What is Optical Fiber?

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  • Written By: Brendan McGuigan
  • Edited By: Bronwyn Harris
  • Last Modified Date: 26 September 2019
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Optical fiber is a term for any sort of plastic or glass conduit meant to transport light. The principles behind it are actually quite old, but in recent years it has become an incredibly important technology, as communications infrastructure has begun to use this fiber to transmit data at extremely high rates. Aside from fiber optic communications, however, it has a number of applications in medicine, consumer products, and physics.

This sort of fiber offers a number of advantages over traditional metal wire, the most important being that there is considerably less signal degradation. Additionally, it is immune to electromagnetic interference, which can seriously impede the transmission of data along normal metal wires. This adds an added security measure, as well, since optical fiber can survive an electromagnetic pulse that would destroy metal cables.

The basic principle behind optical fiber is quite simple: the fiber is coated to make it completely reflective on the inside, so that when light goes in, it reflects without losing any light, and passes down the fiber to the other end. This basic idea, of guiding light by refraction, goes back to the 1840s. By the beginning of the 20th century, some practical applications had been developed, most notably the use of this fiber in dentistry to light up the inside of the mouth.


In the 1920s, the same basic technology was used to transmit full images. During the following decade, the technology was used practically to illuminate the inside of a surgery, allowing for a much more precise operation. It continues to be used in surgery, especially to facilitate less invasive internal surgeries. The first true optical fiber appeared in the 1950s, and by the end of the decade experiments were underway with a type of fiber very similar to that used today, with glass fibers coated with a transparent sheath.

By the 1970s, optical fiber was beginning to be refined, reducing the noise in the signal. These refinements allowed for the possibility that the fibers could be used to transmit actual communication over long distances. This allowed for massive communication backbones to be built, which laid the groundwork for the Internet. At the dawn of the 1980s, General Electric created a method by which extremely long strands could be stretched out, up to 25 miles (40 km) at a time, making massive backbones even easier to construct.

Because of its low level of degradation, or attenuation, optical fiber is ideal for long distance communications. While metal wire requires repeaters to be installed at short distances, to make sure the signal stays strong, fiber optics can be stretched for long distances without a repeater, reducing costs drastically. Additionally, fiber is able to transport a great deal more information than metal wire, making it preferable even over short distances, such as those within a network situation in a single building. Since the fiber doesn’t conduct electricity in the same way metal wire does, it is safe to use in high voltage environments where traditional wiring could be dangerous.


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Discuss this Article

Post 6

Can any one of you help me for my lab report theory and introduction part on 'fiber optic expand and network experiment'?

Post 4

@SkyWhisperer - Light travels at 186,000 miles per second—that’s pretty fast! That’s what makes fiber optics so amazing. You can piggyback a whole bunch of data, including phone calls, Internet traffic, video and audio onto fiber optics and it will travel faster than you can blink.

Post 3

How fast does light travel through fiber cable? I read somewhere that it’s well over 150,000 miles per second.

Post 2

@charred - Yes, it is really amazing. I actually worked a lot with optical fiber when I worked in telecommunications. Our goal was always to build a completely optical fiber network. We used fiber cable for everything except the “last mile” from the network to the customer’s house. Fiber optics on balance was also cheaper, lighter and safer than the alternatives. You can’t beat the call quality either. When you get a long distance phone call from Europe and it sounds like the caller is right next door, that’s fiber optics working for you.

Post 1

This article is an excellent introduction to optical fiber. It’s remarkable when you realize that the strands in fiber cable are the width of a human hair and yet can transport so much information, so fast.

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