temperature. For fibers hermetically sealed with a thin layer of carbon, no change
from initial strength was observed for any of the aged samples (Fig. 14.4).
Similar results were observed for fibers soaked in conventional chemicals,
indicating that carbon coatings can protect fibers from harsh environments and
elevated temperatures more effectively than standard polymer coatings.
14.5 HYDROGEN LOSSES IN OPTICAL FIBERS
14.5.1 Hydrogen-Induced Losses in Nonhermetic
Fibers
In the early 1980s, it was realized that hydrogen-induced losses could impair
optical fiber systems. Fibers exposed to hydrogen, even at low levels, showed
increased losses that, in some cases, caused fiber losses to exceed the system-
aging margin, resulting in system failure. Hydrogen ...