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This paper proposes and comprehensively investigates a robust architecture for free-space chaotic physical-layer secure communication based on Bessel–Gaussian vortex beams (BGVBs). By exploiting the inherent self-healing properties of BGVBs and utilizing the topological charge l and cone angle α as dual degrees of freedom for multiplexing, we effectively mitigate channel impairments through optimized multidimensional mode spacing. Furthermore, by integrating adaptive optics compensation with a hierarchical sparse mode detection algorithm, the system successfully establishes a reliable physical link in the presence of severe atmospheric turbulence and partial beam obscuration. Statistical analysis verifies that the proposed algorithm enables the system to maintain a correct detection probability exceeding 90%, even under closed-loop strong turbulence scenarios. Building upon this robust physical connectivity, we validate an end-to-end performance of four-channel chaotic transmission over a 1 km strong turbulence link. The system achieves high-fidelity chaotic synchronization with correlation coefficients exceeding 0.97. Ultimately, an aggregate transmission capacity of 40 Gbps is realized at an SNR of 20 dB, with the BER consistently remaining below the HD-FEC threshold. Beyond turbulence mitigation, the system exhibits remarkable resilience against macroscopic obstruction; notably, the link sustains a 40 Gbps transmission rate even under a severe occlusion ratio of β =0.5.
Cao et al. (Mon,) studied this question.