Fiber optics are simply strands of flexible glass as thin as human hair that are used for telecommunications.  These strands carry digital signals with light. Even though these cables are made of glass, they are not stiff and fragile. They can bend kind of like wires and are very strong.  When hundreds or even thousands of these strands are arranged in bundles, it is called an optical cable.

These glass cables are covered with a special protective coating called cladding. The cladding is made from a material that reflects the light back into the core or center of the cable. This cladding creates a mirror-lined wall. The final outer layer is a buffer coating to protect this special glass cable from damage and moisture.

Single-mode and multi-mode are the two main types of fiber optic cable. Single-mode fiber cables send signals using laser light. They are smaller in thickness than multi-mode.  Multi-mode fibers send signals using light-emitting diodes or LEDs. They are bigger in thickness or diameter than the single-mode cables. 

Fiber optics work using the total internal reflection principle. When light is transmitted into the glass cable, the light bounces off the reflective cladding on the sides of the glass cable, so the light can travel around corners. In other words, the light bounces off the inside of the cable until it gets to its destination.

There are more parts to the fiber optic system than the cables. The first thing is the transmitter. It produces the signals that will travel through the cable. The optical regenerator is needed when the light signal is weakened by traveling over a long distance and needs a re-boost or strengthening. Actually, the light signal is copied and a new one with the same characteristics is sent by the regenerator. Finally, there is the optical receiver. It receives the light signals and encodes them into a readable form for the device at the end.

Fiber optics have lots of uses. The Internet uses fiber optic cables. It is a perfect application because it is digital information and the fiber optic cables send digitally. Telephones were one of the first uses for fiber optics. Many times internet and telephone signals travel over the same cables. Digital television (also known as cable TV) is often transmitted by fiber optic cables.

Three other kinds of uses are totally different from the above items. One is medical imaging. Surgeons use special scopes using fiber optics to enlarge areas of patients that are hard to see, kind of like a very accurate magnifying glass. A very similar use is mechanical inspection. Engineers and mechanics can use a similar scope device to see hard to reach places during safety inspections. Another similar use is to inspect plumbing and sewer lines.

Fiber optic cables without optical regenerators can be up to about one kilometer in length. With regenerators, they can go on almost forever. They can be placed in buildings, up on power lines, buried in the ground or even placed in the ocean! Fiber optic cables are not perfect; they can break. Sometimes when crews are digging, they accidentally can tear up the cables. They can be repaired using a technique called splicing. It is when a worker cuts off the broken ends and reconnects them using special adhesives, heat, or special connectors.

There are many advantages of fiber optics over traditional wire cables.

Less Expensive. First, fiber optics are less expensive than copper wire. Both customers and service providers (the companies that own the communication system) save money. This is because many miles of optical cable are easier and less expensive to install than the same amount of copper wire or cable.

Thinner. Fiber optics are thinner than copper wire cables, so they will fit in smaller, more crowded places. This is important for underground cable systems, like in cities, where space needs to be shared with sewer pipes, power wires, and subway systems.

Higher Carrying Capacity. More information can also be carried over fiber optic systems. This can be especially important for computers, since a computer has to send so much information at one time. Also, more phone lines can be in one optical fiber. Many people use the same optical cable for phone conversations at the same time.

Less signal degradation. Information gets lost over distances an any kind of wire. But, fiber optic cables don’t lose as much signal (information) as other kinds of wires and cables.

Use Light Signals. Because fiber optics use light signals instead of electricity, the signals don’t interfere with each other. This makes the signals clearer and easier to understand.

Low Power. Optical fiber signals are created using low-power transmitters because the signal degrades less (instead of high-power electric transmitters used for copper wires). Lower power use saves money for users and providers.

Digital Signals. Computer networks need digital information, since fiber optic cables send information digitally, they are the best thing to use for computer networks.

Non-flammable. Since fiber optics send light instead of electricity, fiber optics are non-flammable. This means there is not a fire hazard. Fiber optics also do not cause electric shocks, because they do not carry electricity.

Light weight. Fiber optics are easier to install and transport than copper wires. That is good news for technicians

Flexible. Since fiber optics are more flexible, they can go around corners and into tighter places than traditional cable. This is important in computer and very big office networks.

Fiber optic cables are really amazing. They are used a lot today on computers, cable television, and the most common use in telephone communication. What’s next? No cables?

Citations

Book

Billings, Charlene W. Fiber Optics: Bright New Way to Communicate. Dodd, Mead and Company: New York, 1986.

Online Resources

"Fiber Optics." World Book Online. 7 January 2005 <http://www.worldbookonline.com/wb/PrintArticle?id=ar195490&st=Fiber+Optics>.

"How Fiber Optics Work." How Stuff Works. 7 January 2004 <http://electronics.howstuffworks.com/fiber-optic.htm/printable>.

Images 

Permission to use largest photograph of fiber optics is granted  under the terms of the GNU Free Documentation License from Wikipedia, the Free Encyclopedia.  <http://en.wikipedia.org/wiki/Main_Page>.

Copyrighted images of fiber optics at top of page and last photograph of fiber optics from "Microsoft Office Online" <http://office.microsoft.com/clipart/default.aspx?lc=en-us&cag=1> (October-March, 2004-2005). Clip art available only to licensed users for non-commercial purposes.

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