Performance analysis of the OAM based optical wireless communication systems with partially coherent elegant Laguerre–Gaussian beams in oceanic turbulence

Abstract

The transmission model of partially coherent elegant Laguerre–Gaussian (ELG) beams in oceanic turbulence is established by employing the spatial power spectrum of the refractive index of sea-water and the optics approximation. The mathematical expressions of mode probability, energy content, and orbital angular momentum (OAM) state detection probability for partially coherent ELG beams are obtained. The influences of beam and turbulence parameters on the propagation properties of light beam are illustrated in detail with numerical simulations. Results indicate that partially coherent ELG beams with smaller azimuthal mode, smaller OAM state difference, longer blue–green incident wavelength, and appropriate beam waist are less affected by turbulent ocean. Moreover, the evolution characteristics of laser beam may be able to keep a better quality under the condition of lower rate of dissipation of mean-square temperature, higher rate of dissipation of turbulent kinetic energy per unit mass of fluid, and smaller ratio of temperature to salinity for maritime environment. In addition, the partially coherent ELG beams exhibit more robust resistance to turbulence than the partially coherent standard Laguerre–Gaussian beams. These results are expected to be potential helpful in understanding the optical transmission process in turbulent media and designing the optical vortex communication systems.