Fig. 1. Multi-phase screen method to simulate the process of signal transmission of the slant optical link in seawater

Fig. 2. Schematic diagram of modeling and signal transmission process of the slant optical link in seawater

Fig. 3. Random phase screen for ocean turbulence. (a) Two-dimensional diagram; (b) three-dimensional diagram

Fig. 4. Two-dimensional light intensity distributions of LG beam with different transmission distances under the influence of ocean turbulence

Fig. 5. Two-dimensional phase distributions of LG beam with different transmission distances under the influence of ocean turbulence

Fig. 6. Effects of transmission distance L on LG beam. (a) Scintillation index; (b) detection probability

Fig. 7. Effects of the rate of dissipation of kinetic energy per unit mass of fluid on LG beam. (a) Scintillation index; (b) detection probability

Fig. 8. Effects of the rate of dissipation of mean-squared temperature on LG beam. (a) Scintillation index; (b) detection probability

Fig. 9. Effects of the average temperature on LG beam. (a) Scintillation index; (b) detection probability

Fig. 10. Effects of the average salinity on LG beam. (a) Scintillation index; (b) detection probability

Fig. 11. Effects of transmission distance on LG beam in vertical link and upper and lower horizontal link. (a) Scintillation index; (b) detection probability

Fig. 12. Effects of the slant angle on LG beam. (a) Scintillation index; (b) detection probability

Fig. 13. Block diagram of the UWO-OAM communication system

Fig. 14. Temperature and salinity of seawater at each buoy node at different seawater depths. (a) ID: 5902507 (winter); (b) ID: 4902912 (summer)

Fig. 15. Communication system average BERs for transmitters at different depths with distinct distances in vertical link different oceans. (a) ID: 5902507 (winter); (b) ID: 4902912 (summer)

Fig. 16. Communication system average BERs at different slant angles with distinct distances in different oceans (depth of the transmitter is 400 m). (a) ID: 5902507 (winter); (b) ID: 4902912 (summer)