Seafloor observation network can perform all-weather, long-term, continuous, real-time, and in-situ observation of the ocean by combing various observation methods including cabled seafloor nodes, self-contained nodes, as well as mobile platforms, where reliable and long-term high-speed underwater wireless communication becomes an essential demand. Recently, underwater wireless optical communication (UWOC) has emerged as a highly promising solution and is rapidly becoming a research hotspot for meeting this requirement. In this article, we demonstrate the experiment and application of high-speed UWOC system for deep sea seafloor observation network. To the best of our knowledge this is the first long-term real-time deep-sea UWOC link with bitrate as high as 125 Mbps. Between 30 m distance and at a depth of 1650 m, two-way Ethernet UWOC links are realized with 125 Mbps direction-adjustable green light link and 6.25 Mbps non-line-of-sight (NLOS) blue light link. High quality video transmission of 8K 30 FPS and 4K 120 FPS are realized through high-speed 125 Mbps green light link, with 100% peak signal-to-noise ratio (PSNR) agreement, showing the capability of transmitting high-quality videos lossless. The 30-day long-term measurement results show that the BER performance of both 125 Mbps and 6.25 Mbps links is lower than 10-5, proving the stability and reliability of this UWOC system at depth of 1650 m. The maximum transmission distance for the green and blue light links are estimated to be 117.7 and 128.3 m with considering the geometry loss, which can be extended to 231.6 and 337.5 m without geometry loss. As the first long-term and real-time UWOC system in deep sea, we believe this demonstration can provide valuable experience for further UWOC studies and converged ocean observation networking with cabled and cable-less observation platforms.

翻译：海底观测网络通过整合缆系海底节点、自持式节点及移动平台等多种观测手段，能够对海洋开展全天候、长周期、连续、实时与原位观测，其中可靠且长时段的高速水下无线通信成为关键需求。近年来，水下无线光通信（UWOC）作为一种极具前景的解决方案，正迅速成为满足该需求的研究热点。本文展示了面向深海海底观测网络的高速UWOC系统实验与应用。据我们所知，这是首个比特率达125 Mbps的长时段实时深海UWOC链路。在1650米深度、30米距离条件下，实现了双向以太网UWOC链路，其中包含125 Mbps方向可调绿光链路与6.25 Mbps非视距（NLOS）蓝光链路。通过125 Mbps高速绿光链路，实现了8K 30 FPS与4K 120 FPS的高质量视频传输，峰值信噪比（PSNR）完全一致，展现了无损传输高质量视频的能力。30天长时段测量结果表明，125 Mbps与6.25 Mbps链路的误码率（BER）均低于10⁻⁵，验证了该UWOC系统在1650米深度的稳定性与可靠性。考虑几何损耗时，绿光与蓝光链路的最大传输距离分别估计为117.7米与128.3米；忽略几何损耗时，可扩展至231.6米与337.5米。作为深海首个长时段实时UWOC系统，我们相信本次演示可为后续UWOC研究及缆线与无线观测平台融合的海洋观测组网提供宝贵经验。