass fiber under the action of a constant tensile force in the fiber’s axial direction is obtained using viscoelastic theory. The tensile force is applied to the glass fiber and polymeric coatings. The applied tensile fore is gradually transferred from the polymeric coating to the glass fiber due to the viscoelastic behavior of the former, and the tensile stress in the glass fiber increases with time. This increase accelerates the failure of the glass fiber. The thickness and Young’s modulus of the secondary coating should be increased to ensure the long-term reliability of optical fibers, and the relaxation time of the secondary coating should be significantly larger than the expected lifetime of the optical fiber. However, the ratio of the proof-test load to the allowable external load should be increased if the secondary coating of the optical fiber has a high axial rigidity and low relaxation time.