Fiber optic is often used in telecommunication network. Comparing with electrical cable, signal transmission by fiber optic is faster because it uses light as a signal. Besides that, it is also immune to electromagnetic interference, transmits longer distance, and higher bandwidth data rates. How can fiber optic be a path for light?
Light can travel from edge of fiber optic to another edge. The principle of fiber optic is total internal reflection. Before discuss about total internal reflection, let us review about light refraction. Light will be refracted when light through different medium which their refraction index value is different. For example, if light is emitted from inside the water with certain angle, then it will be refracted when comes out from water to the air. The phenomenon of light refraction is the angles are different. If refraction index of medium where the light comes from higher than refraction index of medium where light goes on, the angle will be bigger. If the initial angle is enlarged, there will be a critical angle, that is the angle when the light is not transmitted to the second medium. Moreover, if the angle is still enlarged, the light will be reflected as total internal reflection.
Fiber optic consists of core and cladding. Core has higher refraction index than cladding, then if light travel inside core with the angle more than critical angle, so there will be total internal reflection. By this phenomenon light can travel from one edge to another edge.
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