Thomas, S.K.Shenoy, A.Satyanarayan, M.N.2026-02-042024IEEE Sensors Journal, 2024, 24, 21, pp. 34251-342581530437Xhttps://doi.org/10.1109/JSEN.2024.3411145https://idr.nitk.ac.in/handle/123456789/21396In this article, we present an indium antimonide (InSb)-based metasurface absorber (MA) using a complementary ring structure. The proposed MA exhibits absorption characteristics in the terahertz frequency range spanning from 1.0 to 2.2 THz. Within this frequency range, the MA demonstrates dual-band tunability, achieving approximately 100% absorption. Geometric parameters such as the outer ring radii, ring width, and InSb layer thickness are systematically adjusted to fine-tune the absorption frequency of the MA. In addition, we explore the refractive index sensing capabilities by introducing different refractive index materials into the air-filled complementary ring cavity. Notably, we achieve a peak refractive index sensitivity of 555 GHz per refractive index unit (RIU) for the first absorption peak at a minimum radius of 60 µm. © 2001-2012 IEEE.Antimony compoundsIII-V semiconductorsIndium antimonidesRefractive indexRefractometersSurface plasmonsTerahertz wavesDual BandMetasurfacePerfect metasurface absorberRefractive index sensingRefractive index sensorRing resonatorSensitivitySurface-plasmonTerahertz frequenciesNatural frequencies