Ultra-thin narrow-band, complementary narrow-band, and dual-band metamaterial absorbers for applications in the THz regime

Abstract

In this paper, ultra-thin narrow-band, complementary narrow-band, and dual-band metamaterial absorbers (MMAs), exploiting the same electric ring resonator configuration, are investigated at normal and oblique incidence for both transverse electric (TE) and transverse magnetic (TM) polarizations, and with different physical properties in the THz regime. In the analysis of the ultra-thin narrow-band MMA, the limit of applicability of the transmission line model has been overcome with the introduction of a capacitance which considers the z component of the electric field. These absorbing structures have shown a wide angular response and a polarization-insensitive behavior due to the introduction of a conducting ground plane and to the four-fold rotational symmetry of the resonant elements around the propagation axis. We have adopted a retrieval procedure to extract the effective electromagnetic parameters of the proposed MMAs and we have compared the simulated and analytical results through the interference theory.

Polarization-maintaining reflection-mode THz time-domain spectroscopy of a polyimide based ultra-thin narrow-band metamaterial absorber

“…The ultra-thin narrow-band MMA 27 is realized with a three-layer metal-dielectric-metal configuration consisting of a patterned frequency-selective surface (FSS) 27 , 30 inspired by ref. 23 , a highly flexible insulating polyimide spacer, and a metal ground plane on a silicon substrate.…”

“…The upper electric ring resonator (ERR) 23 , 27 , 30 (with optimized dimensions specified in Fig. 1(a) ) and the lower ground plane with 100 nm thickness are both made of lossy gold in order to ensure chemical stability and a high electrical conductivity ( σ = 4.09 × 10 7 S/m).…”

“…However, it has been shown in ref. 27 how the proposed narrow-band MMA exhibits a wide angular response for both TE and transverse magnetic (TM) polarizations as the incidence angle θ varies (see Fig. 1(b) ), even if the TE case exhibits the more critical working conditions.…”

“…In this paper, we show how it is possible to realize and characterize at THz frequencies an ultra-thin ground-plane-backed MMA 27 with an extremely selective absorbance spectrum. A specifically designed polarization-maintaining reflection-mode THz-TDS set-up with innovative features is employed for its electromagnetic characterization.…”

Design of a dual-band terahertz metamaterial absorber using two identical square patches for sensing application

“…[18][19][20][21][22][23][24][25][26] Dual-band metamaterial absorbers were also demonstrated using the stacked structural design methods. [27][28][29][30][31][32][33][34] Other structural designs were also suggested to achieve the dual-band absorption performance, including cuboid ferrite particle, 35 circular sector resonator, 36 graphene-SiC hybrid system, 37 cylinder MoS 2dielectric array, 38 and asymmetric double-split ring resonators. 39 Although various kinds of structures have been proposed to achieve dual-band absorption, there are still many similar shortcomings in these designs, which limit their practical application to a certain extent.…”