Blending acoustic beam technologies to improve underwater communication

Underwater acoustic communication is pivotal for deep-sea exploration, environmental surveillance and protection, defense technology, and applications involving unmanned underwater vehicles. However, current technologies exhibit limited bandwidth and require large apertures to form concentrated beams at low frequencies.

To address these challenges, Bell et al. combined two existing technologies: multiplexed vortex beams and parametric acoustic arrays. Parametric acoustic arrays mix high frequency sound waves to generate concentrated low-frequency beams from a compact source. Combining parametric acoustic arrays with a corkscrew-shaped acoustic vortex beam creates a parametric vortex beam (PVB).

The authors numerically modeled multiple co-propagating PVBs to assess their generation, propagation, robustness, and overall feasibility as a method of underwater communication at moderate propagation distances. Compared to traditional methods, the PVBs achieved a more concentrated vortex beam using the same size aperture.

In addition, the authors introduced mathematical methods for interpreting information transmitted with multiple PVBs. The new method successfully retrieved all six alphanumeric characters they tested.

They also investigated receiver design constraints and resilience to real-world challenges, such as noise and source-receiver misalignment. The model showed that an array of nine receiver instruments arranged in a ring could retrieve transmitted information six meters from the source. The receiver was sensitive to misalignment with the source but relatively resilient to noise.

“Together, these results demonstrate that multiplexed PVBs constitute a viable nonlinear extension of vortex-based acoustic communication, combining the benefits of aperture efficiency, channel orthogonality, and tighter directivity to more securely transmit more information over farther distances,” said author Jeff Bell.

Next, the authors plan to figure out a method to keep the PVBs parallel as they propagate further away from the source.

Source: “Multiplexed parametric vortex beams for underwater communications,” by Jeff Bell, Jia-Xin Zhong, and Yun Jing, Journal of the Acoustical Society of America (2026). The article can be accessed at https://doi.org/10.1121/10.0044565 .