Pre-damage chemical bond evolution of laser-irradiated nano-defects characterized by Atomic force Microscopy-based infrared spectroscopy (AFM-IR)

Contaminant defects embedded during the fabrication of micro-nanostructures are critical precursors that trigger localized laser-induced damage under intense irradiation, degrading component performance. In this study, nano-sized defects were artificially introduced to investigate their pre-damage modification. Utilizing Atomic Force Microscopy-based Infrared Spectroscopy (AFM-IR), we captured the chemical bond evolution within these nano-defects prior to detectable morphological damage, demonstrating that microscopic chemical modification serves as a precursor preceding macroscopic laser-induced damage. Combined with temperature field simulations, the evolution mechanism of defects under laser irradiation was elucidated. This work provides physical insights into the damage precursors and offers a high-resolution, highly sensitive, non-destructive diagnostic approach for high-power laser optics.