Research on the influence of anisotropic ocean on the capacity of vortex Hankel–Bessel beam

Abstract

Vortex optical communication is a method to improve the spectral efficiency of underwater wireless optical communication. However, facing the complex marine environment, the turbulence effect in the offshore area is a big challenge to vortex optical communication. Oceanic turbulence will influence the transmission performance of the vortex beam. After turbulent transmission, crosstalk will inevitably occur between different topological modes. This paper studies the degree of crosstalk of Hankel–Bessel (HB) vortex light in different oceanic turbulences. By establishing a mathematical model of anisotropic oceanic turbulence, the main focus is on average temperature dissipation rate, turbulent energy dissipation rate, and temperature-salinity balance parameters. The influence of different turbulence parameters on the propagation of HB vortex light is discussed, and the degree of influence of the above parameters on the channel capacity of the orbital angular momentum HB (OAM-HB) optical communication system is studied. Simulation experiments show that anisotropic oceanic turbulence will cause energy migration in different topological models and cause significant decreases in channel capacity. We observed the capacity of HB vortex beams and compared the communication effects of Laguerre–Gaussian and HB vortex beams in anisotropic ocean turbulence. The communication performance of OAM-HB light in anisotropic turbulent is better than that in an isotropic one. The research results of the transmission characteristics of the vortex HB light underwater show that the OAM-HB underwater communication is worthy of further study.