Electronic communications systems are said to make use of electronic devices with electrons being information carriers for signal processing and transmission. So one may expect optical communications systems to make use of all-optical devices built on photons. The advance in communications from electronic systems to optical fibre systems is one of the greatest achievements in modern technology. Optical communication through fibre cables has several overwhelming advantages over conventional metallic or coaxial cable facilities, such as greater capacity, noise immunity, safety and security, resistance to environmental extremes and low cost in the long run. Optical fibre communications also challenge the “newly-born” satellite communications.