Reflective metasurfaces based on metallic1,2,3 and dielectric4,5 nanoscatterers have attracted interest owing to their ability to control the phase of light. However, because such nanoscatterers require subwavelength features, the fabrication of elements that operate in the visible range is challenging. Here, we show that chiral liquid crystals6,7 with a self-organized helical structure enable metasurface-like, non-specular reflection in the visible region. The phase of light that is Bragg-reflected off the helical structure can be controlled over 0–2π depending on the spatial phase of the helical structure; thus planar elements with arbitrary reflected wavefronts can be created via orientation control. The circular polarization selectivity and external field tunability of Bragg reflection open a wide variety of potential applications for this family of functional devices, from optical isolators to wearable displays.
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The authors thank R. Ozaki for discussions. The authors also thank the DIC Corporation for providing the photoalignment material, and Merck KGaA for providing the chiral dopant. This study was supported by a Grant-in-Aid for JSPS Fellows (15J00288), the MEXT Photonics Advanced Research Centre Program (Osaka University), and JST, PRESTO.
The authors declare no competing financial interests.
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Kobashi, J., Yoshida, H. & Ozaki, M. Planar optics with patterned chiral liquid crystals. Nature Photon 10, 389–392 (2016). https://doi.org/10.1038/nphoton.2016.66
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