Optical fiber is a term for any sort of plastic or glass conduit meant to transport light. The principles behind it are actually quite old, but in recent years it has become an incredibly important technology, as communications infrastructure has begun to use this fiber to transmit data at extremely high rates. Aside from fiber optic communications, however, it has a number of applications in medicine, consumer products, and physics.
This sort of fiber offers a number of advantages over traditional metal wire, the most important being that there is considerably less signal degradation. Additionally, it is immune to electromagnetic interference, which can seriously impede the transmission of data along normal metal wires. This adds an added security measure, as well, since optical fiber can survive an electromagnetic pulse that would destroy metal cables.
The basic principle behind optical fiber is quite simple: the fiber is coated to make it completely reflective on the inside, so that when light goes in, it reflects without losing any light, and passes down the fiber to the other end. This basic idea, of guiding light by refraction, goes back to the 1840s. By the beginning of the 20th century, some practical applications had been developed, most notably the use of this fiber in dentistry to light up the inside of the mouth.
In the 1920s, the same basic technology was used to transmit full images. During the following decade, the technology was used practically to illuminate the inside of a surgery, allowing for a much more precise operation. It continues to be used in surgery, especially to facilitate less invasive internal surgeries. The first true optical fiber appeared in the 1950s, and by the end of the decade experiments were underway with a type of fiber very similar to that used today, with glass fibers coated with a transparent sheath.
By the 1970s, optical fiber was beginning to be refined, reducing the noise in the signal. These refinements allowed for the possibility that the fibers could be used to transmit actual communication over long distances. This allowed for massive communication backbones to be built, which laid the groundwork for the Internet. At the dawn of the 1980s, General Electric created a method by which extremely long strands could be stretched out, up to 25 miles (40 km) at a time, making massive backbones even easier to construct.
Because of its low level of degradation, or attenuation, optical fiber is ideal for long distance communications. While metal wire requires repeaters to be installed at short distances, to make sure the signal stays strong, fiber optics can be stretched for long distances without a repeater, reducing costs drastically. Additionally, fiber is able to transport a great deal more information than metal wire, making it preferable even over short distances, such as those within a network situation in a single building. Since the fiber doesn’t conduct electricity in the same way metal wire does, it is safe to use in high voltage environments where traditional wiring could be dangerous.