Evolution of Fiber

The theory of using light as a transmission medium has been around for quite sometime.

Back in the 1880's Alexander Graham Bell demostrated that light could carry voice through the air with the use of wires. Bell's Photo Phone reproduced voices by detecting vibrations in the amount of sunlight reaching the reciever. His theory was correct. However, it was not very practical, as any objects that got in the way of the light beam caused a disruption at the reciever.
During the 1930's several patents surfaced that used tubing as a waveguide for light. The tubing was big and bulky, and thus impractical for use undergound or in buildings.
Interest in optical fiber technology began to grom significantly in the 1950's, as a patent utlizing a two-layer glass waveguide surfaced. The principal behind the two-layer waveguide was to confine the light signal withing the inner layer (core) by the use of a second layer (cladding) that would reflect the light back into the core, much like the way light is contained within water.
This development became the foundation for optical fiber transmission as we know it today. What was needed at this point was alight source capable of traveling the length of the waveguide.
Un the early 1960's, a laser was first used as a light source, with tremendous results. The high cost of optical lasers, however, still prevented the practical use of optical fiber technology for communications.
In the late 1960's, it was discovered that the high loss of light in optical fiber was do to the impurities of the glass, not its intrinsinic properties.
In the early m1970's, engineers at Corning Glass Works refined the manufacturing process of optical fiber construction, thereby allowing for the use of lower-cost light sources, such as LEDs.
In the 1980's, optical fiber technology began to find its place as the backbone of long distance telephone networks throughout North America.
Presently, with the advances in digital technology and the further development of standards, optical fiber technolgy has become an intergal part of the networks of today, as they have become foundation for tomorrow.

Source :www.elec-toolbox.com/communications/classifications/fiber/fiber.htm