Scientists Say: Fiber optic cable

Fiber optic cables carry digital information across the globe

an illustration shows a cable with a smooth outer coating, which has a bundle of thin, light-carrying fibers inside and sticking out of the end

In fiber optic cables, many hair-thin strands of transparent material carry data coded in light. Images Plus

Fiber optic cable (noun, “FY-ber OPP-tik CAY-bel”)

Fiber optic cables carry data as pulses of light. Those pulses can travel thousands of kilometers (miles) extremely quickly. As a result, fiber optic cables are often used for high-speed communications. That includes phone calls, TV and internet access.

Each fiber optic cable contains many hair-thin strands, or fibers, of a transparent material. That material is usually glass. But sometimes it’s plastic. A single cable may contain only a few fibers. Or it may contain hundreds.

A laser can send pulses of light into the glass or plastic fiber at one end of a cable. The pattern of those light pulses encodes data. Say, the sound of someone’s voice on a phone call or the visuals of a TV show. Those light pulses zip along the fiber optic cable to their destination. There, a receiver decodes the pattern of light into digital data. A device, such as a phone or computer, can then process that information so that we can see or hear it.  

Fiber optic cables were first used to carry phone calls in the 1970s. Now, these cables bring high-speed internet to much of the world. Around the globe, cables are buried underground, hang from poles and snake across the seafloor. Together, they span some 4 billion kilometers (2.5 billion miles) of cable. That’s father than the distance from Earth to Uranus.

But fiber optic cables aren’t only used for communications. Some seismologists use them to listen for earthquakes on the seafloor. (Earth’s rumblings can mess with the light signals sent through a fiber, allowing researchers to detect seismic activity.) Likewise, fiber optic cables can be used as sensors to monitor structures such as bridges or railways. These fibers are even used to provide precise lighting for medical instruments such as endoscopes.

In a sentence

A new chip recently broke the record for highest data transmission speed through a fiber optic cable.

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Maria Temming is the Assistant Managing Editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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