Vivid Structural Color Macropatterns Created by Flexible Nanopainting of Ultrafast Lasers.

Structural colors based on the macro- or nanostructure formation are ubiquitous in nature, having great prospects in many fields as a result of their environmentally friendly and long-term stable characteristics compared to pigments or dyes. However, the current fabrication techniques still face challenges for the generation of high-quality structural color patterns, especially at the macroscale, in an efficient way. Here, we demonstrate a method that exploits a flexible scanning process of generating macropatterns to convert the contour profiles into well-defined sub-micrometer grating structures with unprecedented vivid structural colors, at high speed and low cost on the graphene oxide film. The nature of dynamic beam shaping of the laser line spot allows us to flexibly construct the complex patterns at high speed, in sharp contrast to the traditional point-by-point laser processing. Moreover, the multicolor display of the patterns can be carried out by simply modulating the laser polarization to change the orientation of the sub-micrometer structures, and this nanopainting strategy is further explored to flexibly design the composite image for potential anti-counterfeiting applications.