Effect of temperature on the strength and fatigue behaviour of optical fibres

The fatigue behaviour of a polymer-coated fibre and a silicon oxynitride-coated fibre was measured in water between 25 and 90° C by the dynamic fatigue test technique where strength is measured as a function of stressing rate. The results are analysed in terms of stress corrosion theory. It was found that the silicon oxynitride coating reduced fatigue significantly, but caused a large reduction in strength of the fibre. The implications of these results to the design of optical fibre communication cables, where a high reliability must be assured, is discussed.