Polarization Conversion Based on Mie-Type Electromagnetically Induced Transparency (EIT) Effect in All-Dielectric Metasurface

In this paper, we propose an all-dielectric metasurface to realize the linear-to-circular polarization conversion of resonantly transmitted waves. This metasurface is composed of two intersection bars and four circle bricks. It has numerically demonstrated that the electromagnetic (EM) couplings between dielectric bar and bricks lead to the famous electromagnetically induced transparent (EIT) effect. Subsequently, based on Mie-type EIT resonances for two incident polarizations, the linear-to-circular polarization conversion occur at about 0.47 THz. More importantly, the thickness of our device is subwavelength and it is very transparency for EM waves. We also investigate the dependences of device performance on incident angles of EM waves and structure thicknesses. Device good performance is almost kept at about 0.47 THz for slightly incident angle tilts (theta <= 30 degrees) and tiny changes of substrate thickness. But device performance is strongly dependent on dielectric thickness. These results are very important for its integration to the existing terahertz devices, or its application to future polarization controls.