Reducing orbital angular momentum crosstalk of the Bessel–Gaussian beam for underwater optical communications

We derive analytical expressions of the probabilities for the signal and the crosstalk orbital angular momentum (OAM) states of a high order Bessel–Gaussian beam used in underwater optical communications. Our numerical results show that the probabilities of the signal and crosstalk OAM states are affected by the propagation distance and the parameters of the oceanic turbulence. The receiver aperture can be used to reduce the probabilities of the crosstalk OAM states and the probability of the detected signal OAM states keeps almost unchanged. Our results may improve the quality of optical communications systems.