A fiber optic cable consists of a center glass core through which signals passes. It is surrounded by a glass cladding. Sometimes the cladding is surrounded by PVC to increase the cable strength and provide a support for the cladding. This cladding is sometimes surrounded by metal fibers to give extra strength to the cable. It is finally surrounded by an outer cover known as sheath.
In a fiber optic cable, the electrical signals are converted into appropriate light signals and transmitted through it. An emitter sends the signals from one end of the cable and a light sensor (Photo detector) senses this signals and then converts into its digital equivalent. There is a transceiver located at both ends of the cable where the signals are converted from electrical to light signals and vice versa. Fiber optic cables are available in different sizes with varying core and cladding diameters. But the most commonly used fiber optic cable is the 62.5/125 micrometer. The diameter of the core is 62.5 micrometer and that of the cladding is 125 micrometer. Almost alI network technologies that use fiber optic cable require pair of fibers to create the popular duplex fiber optical cabling. Two sources of lights: Laser and LED are used for fiber optic cable. In a fiber optic cable, signals can be transmitted in only one
direction. So, two strands of cables, each contained in different cladding are used to send and receive data signals. Kevlar fibers are used as a sheathing material as they are extremely strong I Kevlar fiber is an organic, man-made fiber which is five times stronger than steel. It has an advantage of light weight and high strength. It provides high resistance to chemicals and fire and thus protects the signal comfortably.
Fiber Optic cables use the principle of total internal reflection to transmit light signals. Speed of a light differs depending on the mediums. The ratio of the speed of a light in a vacuum to the speed of light in a material is called as a refractive index. The refractive index of the cladding is more than that of the core. Thus light waves bounce back and forth inside the core and thus the signals are transmitted. This phenomenon is known as total internal reflection.
Uses and Need of Fiber Optic Cables
Fiber optic cables are mainly used in environments that are highly susceptible to noise and other interferences. Since these cables carry light signals, they are not prone to any interference problems. These cables are highly secure as they do not emit any external signals. Fiber optic cables are used instead of copper wires due to the following characteristics:
Bandwidth - Carries huge amount of data ranging from 100 Mbps to 1 Gbps.
Segment length - Transmits readable data signals in a range of 2 kilometers to 100 kilometers. This allows the user to transmit data over a long distance.
Interference - Secures data from being secretly read as no electrical signals pass through these types of cables. These cables can be used in areas that are highly susceptible to noise, for example, near T.V. towers, Radio stations, Electric transformers. Copper cables are prone to interference to a certain extent.
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