Prabhathan, P., Sreekanth, K. V., Teng, J., & Singh, R. (2023). Electrically Tunable Steganographic Nano-Optical Coatings. Nano Letters. https://doi.org/10.1021/acs.nanolett.3c01244
Abstract:
Thin film coatings with tunable colors have a broad range of applications, from solid-state reflective displays to steganography and data encryption. Incorporating chalcogenide phase change materials (PCM) in these coatings can provide non-volatility and fast switching speed, resulting in low power consumption and highly scalable devices. Here, we propose a novel approach to PCM-incorporated steganographic nano-optical coatings (SNOC) as thin film color reflectors for optical steganography. The proposed SNOC design combines a broadband and a narrowband absorber made up of PCMs to achieve tunable optical Fano resonance in the visible wavelength range, which is a scalable and iridescence-free platform for accessing the full-color range. We demonstrate that the linewidth of the Fano resonance can be dynamically tuned by switching the structural phase of lossy PCM from amorphous to crystalline, which is crucial for obtaining high-purity colors. For steganography applications, the cavity layer of SNOC is divided into an ultra-low loss PCM and a high index dielectric material with identical optical thickness. We show that electrically tunable color pixels can be fabricated using the SNOC on a microheater device. The proposed platform represents a significant step towards large-scale manufacturing of electrically tunable optical coatings for steganography, image encryption, and data storage.
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Funding Info:
This research / project is supported by the National Research Foundation - Competitive Research Program
Grant Reference no. : NRF-CRP26-2021-0004
This research / project is supported by the National Research Foundation - Competitive Research Program
Grant Reference no. : NRF-CRP23-2019-0005
This research / project is supported by the A*STAR - Individual Research Grant
Grant Reference no. : A2083c0058
This research / project is supported by the A*STAR - Industry Alignment Fund - Pre-Positioning Programme (IAF-PP)
Grant Reference no. : H19H6a0025