Multi-Dimensional Encrypted FSO Communication via Generalized Polygonal Non-Diffractive Vortex Beams and Intelligent Decoding

Free-space optical (FSO) communication holds significant potential for future systems due to its high bandwidth and installation-free advantages. However, FSO faces critical challenges including atmospheric turbulence and security vulnerabilities such as susceptibility to interception. To address these issues, this paper proposes a multi-parameter encrypted FSO communication scheme based on generalized polygonal non diffractive vortex beams (GPNBs). By incorporating multiple structural dimensions with edge count factor, smoothness factor, and topological charge. The system achieves multidimensional information modulation and enhanced encryption capabilities. While a MobileNetV3-Small-based neural network decoder enables high-precision demodulation. Experimental results demonstrate successful transmission of three color images over 1 meter with a bit error rate (BER) of 3.9×10−3using combinations of 8 orbital angular momentum (OAM) modes, 3 smoothness factors, and 3 edge number factors. The non-diffractive characteristics maintain BER at 5×10−2under moderate to high atmospheric turbulence, while the beam's self-healing properties enable recovery from obstructions within 1 meter. This multidimensional encryption mechanism and lightweight neural network decoding strategy provide a promising solution for high-capacity, secure, and robust FSO communication in complex environments.