Chapter 3: Optical Fiber

By 1950, the challenge to scientists studying optical fiber transmission was not whether light could carry information, but whether a glass conduit could be developed that was pure enough to keep losses below 20 dB/km. A flexible glass-coated glass fiber served as a suitable transmission medium for the fiberscope, but losses remained unworkably high for communication applications. Scientists persevered.

In 1970, Corning scientists Robert Maurer, Donald Keck, and Peter Schultz developed a fiber with a measured attenuation of less than 20 dB/km. It was the purest glass ever made, and the breakthrough led to the commercialization of fiber optics for communication applications. Corning's success was the result of a new process for manufacturing optical fiber which they called inside vapor deposition (IVD). Instead of melting the raw silica, the way most glass is made, they formed the glass from vaporized chemicals which were deposited inside a silica tube. The outer tube became the cladding, and the core of the fiber formed within. An inherent disadvantage to this method was that the cladding was formed using the traditional method of making glass. Thus impurities still existed in the cladding and reduced the purity of the overall fiber. Back to the drawing board they went, and before long, Corning scientists had developed a method of outside vapor deposition (OVD) which formed the entire fiber from ultra-pure, vapor deposited chemicals. Today scientists still experiment with ever purer forms of optical fiber, and losses as low as 0.2 dB/km at 1550 nm are not...