Orbital angular momentum mode crosstalk of asymmetric Laguerre–Gaussian beams in a supersonic wind-induced airflow environment

The near-field airflow caused by supersonic wind is an important factor affecting the propagation of vortex beams in airborne optical communications. In this random environment, the orbital angular momentum (OAM)-based communication system will cause signal-mode degradation and mode crosstalk. As an unconventional source, asymmetric vortex beams have unique control dimensions and methods, and the coupling characteristics with a turbulent environment are rarely reported. This paper investigates the propagation of an asymmetric Laguerre-Gaussian beam (ALGB) in the random environment of a supersonic wind-induced airflow, focusing on intensity evolution and OAM mode crosstalk. In addition, the correlation between the OAM spectrum of the order and shift is clearly defined. The propagation of the ALGB in supersonic airflow is first analyzed based on the phase screen model, and the OAM spectrum distortion is discussed in detail. The results show that increasing the wind speed and boundary layer thickness will lead to more serious beam distortion and dispersion of the OAM spectrum. Finally, the propagation of ALGB and conventional Laguerre-Gaussian beam (LGB) is compared, and the research results showed that the ALGB has some unique advantages over conventional LGB.