Cosine-Gaussian Laser Beam Intensity in Turbulent Atmosphere

Abstract

The effects of turbulent atmosphere on cosine-Gaussian laser beams are examined. To this end, a cosine-Gaussian excitation is taken at the source plane, and subsequently the average intensity profile at the receiver plane is formulated. Our formulation correctly reduces to the known Gaussian beam wave result in turbulence and the cosine-Gaussian beam solution in free space (in the absence of turbulence). Variation of the average intensity profile of the receiver plane is evaluated and plotted against the variations of link length, turbulence levels, two frequently used free space optics (FSO) wavelenaths and beam displacement parameters. From these results, it is seen that cosine-Gaussian beam, following the natural diffraction, is eventually transformed into a hyperbolic-cosine Gaussian beam. Hence, the beam energy becomes concentrated around two main lobes at the receiver plane. Combining our earlier result with the findings of this paper, we conclude that cosine-Gaussian and hyperbolic-cosine-Gaussian beam act in a reciprocal manner after having C, propagated. This rneans, starting with a cosine-Gaussian beam excitation, we obtain hyperbolic-cosine-Gaussian distribution at the receiver plane, whereas hyperbolic-cosine-Gaussian beam excitation will yield a cosine-Gaussian distribution. This reciprocity is applicable both in free space and in turbulence.