# High‐Brightness, Wide‐Gamut, and High‐Resolution Structural Colors via Ultrafast Laser Oxidation of Ti/TiO2 Films

## TL;DR

A new laser method creates bright, vivid structural colors on titanium films with high resolution and durability for use in art and anti-counterfeiting.

## Contribution

A scalable ultrafast laser technique for generating high-resolution structural colors using Ti–TiO2–Ti films with controllable oxidation.

## Key findings

- Structural colors achieve over 80% sRGB gamut and 60% peak reflectance.
- Resolution of up to 30,000 DPI is achieved with precise color difference control (ΔE < 3).
- Laser-induced colors show excellent durability in thermal and corrosion tests.

## Abstract

The scalable fabrication of high‐brightness, wide‐gamut, and high‐resolution structural colors remains challenging due to the reliance on complex nanofabrication or coating techniques. Here, we demonstrate a facile and flexible approach to generating vivid structural colors via ultrafast laser processing of Ti–TiO2–Ti sandwich‐structured thin films. The multilayer design enables controlled oxidation with oxide thicknesses exceeding 200 nm under laser irradiation. Optical characterization reveals dual absorption enhancement peaks and a reflection enhancement peak in the visible spectrum. By tuning the accumulated laser fluence, we modulate the oxidation state of Ti and the optical properties of TiO2, achieving vibrant structural colors with high reflectivity and a color gamut exceeding 80% sRGB. Peak reflectance reaches 60%, and the highest color difference (ΔE) control precision is less than 3. Moreover, a resolution up to 30 000 DPI is attained. The laser‐induced structural colors exhibit excellent durability, passing standard tests for thermal stability and corrosion. This method enables direct patterning of high‐luminance colors and holds promise for applications in art, anti‐counterfeiting, signage, and flexible photonic devices.

Ultrafast laser writing on titanium (Ti)–titanium dioxide (TiO2)–Ti sandwich films triggers controllable oxidation (〉200 nm) to create vivid, durable structural colors. The colors reach 〉 80% of the standard RGB (sRGB) gamut, up to 60% peak reflectance, and 30,000 dots per inch (DPI) resolution for art and anti‐counterfeiting.