Mode-dependent crosstalk and detection probability of orbital angular momentum of optical vortex beam through atmospheric turbulence

The crosstalk of orbital angular momentum (OAM) modes is one of the most important issues for free-space optical communication. We theoretically derive a crosstalk model for Laguerre–Gaussian (LG) vortex beams propagating in turbulent atmosphere. The calculated crosstalk of different OAM modes in different turbulence by analytical expression is consistent with experimental measurements. Both theoretical and experimental results reveal that the crosstalk of high order LG vortex beams is more obvious in atmospheric turbulence. Different from the numerical calculation of the integral expression of the previous studies, this analytical expression can directly and quantitatively characterize the crosstalk and the law of different topological charges in vortex beams. Based on this analytical expression, the crosstalk widths of vortex beams with different topological charges can be calculated accurately, so that the optimal sets of OAM modes can be found more easily under each atmospheric turbulence condition. (paper)