Spiral metamaterial for tunable circular dichroism

We propose an electrostatically actuated spiral structures as a metamaterial for circularly polarized light in Terahertz (THz) frequency. Actuation of the spiral structures changes their geometry, and produces a tunable chirality resulting in circular dichroism, which is the differential absorption between the left and right circularly polarized light. Results of the THz-spectroscopy confirmed that the ON/OFF of circular dichroism was achieved with the proposing structures.