Omnidirectional wave polarization manipulation in isotropic polar solids

Abstract

Mode conversion and anomalous wave polarization between shear and longitudinal waves have been mainly explored in anisotropic solids. However, the use of elastic anisotropy inevitably introduces fundamental limitation in operative directions, which is not desirable for applications. In this study, we propose to use two-dimensional (2D) isotropic polar media that exhibit polarity and chirality moduli to achieve the above behaviors in an omnidirectional way, thereby realizing omnidirectional wave polarization manipulation. First, we formulate analytically and numerically a nearly perfect wave mode conversion, enabled by the chirality modulus, through a polar slab. Then, we emphasize that the polarity modulus causes the omnidirectional anomalous wave polarization which features faster shear modes. Two supplementary examples of the anomalous wave polarization, including singly polarized transmission and anomalous wave refraction, are presented. The former corresponds to a “fluid-like” or a “shear-wave” solid, depending on the choice of the polarity modulus. While the latter shows a longitudinal incidence causes no shear refraction beyond a critical angle at the interface between a Cauchy and a polar media. All the cases investigated here are directionally independent, drastically differing from those in anisotropic systems. It is our hope that the isotropic polar media could represent a new platform for the exploration of versatile polarization manipulation devices.