Double-layer metasurface for blocking the fundamental SH wave

This work introduces a double-layer metasurface to isolate the fundamental shear horizontal wave (SH₀ wave). The metasurface is designed to split the SH₀ wave source into two parts and then manipulate the two waves to be out of phase and have equal amplitude upon reaching the end of the metasurface. This results in interference cancellation, effectively blocking the propagation of SH₀ waves into the protected zone. Firstly, the metasurface is designed theoretically, utilizing rectangular strips to constitute the substructure. Subsequently, finite element simulations are conducted to verify the correctness of the theoretical design. Finally, the metasurface is fabricated using 3D printing, and its performance is evaluated through experiments. The results indicate that the metasurface can function as a cage for SH₀ waves, trapping different types of SH₀ waves located at any position within the cage. Furthermore, when the source of SH₀ waves is positioned outside the cage, the metasurface can effectively impede their propagation into the interior region of the cage. The proposed double-layer metasurface provides a simple approach to blocking SH₀ waves, which may have potential applications in practical engineering.