Total conversion between the longitudinal and transverse waves by ultrathin elastic metamaterials with anisotropic resonances

In this work, total conversions between longitudinal and transverse modes are achieved within an elastic metamaterial plate with thickness of two orders smaller than the wavelength. The ultrathin metamaterial plate consists of an array of anisotropic dipolar resonators obliquely-oriented, which can transfer the longitudinal movement into the transverse one, or vice versa, accounting for this effect. A mass–spring model is developed to depict analytically the mode conversion with a quantitative agreement with the simulation. The conversion rate of the metamaterial plate remains above 95% in varying solids, showing good adaptability in practical applications.