High-Brightness and Wide-Gamut Structural Color via Ultrafast Laser-Induced Oxidation

Background: Nature presents a brilliant world of colors built on precisely regulated interactions between light and matter via micro-nano structures. These are primarily classified into pigment colors (chemical) and structural colors (physical). Structural color, generated by light-matter interactions at the nanoscale, offers superior saturation, fade resistance, and environmental stability compared to traditional dyes, making it ideal for information security, high-end displays, and artistic creation. However, traditional fabrication methods are often costly and difficult to scale.

Overview: The team lead by Prof. Min Qiu at Westlake University has developed a new method for producing structural colors using ultrafast laser-induced oxidation. By using a Ti–TiO₂–Ti sandwich thin-film structure and precisely controlling the picosecond laser oxidation process, they achieved high-precision control over oxide layer thickness. This method generates vibrant physical colors through optical interference without any ink or dyes. Experimental results show a coverage of over 80% sRGB gamut, maximum reflectivity above 60%, and a spatial resolution reaching 30,000 DPI. The process is robust against corrosion and harsh environments, and compatible with various substrates including rough stainless steel.

Figure Descriptions:

• Figure 1. Schematic and demonstration of laser-induced coloring based on the Ti-TiO₂-Ti sandwich structure.

• Figure 2. Laser-printed color images, reflection spectra, and color gamut.

• Figure 3. Cross-sectional microstructure and composition evolution under different laser irradiation doses.

• Figure 4. High-resolution laser-printed structural colors and patterns.

With high-NA objectives, the team achieved sub-micron printing, creating color dots smaller than 800 nm and lines of ~1 μm width. This allowed for high-precision printing of complex patterns, such as the aerial view of Westlake University's Yungu Campus, on both polished and rough silicon wafers.

Original link: https://doi.org/10.1002/advs.202523260