4.1 INTRODUCTION

It could be said that the modern era of fiber optics began in 1966, with the publication of the paper Dielectric-Fibre Surface Waveguides for Optical Frequencies by Dr. C.K.Kao and G.A.Hockham of Standard Telecommunications Laboratories Ltd. (STL) [1]. This paper discussed the theory and potential use of optical fiber for communications. Dr. Kao believed that fiber loss could be reduced below 20 dB/km by eliminating metal impurities in the glass. Such attenuation would allow 1% of the light entering 1 km of this type of fiber to successfully reach the other end.

During the same period, Corning Glass Works researchers, R.Mauer, D.Keck, and P.Schultz, were experimenting with high-purity fused silica [2]. They employed titanium as a dopant to produce a higher refractive index (RI) (1.466) fiber core, compared with the surrounding lower RI (1.4584) silica cladding. They were able to draw fibers, at 1900 C, to a diameter of 100 m. In 1970, Method of Producing Optical Waveguide Fibers was filed with the U.S. Patent Office and issued 3 years later as U.S. 3,711,262.

Before 1966, fibers had losses of roughly 1000 dB/km [2]. The Corning team effort reduced this loss to only 16 dB/km, thus demonstrating the feasibility of optical fibers as a communication medium. Such fibers were said to be capable of carrying 65,000 times more information than copper wire [3].

This chapter focuses on the development, science, and performance of protective coatings for optical fiber. The...