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Journal Article
Hybrid State Engineering of Phase-Change Metasurface for All-Optical Cryptography
- Authors
- Chulsoo Choi, Sang-Eun Mun, Jangwoon Sung, Kyunghee Choi, Seung-Yeol Lee, Byoungho Lee
- Issue Date
- 2021-01
- Citation
- Advanced Functional Materials, v.31, no.4, pp.1-9
- ISSN
- 1616-301X
- Publisher
- John Wiley & Sons Ltd.
- Language
- English
- Type
- Journal Article
- Abstract
- Chalcogenide material Ge2Sb2Te5 (GST) has bistable phases, the so‐called amorphous and crystalline phases that exhibit large refractive index contrast. It can be reversibly switched within a nanosecond time scale through applying thermal bias, especially optical or electrical pulse signals. Recently, GST has been exploited as an ingredient of all‐optical dynamic metasurfaces, thanks to its ultrafast and efficient switching functionality. However, most of these devices provide only two‐level switching functionality and this limitation hinders their application to diverse all‐optical systems. In this paper, the method to expand switching functionality of GST metasurfaces to three level through engineering thermo‐optically creatable hybrid state that is co‐existing state of amorphous and crystalline GST‐based meta‐atoms is proposed. Furthermore, the novel hologram technique is introduced for providing the visual information that is only recognizable in the hybrid state GST metasurface. Thanks to thermo‐optical complexity to make the hybrid state, the metasurface allows the realization of highly secured visual cryptography architecture without the complex optical setup. The phase‐change metasurface based on multi‐physical design has significant potential for applications such as all‐optical image encryption, security, and anti‐counterfeiting.
- KSP Keywords
- Amorphous and crystalline phases, Chalcogenide material, Electrical pulse, Optical System, Optical cryptography, Optical image encryption, Phase change, Refractive index contrast, Time Scale, Visual Cryptography, all-optical
This work is distributed under the term of Creative Commons License (CCL)
(CC BY)
(CC BY)
