Abstract
Composite metamaterials (CMMs) with multiple resonant modes enrich their own electric and magnetic properties and hence can achieve complex optical functionalities. In this thesis, first, we realized a two-handed metamaterial that possesses right-handed and left-handed electromagnetic properties in the microwave region by introducing a magnetic-dipole resonance and a standing-wave-like cavity resonance into the unit structure of the metamaterial. Following this work, we combined two distinct resonant structures to form a CMM with multiple resonances for realizing a terahertz-wave ultra-broadband bandpass filter with a broad bandwidth of 0.5 THz and a papery thickness of 38.4 micrometers, so the filter is available for integration into terahertz-wave micro-optical systems. Besides, we also modulated the structure of the CMM to numerically demonstrate a high-profile dualband bandpass filter. In the third work, we further realized another CMM-based optical device: a 90-degree ultrathin polarization rotator (UTPR) with a nearly complete polarization conversion of 97.7 % for the terahertz-wave polarimetry, by integrating the polarization convertibility and the polarization selectivity from two distinct resonant structures. The thickness of the UTPR is only 50.4 micrometers, about 60 times thinner than a commercial half-wavelength quartz waveplates working at the same frequency. All of the CMM-based optical devices possess excellent performances and very compact structures. These substantial advantages demonstrate that CMMs with multiple resonant modes promise significant practical applications in optical devices.