Polarization insensitive terahertz metamaterial absorber

Abstract

We present the simulation, implementation, and measurement of a polarization insensitive resonant metamaterial absorber in the terahertz region. The device consists of a metal/dielectric-spacer/metal structure allowing us to maximize absorption by varying the dielectric material and thickness and, hence, the effective electrical permittivity and magnetic permeability. Experimental absorption of 77% and 65% at 2.12 THz (in the operating frequency range of terahertz quantum cascade lasers) is observed for a spacer of polyimide or silicon dioxide respectively. These metamaterials are promising candidates as absorbing elements for thermally based terahertz imaging.

Metasurface-Based THz Dual-Band Absorber Sensor for the Measurement of Refractive Index Variations of Chemical and Biological Substances

“…Identical results have been obtained for the TE polarisation mode. The values of the Q-factors indicate that the designed dual-band absorber accomplishes a strong frequency selectivity for both the frequencies f1 and f2 demonstrating an overall improvement more than a factor 2 with respect to the best results reported in literature [6,[8][9][10]. In order to explain the physical origins of the two resonances of the dual-band absorber, in panel (b) of Figure 2 are reported its spectral response under the following conditions: (i) if the NA inner square ring is absent, only the resonance centred at f1 is present (continuous black line) with Q'(f1) = 121 and A'(f1) = 58%; (ii) if the outer NA square ring is removed, only the resonance at f2 is observed (red dotted line) with Q'(f2) = 106 and A'(f2) = 98%, thus similar to the corresponding one shown in panel (a) of Figure 1 These results demonstrate that the Q-factors are not affected by the absence of one of the two NA rings and that the resonance at the frequency f1 is strongly enhanced through the e.m. interactions arising in the region between the two NA square rings.…”

Multi‐Spectral Materials: Hybridisation of Optical Plasmonic Filters and a Terahertz Metamaterial Absorber

“…The MM component geometry was inspired by an established THz MM absorber. [ 31 ] The constituent materials and layer thicknesses were altered to optimise the MM absorber for integration with optical plasmonics. The designed MM absorber consisted of a 150 nm aluminium ground plane and a 150 nm hollow cross aluminium ERR, separated by a 3 μ m silicon dioxide spacer.…”

“…The ERR couples to the incident electric fi eld and magnetic coupling is provided by the inclusion of a ground plane, as can be observed by anti-parallel currents on the metal surfaces. [27][28][29][30][31][32] At resonance, absorption is maximised by matching the wave impedance of the MM to the wave impedance of free space and engineering a large extinction coeffi cient. [28][29][30] Our SMM consists of plasmonic fi lters fabricated into the ground plane of a THz MM absorber, which uses a hollow cross shaped ERR.…”

In-Situ Large Area Fabrication of Metamaterials on Arbitrary Substrates Using Paint Process

“…Microwave absorbers are used to reduce radar cross-section and in microwave circuits to reduce electromagnetic interference. Metamaterial-based absorbers can be designed for perfect absorption and have been recently proposed at different frequencies ranging from gigahertz to terahertz including IR and visible region [11][12][13][14][15][16]. A planar metamaterial absorber consists of a periodic patterned layer of resonators on the front-side and another patterned or continuous metal on the backside separated by a dielectric spacer.…”