A Transmissive Linear Polarization and Circular Polarization Cross Polarization Converter Based on All-Dielectric Metasurface

In this article, we propose a metasurface with C2 symmetry in the terahertz band, which consists of an external ring resonator and an inner double split ring resonator. In order to overcome the problems of ohmic loss and low transmission efficiency caused by the metal structure, we selected all-dielectric materials to design. From 2.17 THz to 2.24 THz, through numerical simulation, the device we proposed can achieve high-efficiency cross-polarization conversion of linearly polarized waves and circularly polarized waves, and their transmission efficiency exceeds 0.8. We first explained it through polarization orthogonal decomposition, and then the physical mechanism is investigated specifically by the distribution of electric field and magnetic field, and the influence of structural parameters on the device is also discussed. In addition, the cell we proposed has a thickness of about λ/10, which is conducive to the design and integration of terahertz devices and systems.