Graphene pixel based broadband polarization insensitive THz absorber

Abstract Suppressing undesired radiation and eliminating stray radiation in a high-frequency circuit might be challenging. Ultra-high frequency (UHF) electromagnetic wave absorbers are finding new applications in both the military and civilian domains. Obtaining an ultra-wide absorption band in a thin, single-layer Terahertz absorber becomes difficult. Also, achieving perfect absorption bandwidth on transverse electric (TE) and transverse magnetic (TM) mode is very sensitive. This paper presents a polarization-independent graphene-based absorbers with a near unity absorption band of 2.32 THz and 3.78 THz in a lower mid-infrared regime. The structure’s unit cell consists of cross-slot circular patches with Au as a ground separated by SiO 2 . To improve the absorption band another graphene layer was placed between the top and dielectric material. The absorber is polarization independent under normal incidence because of the deposited graphene structure’s fourfold symmetry. Both TE and TM polarizations were investigated, with wide-band absorption observed up to 60° incident angles in both cases. In terms of the lowest frequency of absorption, the prototype is deemed to be as thin as <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:mn>0.1</mml:mn> <mml:msub> <mml:mrow> <mml:mi>λ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">max</mml:mi> </mml:mrow> </mml:msub> </mml:math> for both absorbers. Similarly, the effective homogeneity criteria in the subwavelength region are supported by the unit cell’s period of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:mn>0.1</mml:mn> <mml:msub> <mml:mrow> <mml:mi>λ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">max</mml:mi> </mml:mrow> </mml:msub> <mml:mo>.</mml:mo> </mml:math> The proposed absorber-2 shows <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>10</mml:mn> <mml:mo>%</mml:mo> </mml:math> higher FBW than existing work.