SIRG: Underwater Optical Modem: The Last Hundred Meters

海洋科学正在开始一个新的阶段，科学家将进入海洋环境，并使用海洋观测站自适应地观测地球-海洋系统，这些观测站提供电力和通信，以访问和操纵实时传感器网络。仪器将插入基础设施，因此，区域传感器覆盖将需要在具有科学意义的地点周围铺设大量电缆，这既昂贵又耗时。随着适合水下作业的“无线”技术的发展，这种限制可能会减少。无线双向数据链路将使自主深潜器能够通过互联网进行远程操作。这将允许高成本、高性能的传感器集中在能够以自适应方式在扩展区域上操作的几个移动的平台上。除了可见光范围外，海洋基本上对电磁辐射是不透明的，因此“无线”水下通信需要开发光调制解调器技术。高数据速率（1-10 Mbit/s或更高）在光谱的蓝色部分在100米量级的范围内是可实现的，并且在良好条件下更高。PI建议设计、制造、测试和验证一个双向光调制解调器，用于将移动的深潜器连接到一个固定节点，该节点又通过光纤电缆连接到海洋观测站。每根电缆将支持多个节点，从而能够覆盖相对较广的区域。随着进一步的发展，光调制解调器技术将能够同时支持每个节点的许多传感器，从而形成类似于蜂窝电话系统的水下网络。基础研究包括随机介质中的光传播，低功率光信号产生，以及宽视场的采集和检测。此外，设计明确用于在移动的车辆上操作的光通信系统提出了新的技术挑战。最后，将移动的平台与海洋观测站连接起来的水下光学通信技术将在生物、化学、物理和地质海洋学等广泛学科中发挥科学作用。

The ocean sciences are beginning a new phase in which scientists will enter the ocean environment and adaptively observe the earth-ocean system using ocean observatories that provide power and communication to access and manipulate real-time sensor networks. Instruments will be plugged into the infrastructure, and hence areal sensor coverage will require the costly and time-consuming lay of numerous cables around a site of scientific interest. This limitation could be reduced with the development of "wireless" technologies suitable for operation underwater. Wireless bi-directional data links would enable remote operation of autonomous deep vehicles over the Internet. This would allow high cost, high capability sensors to be concentrated on a few mobile platforms capable of operating over an extended region in an adaptive manner. The ocean is essentially opaque to electromagnetic radiation except over the visible light range, and hence "wireless" underwater communication requires the development of optical modem technology. High data rates (1-10 Mbit/s or more) are achievable in the blue part of the spectrum over ranges of order 100 meters, and more under good conditions. The PIs propose to design, fabricate, test, and validate a bi-directional optical modem intended to link a mobile deep submergence vehicle to a fixed node which is in turn connected to an ocean observatory by fiber optic cable. Multiple nodes per cable will be supported, enabling the coverage of relatively wide areas. With further development, the optical modem technology will be able to simultaneously support many sensors per node, resulting in an underwater network analogous to a cellular telephone system. Fundamental research includes work on optical propagation in random media, low-power optical signal generation, plus acquisition and detection over a wide field of view. In addition, devising an optical communications system explicitly for operation on a mobile vehicle poses novel technological challenges. Finally, underwater optical communications technology to link mobile platforms to ocean observatories would be scientifically enabling in a wide range of disciplines, including biological, chemical, physical, and geological oceanography.