An ultrathin triple‐band absorber for tuneable THz bio‐sensing

In this paper, a multimode terahertz absorber is implemented using an ultrathin silicon ring with varying multimodal resonance. The rectangular silicon ring is providing three resonances with creating electromagnetic dipoles. The altering of these resonances is explicitly controlled with the help of a circular graphene ring. The graphene ring is used in the centre for tenability and to achieve perfect absorption. An equivalent circuit model is also presented and verified for the proposed structure. The design is intended to measure the glucose percentage in water. In addition, this can be used as a biosensor for the detection of malaria parasite percentage in water. A few important parameters like sensitivity and quality factors are considered to evaluate the performance of the said design. The sensitivity with analyte thickness is found to be 0.445 THz TU −1 , 0.4255 THz TU −1 , and 0.4305 THz TU −1 . The corresponding quality factor is noted for the lower, middle, and upper bands as 235, 653, and 264 respectively. Further, the sensitivity and quality factors were measured just by changing the refractive index. The new estimated values are 0.480 THz RIU −1 , 0.403 THz RIU −1 , and 0.562 THz RIU −1 and corresponding quality factors are 203, 555, and 261 for lower, middle, and upper bands respectively. The design is also expected to flourish as a polarization‐insensitive absorber.