A multi-band THz regime metamaterial design using a paired metallic circular-strip structure

We design a metamaterial structure which shows multi-band negative indices at THz frequencies by using a paired metallic circular-strip structure. The advantages of our design lie (a) in the fact that due to the structural symmetry, the structure responses especially the effective magnetic response are polarization independent; and (b) the structure can operate at least in two frequency bands by simply changing the coupling distance between two or more adjacent metallic strips; whereas (c) the structure is easy to fabricate and is insensitive to small dislocations of the metallic strips. Our structure provides a versatile way of designing metamaterial towards frequency agile and broadband THz materials and devices.