Cavity-based magnetic metamaterials available from microwave to optical wave by tailoring structural parameters

We proposed a magnetic metamaterial (MM) with extremely large positive and negative permeability. The MMs are structured by simple metal cavity resonators, contributing to exciting magnetic responses from toroid current, dipole current, and nearest-neighbor interactions of the cavity resonator array. When the three responses coupled with each other perfectly, a strong magnetic resonance is obtained. Besides, the cavity-based MM benefits suppress the saturation effect of the magnetic response at optical frequencies, different from that common in traditional split-ring resonators. Therefore, the cavity-based MM is available in microwave, terahertz, and optical regions by appropriately tailoring the structural parameters. Such a cavity-based MM holds a promising strong magnetic response from microwave to optic frequencies only by tailoring structural parameters and provides a new design method to construct magnetic MM.