Realizing Ultra-bandwidth Cross-polarization Conversion by a Double-layer Metasurface

In this paper, a double-layer polarization converter which can implement cross-polarization conversion has been proposed in THz band. Over 90% polarization conversion efficiency can be obtained with high quality in the operating frequency range of 0.63-1.50 THz. Relative bandwidth (RB) of the device is 81.7%, which far outweighs the technical specifications of ultra wideband (UWB). The design of the double-layer structure is an extension and improvement of the single-layer. The amelioration after addition of the second-layer structure is reflected in not only operating bandwidth and polarization conversion efficiency but also angle-stability. In the meantime, the thought of adding the second-layer resonant structure to improve the performance of conventional polarization converters is presented. This design has considerable application and development in radar, imaging technologies, communication and so on.