Radial partially coherent beams for free-space optical communications

In this study, a special class of nonuniformly correlated beams with radially symmetric coherence distributions, called radial partially coherent beams (RPCBs), is numerically studied. By spatially modulating uniformly correlated phase screens used for generating conventional Gaussian Schell-model beams, RPCBs with arbitrary distributions of degree of coherence are produced. RPCBs whose degree of coherence decreases from the beam center along the radial direction were found to self-focus in free-space propagation, leading to augmented optical intensity near the beam center. Meanwhile, the scintillation mitigation ability of RPCBs remains significant. By means of wave optics simulation, propagation properties of RPCBs in anisotropic non-Kolmogorov turbulence are analyzed. Simulation results show that, under certain conditions RPCBs are still able to deliver improved performance in anisotropic non-Kolmogorov turbulence. Moreover, due to the elliptical far-field irradiance pattern caused by anisotropy, a matched elliptic receiving aperture can further reduce the turbulence-induced scintillation.