Lower-order-symmetry induced bandwidth-controllable terahertz polarization converter. (13th October 2017) - Zang, XiaoFei
Abstract: A transmission-type terahertz (THz) variable-bandwidth cross-polarization converter consisting of single-layer ultrathin metasurface is designed, fabricated and experimentally demonstrated. Both the simulated and measured results show that the bandwidth of linear polarization conversion is about 0.45 THz with a polarization conversion ratio over 90%. Different from the previous studies that mainly contributed to the geometry phase, the excellent characteristic of our designed device results from field-suppression of co-polarization components and field-enhancement of cross-polarization components, respectively. Even more intriguingly, the bandwidth of cross-polarization conversion is tunable by consecutively breaking the symmetry of the micro-structure, that is, the lower-order rotational symmetry, leading to a lower-order-symmetry-controlled THz cross-polarization conversion. Our study is an important step forward in developing compact, integrated, and bandwidth-controllable THz circuits and functional devices.