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 threads of glass, each only slightly denser than a human hair. The center of each thread 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 main 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.
Benefits of Fiber Optic Cables
Fiber cables offer several benefits over traditional long-distance copper cabling.
- Fiber optics have a higher volume. 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 vulnerable 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 looped together in close proximity to each other. The physical properties of glass and fiber cables avoid most of these issues.