Fig. 20: Plasmonic metamaterials for optical steganography and encryption.
a Plasmonic thermal effect-enabled optical steganography233. Laser scanning guides the assembly of quasi-3D patterned arrays of plasmonic nanoparticle (NP) dimers. Localized photothermal heating selectively removes polymers on gold nanoparticles (GNPs). b The patterned quasi-3D NP dimers exhibit plasmonic coloration post-polymer removal, which can be restored by applying a polymer coating. Reproduced with permission233. Copyright 2021 John Wiley and Sons. c Plasmon-enhanced chirality for information encryption197. Schematic representations of original (blue), vertical (red), and diagonal (green) grating patterns for LH structures. d Corresponding enlarged images. e Schematic illustrations depicting original grating patterns (left), accompanied by vertically formed nanopatterns (center), and diagonal nanopatterns (right) for LH-chiral plasmonic structures. f Schematic diagrams delineating applications in anti-counterfeiting and as chiral quantum dot (QD) codes. Reproduced with permission197. Copyright 2023 Springer Nature Limited.
