Optical fiber

made by drawing glass (silica) or plastic to a diameter

slightly thicker than that of a human hair

to transmit light between the two ends of the fiber

and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than electrical cables.

travel along them with less loss; in addition, fibers are

immune to electromagnetic interference, a problem from which metal wires suffer.

often wrapped in bundles so they may be used to

carry light into, or images out of confined spaces, as in the case of a fiberscope.

of other applications, some of them being fiber optic sensors

and fiber lasers.

that makes fiber optics possible, was first demonstrated by Daniel

Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London, 12 years later.Tyndall also wrote about the property of total internal reflection in an introductory book about the nature of light in 1870:The first working fiber-optical data transmission system was demonstrated by German physicist Manfred Börner at Telefunken Research Labs in Ulm in 1965, which was followed by the first patent application for this technology in 1966.NASA used fiber optics in the television cameras that were sent to the moon. At the time, the use in the cameras was classified confidential, and employees handling the cameras had to be supervised by someone with an appropriate security clearance.

computer networking because it is flexible and can be bundled

as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with much lower attenuation compared to electrical cables. This allows long distances to be spanned with few repeaters.

carry over 3,000,000 full-duplex voice calls or 90,000 TV channels.
Immunity

to electromagnetic interference Light transmission through optical fibers is unaffected by other electromagnetic radiation nearby. The optical fiber is electrically non-conductive, so it does not act as an antenna to pick up electromagnetic signals. Information traveling inside the optical fiber is immune to electromagnetic interference, even electromagnetic pulses generated by nuclear devices.
Low attenuation loss over long distances Attenuation loss can be as low as 0.2 dB/km in optical fiber cables, allowing transmission over long distances without the need for repeaters.
Electrical insulator Optical fibers do not conduct electricity, preventing problems with ground loops and conduction of lightning. Optical fibers can be strung on poles alongside high voltage power cables.
Material cost and theft prevention Conventional cable systems use large amounts of copper. Global copper prices experienced a boom in the 2000s, and copper has been a target of metal theft.
Security of information passed down the cable Copper can be tapped with very little chance of detection

some other materials, such as fluorozirconate, fluoroaluminate, and chalcogenide glasses

as well as crystalline materials like sapphire, are used for longer-wavelength infrared or other specialized applications. Silica and fluoride glasses usually have refractive indices of about 1.5, but some materials such as the chalcogenides can have indices as high as 3. Typically the index difference between core and cladding is less than one percent.
Plastic optical fibers (POF) are commonly step-index multi-mode fibers with a core diameter of 0.5 millimeters or larger. POF typically have higher attenuation coefficients than glass fibers, 1 dB/m or higher, and this high attenuation limits the range of POF-based systems.

a tough resin coating and an additional buffer layer, which

may be further surrounded by a jacket layer, usually plastic. These layers add strength to the fiber but do not contribute to its optical wave guide properties. Rigid fiber assemblies sometimes put light-absorbing ("dark") glass between the fibers, to prevent light that leaks out of one fiber from entering another. This reduces cross-talk between the fibers, or reduces flare in fiber bundle imaging applications.