Influence of Topological Charge Combinations on Double Laguerre–Gaussian Vortex Beams in Turbulent Conditions

Abstract Atmospheric turbulence significantly impacts the propagation of optical vortex beams, making their study crucial for advanced photonic applications. This research investigates the behavior of double Laguerre–Gaussian (LG) vortex beams with varying topological charge combinations under controlled turbulence conditions. The primary goal was to understand how topological charge configurations influence the beams’ scintillation index and interference patterns, with a focus on their practical implications for optical systems.
In this study, we combined numerical simulations and experimental methods. Hybrid binary fork gratings (HBFGs), designed in MATLAB and implemented via a spatial light modulator (SLM), were utilized to generate double LG vortex beams. Experimental conditions were calibrated to match real-world atmospheric turbulence by scaling parameters, such as the refractive index structure constant (Cn2) and propagation length. Beam profiling techniques validated the accuracy of generated beams.
Key findings revealed that beams with identical topological charges reduce scintillation for smaller charge differences but exhibit increased scintillation at larger differences. Conversely, beams with opposite charges showed unique interference patterns, including the disappearance of central rings and prominent fringe contrasts influenced by residual orbital angular momentum. Furthermore, higher-order vortex beams displayed enhanced sensitivity to turbulence, with scintillation indices peaking and then declining as charge magnitudes increased.