学术文献库

The subject area of free space optical communication with optical beam carrying orbital angular momentum has attracted a great deal of research attention since last two decades. Efforts to understand, model and execute communication links through turbulent atmosphere with OAM beams have gained particular importance. In this regard, different types of shape preserving beams, which can withstand turbulences of varying strengths, have been proposed and studied. In this paper, we present a numerical investigation of the propagation characteristics of ring Pearcey vortex beam through turbulent atmosphere. The study details on both moderate as well as strong atmospheric turbulences. Modified von Karman model has been relied on to model random phase screen. In moderate turbulence, the ring PVB preserved its singularity. In strong turbulence, the ring PVB preserved its singularity for short propagation distances but lost its singularity at longer propagation distances. We found that upon increasing the value of topological charge, aperture averaged scintillation index increases. We calculated the aperture averaged SI for different truncation factors and noticed that the ring PVB with a truncation factor 0.1 performed better in stronger turbulence. In moderate turbulence, the aperture averaged SI performed better for shorter propagation distances and relatively larger truncation factors. Further, we calculated the aperture averaged SI for spatially chirped ring PVB, and it has been found that aperture averaged SI improved largely for negatively chirped ring PVB. Furthermore, on comparing the aperture averaged SI of ring PVB and ring Airy vortex beam, it has been noticed that in strong turbulence ring PVB exhibited better aperture averaged SI. Additionally, we have calculated the beam wander for ring PVB and ring AVB and found that ring PVB demonstrates better beam wander.