Abraham van Heel – Clad fibers (1950s); Dr. Charles K. Kao – expresses the possibility of -20dB per km fibers (1966); Robert Maurer, Donald Keck and Peter Schultz – first low loss fiber (1970)

Optic fiber is composed of a thin fiber of glass that traps light within it due to the property of total internal reflection. When light reaches a boundary between two mediums, it is bent, or refracted, depending on two conditions: the ratio of the two refractive indices (speed of light in a vacuum / speed of light in medium), and the angle of incidence. If light in the denser medium strikes the boundary at a very glancing angle (one larger than the critical angle), it will not leave the denser material, but will behave as if the boundary layer were a mirror. This is known as total internal reflection, and is very efficient.
The history of optic fiber extends as far back as the 19^th century. Experimenters, such as Daniel Colladon, demonstrated the total internal reflection of light within streams of water. This was, and still is, used to decorate fountains. Later, bent glass rods were used to direct light for illumination during surgical operations or for use with microscopes. Beginning in the 1920’s, fiber optics was being explored as a means of image transmission. In 1930, Heinrich Lamm transmitted the image of the filament of an incandescent bulb through a bundle of fibers. However, the poor quality of the fibers at that time limited the quality of the picture.
A major problem with fibers of this time was the light loss caused by impurities, or defects in the fiber.
This caused the fiber to have an attenuation of about 1 dB/m, unacceptable for long distance communication. Then in 1953, although he was not the first, Abraham van Heel describes the use of a fiber clad with a sparse glass. This protected the boundary where total internal reflection would occur, yielding a fiber of much higher quality. This improvement left only the problem of light loss caused by impurities. In 1966, Dr. Charles K. Kao proposed that this loss, about 1000 dB/km at the time, could be reduced to below 20 dB/km, a value suitable for the use of fiber optics in telecommunications. In 1970, Robert Maurer, Donald Keck and Peter Schultz of Corning Glass Works produced a fiber with a loss of 20 dB/km.
During the 1970’s optic fibers began to be used in place of copper wire for signal transmission. Semiconductor lasers aided the use of fiber optics in communication by allowing light at a very specific wavelength to be used to minimize attenuation. In 1977, Bell System began sending telephone conversations through fiber-optic cable. Each fiber was capable of carrying 672 voice channels. Then in 1988 the first transatlantic fiber-optic cable was put to use. It used a 1.3 micrometer laser and a single-mode fiber. In 1996, Fujitsu, NTT Labs, and Bell Labs separately sent signals of one trillion bits per second through single fibers.
Optic fiber today is being used in a wide range of applications. Cable and telephone companies are all switching from copper wire to fiber-optic cable because of its high efficiency. In addition to communications, optic fiber is used in many ways such as in surgery, or decoration. It is amazing how fiber optics has grown from lighting fountains, to linking continents.
Optic fiber has revolutionized long distance communications. More and more information is being carried by smaller and smaller cables, and improvements in optic fibers could allow even faster rates of transmission than those in use today.

*Pictures from http://inventors.about.com/library/weekly/aa980407.htm, http://www.fastlinkcabling.com/fiber.html, and http://www.ambalayellowpages.com/jainsons/

Sources:
Bellis, Mary. The Birth of Fiber Optics. 18 Oct. 2003. <http://inventors.about.com/library/weekly/aa980407.htm>

Fastlink Low Cost Fiber Optic Cabling Installation. 18 Oct. 2003. <http://www.fastlinkcabling.com/fiber.html>

Hecht, Jeff. A Fiber-Optic Chronology. 18 Oct. 2003. <http://www.sff.net/people/Jeff.Hecht/chron.html>

Hecht, Jeff. A Short History of Fiber Optics. 18 Oct. 2003. <http://www.sff.net/people/Jeff.Hecht/history.html>

Jainsons (India) Regd. 18 Oct. 2003. <http://www.ambalayellowpages.com/jainsons/>

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