Abstract
This work presents a simple yet effective anti-interference demultiplexing method for electromagnetic Bessel beams carrying orbital angular momentum (OAM), based on smoothed dynamic mode decomposition (smoothed DMD). The method combines conventional dynamic mode decomposition (DMD) with a moving average pre-processing step to enhance its noise resilience. By modeling the azimuthally sampled field as a spatial-temporal signal, smoothed DMD enables accurate extraction of OAM topological charges even under low signal-to-noise ratio (SNR) conditions. Numerical results demonstrate its superior anti-interference performance compared to standard DMD. Moreover, the proposed approach is applicable to scenarios with partial aperture detection and does not rely on the orthogonality of OAM modes, making it particularly suitable for real-world, imperfect conditions. This method offers a robust solution for OAM beam analysis in next-generation wireless communication and sensing applications.