Abstract
Based on the extended Huygens-Fresnel (eHF) principle, approximate analytical expressions for the spectral density of nonuniformly correlated (NUC) beams are derived with the help of discrete model decompositions. The beams are propagating along horizontal paths through an anisotropic turbulent medium. Based on the derived formula, the influence of the anisotropic turbulence (anisotropy factors, structure parameters) on the evolution of the average intensity, the shift of the intensity maxima and the power-in-the-bucket (PIB) are investigated in detail through numerical examples. It is found that the lateral shifting of the intensity maxima is closely related to the anisotropy factors and the strength of turbulence. Our results also reveal that, in the case of weak turbulence, the beam profile can retain the feature of local intensity sharpness, but this feature degenerates quickly if the strength of the turbulence increases. The value of PIB of the NUC beams can be even higher than that of Gaussian beams by appropriately controlling the coherence parameter in the weak turbulence regime. This feature makes the NUC beams useful for free-space communication.
Highlights
The study of laser beams propagation through the atmosphere has received wide attention due to its important applications in high-speed/high-capacity free-space optical communications and remote sensing
The evolution of the average intensity and the scintillation index of the nonuniformly correlated (NUC) beams, propagating through isotropic turbulence, were investigated in [36,37]. These results show that the NUC beams possess a lower on-axis scintillation index and a higher on-axis intensity compared to Gaussian-Schell model beams
We found that the theoretical model for the NUC beams introduced by Lajunen et al is different from the one used in [36,37,38,39,40,41,42]
Summary
The study of laser beams propagation through the atmosphere has received wide attention due to its important applications in high-speed/high-capacity free-space optical communications and remote sensing In these systems, the laser beams experience random refractive index fluctuations induced by atmospheric turbulence. The advantage of the eHF method is that it can be used to treat the propagation characteristics for a wide range of optical fields, including partially coherent fields (see [31,32] and reference therein) The validity of this method extends from weak to strong turbulence. These results show that the NUC beams possess a lower on-axis scintillation index and a higher on-axis intensity compared to Gaussian-Schell model beams This property may be useful in free-space communication. The power-in-bucket of the NUC beam at the receiver plane is presented
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