Guest editorial: Spatially and spectrally flexible elastic optical networking

The traffic carried by core optical networks as well as the per-channel interface rates required by IP routers are growing at a remarkable pace year after year. This trend is due to the widespread deployment of fixed and wireless broadband access networks, the huge growth of video-based services supported by the Internet, and social media applications, as well as a substantially growing amount of machine-to-machine traffic supporting a variety of data-centric applications. Optical transmission and networking advancements have been able to satisfy this huge traffic growth so far by providing the necessary network infrastructure in a cost- and energy-efficient manner, utilizing to the maximum extent the capabilities of optoelectronic and photonic devices across the available bandwidth of deployed optical fibers. However, as we are rapidly approaching fundamental spectral efficiency limits of single-mode fibers, the scientific and industrial telecommunications community foresees that the growth capabilities of conventional WDM networks operating on a fixed frequency grid in conventional wavelength bands are quite limited.