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The Role of Fiber Optic Cables in Computer Networking
October 10, 2018 by Bradley Mitchell
How Fiber Optic Cables Work
Fiber optic cables carry communication signals using pulses of light generated by small lasers or light-emitting diodes (LEDs).
The cable consists of one or more strands of glass, each only slightly thicker than a human hair. The center of each strand is called the core, which provides the pathway for light to travel. The core is surrounded by a layer of glass called cladding that reflects light inward to avoid loss of signal and allow the light to pass through bends in the cable.
The two primary types of fiber cables are called single mode and multi-mode fiber. Single mode fiber uses very thin glass strands and a laser to generate light while multi-mode fibers use LEDs.
Single mode fiber networks often use Wave Division Multiplexing (WDM) techniques to increase the amount of data traffic that can be sent across the strand. WDM allows light at multiple different wavelengths to be combined (multiplexed) and later separated (de-multiplexed), effectively transmitting multiple communication streams via a single light pulse.
Advantages of Fiber Optic Cables
Fiber cables offer several advantages over traditional long-distance copper cabling.
Fiber optics have a higher capacity. The amount of network bandwidth a fiber cable can carry easily exceeds that of a copper cable with similar thickness. Fiber cables rated at 10 Gbps, 40 Gbps, and even 100 Gbps are standard.
Since light can travel much longer distances down a fiber cable without losing its strength, it lessens the need for signal boosters.
Fiber is less susceptible to interference. A traditional network cable requires special shielding to protect it from electromagnetic interference. While this shielding helps, it is not sufficient to prevent interference when many cables are strung together in close proximity to each other. The physical properties of glass and fiber cables avoid most of these issues.
Fiber to the Home (FTTH), Other Deployments, and Fiber Networks
Whereas most fiber is installed to support long-distance connections between cities and countries, some residential internet providers have invested in extending their fiber installations to suburban neighborhoods for direct access by households. Providers and industry professionals call these "last mile" installations.
Some better-known FTTH services in the market today include Verizon FIOS and Google Fiber. These services can provide gigabit (1 Gbps) internet speeds to each household. However, even though providers also offer lower cost, they typically also offer lower capacity packages to their customers.
What Is Dark Fiber?
The term dark fiber (often spelled dark fibre or called unlit fibre) most commonly refers to installed fiber optic cabling that is not currently being used. It sometimes also refers to privately operated fiber installations.