Pub. 4 2014 Issue 2

16 AT THE CENTER OF UTAH INDUSTRY MINING AND FIBER OPTICS I t is incredible but true: one of the most important technological innovations in communication is based on glass. Since the main ingredient for glass is silica from sand and other minerals that have been melted together by extremely high temperatures, the only reason people can make optic fibers is because of mining. If you are wondering what the two most commonly used ingredients for glass are, they are soda ash and limestone; but other materials can be added to create specific colors or properties. For example, it is possible to change physical and optical properties, such as the index of refraction, the coefficient of expansion, and the melting point just by adding specific ingredients to the glass. The idea is to create glass so pure that if you were to look through miles of solid-core optical fiber glass, you would still be able to clearly see whatever is on the other side of the glass. The Internet, cable television, and telephones are all products that benefit enormously from fiber-optic cables. U.S. telephone companies use more fiber optic cables than anyone, but they are also used on power lines, where they can be retrofitted onto existing lines with minimal additional load; computer networks designed for local access; and to transmit videos. There are also low-power hybrid cables capable of carrying both data and small amounts of on-demand optical power. What exactly is a fiber-optic cable, and why is it so useful? The answer to the first question is simple: the fiber in a fiber-optic cable is made of high- quality glass that is categorized as being optically pure and that is also extremely strong and thin. In fact, the diameter of each fiber is about the same as the diameter of a single strand of hair. It shouldn’t surprise you that the fibers are strong; remember, after all, that volcanoes produce obsidian — a form of glass that is usually black, and that was used anciently whenever someone needed something hard and sharp for things like knives and arrow heads. In fact, doctors still use obsidian today in some of their surgical scalpels because it works as well as, or better than, surgical steel. The answer to the second question also is simple. Systems that use fiber-optic cables are faster, transmit more data, and do a great job of transmission. If Alexander Bell had his way, he would have used fiber-optic cables from the very beginning. When he began his first attempts to create the telephone, he started the process around 1880 by tr ying to use light in order to communicate. What he needed (and didn’t have) was a laser and something to direct it through, optical fiber. The laser was invented in 1960; in 1966, researchers discovered that they could use silica glass fibers to transmit light waves. By 1970, commercial optical fibers were being produced, and new kinds of lasers had been developed that took advantage of them. Datalinks that consisted of lasers and light detectors were used to convert analog electronic signals into digital pulses of light that could then be transmitted through fiber-optic cables to another datalink that would convert the digital light pulse back into electronic signals. How, exactly, does a fiber-optic cable work? Once the strands of optically pure glass have been created, they