Adaptive optics pre-compensation for orbital angular momentum beams transmitting through simulated atmospheric turbulence.

We propose an adaptive optics (AO) pre-compensation scheme to improve the transmission quality of orbital angular momentum (OAM) beams in atmospheric turbulence. The distortion wavefront caused by atmospheric turbulence is obtained with the Gaussian beacon from the receiver. The AO system imposes the conjugate distortion wavefront onto the outgoing OAM beams at the transmitter, tto achieve the pre-compensation. Using the scheme, we conducted transmission experiments with different OAM beams in the simulated atmospheric turbulence. The experimental results indicated that the AO pre-compensation scheme can improve the transmission quality of the OAM beams in the atmospheric turbulence in real-time. It is found that the turbulence-induced crosstalk effects on neighboring modes are reduced by an average of 6 dB, and the system power penalty is improved by an average of 12.6 dB after pre-compensation.