Design of tunable terahertz metamaterial for variable optical attenuation and sensing applications

In this work, an actively tunable terahertz metamaterial (TTM) is proposed to realize variable optical attenuation and sensing applications. The unit cell of TTM is composed of H-shaped resonator (HSR) and C-shaped resonator (CSR). The resonant frequency can be tuned from 0.60 THz to 0.82 THz and show an analog electromagnetically induced transparency (EIT) phenomenon. By adjusting the geometry parameters of HSR and CSR, the enhanced quality (Q) factor is obtained from 2 to 14. Moreover, the CSR can be rotated from 0° to 90° to show the potential in the variable optical attenuator (VOA) application. The resonant intensity at 0.60 THz can be gradually decreased and then disappeared eventually when the CSR rotated from 0° to 90° in TE mode. While the resonant intensity at 0.60 THz can be gradually increased and then reach maximum value from 0° to 90° in TM mode. To demonstrate the proposed TTM can be used for the environmental sensing application, the TTM is exposed on the ambient environment with different refractive indexes from 1.0 to 2.2. The maximum sensitivity is 67 GHz. This work offers a novel approach for the THz metamaterial using for the VOA, optical switching, and sensing applications.