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Broadband infrared circular dichroism in chiral metasurface absorbers
摘要： Chirality is ubiquitous in nature and it is essential in many fields, but natural materials possess weak and narrow-band chiroptical effects. Here, chiral plasmonic metasurface absorbers are designed and demonstrated to achieve large broadband infrared circular dichroism (CD). The broadband chiral absorber is made of multiple double-rectangle resonators with different sizes, showing strong absorption of left-handed or right-handed circularly polarized (LCP or RCP) light above 0.7 and large CD in absorption more than 0.5 covering the wavelength range from 1.35 μm to 1.85 μm. High broadband polarization-dependent local temperature increase is also obtained. The switchable infrared reflective chiral images are further presented by changing the wavelength and polarization of incident light. The broadband chiral metasurface absorbers promise future applications in many areas such as polarization detection, thermophotovoltaics, and chiral imaging.
关键词： chiral image,broadband,Chiral metasurface,circular dichroism
更新于2025-09-23 15:19:57
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Semi-Analytic Modeling of Chiral Metasurface Stacks
摘要： Metasurfaces allow anisotropic polarization states to be designed freely from the geometry, material and distribution of their constituent subwavelength structures or particles as well as their arrangement. It was shown recently that multilayer metasurfaces can exhibit a chiral polarization response without having chiral particles or near-field induced bianisotropy. Such stacked metasurfaces couple modally in the far-field and are geometrically chiral only as a complete system, even though their constituent parts are not. In our contribution we employ a semi-analytic approach to derive a model of a chiral metasurface stack consisting of two nano-wire based metasurfaces with rotated unit cells, separated by a spacer layer. Using a fabricated sample as a basis for our discussion, we explain the origin of its polarization response and unravel the role of the spacer layer separating the two metasurfaces.
关键词： chiral metasurface,spacer layer,semi-analytic modeling,nano-wire,polarization response
更新于2025-09-11 14:15:04
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Dual-band asymmetric optical transmission of both linearly and circularly polarized waves using bilayer coupled complementary chiral metasurface
摘要： It is highly desirable to develop asymmetric transmission (AT) devices for both linearly and circularly polarized light. However, currently existing metamaterial-based AT devices require multi-step micro-nano fabrication processes and usually realize AT responses only for linearly or circularly polarized waves, not simultaneously for both. We here propose a dual-band AT device for both linearly and circularly polarized waves in the near-infrared region by using a bilayer coupled complementary chiral metasurface, which includes a half-gammadion-shape gold (Au) structural layer and its Babinet’s complimentary copy. Unlike other multilayer AT devices working at optical frequencies, it takes less micro-nano fabrication steps. Besides, with the help of chirality and the inherent near-?eld coupling e?ect between the two complementary Au layers, the maximal AT parameters for linearly and circularly polarized waves can reach up to 0.45 and 0.56, respectively. The underlying mechanisms of dual-band AT responses are also investigated in depth from the perspectives of chirality and coupling e?ect. Our work o?ers a new and simple approach to high-performance AT devices, helps to better understand near-?led coupling e?ect in coupled complementary metasurfaces, and also expands their application ?elds.
关键词： chiral metasurface,asymmetric transmission,polarization conversion,coupling effect,near-infrared
更新于2025-09-11 14:15:04