Adaptive Optics for GEO-Feeder Links: from Performance Analysis via Reciprocity Based Models to Experimental Demonstration
Résumé
High capacity GEO-Feeder optical links are very promising but constitute a real challenge for the whole transmission chain. The modeling and mitigation of turbulence effects is a particularly critical issue that drives the other subsystems design requirements. Building on SAOST, our reciprocity based performance evaluation tool, we study the GEO-Feeder link scenario: adaptive optics error budget and performance in terms of link availability threshold, for forward and return links, as a function of the number of corrected modes and of the ground telescope diameter. Adaptive optics correction is shown to be essential both for downlink and uplink. Choosing a large diameter is highly beneficial for downlink, pointahead anisoplanatism is however shown to level uplink performance for diameters above a few tens of centimeters. The article also demonstrates that the reciprocity, beyond providing powerful numerical tools, is a key principle for an indepth understanding of the physical effects impacting adaptive optics assisted ground-space optical links. These theoretical results are complemented by a brief presentation of FEEDELIO, the first experimental demonstration of uplink pre-compensation performed on a slant line of sight representative of a GEO-Feeder link.
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