FEATURE
LIFE EXPECTANCY OF A FIBER OPTIC CABLE BY JAVIER VALDEZ AND GILBERTO GUITARTE
T
he article on the life expectancy of fiber optic cables reveals a scientifically estimated lifespan of 25 years for submarine cables, based on environmental stresses and technological advancements. It highlights the dynamic nature of the telecommunications industry, where increasing bandwidth demands may prompt more frequent updates and replacements of these cables. When we read the list of projects already executed and those that are about to be executed related to submarine fiber optic cables, we observe a constant: the period between the date of entry into service of the cable and the estimated date of decommissioning is stated as 25 years. We rightly wonder if this is a financial assumption or if it is expected that after 25 years the cable will no longer be reliable and perhaps it is time to take it out of service... Well, they can be the first and the second together, but the reality is that scientifically determined life expectancy is the one that must be taken into account for the operation of that submarine cable with limited risk. The life expectancy of a submarine cable is estimated by various scientific methods, between 20 and 30 years (hence the famous 25 cited by various media) and the most important manufacturers of fiber and optical cables in the world, as well as the scientific documents of regulations and verification tests by ITU and IEC, are involved in this esti-
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mate. as the two most important to mention in this aspect. Both regulatory organizations worked with the methodology of stressing the phenomena that can produce mechanical or optical failures in fiber and cable, measuring performance parameters and their evolution over time under constant conditions, and with isolation of variables in some cases or a combination of them in others. Both accept with scientific rigor the validity of the concept -or theory- of “accelerated aging”, in order to then be able to extrapolate in time the moment when unacceptable performance values are reached, whether they are high-risk entry, or total failure in service. The amount of material documented by these organizations is incredible and we list all of them at the end as references so that the reader of this article can verify them and deepen their knowledge of the detail provided by them. It is very important to emphasize that an optical fiber has extrinsic faults (failures in the glass due to manufacturing process, winding, storage, installation, stripping of the fiber during the splicing or connectorization process) and intrinsic failures (inherent to the physical resistance of the glass itself ). There are examples of variations in stress over time (stress histories) and geometries such as: • Constant Tension (such as directly buried cable, or bending in a splice or reserve closure). • Variable voltage (due to variations in temperature, wind,