Abstract
An ultra-wide-angle THz metamaterial absorber (MA) utilizing sixteen-circular-sector (SCR) resonator for both transverse electric (TE) and transverse magnetic (TM) mode is designed and investigated numerically. At normal incidence, the absorptivity of the proposed MA is higher than 93.7% at 9.05 THz for different polarization angles, due to the rotational symmetry structure of the unit cell. Under oblique incidence, the absorptivity can still exceed 90%, even when the incident angle is up to 70° for both TE and TM mode. Especially, the frequency variation in TE mode is less than 0.25% for different incident angles from 0° to 70°. The electric field (Ez) distributions are used to explain the absorption mechanism. Numerical simulation results show that the high absorption with wide-angle independence stems from fundamental dipole resonance and gap surface plasmons. The broadband deep-infrared MA is also obtained by stacking three metal-dielectric layers. The designed MA has great potential in bolometric pixel elements, biomedical sensors, THz imaging, and solar cells.
Highlights
Electromagnetic (EM) metamaterials, which are composed of artificial sub-wavelength materials and present exotic properties not found in nature, have been paid widespread attention in the frequency range from visible to microwave band [1,2,3,4]
Tao et al presented THz metamaterial absorber (MA) in the terahertz (0.1–10 THz) region, which was composed of a top split-ring resonator and a bottom cut-wire metal separated by a dielectric layer [18]
MA based on square patches, and the absorption intensity decreases with the increase of the incident angle [29]
Summary
Electromagnetic (EM) metamaterials, which are composed of artificial sub-wavelength materials (so called meta-atom or meta-molecules) and present exotic properties not found in nature, have been paid widespread attention in the frequency range from visible to microwave band [1,2,3,4]. To obtain the wide-angle absorption, different resonance structures of the unit cell have been designed. Numerically and experimentally investigated the wide-angle stability of the single band MA based on the split ring resonators [22]. Zhu et al proposed the THz. MA based on square patches, and the absorption intensity decreases with the increase of the incident angle [29]. MA based on square patches, and the absorption intensity decreases with the increase of the incident angle [29] He et al numerically demonstrated the wide-angle properties of THz MA using saw-shaped annular patches resonator below 50◦ [33]. The previous THz MA showed angle-insensitive absorption with greater than 90%, only in the case of TM mode Their absorptivity and absorption bandwidth decreased with the increase of incident angle in TE mode.
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