Optical fibres in telecommunications
One application of optical fibres IS their increasing importance 1D telecommunications. Research is already far advanced and production of the necessary equipment has begun. It is expected that, by the end of the century, if not before, optical fibres will
have largely replaced copper cables, not only for telephone conversations but also for transmitting pictures, television programmes, computer information and so on. Briefly, in the case of a telephone conversation, the energy of sound waves entering the microphone is transferred to electric wave energy. This is transferred to electric pulses and the energy of these controls light pulses which travel through the optical fibre. At the receiving end, the light energy is transferred back to sound energy. One big advantage of an optical fibre is its small size and weight compared with a copper cable of equivalent signal carrying capacity. This is an important factor in a spacecraft or an aircraft. See also Fig. 24.25 (a).