Design and study of an OAM-based advanced multiplexing technique for FSO communication system under turbulent channel conditions

The large unlicensed spectrum and high data transmission rate of Free Space Optical (FSO) communication have drawn a lot of interest. Nevertheless, meteorological circumstances and atmospheric turbulence limit the FSO system’s performance. The capacity of FSO system can be greatly increased by wavelength division multiplexing (WDM), although WDM is inadequate in extreme turbulent environment. To overcome these limitations, integrating WDM with advanced multiplexing techniques such as Polarization Division Multiplexing (PDM) and Orbital Angular Momentum (OAM) enables a more spectrally efficient system capacity enhancement, even under severe turbulence and adverse weather conditions. This paper proposes a $\mathbf{1 6}$-channel WDM system utilizing OAM-PDM and evaluates its performance under various turbulence conditions.