Major characteristic of a telecommunication system is unquestionably its information-carrying capacity. Though, capacity is the priority for system users, but the extent of limit is decided by the Shannon-Harley theorem. The capacity is proportional to its bandwidth, which in turn is proportional to the frequency of the carrier. High-speed communication systems use light-as a carrier with the highest frequency among all the practical signals. This demands the use of Guiding media-fibre, high sensitivity detectors, receivers and switches. The explosive growth of Internet traffic, deregulation and the increasing demand of users, therefore, require more bandwidth, which is controlled only by optical networks which can deliver the required capacity. The physics of such optics based telecommunication systems involve some fundamental concepts such as light scattering, superposition of waves, optical excitations of electrons in semi-conducting crystals and in glasses. The art of optical communication using fibre optical cable for information exchange is one of the recurring themes of this paper.