Fiber Optic Cable

What is Fiber Optic Cable??

• A technology that uses glass (or plastic) threads (fibers) to transmit data.
  
• A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves.
  
• Fiber optics is a particularly popular technology for local-area network. In addition, telephone companies are steadily replacing traditional telephone lines with fiber optic cables. In the future, almost all communications will employ fiber optics.

Uses of Optical Fiber

• As a medium for telecommunication and networking because it is flexible and can be bundled as cables.
  
• Fibers can be used as light guides in medical and other applications where bright light needs to be brought to bear on a target without a clear line-of-sight path.
  
• Used as sensors to measure strain, temperature, pressure and other parameters.
  
• Bundles of fibres are used along with lenses for long, thin imaging devices called endoscopes, which are used to view objects through a small hole. Medical endoscopes are used for minimally invasive exploratory or surgical procedures (endoscopy). Industrial endoscopes (see fiberscope and borescope) are used for inspecting anything hard to reach, such as jet engine interiors.
  
• In some high-tech buildings, optical fibers are used to route sunlight from the roof to other parts of the building.
  
• Optical fibers have many decorative applications, including signs and arts, artificial Christmas tree, and lighting.
  
• A few communities have Fiber to the Home technology which provides subscribers with Ultra High Speed Internet, Telephone, and Television services.

Two Major Types of Fiber Optic Cables

• Single-mode: uses a specific light wavelength. The cable's core diameter is 8 to 10 micrometres. Single-mode fiber is often used for intercity telephone trunks and video applications.
  
• Multi-mode: uses a large number of frequencies (or modes). The cable's core is larger than that of single-mode fiber. Multimode fiber is the type usually specified for LANs and WANs.

Advantages

• Lower cost in the long run.
  
• Low loss of signal (typically less than 0.3 dB/km), so repeater-less transmission over long distances is possible.
  
• Large data-carrying capacity (thousands of times greater, reaching speeds of up to 1.6 Tb/s in field deployed systems and up to 10 Tb/s in lab systems).
  
• Immunity to electromagnetic interference, including nuclear electromagnetic pulses (but can be damaged by alpha and beta radiation).
  
• No electromagnetic radiation; difficult to eavesdrop.
  
• High electrical resistance, so safe to use near high-voltage equipment or between areas with different earth potentials.
  
• Low weight.
  
• Signals contain very little power.
  
• No crosstalk between cables.
  
• No sparks (e.g. in automobile applications).
  
• Difficult to place a tap or listening device on the line, providing better phyisical network security

Disadvantages

• High investment cost.
  
• Need for more expensive optical transmitters and receivers.
  
• More difficult and expensive to splice than wires.
  
• At higher optical powers, is susceptible to "fiber fuse" wherein a bit too much light meeting with an imperfection can destroy as much as 1.5 kilometers of wire at several metres per second. A "Fiber fuse" protection device at the transmitter can break the circuit to prevent damage, if the extreme conditions for this are deemed possible.
  
• Cannot carry electrical power to operate terminal devices. However, current telecommunication trends greatly reduce this concern: availability of cell phones and wireless PDAs; the routine inclusion of back-up batteries in communication devices; lack of real interest in hybrid metal-fiber cables; and increased use of fiber-based intermediate systems.