# Extending UWOC System Applications through Photon Transmission Dynamics Study in Harbor Waters
## 1 Introduction  
Comprehensive ocean exploration has emerged as a critical focus, garnering significant attentions within scientific, industrial, and military sectors. Key areas such as safety, weather monitoring, and marine commerce are heavily dependent on an in-depth understanding of the marine environment [1]. Yet, exploring this complex terrain, particularly in deep ocean areas, is fraught with challenges. These include high costs, inherent dangers, and technical difficulties. In response to these challenges, there has been rapid advancement in technologies such as underwater wireless sensing, underwater imaging detection, and development of both manned and unmanned underwater vehicles [2]. Consequently, the demand for advanced underwater communication technology, capable of high-rate data transmission, has intensified. Such technology is essential for not only transmitting observational data, but also for gaining a deeper understanding of the marine environment [3]. Underwater wireless communication is a pivotal technology in ocean exploration and operations. Electromagnetic waves, typically employed for communication, face significant attenuation in underwater environment due to the high electrical conductivity of seawater. As a result, sound waves have become the prevalent medium for underwater wireless communication. Despite their ability to cover distances of kilometers, acoustic systems are limited by their transmission bandwidth, typically only reaching speeds of a few Kbps. Moreover, the slow propagation speed of sound underwater poses substantial challenges for real-time, high-speed communication [4]. Further complicating the issue, acoustic communication equipment often suffers from drawbacks such as large size and high energy consumption, which impedes its development and widespread adoption. Finally, certain frequencies of acoustic signals can significantly harm marine organisms, affecting their health, predation behaviors, and migration patterns. In contrast, underwater wireless optical communication (UWOC) presents several advantages over traditional radio frequency, acoustic communication, and wired communication methods. UWOC is notable for its higher data transmission rates, lower latency, and greater flexibility [5; 6; 7]. Capable of covering hundreds of meters and potentially achieving Gbps transmission rates, UWOC holds promising application potential in areas such as high-capacity data transmission in deep-sea environments, remote control and monitoring of underwater robotics, and deep-sea oil and gas exploration [8; 9; 10; 11; 12]. These advantages position UWOC as a technology with significant potential for advancing the field of underwater communication. Currently, the mechanical shell of UWOC system in practical applications is predominantly constructed by titanium alloy, an inert metal material. The system's optical window typically utilizes materials such as sapphire, acrylic, or quartz glass [13]. Additionally, the outer layers of the power supply and network transmission cables are designed to be waterproof, corrosion-resistant, and capable of withstanding pressure. In summary, the materials mentioned above are essentially harmless to aquatic organisms and marine environment in short-term exposure scenarios. Moreover, the light source's intensity used for communication is generally not excessively high. However, during prolonged underwater operation, marine microorganisms may adhere to the surface of shell and optical window, significantly impairing the communication system's functionality. The transmission of light through seawater channels is significantly influenced by dynamic seawater conditions. During transmission, light absorption reduces the total propagation energy, while scattering caused by water particles leads to increased pulse spread in the time domain of the optical signal [14]. Additionally, multiple scatterings result in increased geometric loss in communication links [15].