FIBRE OPTIC COMMUNICATION

Fibre-optic communication is the method of transmitting information from one place to another as pulses of light travelling through an optical fibre, working on the underlying principle of total internal reflection, which traps and guides the light along the length of the fibre core without it escaping out the sides. Light itself has a very high frequency (roughly 400 THz to 790 THz) compared with microwave radio systems, which is part of why an optical-fibre channel can carry so much more information than a conventional radio link. Optical fibres are commonly made from silica glass or silicon dioxide, a material that is highly abundant on Earth; more specialised applications now also use materials such as chalcogenide glasses and fluoroaluminate crystalline materials, chosen because they transmit larger infrared wavelengths more efficiently and offer better overall transmission capability. Because optical fibres are not electrically conductive, they are especially preferred wherever multiple communication channels must be laid close together and isolation from electrical and electromagnetic interference is important. Fibre-optic systems find applications in international and inter-city communication, dedicated data links, plant and traffic control systems, and defense applications, and most transatlantic telecommunication cables linking the United States and Europe are, in fact, fibre optic. Their merits include being very thin and far lighter than equivalent copper cables, offering a much larger bandwidth and therefore a much larger information-carrying capacity, complete immunity to electrical interference, and typically being cheaper than copper cable of comparable capacity; their demerits are that the fibres themselves are more physically fragile than copper wire and the overall technology remains comparativ …