Simulation of Beam Characteristics in Long-distance Underwater Optical Communication

Underwater optical wireless communication (UOWC) technology has become an attractive alternative for high-bandwidth and low-latency underwater communication applications. However, due to the light beam attenuation caused by absorption and scattering of seawater, the available distance of UOWC is limited severely. In this paper, a model based on Monte Carlo (MC) method is established to investigate the characteristics of laser beam propagation in long-distance communication, especially the relation of distance and water turbidity. Then, some virtual Gaussian beams with different divergence angles are simulated in three typical ocean waters and the characteristics of photon distribution are also evaluated. The results suggest that the influence of initial divergence angle on received power in turbid harbor water is not as crucial as in clean water for the long distance application. With the conditions of 4° initial beam divergence, 1 millimeter beam width, 0.5 meter receiver aperture and 180° field of view (FOV), the simulated link distance can reach 40 meters in harbor water.