The History of Fiber Optics

Lasers, which are crucial in the development of fiber optics, trace their roots to the principles of quantum mechanics. Einstein defined the photoelectric effect in 1905, syaing that electrons could absorb and emit energy of photons. In 1917, he theorized that an emission could be "focused" to a single frequency, called "stimulated emission". Stimulated emission is when atoms are boosted to an excited state, generally through exposure to light. Scientists in the 1950s stimulated the emission of microwaves with a device called the maser. It was thought that stimulated emission could be applied to visible light and scientists began building lasers, devices that emit highly focused beams of light. There was a lot of enthusiasm among journalists and the entertainment industry (most notably in the James Bond movie Goldfinger) but lasers were far from having any practical applicatioins.

Transistors, invented in 1948, replaced vacuum tubes that had been used in old TVs, radios and computers. The early lasers resembled vacuum tubes in that they were bulky and fragile. It was hoped that lasers might make a transition similar to that of vacuum tubes to transistors. Transistors also stimulated research on semiconductors which would be important in the early history of lasers.

One of the problems with early lasers was overheating. A solution came in 1963 with the semiconductor sandwich, a laser wedged between two other materials to manage temperature. This led to "heterostructure" lasers, mini semiconductor devices capable of operating at room temperature.

Lasers were getting better, but it was necessary to find a way to transmit light over long distances if communication by light was to be possible. Radio waves are capable of piercing fog and rain with ease, however a rainy day could block light and shut down communications. Light needed a conduit analogous to telephone lines. In 1966, scientists found that the high losses of light transmissions (up to 99%, even over short distances) were due to minute impurities in the glass fibers, not the intrinsic limits of the glass itself. There was hope that a solution could be found. And in 1970, three scientists at Corning Glass Works created an optical fiber hundreds of yards long with crystal clarity.

This was a turning point. With the semiconductor laser and an effective conduit, fiber optics technology could move out of the laboratory and into the marketplace. However, there were still some problems with laser reliability, so LEDs were used for light communications over modest distances. Then molecular beam devices came onto the scene; they were highly efficient lasers that used less current. This made them economically feasible as well as efficient.

Commercial trials began in Atlanta in 1976 with AT&T. The first transatlantic cable was laid in 1988. Subsequent technological advances strengthed weak signals with all fiber optic systems. Previously, the system was limited to the capacity of electronic amplifiers, which was considerably less than the other fiber-optic components. Fiber optic amplifiers were created bye doping the glass strands to act as a laser themselvs and amplify the signal without electronics.

The history of fiber optics is not complete. This technology will continue to be important in the future. Not even ten years ago, the first Pacific cable was laid in 1996. Telecommunications companies are currently working to lay the "last mile" of cable, from the central station to the home. Already, many businesses have high speed data lines however they are simply too expensive for residential use at this point in time.