Fiber Optic Facts



  • Fiber optic cables are bundles of thin, transparent glass threads that transmit messages by light.
  • The light is transmitted in coded pulses.
  • A thin layer of glass, called cladding, surrounds each fiber and stops light from escaping.
  • The cladding reflects all the light back into the fiber so that it bends round with the fiber. This is called total internal reflection.
  • Single-mode fibers are very narrow and the light bounces very little from side to side. These fibers are suitable for long-distance transmissions.
  • Aiming light into the narrow core of a single-mode fiber needs the precision of a laser beam.
  • Multi-mode fibers are wider than single-mode fibers. They accept LED (light emitting diodes) light, so they are cheaper but they are unsuitable for long distances.
  • The largest cables can carry hundreds of thousands of phone calls or hundreds of television channels.
  • Underwater fiber optic cables transmit signals under the Atlantic and Pacific Oceans.
  • Optical fibers have many medical uses, such as in endoscopes. These arc flexible tubes, with a lens on the end, that are inserted into the body to look inside it. Optical fibers are used to measure blood temperature and pressure.