High-capacity wavelength division multiplexing optical transmission systems

The new services and constantly growing number of users develop constant pressure for current transmission systems. Although the first optical systems started to be used at the beginning of 1980s, the last forty years have brought unprecedented development of these systems. Today's optical transmission systems play key role for satisfaction bandwidth demands. This paper provides short insight into the technological evolution of optical transmission systems and show why these systems arc mostly used in long-haul and metro networks. The first transmission systems had transmission capacity around 45 Mb/s, today's capacity is beyond 2 Pb/s. We looked at the key technologies as well as their future trends.