Phase preservation characteristics of perfect vortex beams in complex scattering media

In complex scattering media, the intensity distribution and wavefront phase of optical fields are severely distorted by multiple scattering and random refraction, significantly limiting applications in deep optical imaging, optical communication, and biomedical sensing. Perfect vortex beams (PVBs), whose ring radius is independent of topological charge and which exhibit stable orbital angular momentum (OAM) mode distributions, are regarded as ideal candidates for propagation in complex scattering environments. In this work, Monte Carlo simulations combined with experimental verification were employed to systematically investigate the propagation behavior and OAM phase preservation characteristics of PVB in multiple-scattering media. Furthermore, the transport-of-intensity equation method was employed to reconstruct the scattered spiral wavefronts without requiring a reference beam, thereby simplifying the optical setup and enabling stable phase retrieval in scattering environments. The results demonstrate that PVBs retain the incident OAM mode with high purity over the moderate scattering range (d/l* = 2–6). Under stronger multiple-scattering conditions (d/l* = 10), residual OAM-correlated phase information and recognizable topological features remain detectable within the main annular region. More importantly, the topological-charge-independent annular geometry of PVBs maintains a nearly constant beam size across different OAM states, thereby minimizing additional scattering-induced modal degradation associated with beam-size variations and improving the distinguishability of higher-order OAM modes. This study provides new insights for optical sensing, biomedical imaging, and highly robust optical communication in complex scattering environments.