Theory and Realization of Nonresonant Anisotropic Singly Polarized Solids Carrying only Shear Waves

Due to the complex polarizations of waves in elastic media, achieving broadband wave engineering in elastic metamaterials (EMMs) proves to be much more difficult than in the acoustic or electromagnetic counterparts. By designing a nonresonance-based singly polarized solid (SPS) with deep-subwavelength scale microstructures, we experimentally demonstrate that elastic wave polarization can be tailored in a broad frequency range. With an inverse design on the EMM's elasticity tensor, interesting wave behavior in a "fluidlike solid" or "shear-wave solid" can be achieved. By measuring the longitudinal as well as shear wave's propagation through the fabricated SPS layers with less than 1/20λ thickness, nearly total transmission or reflection for the targeted wave polarizations can be observed at different frequencies. Our work opens an alternative avenue for broadband elastic metamaterials design based on wave polarization engineering with various potential applications in the fields of structural monitoring, elastic wave communications, and ultrasonic elastography.