Abstract-Tunable terahertz metamaterial absorber based on electricity and light modulation modes

Jinfeng Wang, Tingting Lang, Zhi Hong, Tingting Shen, and Gangqi Wang

(a) Schematic view of the proposed tunable THz absorber. (b) Unit cell of the structure with geometrical parameters, the parameters of the absorber are set as p = 80 μm, t = 2 μm, h = 50 μm, b = 0.2 μm, a = 40 μm. The permittivity dispersion (real part: dotted line and imaginary part: solid line) of doped Si in the different layer under the pump fluence of 200 μJ/cm2 is shown on the middle.

https://www.osapublishing.org/ome/abstract.cfm?uri=ome-10-9-2262

In this paper, a metamaterial absorber that achieved absorption tuning by electricity and light control has been proposed in the terahertz (THz) regime. The THz absorber exhibits an absorbance of 97.5% at a resonant frequency of 0.245 THz. First, we simulated the absorption spectra under different structural parameters. Then the absorption characteristics are analyzed under different Fermi energies and pump fluences. When the Fermi energy changes from 0 to 1 eV, the peak absorbance decreases from 97.5% to 56.2%. As the fluence of the pump beam increases from 0 to 100 µJ/cm2, the peak absorbance decreases from 97.5% to 42.8%. The amplitude modulation depth T of our designed absorber is approximately 0.55. Electric and magnetic resonances are proposed in this article, which allows for nearly perfect absorption. Finally, the absorption for both transverse electric and transverse magnetic modes were investigated under different incident angles, from 0° to 75° with a step-width of 15°. The absorber can be potentially applied to THz detection, imaging, and sensing.

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