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OPTICAL FIBRES, Effect of dispersion is cumulative & results in…
OPTICAL FIBRES
Basic structure 
Jacket :black_flag: - Determines the mechanical robustness of the cable and usually plastic and PVC.
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Cladding :black_flag: - Dielectric material with index of refraction less than the core material where it is made of glass or plastic.
Core :black_flag: - Light propagation medium, dielectric material usually glass and does not conducts electric.
Working Principle
When an ray of light travels from a denser to a rarer medium such that the angle of incidence is greater than the critical incidence, the ray reflects back into the same medium this phenomenon called TIR(Total Internal Reflection).
Acceptance Angle - To capture & ensure that rays entering the fibre end surface remain inside the core, the rays must approach the fibre ends at angles less than the acceptance angle for the fibre.
Classification of fibres
Core-cladding size - :lock: The function of the cladding is to provide a lower refractive index at the core interface in order to cause reflection within the core so that light waves are transmitted through the fiber.
Fibre materials :lock:
Plastic-clad silica fiber (PCS) is an optical fiber that has a silica-based core and a plastic cladding. PCS fibers in general have significantly lower performance characteristics, particularly higher transmission losses and lower bandwidths, than all-glass fibers.
Photonic crystal fibers (PCFs) are optical fibers that employ a microstructured arrangement of material in a background material of different refractive index. The background material is often undoped silica and a low index region is typically provided by air voids running along the length of the fiber.
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Propagation path :lock:
The fact that the higher order modes travel farther in the glass core means that they have a greater likelihood of being scattered or absorbed, the two primary causes of attenuation in optical fibers. Therefore, the higher order modes will have greater attenuation than lower order modes, and a long length of fiber that was fully filled (all modes had the same power level launched into them) will have a lower amount of power in the higher order modes than will a short length of the same fiber.
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Effect of dispersion is cumulative & results in increasing pulse spreading with fiber length. When pulse is overlapping, the information error occur making the dispersion sets a limit to the maximum link length possible for a certain bit rate (BR).
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