Japanese tech company Kyocera has developed underwater optical communications (UWOC) technology that enables short-distance, high-speed wireless communication. According to its press release, this allows data transmission speeds of up to 5.2 Gbps in freshwater laboratory settings, which is much faster than the few Mbps that typical underwater acoustic communications systems achieve.
The company achieved this by developing a laser specifically tailored for underwater communications using its own protocols and physical layers. Aside from that, it has an optical front-end circuit — the hardware that converts light into electrical signals — that can hit bandwidths greater than 1 GHz, making it around 2.5x faster than its competition.
This development is crucial for advancing underwater drone technologies, as it enables them to stream data to users on the surface or aboard a mothership, including high-resolution photos, a live video feed, and sensor data. This makes them useful for underwater inspections and can even be used to simultaneously communicate with multiple sensors for comprehensive data collection.
This still would not replace underwater fiber-optic cables for long-distance communication, though, as UWOC are typically limited to around 100 meters. Since the laser travels through water, this can greatly impact its range. And because it requires line-of-sight, you cannot use UWOC to control a drone for exploration, and even passing marine life can disrupt the connection.
However, it’s great for specific applications, especially with its high speed, massive bandwidth, and low latency. It’s also harder to intercept versus acoustic signals, which propagate in the water in all directions, and are heavily affected by environmental noise like ship engines and the sound emitted by large undersea mammals.
Aside from controlling underwater drones, this technology could also be used for communicating with permanently installed sensors. These can be used for monitoring undersea infrastructure, including fiber optic cables and pipelines, as well as for automatically tracking tagged marine wildlife when they come within range of a UWOC sensor. It may even serve in military applications, where it can be used to communicate with underwater drones launched from submarines or larger boats.
Jowi Morales is a tech enthusiast with years of experience working in the industry. He’s been writing with several tech publications since 2021, where he’s been interested in tech hardware and consumer electronics.
There have been subsurface optical communications link experiments at multi Gbps data rates for well over a decade. The issue in the open ocean is variability of the ocean itself -- everything from particles in the water to currents.
In one set of experiments well over half a decade ago the organization was able to do a link with reasonable bit error rates at 10 km or more. They moved 10 km down the coast at the same distance from shore and could not close the link at 1 km no matter what they tried. The details of that set of experiments are not public since those experiments were done for the U.S. DoD.
The short range (<< 1 km) optical is barely more useful than the very short range RF communications (typically << 100 m and sometimes << 10 m).
High data rates are ineffective without distance -- not unlike the optical bridges back in the 80s that could only go 100 m or so (and were useless during heavy rain or fog). The goal needs to be a reasonable data rate (> 1 Mbps) at a reasonable bit error rate (< 1e-6) at > 20 km at depths over the range of < 1 m to > 100 m. When that is accomplished then press releases will be well justified.
This was my reaction as well, until I saw they were in FRESH water. I don't have knowledge of freshwater optics.
However, sugar water optics might offer some perspective or at least be amusing.
I'm interested in this multi-Mbps acoustic tech the author mentions. I've been a hobbyist in this space for a few years and I haven't heard of any devices achieving throughput anywhere near that high, even theoretically. The attenuation and SNR of ultrasound in any natural water environment is pretty severe.
The tech in the article is interesting but I'm struggling to see the real applications (i.e. not giddy engineer suggestions) given the constraints of water clarity, LOS, and signal lock of a 1D beam in unstable 3D space.
Small ROVs don't have the inertia to lock this kind of signal at any kind of distance, and large ROVs are tethered for a reason; of things go sour, you pull it up. In either size case, the risk of loss is huge without a tether and these constraints.
Maybe the Navy for ship-sub or sub-sub comms without surfacing?
This may work with tap water, but good luck running this in actual natural water somewhere outside. It gets rather dirty when a drone or rain stirs up the sediments.
