Tunable UWB/Narrowband Terahertz Metasurface Absorber Through Controlled Relaxation Time

• Published in: 2024 IEEE Wireless Antenna and Microwave Symposium (WAMS) pp. 1 - 6
• Main Authors: Maurya, Naveen Kumar, Krishna, Raji, Ghosh, Jayanta, Subramanian, Sugumaran
• Format: Conference Proceeding
• Language: English
• Published: IEEE 29.02.2024
• Subjects: Absorption; Conductors; Fabrication; Graphene; Metasurface; Metasurfaces; Microwave antennas; Relaxation time; Surface Plasmon polariton (SPP); Tunable; Wireless communication
• DOI: 10.1109/WAMS59642.2024.10527810

This work presents the design of a polarization-insensitive graphene-based tunable metasurface absorber (TMSA) for a terahertz (THz) regime. The TMSA can provide ultra-wide and narrowband absorptivity response by properly selecting the relaxation time value (\tau) before fabrication. The TMSA provides a bandwidth (BW) of 193.4% with absorptivity (A(f))\geq 90\% for \tau=0.06 ps. At the same time, an absorption BW of 6.86% could be achieved from the same design by selecting \tau=1 ps. The thickness of ultrathin TMSA is only 3 \mu \mathrm{m} , corresponding to \lambda_{g}/638.87 , where \lambda_{g} is guided wavelength computed at 0.1 THz. The periodicity (\lambda_{g}/191.66) of TMSA is also quite less to ensure effective homogeneity condition. The absorber works well under both transverse electric (TE) and transverse magnetic (TM) polarizations for wide incidence angle (\theta) . TMSA provide A(f)\geq 90 % for \theta\leq 60^{\circ} when working as UWB absorber and provide A(f)\geq 75\% for \theta\leq 60^{\circ} when working as narrowband absorber. TMSA also provides a shift in the absorption peak from 3.5 to 6.2 THz by varying chemical potential (\mu_{c}) from 0.3 to 1 \text{eV} when \tau is kept fixed at 1 ps.