EXPERIMENTAL AND SIMULATED STUDY OF DUAL-BAND CHIRAL METAMATERIALS WITH STRONG OPTICAL ACTIVITY

A dual-band planar chiral metamaterial (CMM) with strong optical activity is experimentally constructed by twisted split rings. Resonant frequencies with strong optical activity are around 7.9 and 8.9 GHz for right circularly polarized (RCP) and 9.95 and 10.9 GHz for left circularly polarized (LCP) wave, respectively. In particular, the two independent eigenfrequencies depend sensitively on the twist angles, which can offer a convenient approach in building multiband or tunable CMMs. With the twist angle increased from 0 degrees to 90 degrees, the resonant frequencies play an obvious blueshift for RCP wave and redshift for LCP wave, respectively. Current distributions are also studied, which demonstrate that the observed resonances are linked to the excitation of multimodal standing current waves. Microwave experiments are performed to successfully realize these ideas and results are in good agreement with the numerical results. (C) 2014 Wiley Periodicals, Inc.