Surface Coloring and Plasmonic Information Encryption at 50000 dpi Enabled by Direct Femtosecond Laser Printing.

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Femtosecond (fs) laser pulses induce nonequilibrium states in matter, enabling precise surface modification.
• Plasmonic nanostructures are crucial for optical applications, but their fabrication often requires complex methods.

Purpose of the Study:

• To develop a template-free method for creating diverse plasmonic morphologies on gold surfaces using fs-laser patterning.
• To achieve high-resolution structural color printing and information encryption with tunable optical properties.

Main Methods:

• Utilizing fs-laser patterning to induce thermomechanical effects and ultrafast solid-to-liquid transitions on gold surfaces.
• Creating diverse plasmonic nanomorphologies with controlled orientation within subwavelength lattices.

Main Results:

• Achieved pronounced surface reflectivity modulation, resulting in structural color effects with tunable tone and saturation.
• Demonstrated template-free color printing at a lateral resolution up to 50000 dots per inch.
• Successfully encrypted optical information within colorful images via modulated plasmonic responses, retrievable with cross-polarized optical visualization.

Conclusions:

• Fs-laser patterning offers a versatile and high-resolution approach for fabricating plasmonic nanostructures for advanced optical applications.
• The method enables integrated functionalities of high-resolution coloring, information encryption, and security labeling on demand.