Transfer of fractional orbital angular momentum in atomic vapor in a five-level system

Abstract We present a theoretical investigation into the transfer of fractional orbital angular momentum (FOAM) in a five-level atomic system and study its interference with a Gaussian field of the same frequency. Through simulations and analysis, we demonstrate that the number of doughnuts in the superposition field remains consistent with that of the FOAM field, meaning the persistent presence of the doughnut-shaped defect. We also observe significant alterations in both spatial intensity distributions and the intensity of the superposition field by increasing the intensity of the control field, and its spatial intensity distributions more clearly exhibit the characteristic of uneven spatial distribution of FOAM vortex light. Interestingly, the intensity distributions within the inner ring of the superimposed field display greater unevenness compared to the outer ring. Additionally, the phase distributions of the superposition field resulting from the interference between the Four-Wave Mixing (FWM) field and the Gaussian field are examined, revealing irregular period distributions consistent with those observed in the FOAM vortex field. These findings provide theoretical support for the propagation and manipulation of FOAM vortex beams in atomic systems, offering potential implications for applications involving fractional orbital angular momentum in atomic systems and enhancing information transmission capacity.