Adaptive turbulence compensation with a hybrid input-output algorithm in orbital angular momentum-based free-space optical communication.

Atmospheric turbulence is a major challenge for practical orbital angular momentum (OAM)-based free-space optical (FSO) communication systems that causes intermodal crosstalk and degrades the performance of the system. Herein, we propose a hybrid input-output algorithm (HIOA)-based adaptive optics (AO) system to compensate for distorted OAM beams. The principle and parameters of the HIOA-based AO system in an OAM-based FSO system are analyzed, and the performance is discussed. The simulation results indicate that the HIOA-based AO system can effectively correct distorted OAM beams and that the HIOA improves the compensation performance and convergence speed compared to the traditional Gerchberg-Saxton algorithm. Moreover, we analyze the compensation performance based on different probe beams. Using an OAM beam with state l=1 as a probe beam can yield better correction effects than a Gaussian beam. This work verifies the feasibility of using an HIOA for adaptive turbulence compensation and provides new insights into OAM communication systems.