Large-area wide-angle spectrally selective plasmonic absorber

Abstract

A simple metamaterial-based wide-angle plasmonic absorber is introduced, fabricated, and experimentally characterized using angle-resolved infrared spectroscopy. The metamaterials are prepared by nano-imprint lithography, an attractive low-cost technology for making large-area samples. The matching of the metamaterial's impedance to that of vacuum is responsible for the observed spectrally selective "perfect" absorption of infrared light. The impedance is theoretically calculated in the single-resonance approximation, and the responsible resonance is identified as a short-range surface plasmon. The spectral position of the absorption peak (which is as high as 95%) is experimentally shown to be controlled by the metamaterial's dimensions. The persistence of "perfect" absorption with variable metamaterial parameters is theoretically explained. The wide-angle nature of the absorber can be utilized for sub-diffraction-scale infrared pixels exhibiting spectrally selective absorption/emissivity.

Metamaterial Electromagnetic Wave Absorbers

“…Other ways of combining resonators in one unit cell have been shown; for example, by stacking multiple layers in which resonators share the same ground plane, [ 84 ] (see Figure 10 b). Another method utilizes the different sections of a single structure that resonate at different frequencies to obtain multiple resonances, [ 51 ] as shown in Figure 10 c. Recently, another approach to realize broad band absorptivity has been proposed: incorporating lumped elements into the metamaterial resonators, which seems to be a promising way of fabricating large area samples is nano-imprint lithography, [ 90 ] which utilizes a reusable mold. The mold creates patterns by mechanically pressing on the resist followed by subsequent processes, an example of which is shown in Figure 9 h.…”

“…For wide angles of incidence, the surface plasmon propagation length, L p , can become short, L p ≤ a , where a is the lattice constant, and therefore make interactions between neighboring unit cells very small. [ 90 ] This has the potential application of making small pixels for detection purposes.…”

Superabsorption of acoustic waves with bubble metascreens

“…Indeed, the bubble layer is an acoustic open resonator, with leakage and dissipative Q factors given by Q 1 leak = Ka and Q 1 diss = , respectively. Thus, it can be seen that the = Ka prescription for maximizing absorption is analogous to the so-called critical coupling condition in waveguide theory [26,27].…”

Tuning infrared emission from microstrip arrays

“…These two types of standing waves, controlled by either a grating period or the dielectric thickness, should interact with each other. Some papers have already considered the behavior in this regime, 2,10,11,16,21,31 but they typically show results for only a few values of h d or λ. We present a more systematic study that clarifies trends and reveals some surprises.…”