## 1 Introduction  
We provide a summary that highlights the perspectives of optical wireless communication (OWC) technologies. Without the use of a simulation in this study, the main focus of this research will be designated. Wireless communication is popular in a wide range of devices worldwide. The application of wireless communication on land and underwater is of great interest to the industrial, military, and scientific communities [1, 2]. Acoustic systems have enjoyed great success underwater owing to their ability to communicate over many kilometers, which has promoted research in this field, thus improving this technology. Numerous studies have been conducted to enhance the performance of acoustic communication channels [3, 4, 5, 6, 7]. Nonetheless, its performance is related to its physical nature, which limits the bandwidth, results in high potential, and produces high transmission losses, time-varying multi-path propagation, and Doppler spread [8, 9, 10, 11, 12, 13]. These limitations prevent autonomous underwater vehicles from transmitting high-definition, real-time videos via acoustic communication. Therefore, complementary technology is required to achieve broadband multimedia underwater communications. Real-time video transmissions, including the teleoperation of submarines and remote monitoring of underwater stations and seaport stations, are attractive and important assets for underwater applications [14, 15, 16, 17]. Radiofrequency (RF) waves, owing to their nature, are a more common and diffused technique used in global communications, but even they are unsuitable underwater because they are sturdily attenuated [18]. In addition, owing to the pure performance features of standard acoustic underwater communication such as its high bit error rate (BER), large and variable propagation delays, and low bandwidth, it is particularly vulnerable to malicious attacks [19]. Visible-light communication (VLC) can be used to address these problems. In VLC networks, the VL spectrum (400-700 nm) used for illumination is modulated to transmit data [20; 21; 22; 23; 24; 25; 26; 27]. As in VLC systems, in underwater optical wireless communication (UOWC) systems, the potential light sources are LDs instead of LEDs. Both have advantages--LDs feature a higher modulation bandwidth compared to LEDs--but LEDs have a higher power efficiency, lower cost, and longer lifetime, which makes them more suitable for medium-bit-rate applications. Unfortunately, the performance of UOWC is limited to a short range [28]. Therefore, although submarine optical communication systems are becoming commercially available [29], extensive research is being conducted on methodologies and systems for the transfer of broadband optical signals at higher distances. In the future, many underwater applications will comprise the use of optical communication. However, UOWC technology cannot completely replace acoustic communication. Therefore, studies on hybrid acoustic-optic communications have been conducted [30; 31; 32; 33]. These results are promising and should be further investigated. Figure 1 presents a generic UOWC scenario. It shows several platforms (divers, ships, submarines, submarine sensors, etc.) connected by light beams. An OWC provides many technical benefits such as high rates of transmission and secure connections in addition to economic benefits such as low operation costs and easy installation. Moreover, as the optical band is not included in the telecommunications protocols, it does not require payment of licensing fees and tariffs [34; 35; 36; 37; 38; 39; 40]. The main disadvantage of the UOWC is that optical signals are highly absorbed by the medium of water; the second problem is optical scattering due to the particles present in the sea. Nevertheless, in the visible spectrum, seawater has lower absorption in the blue/green zone. By exploiting this physical feature and working with signals with wavelengths in the blue/green region of the spectrum, high-speed connections can be realized according to the type of water.