The exponential increase in data center system bandwidth densities necessitates the migration of optical connectivity into the system enclosure. This is reflected by the emergence of a new technology eco-system including board-mountable optical engines and board-level optical interconnect. We consider how data center architectures are evolving and investigate the relative maturity and viability of various optical interconnect technologies. We also discuss current European research activities to develop disruptive optical interconnect solutions across all hierarchical levels of the data system from rack-to-rack, board-to-board, chip-to-chip and ultimately on-chip photonic interconnect. An early outcome of these activities has been the successful demonstration of an optically enabled data storage system.
