Graphene-based compact polarization-insensitive broadband terahertz absorber for sensing applications

This paper presents a compact broadband absorber designed for sensing applications at terahertz frequencies. The proposed design includes a dielectric material, a metallic ground plane made of copper, and a graphene-based elliptical slot-loading rectangular resonator. The unit cell of the proposed absorber measures dimensions of 6 mu m x 6 mu m. The proposed absorber demonstrates remarkable absorption characteristics, with over 90 % absorption across a wide frequency spectrum of 0-18 THz. At 12.2 THz, the absorption performance is nearly perfect, with an absorption rate of 99.9 %. Further, the proposed absorber has a symmetric design, facilitating it to be insensitive to polarization. It possesses stable characteristics for both Transverse-Electric (TE) and Transverse-Magnetic (TM) waves for the incidence angle (theta) >= 40 degrees. Additionally, the performance of the suggested absorber is analysed with regard to the effects of various analyte materials as well as modifications in the graphene characteristics. This graphene-based absorber outperforms previously reported THz absorbers in terms of relative bandwidth, absorption peak, oblique stability, and overall volume.