Specialty Optical Fibers Handbook

be durable in the field, with millions of kilometers of fiber already in operation

for more than 20 years.

4.2 EARLY HISTORY OF COATINGS FOR OPTICAL

FIBER

Although the inherent strength of pure silica [4] is known to be nearly

14,000 N=mm

2

, it soon became apparent, during the development of optical

fibers, that some type of protective coating was required to shield the fibers

from abrasion to preserve their strength. The combination of moisture and stress

causes microscopic flaws in the glass to propagate, resulting in fiber failure.

Without protective coatings, optical fibers would never have been a practical

alternative to copper for telecommunications.

According to Stevens and Keough [5], the prime requirements for optical fiber

coatings were protection ...