Electromechanically tunable terahertz T-shaped metamaterial for environmental sensing application

A tunable terahertz (THz) metamaterial (TSM) with face-to-face T-shaped structures is proposed. By changing the gap (g) between two T-shaped structures, TSM shows its tunability in the range from 0.87 THz to 0.88 THz in TE mode and from 0.68 THz to 0.74 THz in TM mode. While changing the longitudinal offset distance (l) between the two T-shaped resonators, TSM shows different trends for different l values considering both the resonance and full width at half maximum (FWHM). When l = 80 μm, there exhibits a non-linear resonance shift from 0.83 THz to 0.87 THz. Moreover, when TSM is exposed to surrounding environment with different refractive indexes (n), TSM presents red-shift phenomena in TE mode with linearities of 0.990 at most. The quality (Q) factor reaches maximum value as 23.17, which exhibits the tunability and sensitivity (S) of 79.73 GHz/RIU for different g values. S values of the TSM configuration show the inverse trend with the increase of n value of the surrounding environment against the Q-factor. These characteristics enable the proposed TSM to have a more diverse and segmented flexible application prospect in tunable biomedical, chemical detection, and environmental sensing fields.