Lifetime of Optical Fibers Submitted to Thermo-Mechanical Stresses

The reliability and the expected lifetime of optical fibers used in telecommunication technologies are closely related to the thermo-mechanical and chemical environment actions on silica network. To ensure the long-term mechanical strength of the optical fibers, a polymer coating is applied onto fibre surface during fiber fabrication. The coating protective action includes several functions, such as: to protect glass fiber from any external damage, to limit chemical attack, in particular those of water and temperature.This paper presents the results of new silica optical fibers aged in hot water between 20 °C and 70 °C and subjected to mechanical static bending stresses from 2.5 GPa to 3.2 GPa. The mechanical strength of optical fibers aged in distilled water at different temperatures was studied. Optical fibers were then wound around ceramic mandrels with different diameters in order to evaluate the influence of the static bending stresses on the lifetime of the fiber. Dependence of the time to failure on temperature was observed and different fatigue parameters such as activation energy, fiber lifetime and stress corrosion parameter can be analyzed and a behavior law can be proposed.