# Laser Transmission Characteristics of Seawater for Underwater Wireless Optical Communication
## 4 Conclusions
In coastal and turbid harbor waters, it is necessary to magnify the FOV of the receiver to achieve a high receiving gain at the long attenuation length. According to the results of the power losses at different offsets of the receiving plane in different waters, there are significant differences in the position strategies of receivers for different water types. In clear water, the beam spreading is inconspicuous, which indicates that the receiver must be at the center of the receiving plane to achieve high receiving gain. In coastal and turbid port waters, the receiver must be at the center of the receiving plane for high receiving gain at short transmission distances, but not necessarily at long transmission distances where the difference in received power at different positions on the receiving plane gradually decreases. This study utilized the optical properties of three typical oceanic water types for simulations, leading to valuable insights for designing communication systems in various marine environments. This approach enables a comprehensive assessment of performance factors such as link distance, transmission rate, and error rate. This study takes the narrow beam laser wavelength of 532 nm as an example to analyze the transmission characteristics. However, there may be differences in transmission characteristics in other visible-light wavelengths due to differences in absorption and scattering properties. The wide-beam LED would result in differences in transmission characteristics as well. For this study, we considered three types of typical waters. Nevertheless, the real-time analysis of the transmission characteristics should account for the temporal and spatial changes in the properties of marine waters. Therefore, when designing communication systems for specific application scenarios, it is necessary to consider the light source used and the properties of the water type applied. In addition, other factors influencing the performance of the UWOCsystem, such as turbulence, upper-layer oceanic bubbles, and chlorophyll depth profile were not considered in this study. Future research should focus on analyzing temporal dispersion characteristics to enhance underwater communication solutions. Conceptualization, R.Y., T.Z. and C.L. ; methodology, R.Y. and T.Z. ; software, R.Y. and T.Z. ; validation, R.Y. ; formal analysis, R.Y. ; investigation, R.Y. and T.Z. ; data curation, R.Y. ; writing--original draft preparation, R.Y. ; writing--review and editing, R.Y., T.Z., C.L., H.G. and L.H. ; visualization, R.Y. ; supervision, T.Z. ; project administration, T.Z. and C.L. ; funding acquisition, T.Z. and C.L. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China [grant numbers 42376182, T222010, and 41276041] and the NSFC-Shandong Joint Fund for Marine Science Research Centers [grant number UI406405]. No applicable. The raw data supporting the conclusions of this article will be made available by the authors on reasonable request. We would like to express our gratitude to the Marine Big Data Center at the Institute for Advanced Ocean Study of Ocean University of China for their support in data conversion and storage. We also appreciate the professional and technical services provided by [PERSON]. We sincerely thank the anonymous reviewers for their constructive suggestions, which significantly improved the quality of this manuscript. The authors declare no conflicts of interest.