Space-time-coded high-speed reconfigurable card-to-card free-space optical interconnects

Space-time-coded, free-space-based card-to-card optical interconnects for data centers and high-performance computing are proposed and experimentally demonstrated in this paper. Free-space propagation, which enables flexible and reconfigurable interconnections, is used in conjunction with 2 χ 2 extended Alamouti space-time coding, which reduces the inter-channel crosstalk and improves the sensitivity of the interconnects. Experimental results show that, for 2 × 2 10 Gb/s reconfigurable optical interconnects, space-time coding extends the maximum interconnection range by more than 48% and improves the receiver sensitivity. In addition, the impact of air turbulence on the proposed space-time-coded, free-space-based reconfigurable optical interconnects is experimentally investigated and results show that the interconnect performance is slightly degraded even under relatively strong air turbulence, where the maximum interconnection range is reduced only by around 4 cm.