Fibre optics is the transmission of light through fibres or thin glass rods with a high refractive index over a distance.

It is based on the principle of total internal reflection. This means light that is travelling thru the core hits the outside surface at an angle of incidence greater than the critical angle for that material, so that all the light is reflected back into the fibre without loss. To stop light scattering the core is clad with a glass of a much lower refractive index. Fibre optics is used in many different areas of …

…replacing electrical (coaxial cables which are made of copper). The Advantage of optical over copper cables are they can carry higher amounts of information and faster, undersea optical cables that have a diameter the size of a golf ball can carry 62,500 pages a second or 200,000 telephone calls at once. Also the light can travel a longer distance until repeaters are used. Fibre optic repeaters are usually placed 100km apart compared to 1.5 km for electrical systems.