A terahertz metamaterial based on electromagnetically induced transparency effect and its sensing performance

We present a terahertz metamaterial based on electromagnetically induced transparency (EIT), of which the unit cell is made up of the coupled bright circular split-ring resonator (CSRR) and dark square split-ring resonator (SSRR) with practically equal resonance frequency. With the strong coupling of bright mode and dark mode, a sharply narrow transparency peak is observed at terahertz region. Then, the influences of the physical parameters on EIT-like effect are simulated and analyzed by the electromagnetic simulation software CST. Furthermore it is numerically demonstrated that the EIT-like metamaterial is a promising candidate for sensing with refractive index sensitivity of 96.2 GHz/RIU, which means that the transmission peak of the sensor shifts 96.2 GHz per unit change of refractive index of the surrounding medium. Finally, transmission responses of the sensor based on EIT-like effect are investigated by terahertz time-domain spectroscopy, showing a good perception capability consistent with the simulation results. With the property of high refractive index sensitivity, the metamaterial can play an important role in terahertz sensing and detection technology.