Numerical simulation of a narrow-band terahertz absorber for refractive index sensing at higher terahertz region

In this work, we present a narrow-band metamaterial-based sensor for refractive index sensing in terahertz region. The proposed sensor design employs gold resonator array on a poly imide substrate. The simulation results have shown that the sensor attains high resonance peak at 9.778 THz with absorption of over 98%. The proposed terahertz sensor exhibits a high-quality factor of 109 and a Figure Of Merit (FOM) of 12.35 RIU -1 . The absorption mechanism is explained by the transverse electric field distribution in the resonators. To investigate the influence of the substrate on the performance of the sensor, the same design has been simulated using Poly Vinylidene Fluoride (PVDF). The sensitivity of the sensor reaches a level of 1.104 THz/RIU operating at 9.778 THz which overcomes the challenge of material loss at elevated terahertz frequencies. The proposed metamaterial sensor for elevated terahertz region has greater potential in the fields of environmental monitoring, material identification, and biosensing.