Overview

Optical fibers truly represent a photonic revolution that has resulted in the creation of many fortunes. Their enormous transmission capabilities and unique optical properties (e.g., allowing light to be guided around corners) have changed many parts of the electro-optics environment and have been the foremost technical enabler for optical telecom. As commonplace as fiber optics appears to be today, as recently as the 1970s, they were considered exotic. In fact, it was an economic adventure when several firms first offered scientific fiber optic test apparatus in the late 1970s, and the first telecom fiber cable was not lit until 1977.

Fibers are very pure strains of optical material. Generally, telecom fibers are fused silica, typically with one impure molecule in a billion. They are far more transparent than air and as strong as steel. An optical fiber works by playing a quantum electrodynamic (QED) trick: exploiting the total internal reflection and then guiding the light wave along its length that's why it is called waveguide. This total internal reflection results at the interface between two materials of different indices of refraction. An optical fiber is constructed so that the fine strand of transparent material is cylindrically "clad" with a lower-index material. That is, the core has a slightly higher index of refraction than the cladding such that it provides total internal reflection. Usually, an additional surrounding coating and sheavings are provided for protection and strength. Typically, this is referred to as a buffer or protectant. In practice,...