Stress-free aging of optical fibers in liquid water and humid environments: part 1

The strength degradation of three commercially available telecommunications fibers was evaluated after stress-free aging in 85°C liquid water, 85°C at 94% r.h., 85°C at 85% r.h., and 85°C at 60% r.h. Interim results show that the three fibers show different aging resistances, depending on the environment. Strength loss of up to 50% after 45 days in 85°C water was observed. Atomic Force Microscopy was used to image the cladding surface, and estimate the strength determining flaw size. The data show qualitative correlation between strength loss and flaw size. While the mechanisms underlying stress-free crack growth are not well understood, strength degradation must be predicted, nonetheless, in order to ensure acceptable reliability for fiber-based systems in the outside plant.