Study of a Double-Open-Ring Terahertz Metamaterial Sensor

A double-opening ring-type terahertz metamaterial sensor that can be used to detect the refractive index of a material has been designed, which consists of two parts: a metamaterial structure nested with double-opening circular and square rings and a polyimide substrate. When terahertz is vertically incident on the metamaterial surface, the sensor structure forms three high-Q resonance peaks (center frequencies f1 = 0.74THz, f2 = 1.39THz, f3 = 1.70THz.) in the range of 0.4–1.8 THz. By analyzing the current distribution on the surface of the metamaterial structure, the mechanism of different resonance generation can be obtained. In addition, the application of the sensor in refractive index sensing is also explored. Under a certain thickness of the object to be measured, the sensor has superior sensing characteristics with a sensing sensitivity of up to 161.6GHz/RIU, 279.3 GHz/RIU and 309.2 GHz/RIU at the resonant frequencies respectively. At the same time, the sensor is also insensitive to the polarization angle in the range of 0–30 degrees, which makes the performance more stable. Its multiple resonance peaks can be utilized for high sensitivity refractive index sensing.