Fiber optics is a technology that uses optical fibers, which are long glass-like flexible strands roughly the diameter of a human hair. With the use of this latest technology, large amounts of data can be transmitted over long distances. The optical fibers are used to broadcast light signals and audio signals, producing distortion-free sound. In addition, fiber optics is useful in medical procedures (for internal inspection of the body), automobiles, and aircraft.
Though fiber optics was first invented in the 1930s, the use of this technology barely started in the late 1960s. A serious momentum occurred in the 1980s when the phone companies started to replace their long distance copper cables with fiber cable. Gradually, all transmission systems and networks started using fiber cables.
A fiber-optic relay system contains a transmitter that produces and encodes the signals, an optical fiber that transmits the signals over a distance, an optical regenerator that is essential to boost the signal for long distances, and an optical receiver, which receives and decodes the signals.
Optical fibers are generally arranged in bundles known as optical cables. Each bundle is protected by a jacket, the cable’s outer covering. A single optical fiber consists of core (the central part where the light travels), cladding (special additives surrounding the core), and buffer coating (plastic coating that guards the fiber from break and moisture). The cladding has a high index of refraction so that the light is internally reflected and zigzags through the fiber instead of leaking out. fiber construction
Optical fibers are classified into two types, single-mode fibers and multi-mode fibers. Single-mode fibers feature small cores (around 3.5 x 10-4 inches or 9 microns in diameter) and broadcast infrared laser light of wavelength 1,300 to 1,550nm. Multi-mode fibers have larger cores (2.5 x 10-3 inches or 62.5 microns in diameter), transmitting infrared light (wavelength ranges from 850 to 1,300nm) from LEDs. There are a few optical fibers, which are made from plastic, having a large core (0.04 inches or 1 mm diameter) and send visible red light of wavelength 650 nm from LEDs.
Compared to the copper wires, optical fibers are less expensive, thinner, have higher carrying capacity, less signal degradation, carry digital signals, and are non-flammable, lightweight, and flexible. Since signals degrade less, lower-power transmitters are used instead of the high-voltage electrical transmitters required for copper wires. The signal coming out of a fiber wire possesses the same quality and intensity as when it was first entered into the cable. An optical cable is resistant to electromagnetic interference, as well as to crosstalk from adjoining wires.