Influence of atmospheric turbulence on coupling space light into single mode fiber

Based on weak turbulence theory, an average coupling efficiency model and a relative power fluctuations model are derived for coupling space light into single mode fiber in the presence of atmospheric turbulence. The effects of turbulence-induced wavefront distortion, scintillation, aperture averaging and residual tracking error of the angle-tracked coupling system are considered together. Using the Hufnagel-Valley 5/7 refractive-index structure model, average coupling efficiency and relative power fluctuations are investigated for both downlink and uplink. It is shown that for downlink, with the increase of receiver aperture, the relative power fluctuations first decrease due to the aperture averaging, and then increase due to the turbulence-induced wavefront distortion, and for uplink, t