Upconversion Laser Direct Writing Using NIR Light-Responsive Nanocomposites for Photopatterning and Reconfiguration of Dynamic 3D Microstructures.

Dynamic three-dimensional (3D) patterns exhibit superior capabilities compared to their static counterparts, playing crucial roles in applications such as rewritable data storage and updatable information encryption. However, the efficient fabrication and reconfiguration of 3D patterns require suitable methods and materials. In this work, we explore the fabrication and reconfiguration of dynamic 3D patterns using upconversion laser direct writing in combination with near-infrared (NIR) light-responsive nanocomposites. We have developed a system that utilizes a cost-effective continuous-wave (CW) NIR laser to induce reversible photoreactions at the laser focus, thereby fabricating dynamic 3D patterns by moving the laser focus. By integrating upconversion nanoparticles (UCNPs) with photoswitchable materials, including spiropyran (SP), diarylethene (DTE), and azobenzene (AZO), within a polymer matrix, we enable localized photoisomerization through focused laser irradiation. The reversibility of the photoswitching process renders the resulting 3D patterns erasable, rewritable, and dynamic. This technique represents a universal and economical method for dynamic 3D photopatterning, particularly promising for advancing information encryption, optical storage, and data security technologies.