Looking Into Fiber Optic Cable

Looking Into Fiber Optic Cable

Fiber optic cable is the “next generation” of cabling that our electronic/digital services will be delivered by in the very near future. In fact, fiber is coming close to completely taking over the market in Europe for TV, phone, and Internet services. The reason for this is multi-fold, and we’ll go into these.

I’m also going to briefly outline the history of fiber and, even more briefly, how it’s made. Lastly, for those that want a little more technical information about fiber and some of the abbreviations we use in the communications industry, I’ll shed some light here, as well.

Why is Fiber Optic Cable Growing in Popularity?

The answer depends on who you ask. The end-user consumer is going to tell you the best thing about fiber optics is the fast Internet speed it enables. The Chief Technology Officer at the telecom company may give you three or four different reasons.

Some of these reasons may include:

  • Less loss of signal over distances. This means less repeating/amplifying equipment is required on longer cable runs. This is especially meaningful for rural carriers.
  • More data can be transmitted over a single cable. This means the company can offer more services (such as more channels) and faster Internet speeds.
  • Connections are more secure and less prone to atmospheric deterioration (corrosion on copper causes signal loss).

Although technology keeps giving us incremental increases in the speed at which data/information can flow over copper wires, there is a finite limit to how much that cable can carry. Additionally, as the amount of data being transmitted increases, the distance that data can reliably travel decreases, without some sort of signal amplification or repeating equipment.

Fiber optic cable is also limited as far as the amount of data that can be transmitted over a single cable (fiber/strand). Whereas commercial networks have currently topped out at just over one Gigabyte in speed, within the confines of a commercial building, current technology has fiber optics transmitting more than one hundred times as much data, over distances of miles.

How Data Is Transmitted Over Fiber Optic Cable

Data, whether sent over fiber optic or copper cables, travels at the speed of light. This is physics. The difference between the two is how the signals they carry are configured, for lack of a better word. Both sets of signals are digital, thus they are both a conglomeration of ones and zeros. However, the signal going over the copper cable is purely electronic (usually around five volts), while the signal on the fiber is light-based.

Fiber Optic Cable
Image via Wikimedia Commons

Your local cable company is able to supply you with 1000 channels (including music channels) and phone and Internet service over the existing copper cable through a process that the industry calls “single cable distribution.” The frequencies of the various signals being sent over the wire are varied in order for the equipment to be able to distinguish between them. The limitation here is that there only so many frequencies to use. Distance is limited in copper because of the inherent resistance of the copper attenuating the signal rapidly.

Data on fiber is contained in a coherent light beam that is sent over the glass fiber and is created by a laser. Multiple data streams can be input onto the fiber optic cable by varying the frequency of the laser. Since light can be measured by the color it emits, it can be said that these extra data streams are added by varying the color of the lasers used. Since the light from the laser attenuates much more slowly, data can be sent over much larger distances on fiber.

And yes, the laser beam the fiber carries can cause severe eye damage.

A Brief History of Fiber Optic Cable and How It’s Made

The general idea behind fiber optics was conceived by researchers in England in the mid-Sixties. However, technological deficiencies kept them from realizing their goal. In 1970, a team at Owens Corning was able to manufacture a glass strand pure enough to transit light over distances greater than a few feet. Engineers at Bell Labs are the ones that came up with the lasers that started the fiber revolution.

Most people are unaware of the fact that fiber optic cable is a thin strand of glass (about twice as thick as a human hair) that is flexible and covered with a rubber or plastic buffer. The glass fiber is created using a heat extrusion process where the fiber is stretched and stretched until the required thickness is met. This hair-fine glass fiber is then fed through a soot deposition furnace where a film of soot (yes, from burning) is deposited onto the bare fiber. This soot is part of what keeps the beam of light coherent and inside the fiber.

The fiber is then cut into the required lengths and a colored plastic/rubber coating is applied. This coating can be one of six colors (in distribution networks)-white, grey, blue, green, orange, and brown, which is then further covered by a black rubber/plastic coating. However, there are a number of other colors that are used when the fiber bundle contains more than six strands. The different colors are how we identify which fiber, or strand, goes where. How Stuff Works has a great piece that goes into good detail on how fiber is made and how data is transmitted over it.