Study on the propagation characteristics of coherent synthetic vortex beams in atmospheric turbulence

For free space optical transmission, vortex beam can greatly improve the channel capacity, but it is easy to be affected by atmospheric turbulence. To solve this problem, in this paper, a radially aligned Gaussian beam array is loaded with a discrete vortex phase-coherent synthetic vortex beam. Based on the multi-phase screen numerical simulation method, the transmission of the synthetic vortex beam in Von Karman spectrum atmospheric turbulence is simulated, and the intensity distribution, drift and flicker characteristics of the beams under different turbulence intensity are studied. The effect of topological charge on light intensity flicker and beam drift is also discussed. The simulation results show that when the coherent vortex beam is transmitted in atmospheric turbulence, the turbulence makes the intensity distribution at the receiving end disordered and the phase distribution distorted. With the increase of turbulence intensity and transmission distance, the scintillation index and drift mean square error will increase, but when increasing to a certain extent, the scintillation index will tend to be flat. Under the same transmission conditions, the more topological charge of the beam, the better the transmission quality of the coherent synthetic vortex beam.