Introduction To Fiber Optics

Fiber optic cables are a key component of many telecommunications systems. They can also used in applications beyond communications — for things such as autos, medicine, robotics, and more. Fiber optics can show up in something as mundane as a child's toy, or a plastic Christmas tree. However, our focus in this paper is going to hone in upon fiber as it is used in the world of telecommunications.

Why is fiber used for telecommunications? There are two primary reasons: Bandwidth, and distance. Bandwidth refers the amount of data that can be passed along a cable in a given time period. If we think of cables as pipes, then bandwidth is the amount of water that can flow through the pipe in a second. The bigger the pipe, the more water can flow. Consider a normal communication cable that may be used to carry a single phone call. It is built out of copper, and may have the bandwidth of a normal drinking straw. By comparison, a fiber cable of the same physical size would have the actual bandwidth of the Alaska pipeline!

Another advantage that fiber optic cables have over copper cables is distance. In many instances, copper communications cables are limited to a range of 100 meters or less. Fiber cables, on the other hand, can usually reach a maximum distance of 2 kilometers, and in some instances, can stretch up to dozens of kilometers. This makes fiber ideal for applications where signals have to travel over long distances.

So what is special about fiber optic cables? The first thing that is different about them is their construction. As mentioned above, most communications cables are made of copper, and conduct electrical signals. Fiber optic cables are made out of glass, and carry pulses of ligh energy. The idea of a flexible piece of glass sounds a bit counter-intuitive, but in some ways, fiber cables are stronger and more durable than copper cables.

The idea for carrying light over a reflective path originated in the 19th Century as a parlor trick involving a lamp and a fountain of water. Several decades later, scientists at Corning developed the first practical fiber optic cables in the 1970s, based on the idea of "total internal reflection". This is the principle that fiber cables are built upon, and it basically means that an optical fiber consists of a core of transparent glass, surrounded by outer layer, (called "cladding") of slightly less transparent glass which reflects the light back into the core.

Today, fiber optic cables are used for many different telecommunication applications. Their long-distance capabilities make them ideal for phone companies and other communications service providers that want to provide voice and data links across oceans or continents. The growth of the Internet over the past 20 years has been enabled by fiber optic infrastructure, and has driven new investment. As the demand for more services as grown, "Fiber To the Home" or "FTTH" as it has been called, has resulted in billions of dollars of new fiber installed in telephone company and internet service provider networks.

Fiber optic cables are also seeing much growth in private networks—data centers, data warehouses, server farms, SANs, and LANs. Here the demand is not so much for fiber's unique distance capabilities, but for its unmatched bandwidth. As Ethernet backbone speeds move from 100 Mbps to 1Gig to 10Gig and beyond, fiber is better positioned than copper to support these changing needs.

This white paper is for informational purposes only and is subject to change without notice. C2G makes no guarantees, either expressed or implied, concerning the accuracy, completeness or reliability of the information found in this document.