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= Basics of fiber optic communication =

Fiber-optic communication
Fiber-optic communication is a method of transmitting information from one place to another by sending the signal in the form of light through an optical fiber.

Fiber optic cable construction
It consists of Core cladding and Protective sheeth.

Core This is the physical medium that transports optical data signals from an attached light source to a receiving device. The core is a single continuous strand of glass or plastic that’s measured in microns (µ) by the size of its outer diameter. The larger the core, the more light the cable can carry. All fibre optic cable is sized according to its core’s outer diameter. The three multimode sizes most commonly available are 50, 62.5, and 100 microns. Single-mode cores are generally less than 9 microns.

Cladding This is the thin layer that surrounds the fibre core and serves as a boundary that contains the light waves and causes the refraction, enabling data to travel throughout the length of the fibre segment.

Protective sheeth:This is the outer layer of any cable. Most fibre optic cables have an orange jacket, although some types can have black or yellow jackets.

Working Principle of Optical fiber
Working Principle of Optical fiber is Total internal reflection phenomenon. Total internal reflection

Total internal reflection is a phenomenon that occurs when light travels from a more denser medium (or a medium with higher refractive index) to a less denser one (lower index), such as glass to air or water to air. When light travels from an optically dense medium to a less optically dense medium, the light refracts away from the normal. If the angle of incidence is gradually increased, one will notice that at a certain point, the refracted ray deviates so far away from the normal that it reflects rather than refracts.

Advantages of Optical fiber communication:
1.Bandwidth: Fibre optic cables have a much greater bandwidth than metal cables. The amount of information that can be transmitted per unit time of fibre over other transmission media is its most significant advantage. With the high performance single mode cable used by telephone industries for long distance telecommunication, the bandwidth surpasses the needs of today's applications and gives room for growth tomorrow. 2.Low Power Loss: An optical fibre offers low power loss. This allows for longer transmission distances. In comparison to copper; in a network, the longest recommended copper distance is 100m while with fibre, it is 2000m.

3.Interference: Fibre optic cables are immune to electromagnetic interference. It can also be run in electrically noisy environments without concern as electrical noise will not affect fibre.

4.Size: In comparison to copper, a fibre optic cable has nearly 4.5 times as much capacity as the wire cable has and a cross sectional area that is 30 times less.

5. Weight: Fibre optic cables are much thinner and lighter than metal wires. They also occupy less space with cables of the same information

6.capacity: Lighter weight makes fibre easier to install. 7.Safety : Since the fibre is a dielectric, it does not present a spark hazard.

8.Security: Optical fibres are difficult to tap. As they do not radiate electromagnetic energy, emissions cannot be intercepted. As physically tapping the fibre takes great skill to do undetected, fibre is the most secure medium available for carrying sensitive data.

9.Flexibility: An optical fibre has greater tensile strength than copper or steel fibres of the same diameter. It is flexible, bends easily and resists most corrosive elements that attack copper cable. Disadvantages:

1.Cost:Cables are expensive to install but last longer than copper cables.

2.Fragile: Fibres can be broken or have transmission loses when wrapped around curves of only a few centimetres radius. However by encasing fibres in a plastic sheath, it is difficult to bend the cable into a small enough radius to break the fibre.

Applications of Fiber optic communication
Optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication, and cable television signals. Due to much lower attenuation and interference, optical fiber has large advantages over existing copper wire in long-distance and high-demand applications.