Water wave diodes

Seaports are crucial components of maritime transportation systems. However, the presence of water waves significantly affects the speed and stability of vessels passing through ports, reducing the port efficiency. Traditional methods of blocking waves are not feasible since they also impede vessel passage. Therefore, finding a solution that effectively mitigates water wave impact while allowing unhindered vessel passage is of paramount importance in maritime transportation. In this article, we introduce a gradient refractive index profile into water wave manipulation and design a novel waveguide isolator device. It functions similarly to an electrical diode, allowing water waves to pass in one direction while blocking them in the opposite direction. Moreover, its waveguide-like hollow structure enables it to block water waves without hindering the passage of vessels. We elucidate the wave-blocking mechanism through mode analysis and numerical simulations, and experimentally validated the device, observing a significant “water wave diode effect.” This effect effectively blocks water waves in one direction while allowing passage in the other. This is the first time that blocking water waves without hindering vessel passage has been realized in the experiment, showing great potential for applications in maritime ports and ocean freight transport.