Coating additives for enhanced mechanical reliability of fused silica optical fibers: Effect on mechanical and optical performance

It is now well known that fused silica optical fiber can suffer from enhanced strength degradation after prolonged exposure to aggressive environments. This is caused by corrosion of the glass surface by moisture leading to roughening, strength loss, and, potentially, problems with handleability. It has been found that addition of nanosized silica particles to the polymer coating can improve the long term mechanical reliability by slowing corrosion and delaying the onset of strength loss. However, previous studies have shown that addition of these particles can lead to unacceptably high added optical loss, when measured using the "basketweave" test. In this work, it is shown that the added loss caused by coating additives can be reduced by improving the mixing and dispersion of the silica powders in the polymer. It is further shown that well dispersed powders still substantially improve the long term fatigue and aging behavior. This clearly shows that coating additives can improve the mechanical reliability without significantly degrading the optical performance.