Spiral spectrum evolution of elliptical vortex beams with low coherence and radial polarization propagating through atmospheric turbulence

This study investigates the propagation characteristics and evolutions of the spiral spectrum for partially coherent radially polarized elliptical vortex (PCRPEV) beams in atmospheric turbulence. Analytical expressions for the cross-spectral density matrix are derived theoretically, and the mechanisms of diffraction and random perturbations on the spiral spectrum are systematically analyzed. Outcomes show that in the initial stage, the spiral spectrum is dominated by the optical field structure, where radial polarization causes splitting of the topological charge, and ellipticity breaks the beam symmetry, leading to an asymmetric energy distribution. During propagation, significant mode crosstalk occurs, which eventually reduces to a symmetric steady state centered on non-vortex modes. Increasing the zenith angle and reducing the coherence length and initial topological charge number accelerate the attenuation of the main mode energy; furthermore, the longer wavelengths and optimized beam parameters can effectively suppress turbulence-induced mode crosstalk. This research provides a theoretical foundation for applications in turbulent channel communication.