Adaptive Optics for the Mitigation of Atmospheric Effects in Laser Satellite-To-Ground Communications

Laser links have become a promising solution for bottle-necks in satellite-to-ground communication links (SGL). Investigations, however, show that atmospheric index-of-refraction turbulence has a significant impact especially on coherent and fiber-coupled communication schemes. This thesis investigates adaptive optics techniques for the correction of atmospherically distorted wavefronts. Atmospheric measurements in SGLs from two LEO satellites form the basis of this work. An analysis of conventional wavefront sensors widely used in astronomy disclosed performance limitations. Based on the findings self-referencing interferometers appear to be a promising solution for the difficult atmospheric conditions in these scenarios. Instantaneous phase-shifting interferometers and Fourier fringe analysis techniques are introduced as a new solution in this application. A lab implementation in the atmospheric testbed supports the obtained results.