文章基本信息

标题：Gap-plasmon-driven spin angular momentum selection of chiral metasurfaces for intensity-tunable metaholography working at visible frequencies
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作者：Yang Younghwan ; Kim Hongyoon ; Badloe Trevon 等
期刊名称：Nanophotonics
印刷版ISSN：2192-8606
电子版ISSN：2192-8614
出版年度：2022
卷号：11
期号：17
页码：4123-4133
DOI：10.1515/nanoph-2022-0075
语种：English
出版社：Walter de Gruyter GmbH
摘要：Tunable metasurfaces can replace conventional bulky active optical modules to realize practical flat optical devices such as lenses, LiDAR, holography, and augmented reality. However, tunable metasurfaces have generally been limited to switching between two distinct states. Here, we present liquid crystal (LC) integrated chiral metasurfaces, of which the metahologram intensity can be adjusted continuously between fully ‘on’ and ‘off’ states. The chiral metasurface consists of a gap-shifted split ring resonator (SRR), and exhibits spin angular momentum selection that reflects left-circularly-polarized light but perfectly absorbs right-circularly-polarized light (99.9%). The gap-shifted SRR realizes spin angular momentum selection using a metal–dielectric–metal multilayer structure and thereby induces a strong gap-plasmonic response, achieving the maximum calculated circular dichroism in reflection (CDR) of 0.99 at the wavelength of 635 nm. With the chiral metasurface, metaholograms are demonstrated with tunable intensities using LCs that change the polarization state of the output light using an applied voltage. With the LC integrated chiral metasurfaces, 23 steps of polarization are demonstrated for the continuous tuning of the holographic image intensity, achieving measured CDR of 0.91. The proposed LC integrated spin-selective chiral metasurface provides a new resource for development of compact active optical modules with continuously-tunable intensity.