A tunable, dual band graphene terahertz absorber with equivalent circuit modeling

Graphene-based metamaterials are increasingly capturing the interest of the research and scientific community for the development of reconfigurable optical devices. This paper focuses on a broadband metamaterial-based absorber at two different frequency range of the terahertz (THz) region. We have designed a graphene-based dual circular ring metamaterial absorber (GDCRMA) with a minimal thickness of 0.06λ, with respect to lower resonant frequency. The proposed absorber exhibits dual-band absorption spanning from 0.6 to 1.75 THz and 3.25 to 4.08 THz having a fractional bandwidth of 98.29% and 22.67%. Notably, the GDCRMA demonstrates polarization-insensitivity (up to 90°) and angle-insensitivity (up to 45°). The metamaterial behavior in the proposed absorber is underscored by the manifestation of negative values in effective permittivity and permeability. Additionally, it is observed that the absorption intensity well tunes in accordance with the varying chemical potential. Furthermore, an equivalent circuit model for the GDCRMA has been meticulously crafted yielding a remarkable concurrence with simulated outcomes. The proposed absorber’s capability to maintain a large bandwidth with dual band absorption, alongside absorption amplitude tunability and polarization insensitivity, underscores its unique features. Such characteristics make the designed absorber an ideal candidate for applications in high frequency switching operations, boolean logic devices, imaging, and wireless communication.