Sébastien Bigo

Director of WDM Dynamic Networks in Bell Labs at Alcatel-Lucent, France

Sustaining traffic growth: from transmission capacity to network capacity

The x10 growth rate of transmission capacity records in research labs has fallen below the growth rate of data traffic over the past 10 years. Recent long distance demonstrations rely on the simultaneous optimization of modulation, coding, digital signal processing and coherent technologies to unprecedented levels of tuning, but with sizable gains. Other experiments based on more disruptive technologies like spatial division multiplexing are struggling to meet distance and complexity requirements, but open radically new paths for the future of transmission. We will draw a short history of trends in transmission and illustrate it with results from our laboratory.

It has become timely to raise awareness what network capacity is much more than transmission capacity. While every new dB on transmission brings us closer to the limits of information theory, optical networks are still largely over-provisioned, with large margins stemming from today’s simplistic set-and-forget mode of operation of the physical layer. When bandwidth becomes scarce, the dynamic allocation of resources and adaptation of spectral efficiency to physical limits becomes new frontiers. This is little doubt that the realm of intelligent elastic optical networking is ahead of us. We will provide example of the most promising trends along that path.

Dan Marom

Head of Photonic Devices Laboratory, The Hebrew University of Jerusalem, Israel

2015-2016 IEEE Photonics Society Distinguished Lecturer

Switching technologies for spatially and spectrally flexible optical networks

Today’s fiber-optic communication networks span the globe, delivering broadband information across all market segments and connecting massive datacenters, businesses, and individual user’s homes. As such, optical networks must operate reliably and efficiently when transporting the massive information capacity of the Internet, allowing networks to adapt to growing and changing demand flows and occasional interruptions. Wavelength-selective switches (WSS) have been instrumental in fulfilling this role, enabling all-optical spectral routing of individual wavelength-division multiplexed (WDM) communication channels at network nodes.

The recent introduction of space-division multiplexing (SDM) to the optical communication domain with new fiber types, in order to economically support the exponentially growing capacity, necessitates complementary components for implementing SDM-WDM optical networks. SDM is typically realized with either multi-core or few-mode fibers and great capacity achievements have been demonstrated to-date in each fiber solution. Wavelength-selective switching functionality for these two fiber types has recently been introduced. A joint-switching WSS concept has been realized for multi-core fibers, enabling information to be encoded and routed on the SDM-WDM optical network as a spatial super-channel (single wavelength channel spanning multiple cores). This spatial super-channel routing concept with joint-switching WSS also extends to few-mode fibers. Hence a single WSS can then be used in analogous fashion to the single-mode fiber networks, thereby heralding the cost-savings benefits of SDM. A WSS with direct few-mode fiber interfaces has been demonstrated with the few-mode beams routed in free-space just as the single mode beam does in a conventional WSS. A study on the pass band filtering effect and mode mixing due to the spectral switching of dispersed components revealed the spatial-spectral interplay in the mode-dependent loss attributes of the few-mode fiber WSS. Such advanced WSS prototypes will serve the next generation transport networks when SDM is fully adopted by carriers.

Marco Schiano

Project Manager at Telecom Italia

Transport networks challenges between layers integration and service differentiation

After a decade of disruptive optical innovation, transport networks are undergoing deep transformations driven by evolving requirements and new optimization opportunities. The novel requirements come from new clients such as content distribution and data centers networks whose traffic will be affected by large size and pattern variations compared to the traditional IP traffic. At the same time, new optimization opportunities arise from the network system manufacturers outstanding capabilities of integrating complex optical and electronic functions in compact equipment. Network control paradigms are also moving from the GMPLS protocol suite to transport SDN orchestrators and controllers, paving the way to effective multi-layer and multi-vendor networking. After the analysis of the evolving transport network requirements this presentation will provide some hints on the architectures and technologies that are the best candidates for future networks. Some open issues are also discussed as possible research topics.