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Infrared subwavelength focusing metasurfaces for harvesting heat from the Eartha??s back radiation
摘要： In this paper, we introduce two different metasurfaces that can achieve subwavelength focusing of the electromagnetic radiation in the infrared range with transmission ef?ciencies reaching 46% and 74.33% in silicon and thus they can be integrated in heat harvesting applications. We made our designs at the wavelength of 10 μm which is the peak of the back radiation of the Earth. In designing our metasurfaces in the infrared range, we used the phase modulation techniques that proved to be useful in the visible domain. The best focusing resolution achieved in our metasurfaces is 0.26λ (super-focusing). In addition to heat harvesting, the two proposed metasurfaces can be useful in other compact applications that require manipulating the mid-infrared radiation on a very small scale. We used copper and silicon in our metasurfaces which are speci?cally suitable for the mid-infrared range besides being CMOS compatible. In this paper, we also explained how heat can be harvested from the introduced metasurfaces using the Seebeck effect.
关键词： plasmonics,subwavelength focusing,planar lens,phase modulation,heat harvesting,metasurface,mid-infrared focusing
更新于2025-09-19 17:13:59
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Super-Oscillatory Metalens at Terahertz for Enhanced Focusing with Reduced Side Lobes
摘要： In this paper, we design and numerically demonstrate an ultra-thin super-oscillatory metalens with a resolution below the diffraction limit. The zones of the lens are implemented using metasurface concepts with hexagonal unit cells. This way, the transparency and, hence, ef?ciency is optimized, compared to the conventional transparent–opaque zoning approach that introduces, inevitably, a high re?ection in the opaque regions. Furthermore, a novel two-step optimization technique, based on evolutionary algorithms, is developed to reduce the side lobes and boost the intensity at the focus. After the design process, we demonstrate that the metalens is able to generate a focal spot of 0.46λ0 (1.4 times below the resolution limit) at the design focal length of 10λ0 with reduced side lobes (the side lobe level being approximately ?11 dB). The metalens is optimized at 0.327 THz, and has been validated with numerical simulations.
关键词： metamaterials,evolutionary algorithm,metasurfaces,terahertz,metalens,terahertz focusing,subwavelength focusing,super-oscillatory lens
更新于2025-09-09 09:28:46
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Subwavelength focusing of a cylindrically symmetric plano-concave lens based on a one-dimensional Thue–Morse photonic quasicrystal
摘要： A cylindrically symmetric plano-concave lens based on a one-dimensional (1D) Thue–Morse photonic quasicrystal (PQC) is proposed. Sub-wavelength focusing characteristics with an incident cylindrical vector beam are investigated. Numerical results reveal that the lens can exhibit polarization-independent, high-resolution, and low-side-lobe characteristics, simultaneously for near-?eld and non-near-?eld. Furthermore, the lens can achieve perfect focusing and size-independent characteristics with equal-proportion scaling of the size of the lens at the corresponding center frequency. The focusing mechanisms of the lens are explained by analyzing the transmission spectrum, dispersion relation of a 1D periodic photonic crystal, and transmission spectrum of the 1D Thue–Morse PQC.
关键词： cylindrical vector beam,Subwavelength focusing,plano-concave lens,photonic quasicrystal
更新于2025-09-04 15:30:14