Propagation Factors of Partially Coherent Model Beams in Oceanic Turbulence

Abstract

Based on the extended Huygens–Fresnel principle and second-order moments of the Wigner distribution function, we have derived the analytical expressions of the propagation factor of four kinds of partially coherent model beams in oceanic turbulence, including Gaussian Schell-model (GSM), Bessel–Gaussian Schell-model, Laguerre–Gaussian Schell-model, and cosine-Gaussian Schell-model (CGSM). It is found that the modulation of the spectral degree of coherence takes advantage over the GSM beams for reducing the turbulence-induced degradation. The beams with larger index ( $n$ , $\beta $ , $m$ ), initial beamwidth, and the wavelength or the smaller coherent length will be less affected by the oceanic turbulence. In addition, the influences of the oceanic parameters on the beam quality are discussed in detail, and the degradation of beams can be enhanced with the decrease of the rate of dissipation of turbulence kinetic energy per unit mass of fluid and the increase of the rate of dissipation of mean-square temperature, also the salinity fluctuation has greater contribution to the decrease of the beam quality than that of the temperature fluctuation. Moreover, the comparison of the normalized propagation factor of the four kinds of beams demonstrates that the CGSM is more robust against the oceanic turbulence than other partially coherent model beams. Our results can be helpful in the design of an optical communication system in an oceanic environment.