According to foreign media reports, radio waves cannot be transmitted in water, which makes it difficult for divers or submersibles to transmit information to the surface by wireless transmission.  However, scientists are trying to change this situation by developing an underwater version of Wi-Fi. As early as 2018, researchers at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia began research on how to use lasers to transmit high-definition video underwater.

Users such as divers wearing respirators must first send data from a smartphone placed in a waterproof case. The data is initially transmitted in the form of radio waves to a small device mounted on the diver’s gas tank a few feet away.

Then, the microcomputer in the device converts the data into a series of ultra-high-speed optical pulses, and each pulse is displayed in the form of a binary code. These pulses are then emitted to the surface of the water, either using a 520-nanometer integrated laser or a group of green LEDs-LEDs can send data to a relatively short distance with very little energy, while lasers can send data to a farther distance but requires more energy.

After reaching the water surface, the photodetector located on the bottom of the ship will receive the light pulse, and then converted back to the original photo or video by the computer connected together. These files can be uploaded to the Internet via satellite.

As of now, the Aqua-Fi system has been used to upload and download multimedia in two still waters several meters apart. But before it can be put into practical use, researchers must adjust it to meet challenges such as the light scattering effect of fast-moving water – to do this, you may need to use a spherical receiver, which can be used to detect optical pulses from all directions.

“We have created a relatively cheap and flexible way to connect the underwater environment with the global Internet,” said Associate Professor Basem Shihada, the chief scientist of this research, “We hope that one day, Aqua-Fi will be like the water surface. Wi-Fi is also widely used underwater.”