Optical fiber communication is made successful with the invention of optical fiber cables,which is readly available as the raw material is sand or silica.The opticalfiber consist of a core and a cladding.Core have high refractive index than cladding,but the difference is only small. It works on the principle of total internal reflection .When the light travels from denser medium ,if the incident angle is greater than a particular values(it is called critical angle.) all the light will be reflected.This is called total internal reflection.Critical angle is the angle of incidence above which total internal reflection occuurs.There are two types of fibers single mode and multi mode,For carrying light over long distances we opt only single mode fibers . Also multimode fibers suffer losses like modal dispersion which affects the bandwidth carrying capacity.Multimode has large core diameter,also less precise.
Components
The Fiber optical cable comprises of an outer jacket(usually orange coloured),inside that there will be an inter coveringof black color.Inside that there will be binder which will be of plaster or yarn.Inside that the buffer tubes will be there.mostly all the buffer tubes wont be filled with fiber,some will be empty they are called fillers or dummy buffer tubes.Along with that there will be a srength member which will be made of glass reinforced plastic or fiber reienforced plastic.It will give the fiber proper strength from breaking while we bend the cable.Inside the buffer tubes there will be optical fibers.They will be coated with an acrylic coating called primary coating.when we remove that we get bare fiber.
Usually the optical fiber cables will be available in bundles of 2 km 4 km...For long distance cable laying we have to join the cables after 2 kms...This process we are using is called Fiber Splicing.
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