Performance analysis of various optical vortices for vertical underwater optical wireless communication using multi-phase screen modeling

A simulation-based approach has been developed for vertical underwater optical wireless communication (VUOWC) using multi-phase-screen modeling. The simulation incorporates absorption, scattering, and vertical underwater turbulence of the ocean for the first 100 m depth. To generate the turbulent phase screens, the data of temperature and salinity variations along the 100 m depth, measured from the tropical region of the ocean is used. A realistic depth-dependent channel model is employed by incorporating absorption, scattering, and vertical optical turbulence. The study investigates the efficacy of various optical vortices in this simulated VUOWC system. The optical vortices such as single charge vortex beam, vortex dipole beam, and sine-hyperbolic Gaussian vortex beam (ShGvB) are considered for the propagation. The communication metrics such as BER, SNR degradation, beam spread, and scintillation index are evaluated. The results show that the ShGvB outperforms well in VUOWC systems with the smallest beam wander, scintillation, and lowest BER over the entire propagation distance. This study demonstrates the potential of the ShGvB for a high-reliability long range VUOWC applications.