Investigation on 160 Gb/s Dense Wavelength Division Muliplexed Systems

Abstract

The tremendous growth of Internet traffic has created increasing demand on high capacity optical communications networks. The optical transmission networks offer improved possibilities for dealing with ever growing demands on transmission bandwidth and system capacity. In the last 20 years, the optical transmission networks have become one of the most important part in the telecommunication hierarchy, whose seamless integration with conventional network applications and services forces a further development and a broader deployment of optical networks in all telecommunication areas. Making a classification of different optical transmission networks, it can be distinguished between Access, Metro and Core (or back-bone) networks. This is the most convenient network classification made to the transmission distance or network diameter. Access networks as the base of the telecommunication hierarchy, are characterized by the interaction between numerous different network technologies based on different transmission media e.g. wire, wireless or fiber. These networks possess a small total capacity and inter-operational functionality between different transmission protocols (e.g. TCP/IP, ATM) and services (e.g. ISDN, DSL). The conventional wire based data transmission dominates the access area, making these networks to become a bottleneck of data transmission in the future. The implementation and deployment of optical networks in this region e.g. fiber-to-the-home (FTTH) and fiber-to-the-business (FTTB) would address the bottleneck problems, hence enabling an even broader bandwidth access than with conventional wire based technologies (e.g. DSL). But this is rather a question of deployment strategy and cost than of the achievable transmission performance. Metro area networks (MANs) accumulate the traffic from the access networks with different protocols and services, enabling its further transmission over longer distances. The MANs are based on optical transmission technologies and they are characterized by a limited transmission distance (< 200 km) and an increased network complexity. Furthermore, MANs have to deal with different communication protocols, thus requiring close interaction between the network management and transmission infrastructure, which results in the fact that the channel data rates used here are rather small (<10 Gb/s/ch, at the moment). The core networks connect numerous MANs over distances larger than 200 km. Basically, it can be distinguished between terrestrial and under-sea core networks. The under-sea networks are characterized by point-to-point transmission, ultra long-haul transmission distances (>1000 km), and specialized component characteristics (e.g. component life times and customized fiber types). The core networks possess an increased transmission capacity based on larger channel data rates. The upgrade of core networks represents the first step for a faster worldwide communication. The deployment of future optical networks and upgrade of existing ones will be governed by the growth of the traffic in all network areas. The question arising here, is what is the best transmission technology to be implemented in future systems. Dense wavelength division multiplexing (DWDM) networks has emerged as a very attractive option.