Propagation of polarized double-elliptical vortex beams in atmospheric turbulence

This paper utilizes the stepwise phase screen method to study the intensity distribution and axial scintillation factor evolution characteristics of double-elliptical vortex beams with varying polarization directions and topological charges during turbulent atmospheric transmission at different intensities. The research reveals that the axial scintillation factor of a double-elliptical vortex beam is smaller than that of a single-elliptical vortex beam. As the polarization angle between the inner and outer elliptical vortex beams increases from 0 to π/2, the axial scintillation factor decreases gradually. The study also finds that for double-elliptical vortex beams with perpendicular polarization directions for the inner and outer rings, when the topological charge of the inner elliptical vortex beam is one and that of the outer elliptical vortex beam is even, the scintillation factor decreases significantly with increasing transmission distance in weak turbulence conditions and is lower than that of double-elliptical vortex beams with identical inner and outer polarization parameters. However, as turbulence intensifies, the automatic compensation effect of light intensity cannot mitigate the disturbances caused by turbulence, leading to an increased scintillation factor. When the topological charge of the outer ring is odd, the axial scintillation factor does not decrease with increasing transmission distance and exhibits high fluctuations. For double-elliptical vortex beams with an inner-beam topological charge of two and perpendicular polarization directions for the inner and outer rings, the axial scintillation factor is smaller than that of a beam with an inner-ring topological charge of one. As the transmission distance increases, the scintillation factor gradually increases. The evolution of the scintillation factor is less influenced by the outer ring's topological charge and remains lower than that of a double-elliptical vortex beam with identical inner and outer polarization parameters. The rate of change is slower, but the trend of increasing scintillation factor becomes more pronounced with increasing turbulence. Therefore, by optimizing the topological charge and ensuring perpendicular polarization between the inner and outer elliptical vortex beams, the ability of the double-elliptical vortex beam to suppress turbulence-induced disturbances can be further enhanced.