Application of free-space optics in future data centers (Conference Presentation)

The architectural issues related to growth capability, dynamicity, and bandwidth requirements in data centres (DCs) impact the connectivity requirements. The larger the DC, the more challenging and complex the cabling becomes. The traditional approach, which is still the case for smaller DCs, uses long individual patch cords between different DC network tiers. However, in medium to large DCs, a large number of patch cords are required, which are less robust and create the prospect for problems resulting from bending, crushing and scalability. Additionally, the progression toward 40 and 100 Gbit/sec transmission rates is paving the way for parallel optics in place of serial connections. Therefore, the way forward would be to exploit the dual benefits of optical fibre and free space optical communications for both inter- and intra-rack links to address the challenges facing future DCs, in particular their energy efficiency. This hybrid optical fibre-optical wireless architecture can provide unprecedented degrees of flexibility thus offering a number features including (i) relatively easy reconfiguration of the connectivity within DC; (ii) drastically reducing the number of cable interconnections; (iii) acting as an enabler for network operators to deploy topologies that would otherwise remain impossible due to the substantial cabling complexity. This talk gives an overview of optical wireless communications (mostly FSO), which and its use in DCs. The FSO technology is compact, low power and energy efficient, where it uses mirror arrays with flat and concave mirrors to establish links between server, switches, rack, etc.