Analysis of thermally induced loss in fiber-optic ribbons

In this paper, added loss during temperature cycling in a given ribboned fiber is shown to be caused by thermally induced axial compressive strain imparted to the fiber. A microbending-sensitivity parameter δ is introduced which reduces all loss-strain curves corresponding to different fibers to one characteristic master curve. Thermoviscoelasticity theory is used to calculate the time- and temperature-dependent compressive strain imparted to a ribboned fiber during a standard environmental cycle. Combining these analytical results with environmental data, the functional relationship between fiber-compressive strain and the added loss for a fiber of any given δ in an Adhesive-Sandwich Ribbon (ASR) with Urethane-Acrylate (UA) coated fibers has been determined. Using this analysis, the added loss for a UA ASR can now be predicted for any environmental cycle. The critical material properties that dominate the environmental performance of ASRs are the tape shrinkback at elevated temperatures and the product αEA of the coefficient a of thermal expansion, the time- and temperature-dependent relaxation modulus E, and the area A of the coating.