Extrinsic Polarization‐Enabled Covert Plasmonic Colors Using Aluminum Nanostructures

Abstract

Subwavelength structures can provide a versatile platform for displaying various colors. Here, a reflection-type approach to structural colors enabled by an extrinsic polarization-dependent plasmonic resonance using aluminum nanohole arrays is presented theoretically. Usually, nanohole arrays with small hole sizes support whitish structural colors due to the narrow-band reflection dip and high-reflection nonresonant background. Interestingly, the lineshape of the resonance can be converted from a reflection dip with a high background to a reflection peak with negligible background using a pair of linear polarizers to select the polarization states of the incident light and the detected signal. Therefore, the resultant colors can be switched between whitish colors and vibrant colors, which are covert and overt under a white lighting condition, respectively. Due to the huge contrast between the two types of colors, this approach provides a novel scheme for the development of security-related color labels.

Structural Colors by Synergistic Birefringence and Surface Plasmon Resonance

“…With the rotating f-GNRs2 film and altering light retardation due to various CNC contents in the f-CNCs films, the flower pattern exhibited distinct, adjustable color combinations. Although sophisticated and promising manipulations of plasmonic colors have been performed via complicated micro- and nanofabrication methods, for example, the widely used physical vapor deposition to selectively coat metal layers, a general method to prepare composite polymer films with embedded nanorods with tunable morphologies and an optical mechanism is still highly desired. ,,− In this work, we presented an effective and cost-efficient method to achieve flexible color manipulation of polymer films by integrating CNCs with birefringence and GNRs exhibiting SPR. Using this method, polymer films containing aligned GNRs and/or CNCs not only showed a much wider range of adjustable structural colors than existing methods but also can be expanded to other potential nanomaterials.…”

Recent progress on structural coloration

“…gratings [115,116] , holes [117] , nanopillars [118] , etc. [119][120][121][122] enables the manipulation of light through plasmonic effects.…”

“…In the pursuit of overcoming limitations associated with traditional pigments and dyes, researchers have explored the intricate interaction between metals and light. The use of metal nanostructures, such as gratings [115,116] , holes [117] , nanopillars [118] , etc. [119–122] enables the manipulation of light through plasmonic effects.…”