Optical test bench experiments for 1-Tb/s satellite feeder uplinks

Due to expected capacity bottlenecks of exploited microwave technologies, feeder links for data relay or broadband access systems will require the implementation of high capacity optical communication links between space and ground. In this context, it is necessary a detailed investigation of the optical technologies and techniques that could enable the transmission of high data rates at optical frequencies through the Earth’s atmosphere, with regard to all kinds of atmospheric phenomena. In particular, the adverse effects of atmospheric turbulence fading are of special relevance to optical communication systems for ground-to-space uplink applications. Although previous studies and experiments have demonstrated the feasibility of such optical links at low data rate, research is still needed to identify technical solutions and strategies adapted to the specific constraints imposed to these high-speed links in order to ensure the required level of performance. Against this background, various test benches have been developed in order to characterize different modulation and detection techniques for optical communication systems prior to be incorporated in the conceptual design of future 1-Tb/s ground-space optical links. The expected performances of such an experimental demonstration are derived based on simulation models taking into account atmospheric turbulence effects, in order to prove the feasibility of reliable ground-space high date rate optical communication links. Our first simulation studies, considering On-Off Keying (OOK) and Differential Phase Shift Keying (DPSK) modulations, have allowed us to understand the complexity of the link and to optimize both the transmitter and the receiver to achieve acceptable performance levels.