Specialty Optical Fibers Handbook

the use of hermetic fiber coatings. Design rules limit the stresses seen by fibers,

greatly decreasing fatigue-induced weakening of nonhermetic fibers. Similarly,

optical fiber cable designs and materials have been improved so that H

2

evolu-

tion in a cable is a relatively uncommon event, and the extra protection offered

by a carbon coating is not usually required. However, there are a growing

number of specialty applications that do require that the fiber be protected

from H

2

aging and/or fatigue. Fiber sensors used in oil-well data logging need

the protection offered by carbon coatings, to protect the fibers from both fatigue

and hydrogen aging. Tightly routed fibers, for instance, in airframes or ultra-

compact fiber modules, can avoid fatigue and ...