The phenomenon of guiding light through bent glass has been early given by Leonardo DaVinci in one of his notebooks. But, he has not been able to verify this assertion. What is known for certain is that total internal reflection of light in a beam of water, basically guided light, and was given by the physicist John Tyndall in either 1854 or 1870, depending upon which reference you consult. Tyndall showed that light could be bent around a corner while it traveled through a jet of pouring water. Using light for communications came after this. . In 1934 the first patent on guided optical communications over glass was obtained by AT &T. unfortunately, no materials were available at that time to fabricate a glass (or other type of transparent material) fiber optic cable with sufficiently low attenuation to make guided optical communications possible.
Between 1968 and 1970, experts who were working at a number of different academic, industrial and government laboratories dropped the attenuation of glass fiber optic cable from over 1000 dB/km to less than 20 dB/km. Corning patented its fabrication process for the cable. In the late 1980's and 1990's this progress increased with the even lower cost plastic fiber optic cable and Plastic Clad Silica (PCS). In last few years a number of oceanic fiber optic cables have been fabricated. One cable was fabricated in 1990. That was relatively non-controversial. However, as additional cables were introduced, the coastal fishing industry became increasingly concerned about the loss of fishing ground resulting from cable placement, and their liability should they come into contact with a cable. Another cable was fabricated in 1998. To represent their interests a number of coastal fishers formed a committee. After discussion on numerous issues, the fishers and the cable owner reached on a conclusion that has served as the basis for later agreements' between these two groups in Oregon.
Two concentric layers termed the core and the cladding are the basic composition of a fiber optic cable. These layers are shown in the following figure.
Fiber Optic Cable, 3 dimensional view and its basic cross section
Both core and cladding have different refraction indexes with the core having R1 and the cladding R2. Light is piped through the core. In Fiber optic cable an additional coating termed as jacket is also provided around the cladding. Core, cladding and jacket are all shown in the three dimensional view on the left side of above Figure. The jacket is usually made up of one or more layers of polymer. This jacket protects the core and cladding from shocks that might affect their optical or physical properties. It acts like a shock absorber. The jacket also provides protection from abrasions, solvents, Small oil