Publication

Abstract : This paper presents a systematic approach for designing an ultra-wideband (UWB) absorber for terahertz (THz) applications. The metasurface consists of top patterned graphene ( G p a t ) and bottom continuous graphene ( G c o n t ), each having a thickness of 0.335 nm and separated by a 3 μ m thick silicon dioxide ( SiO 2 ) dielectric. Multiple absorbing modes have been generated by engraving rectangular, star-shaped, and circular ring slots on the top G p a t resonating at 3.22, 4.52, and 0.32 THz, respectively. A circular ring slot works as a coupling controller and helps to combine different slot resonances. The mode merger technique, along with the high plasmonic coupling between G p a t and G c o n t controlled by G c o n t help to attain an absorption bandwidth (BW) of 5.9 THz (193.44%) with absorptivity ≥ 90% ranging from 0.1 to 6 THz. The periodicity and thickness of the proposed polarization-insensitive metasurface are found to be λ 0 /300 and λ 0 /996.68, respectively, where λ 0 is free space wavelength computed at 0.1 THz. Absorptivity ≥ 80% for incidence angle up to 60 ∘ under both transverse electric (TE) and transverse magnetic (TM) polarization has also been achieved. The absorber provides excellent frequency tunable characteristics over a UWB band and shows blue-shift with increased chemical potential ( μ c ).