Scintillation index of a partially coherent flat-topped rectangular array beams propagating in a bidirectional link

Free space optical communication links for hypersonic vehicles are severely challenged by the co-existence of a surface plasma sheath and atmospheric turbulence, both of which induce random media fluctuations that degrade communication stability.We theoretically derive the on-axis scintillation index of a partially coherent flat-topped rectangular array beam propagating through a bidirectional link consisting of plasma and atmospheric turbulence based on the Collins formula. Numerical results demonstrate that the on-axis scintillation index increases monotonically with propagation distance, and the influence of the bidirectional atmospheric turbulence and plasma link on the on-axis scintillation index can be effectively mitigated through coherence manipulation. Under different strengths of atmospheric turbulence, the effect of the inter-beamlet distance on the on-axis scintillation index of the partially coherent flat-topped rectangular array beams remains consistent. Specifically, a larger separation between adjacent beamlets yields a smaller on-axis scintillation index. The findings of this work are expected toprovide a theoretical basis for FSO communications of hypersonic vehicles in complex environments.