A metamaterial absorber for the terahertz regime: design, fabrication and characterization

Abstract

We present a metamaterial that acts as a strongly resonant absorber at terahertz frequencies. Our design consists of a bilayer unit cell which allows for maximization of the absorption through independent tuning of the electrical permittivity and magnetic permeability. An experimental absorptivity of 70% at 1.3 terahertz is demonstrated. We utilize only a single unit cell in the propagation direction, thus achieving an absorption coefficient alpha = 2000 cm(-1). These metamaterials are promising candidates as absorbing elements for thermally based THz imaging, due to their relatively low volume, low density, and narrow band response.

Broadband polarization-independent resonant light absorption using ultrathin plasmonic super absorbers

“…Resonant light absorption in metallic structures has been widely studied both theoretically and experimentally in arrays of metallic gratings 1 -5 , nanoparticles 6,7 and subwavelength slits 8,9 . Metamaterials are also promising candidates to enhance electromagnetic wave absorption, and have been shown to yield perfect absorption at microwave 10 , terahertz 11 and infrared 12 -14 frequencies. To date, however, resonant absorption schemes using plasmonic nanostructures and metamaterials have been designed to absorb light within a narrow wavelength range, and with few exceptions 6,7,14 , the resonant absorption behaviour strongly depends on the incident polarization.…”

Dual Band Switchable Metamaterial Electromagnetic Absorber

“…As a result, the working frequency of the absorber is switchable between two frequency bands through controlling the bias of the coupling diodes. In the previous metamaterial absorber, the ELC structure resonates in the first mode, the LC resonant mode, to achieve perfect absorption [6,7]. To compare, the distribution of E y and surface current of the ELC structures working in LC resonant mode is simulated at peak absorbing frequency and illustrated in Figs.…”

“…Recently metamaterials have been employed to construct EM wave absorbers [6][7][8][9][10][11][12]. Through designing the inclusion structures, the effective EM parameters of metamaterials can be tailored and unique values which are less than unity or even negative can be achieved.…”

“…Although metamaterial absorber has relatively narrow bandwidth, it possesses many advantages such as high absorption, low density, and thin thickness. Moreover, the frequency response can be tailored or scaled from microwave to terahertz and infrared regimes through carefully designing the constituent resonant structures [6][7][8].…”

Near-perfect 'black'

“…"But being able to image at different wavelengths means you might obtain spectroscopic information about what you are imaging, so that you can determine if it is harmful. " Padilla and his colleagues have already managed to scale down their design to work at terahertz and far-infrared frequencies 3 . But he says that making a perfect black in the visible range will be hard, because the components would have to be so small.…”