Capacity of the Weakly Absorbent Turbulent Ocean Channel with the Coaxial Double-Position Power Gaussian Vortex

Abstract

Turbulence and absorption of seawater are two important factors affecting the signal transmission quality of underwater optical communication link. Here, we study the channel capacity and bit error rate of an underwater extinction communication link with a coaxial double-position power Gaussian vortex carrier based on Rytov approximation theory. The study finds that channel capacity and bit error rate are the nonlinear functions of the dimensionless structural parameter and reach maximum and minimum values at |α| = 1, respectively. The seawater absorption has a great influence on the channel capacity but not bit error rate. The communication link with large receiving aperture, small transmitting beam diameter, long wavelength of light source in a seawater window, and more OAM channels has high channel capacity.

The spiral phase spectrum of the composite power Gaussian vortex beam in plasma sheath turbulence

“…At the source plane, the complex amplitude of the CPG vortex beam, which is formed by the superposition of two power Gaussian beams with opposite OAM vortices, can be expressed as [22]…”

“…Based on the Huygens-Fresnel diffraction integral, the complex amplitude of the CPG vortex beam at a propagation distance z in free space is [22]…”

“…Li et al studied the transmission characteristics of a coaxial composite terahertz vortex beam on plasma plates using the vector angular spectrum expansion method and observed that the detection probability of the primary OAM mode was affected by the radial integration distance [21]. Yan et al introduced a coaxial dual-position power Gaussian vortex beam with two different rotation directions and amplitudes for OAM vortices and focused on the evolution of its single-singularity vortex form in oceanic turbulence, demonstrating that a smaller topological charge brings about a lower bit error rate [22].…”