Silicon-doped cylindrical arrays for ultra-broadband terahertz absorber with polarization independence

Abstract

Abstract A cylindrical silicon-doped terahertz absorber is proposed, which can have polarization-independent and ultra-broadband merits. The silicon-doped absorber consists of a double-layer cylindrical Si/SiO2 arrays, and its absorptivity can be more than 95% at 0.9–5.8 THz. The absorption of cylindrical absorber exceeds 90% at 0.9–5.8 THz within the incident angle of 0–52°. Besides, the energy distribution of the electromagnetic field is clearly shown by finite element method. Moreover, the absorber is analyzed by impedance matching theory, which can explain the phenomenon of high absorption efficiency. Compared with the reported reference planar absorber and reference broadband absorber, the cylindrical absorber has better absorption spectrum and relative bandwidth ratio. Therefore, the ultra-wideband terahertz absorber has great potential in the fields of biomedicine and thermal imaging.