A water wave incident on a grooved wall is shown to be analogous to electromagnetic waves called surface plasmon polaritons.
The ability of metamaterials to steer light has enabled amazing inventions from superresolution microscopes to “invisiblity” cloaks. But the physics underlying these structures also applies to other waves, such as acoustic, seismic, and water waves. Huanyang Chen and his colleagues at Xiamen University in China have demonstrated a structure that can change the propagation of surface water waves, making a localized wave that is analogous to an electromagnetic excitation called a surface plasmon polariton [1].
Surface plasmon polaritons occur at the interface between a dielectric and a negative-permittivity material such as a metal. Generating an equivalent excitation in surface water waves requires a similar sort of interface, such as that between water and a vertical barrier. In this case, the water’s parameter that is analogous to a metal’s permittivity is its depth. Of course, it’s impossible for water to have negative depth, but using metamaterials, Chen and his colleagues engineered the boundary conditions of the waves to achieve the same effect.
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