Engineering a terahertz plasmonic filter based on graphene H-shaped waveguide tunable for dual sensing of refractive index and temperature

Abstract This study presents a novel graphene-based H-shaped plasmonic filter for terahertz and mid-infrared applications, leveraging graphene’s exceptional plasmonic properties. Through 3D finite-difference time-domain simulations, we optimized key geometric parameters to achieve strong resonance peaks and efficient light confinement. The filter demonstrates remarkable electrical tunability, with resonance frequencies linearly shifting from 10.5 to 18.47 THz as graphene’s chemical potential increases from 0.2 to 0.6 eV, enabling dynamic reconfiguration without structural changes. Additionally, the device exhibits dual sensing capabilities, with refractive index sensitivity of 3.16 THz RIU −1 and temperature sensitivity of 0.1 THz K −1 , making it suitable for environmental monitoring and sensing. Electric field analysis revealed localized plasmonic excitations at resonant frequencies, confirming efficient energy confinement in the H-shaped structure. These findings highlight the filter’s multifunctionality as both a tunable optical component and sensitive detector, outperforming conventional metal-based plasmonic devices. The compact design and graphene’s compatibility with photonic integration suggest promising applications in next-generation communication systems, lab-on-chip devices, and nanophotonic circuits. This work advances graphene plasmonics by demonstrating a versatile platform combining tunable filtering with high-sensitivity detection capabilities.