Tunable terahertz metamaterial using electric split-ring resonator with refractive index sensing characteristic

We present a design of tunable terahertz (THz) metamaterial (TTM) with single- and dual-band filtering, polarization-dependent, and switching characteristics. The proposed device is composed of electric split-ring resonator (eSRR) with I-shaped and T-shaped structures on silicon on insulator (SOI) substrate. By exploiting electrostatic force to change the displacement of the middle I-shaped metamaterial along the y-direction and z-direction, the electromagnetic responses of TTM can be controlled. TTM exhibits resonance-insensitive to the displacement of I-shaped metamaterial along the y-direction. By moving the I-shaped metamaterial along the z-direction, TTM shows the switching characteristic between single-to dual-resonance in TM mode, and the free spectrum ranges (FSR) could be bi-directionally narrowed 0.672 THz and broadened 0.744 THz in TE and TM modes, respectively. To further enhance the flexibility of the TTM device, it is exposed to an ambient environment with different refraction index for high-efficiency environmental sensors. The correlation coefficient is over 0.987. These results open an avenue to be potentially used for tunable detector, sensor, and switch in the THz-wave optoelectronics applications.