Absorption enhancement in silicon-based dielectric resonator for quad-band terahertz biosensing

Abstract

A technique is implemented to obtain the multi-band perfect absorption (nearly 100%) in an ultrathin silicon-based dielectric resonator (DR) using perturbation. A silicon-based plus-shaped resonator is utilized to design the proposed absorber which provides the four narrow-band absorptions at frequencies of around 5.75, 6.14, 6.48, and 7.24 THz with the level of absorption 54%, 20%, 95%, and 96%, respectively. The plus-shaped resonator is perturbedby cutting slot of plus shape in such a way that it obtains perfect absorption with sufficient guard-band to prevent the multi-band interference in each band. This perturbation provides four absorption peaks at frequencies of around 5.80, 6.27, 6.80, and 7.23 THz, with highly improved absorption in all the bands, i.e., 99.84%, 99.78%, 99.51%, 98.42%, respectively. The ultranarrow absorption peaks with narrow FWHM are suitable for the application of THz biosensing and refractive index analysis. The performance of the proposed absorber is studied with the variation in refractive index of sample. It is found that the proposed absorber provides the high sensitivity 0.186, 0.29, 0.2485, 0.43 THz/RIU and quality factor 280, 185.79, 320.42, and 131.51 for different bands, respectively. The proposed absorber performance is also studied for various THz biosensing applications like the detection of various viruses, malaria, and cancer in the human body at various stages.