Frequency multiplexing with dispersion-engineered elastic metasurfaces

Distinguishing the frequency components of elastic waves is essential for ensuring the stability of mechanical systems. Herein, a frequency-multiplexed elastic metasurface is introduced, utilizing a dispersion engineering. The proposed dispersion-engineered elastic metasurface multiplexes frequency-dependent phase profiles, enabling frequency-selective wavefront tailoring. The phase profiles of the meta-atoms, derived from Kirchhoff-Love plate theory, are controlled solely by the plate thickness, eliminating the need for a typically required extensive meta-atom library or complex optimization. Integrating the metasurface with a piezoelectric element converts the focused elastic energy into an amplified electrical signal. Therefore, the magnitude of extracted energy alone reveals the underlying spectral information through spatial information. Our finding presents the first design methodology for a dispersion-engineered elastic metasurface, overcoming limitations of conventional elastic metasurfaces by encoding multiplex information in a passive framework. Accordingly, the proposed dispersion-engineered elastic metasurface can be incorporated into various plate-based mechanical systems for next-generation technologies.