High-accuracy atmospheric turbulence compensation based on a Wirtinger flow algorithm in an orbital angular momentum-free space optical communication system

Abstract

In this study, high-accuracy atmospheric turbulence compensation based on a Wirtinger flow (WF) algorithm in an orbital angular momentum-free space optical system is demonstrated. An adaptive optics compensation approach based on the WF sensing part is introduced. In addition, the configuration complexity of the wavefront sensing part is reduced to one input. The WF algorithm can be considered as a gradient descent method with two steps, initialisation and iteration, which effectively prevent a fall into the local optimal solution. The compensation performance of the WF algorithm is numerically simulated. The simulation results demonstrate that the compensation can effectively eliminate the impact of atmospheric turbulence. The performance parameters, namely, root-mean-square (RMS) error, mode purity, crosstalk and bit error rate, are significantly improved. In particular, the RMS error reduces to 10−15 compared with 10−2 for the conventional Gerchberg–Saxton algorithm. The performance of the simulations indicates the high effectiveness and accuracy of the WF algorithm.