Both channel coding and wavefront correction on the turbulence mitigation of optical communications using orbital angular momentum multiplexing

•We propose a turbulence mitigation scheme for optical communications using orbital angular momentum multiplexing based on both channel coding and wavefront correction.•We use a Shack–Hartmann wavefront correction method to mitigate the phase distortion to reduce the crosstalk. We further use channel coding to correct the burst and random errors.•We adopt the method using two static optical elements to convert the different helically phased OAM states to different lateral positions in the channel de-multiplexer.•The scheme has a better mitigation effect than that using only wavefront correction method.•The scheme has a better mitigation effect than that using only channel coding technique.

A free-space optical (FSO) communication link with multiplexed orbital angular momentum (OAM) modes has been demonstrated to largely enhance the system capacity without a corresponding increase in spectral bandwidth, but the performance of the link is unavoidably degraded by atmospheric turbulence (AT). In this paper, we propose a turbulence mitigation scheme to improve AT tolerance of the OAM-multiplexed FSO communication link using both channel coding and wavefront correction. In the scheme, we utilize a wavefront correction method to mitigate the phase distortion first, and then we use a channel code to further correct the errors in each OAM mode. The improvement of AT tolerance is discussed over the performance of the link with or without channel coding/wavefront correction. The results show that the bit error rate performance has been improved greatly. The detrimental effect of AT on the OAM-multiplexed FSO communication link could be removed by the proposed scheme even in the relatively strong turbulence regime, such as Cn2=3.6×10−14m−2/3.