In extremely strong turbulent horizontal atmospheric optical links, field correlations of flat-topped Gaussian incidence are evaluated. Field correlations are represented versus the diagonal distance at the receiver plane, for variations in the number of beams forming the flat-topped structure, receiver points, source sizes, link lengths, structure constants and the wave-lengths. Our results in extremely strong turbulence are compared to their free space counterparts which only reflect the diffraction patterns at the receiver plane. The effects of the inner scale of turbulence on the field correlations in extremely strong turbulence are examined in detail and it is observed that the size of the inner scale in extremely strong turbulence can considerably influence the field correlations of flat-topped beams.
