Guest Editorial Energy-Efficiency in Optical Networks

THE increasing concern for environmental and cost issues has made energy efficiency in telecom networks an important theme. According to a recent report [1], today’s networks are wasting a lot of energy by consuming 10,000 times more energy than what is really needed. The Internet currently consumes about 0.4% of the total electricity in broadband-enabled countries and is foreseen to quickly reach 1% with the current trend of data transmission rate increase [2]. These numbers have triggered tremendous efforts and collaborations between industry and academia to address this epidemic and challenging problem. Consequently in 2010, Green Touch [3]—a consortium of leading Information and Communications Technology (ICT) industry, academic and non-governmental research experts, was launched aiming to make communications networks 1,000 times more energy-efficient within five years. The joint effort to reach this goal would not only reduce the world’s carbon emissions directly contributed by the ICT sector (which is estimated to be around 2%), but also lower the remaining 98% of the carbon emissions contributed by all the other sectors directly and indirectly affected by ICT [3]. Optical communication and networking technologies have been widely applied to both access networks and Internet optical backbone, and further incorporated with other wired and wireless systems in order to enable an end-to-end serviceprovisioning platform and to support specific application scenarios. This leads to a design paradigm of integrated optical networks, which targets better exploration of user experiences, network/carrier economics, and control/management flexibility by way of heterogeneous system integration, end-to-end considerations, and global optimization. Such a design paradigm has driven the emergence of many exciting research topics and applications, such as Long-Reach Passive Optical Networks (LR-PONs), translucent optical networks, Fiber-Wireless (FIWI) integration, and Radio-over-Fiber (RoF).