Optical system could revolutionize underwater communications

Underwater Remotely Operated Vehicles (ROV’s) are at the forefront of new discoveries and important research in the ocean depths, but they are still hindered by cumbersome cables that connect them to their support ships at the surface. It brings back memories of the days before radio-controlled toys, when our remote-control cars had wires coming out of them that ran up to the controllers in our hands. Now, thanks to scientists and engineers at Woods Hole Oceanographic Institution (WHOI), ROV’s may soon be set free from their tethers. The researchers have developed an undersea optical communications system, which they describe as “a virtual revolution in high-speed undersea data collection and transmission.”

ROV’s currently require cables because radio signals travel very poorly through water – the only way of instantly transferring data to and from deep submersibles is via a hard-wired connection. Data can also be sent through the water using acoustic techniques, but it travels relatively slowly and has a limited bandwidth.

WHOI’s optical system promises near-instant data transfer and real-time video from un-tethered ROV’s, autonomous underwater vehicles, and seafloor data-collection/transmission sites such as NEPTUNE. It would be used in conjunction with acoustic communications, which would take over once the vehicles moved out of optical range (presumably if you were using it to control an ROV, you would have to keep it within optical range?). Not only would this system free things up, but it would also allow for smaller, lighter ROV’s, as they wouldn’t need to heft that heavy cable around behind them. Smaller submersibles could in turn mean smaller research ships and smaller support crews, according to WHOI.

The press release from Wood's Hole isn't particularly clear on exactly how the system would work, as optical data is usually transmitted via fiber optic cables. In any case, so far its designers have achieved data rates of 10 to 20 megabytes per second, through 100 meters of water. This July, they’re planning a full-scale application, in which they will be deploying the system on an undersea data-collection/transmission site in the Northwestern US.