Intensity fluctuations of partially coherent cos Gaussian and cosh Gaussian beams inatmospheric turbulence

Abstract

On-axis and off-axis scintillation indices of partially coherent collimated cos Gaussian andcosh Gaussian beams are evaluated on their propagation in a weakly turbulent atmosphere.In the coherent limits, our results are in quite good agreement with those for the existingRytov scintillation index of coherent cos Gaussian and cosh Gaussian beams,especially for very small and very large sized beams and at weaker turbulence levels.The on-axis scintillation index becomes lower as the degree of source coherencedecreases for both cos Gaussian and cosh Gaussian beams. Comparing to thepartially coherent Gaussian beam on-axis scintillations, partially coherent cosGaussian beam scintillations are generally lower and partially coherent cosh Gaussianbeam scintillations are higher. Scintillations of Gaussian beams are very closeto the scintillations of equal-power cos Gaussian and are quite similar to thescintillations of equal-power cosh Gaussian beams. Off-axis evaluations yield that thescintillations of both cos Gaussian and cosh Gaussian beams increase as the diagonaldistance from the origin increases, being valid for all degrees of partial coherence.