Mechanical Activity of a Chiral Slab Sandwiched between Achiral Half-Spaces

A plane wave propagating in effectively chiral composites (ECC) has been asymptotically investigated. In general, the ECC can be fabricated by embedding a helical arrangement of microstructures in the soft matrix. Such a material is mirror asymmetric or chiral; therefore, six independent wave numbers can be found. They are associated with two sets of nondispersive longitudinal fields and four sets of dispersive circularity polarized transverse fields. In this work, we study the reflected and transmitted fields of a normally incident plane wave propagating at achiral-chiral-achiral interfaces. The numerical study indicates that the longitudinal wave is unaffected by the sandwiched chiral layer, while the polarization of the transverse transmitted wave is significantly influenced by it. Furthermore, when a normally incident SV-wave (vertical shear wave) propagates in the upper half-space, the coupled SV- and SH-waves (horizontal shear wave) can be found in the lower half-space. The polarization of the transmitted field is affected by the handedness of the intermediate chiral layer.