Extremely thin metamaterial absorbers for subterahertz waves: from fundamentals towards applications in uncooled bolometric sensors

Microstructured frequency selective quasi-optical components for subterahertz and terahertz applications

“…When designed properly, MMSs are proven to be extremely effective in realizing the regime of perfect resonant absorption under conditions of smallness of the absorber thickness d with respect to the operating free-space wavelength λ. The ultra-thinness condition (d / λ << 1) is essential for bolometric detectors as it allows to decrease the absorber's heat capacity and therefore to achieve high sensitivity and relatively low response time of the bolometric device 10 . The high-performance ultra-thin absorbers are typically implemented in a high-impedance surface configuration, when a single-layer sub-wavelength MMS or metasurface is placed over the grounded dielectric substrate.…”

“…The high-performance ultra-thin absorbers are typically implemented in a high-impedance surface configuration, when a single-layer sub-wavelength MMS or metasurface is placed over the grounded dielectric substrate. Such structures can be considered as a kind of metamaterial 11 , which exhibits strong magnetic properties at the absorption resonance 10 . The absorption fractional bandwidth Δλ/λ for these structures relates to their thickness through the quasipower law Δλ/λ ~ (d / λ) α (where α=1÷2) that points out their ideal applicability to bolometric detectors with a high spectral resolution.…”

“…Such a synthesis is proven to be very effective when metallized microstructures (MMSs) of subwavelength topology are employed for frequency selective manipulation of amplitude, phase and polarization properties of quasi-optical THz beams [1][2][3][4][5][6][7][8][9][10][11][12][13] .…”

High-performance spectrally selective pyroelectric detection of millimeter and submillimeter waves using ultra-thin metasurface absorbers

“…The relations (2) distinctly necessitates the use of low-loss materials in the MSA configuration as it allows minimizing the thickness and bandwidth of a thermal sensor due to decreasing the resistive parameter‫.ݎ‬ In this work, polypropylene (PP) and thermally sputtered aluminium were chosen as optimal materials for the MSA implementation (see also [8,9]). …”

“…1,a). In an equivalent circuit approach [8,9] the lossy grounded slab of a small thickness (݀/O ≪ 1) is described as an effective inductor with the input impedance ܼ ܵ ≅ ݆Z‫ܮ‬ ܵ + ܴ ‫ܲܩ‬ , where ‫ܮ‬ ܵ = ߤK 0 ݀/ܿ 0 , ߤ is the relative magnetic permeability of the slab, K 0 ≅ 377 : is the free spaceimpedance, ܿ 0 is the speed of light, Z is the angular cy, ܴ ‫ܲܩ‬ is the lumped resistance. The MSA is interpreted as a parallel connection of the impedanceܼ ܵ and the FSS impedance ܼ ‫ܵܵܨ‬ = ‫ܥ݆߱(/1‬ ‫ܵܵܨ‬ ) + ‫ܮ݆߱‬ ‫ܵܵܨ‬ + ܴ ‫ܵܵܨ‬ (Fig.…”