Fiber Optics
Fiber optic communication uses light signals guided through a fiber core. Fiber optic cables act as wave guides for light, with all the energy guided through the central core of the cable. The light is guided due to the presence of a lower refractive index cladding around the central core. Little of the energy in the signal is able to escape into the cladding and no energy can enter the core from any external sources. Therefore the transmissions are not subject to any electromagnetic interference. The core and the cladding will trap the light ray in the core, provided the light ray enters the core at an angle greater than the ‘critical angle’. The light ray will then travel through the core of the fiber, with minimal loss in power, by a series of total internal reflections. Figure shown below illustrates this process.
Applications for fiber optic cables
Fiber optic cables offer the following advantages over other types of transmission media:
- Light signals are impervious to interference from EMI or electrical crosstalk
- Light signals do not interfere with other signals
- Optical fibers have a much wider, flatter bandwidth than coaxial cables and equalization of the signals is not required
- The fiber has a much lower attenuation, so signals can be transmitted much further than with coaxial or twisted pair cable before amplification is necessary
- Optical fiber cables do not conduct electricity and so eliminate problems of ground loops, lightning damage and electrical shock
- Fiber optic cables are generally much thinner and lighter than copper cables
- Fiber optic cables have greater data security than copper cables
Fiber optic cable components
The major components of a fiber optic cable are the core, cladding, coating (buffer), as shown in Figure below. Some types of fiber optic cable even include a conductive copper wire that can be used to provide power to a repeater
The fiber components include:
- Fiber core
- Cladding
- Coating (buffer)
- Strength members
- Cable sheath
There are four broad application areas into which fiber optic cables can be classified: aerial cable, underground cable, sub-aqueous cable and indoor cable
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