Fiber Optic Communications

The use of optical fiber as a replacement for copper media is proving to be an irresistible force for handling the enormous amounts of information that must be transmitted across the country or even around the world. Today it is also becoming the medium of choice for transmitting between and within buildings. The principles of guided light transmission were known in the nineteenth century. In 1870, John Tyndall demonstrated this principle before the British Royal Society. He showed that light was conducted in a curved path along an illuminated stream of water flowing from a hole in a tank. This experiment illustrated the concept of total internal reflection, wherein light rays propagate by reflection off the boundaries of a medium and escape primarily at the opposite end of the “conductor.” A later researcher, Alexander Graham Bell, studied the possibility of transmitting speech on a beam of light to a device called a photophone. As early as 1910, theoretical studies had been completed by Hondros and Debye on dielectric waveguides.