Design of a low-THz linear-to-circular polarization conversion metasurface

A study on designing a linear polarization (LP) to circular polarization (CP) converter at low THz frequencies is presented. The proposed design is composed of a periodic arrangement of 4-micron thick gold, anisotropic patches deposited on a quartz substrate, with a gold ground plane backing the wafer. The materials were chosen to minimize reflection loss, with the quartz providing an optically flat surface. Simulations have been carried out using CST Microwave Studio to extract and evaluate the operation bandwidth and the reflection losses of the proposed design. The design achieves more than 120 GHz left handed circular polarization (LHCP) bandwidth and more than 65 GHz right handed circular polarization (RHCP) bandwidth with 3 dB axial ratio bandwidth more than 89.9% and a 3 dB axial ratio bandwidth of 26.5% respectively. The proposed design can be fabricated using standard microfabrication methods.