Polarization-independent and highly sensitive tunable graphene-based THz metamaterial absorber for sensing application

This study presents a novel graphene-based tunable absorber designed for terahertz (THz) applications to acquire high sensitivity and polarization insensitivity. The structure utilizes a unique design of concentric graphene sheet. The designed structure was previously analyzed by employing the finite-difference time-domain method, which demonstrated near-perfect absorption in the THz region. Here, we thoroughly investigated the effect of the key parameters by varying period, inner radius, outer radius, and incidence angle under both transverse magnetic and electric field polarizations on the absorption profile. The proposed design demonstrates polarization insensitivity, which ensures robust performance under various polarization states. Furthermore, we analyzed the effect of Fermi energy on the absorption spectra. Due to the outstanding tunability of graphene and its high sensitivity towards environmental changes, the absorber exhibits an impressive sensitivity of $15400 \mathrm{~nm} /$ RIU, which makes it highly effective for refractive index sensing in the THz region. The proposed absorber is beneficial for various sensing and detection applications in the THz region.