Core: The core is the glass in the center of the fiber through whichthe light pulses travel.
Cladding: This glass surrounds the core and prevents light from escaping
Coating: The coating is designed to protect the fiber from dust and scratches and is made of a layer of a soft, plastic-like substance called acrylate.
Both the core and the cladding are made from ultra-pure glass, though the cladding is actually more pure than the core. This small difference between the two glasses contains the light pulses in the core.
How it works:
A glass tunnel through which the light travels is created. When the light hits the cladding, it interacts with and reflects back into the core. Because of this design, the light can "bend" around curves in the fiber and makes it possible to travel further distances without having to be repeated.
The light that travels along the fiber is made up of a binary code that pulses "on" and "off" and determines what information a given signal contains. The advantage of fiber is that these on/off pulses can be: translated video, computer, or voice data depending on the type of transmitter and receiver used.
Facts About Fiber Optics:Fiber optics were needed because television cables were becoming more capable of carrying more information than copper wire so computer and telephone companies needed something to compete.
Currently all new undersea cables are made of optical fibers. Experts say that sometime in the early 21st century, 98% of copper wire will be replaced by fiber optic cable. Fiber optic cable installed for copper wire that already needs replacing is less expensive since it only needs repeaters to amplify the signals running through it every six miles rather than every mile.
Optical fiber phone lines cannot be bugged or tapped.
A fiber is thinner than a human hair.
Advantages of Fiber Optic Cables Over Copper:Speed: Fiber optic networks operate at speeds up to 2.5 gigabits per second, as opposed to 1.54 megabits per second for copper. Soon, a fiber optic system will be able to transmit the equivalent of an entire encyclopedia (24 volumes) of information in one second. Fiber can carry information so fast that you could transmit three television episodes in one second.
Bandwidth: Taken in bulk, it would take 33 tons of copper to transmit the same amount of information handled by 1/4 pound of optical fiber.
Resistance: Fiber optic cables have a greater resistance to electromagnetic noise such as radios, motors or other nearby cables. Because optical fibers carry beams of light, they are free of electrical noise and interference.
Capacity: Fiber optics have a greater capacity for information which means smaller cables can be used. An optical fiber cable the size of an electrical cord can replace a copper cable hundreds of times thicker.
Why Fiber Optics?
LAN's developed as a result to the information explosion thatoccurred in the late 1980's. The need for office, laboratory, and
factory computers to share information became essential. Since the 1980's, many media have been developed for use in LAN's, each meeting a specific user demand. Glass fiber was developed for use in long distance, high bandwidth applications, but the high cost of hardware
and installation has daunted users.
Twisted pair, on the other hand, was developed as a low cost alternative medium for use in shorter distance applications. Twisted pair seemed to be an ideal medium for LAN's, but as computer graphics have become more "graphic intensive", LAN's have been required to transmit a much greater volume of information, requiring a media with a much higher bandwidth. Since twisted pair is not capable of supporting the higher signaling rates, there has been an increased interest in developing a low cost fiber solution.