Scintillations of partially coherent annular and flat-topped array beams in extremely strong turbulent medium

Scintillation index of partially coherent multi-Gaussian array beams is analytically derived and numerically evaluated in extremely strong atmospheric turbulence. In the evaluations, partially coherent annular array and flat-topped array beams are considered. When compared to the non-array partially coherent multi-Gaussian beam, it is shown that such array beams have smaller scintillations. The scintillation index is found to decrease with an increase in the number of beamlets. Laser array beams exhibit less scintillations when the beams become less coherent. Scintillations decrease when the radial distance of beamlets from the origin increases. At a fixed degree of partial coherence, thin ring sized annular array beams possess smaller scintillations than the thick ones. Flat-topped Gaussian array beams with higher flatness parameter, N have smaller scintillations in extremely strong turbulence.