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Ultra-Thin Metasurface Absorbers for Subterahertz Band: Theoretical Aspects and Detector Applications

The results of theoretical and experimental investigations of high-performance ultra-thin metasurface absorbers designed for narrow-band operation at subterahertz frequencies are presented. Implemented in a high-impedance surface configuration with a deep-subwavelength thin ground polypropylene substrate, the absorbers are intended for using as the photo-sensitive layers in wavelength-selective thermal detectors. A compact closed-form equivalent circuit formulation verified by full-wave simulations, as well as the route towards an optimal design of the spectrometric absorber are discussed. In addition, a spectrometric array of metasurface-absorber-integrated pyroelectric detectors with spectral peak sensitivities positioned in the range of 0.094-1 THz and providing the selectivity bandwidth of several per cent is described.