Dynamic optical tuning and sensing in L-shaped dirac semimetal-based terahertz metasurfaces

Dirac semimetals (DSMs) have emerged as promising materials for terahertz applications due to their exceptional electronic, optical, and topological properties, as well as their reliable chemical tunability. This study explores a DSM-based tunable terahertz absorber with multi-band absorption characteristics. The absorber features a three-layer metasurface design, leveraging the unique properties of DSMs to achieve high sensitivity and tunability. By adjusting the Fermi energy or modifying structural parameters, precise control over the resonant frequencies across five distinct absorption modes was achieved. Numerical analysis demonstrates strong absorption and excellent polarization insensitivity in the 7–12 THz range. The device also exhibits outstanding refractive index sensitivity, with all modes exceeding 2500 GHz/RIU and a maximum sensitivity of 3440 GHz/RIU, making it a compelling candidate for advanced sensing applications.