Plasmon‐Enforced Sub‐120 fs Ultrafast Responses Within Laser Printed Color Surfaces

ABSTRACT Based on the laser resonant absorption in an optical attenuated Fabry‐Pérot (FP) cavity formed by the Ag thin film, an insulator layer HfO 2 , and an Al reflector, we establish a comprehensive framework from the ultrafast dynamics to the nanoscale fabrication of plasmonic nanostructures. First, we investigated the hot‐electron dynamics by the femtosecond pump‐probe spectroscopy, revealing an ultrafast relaxation time of ∼120 fs under resonant excitation of the plasmonic FP cavity. Furthermore, using resonant femtosecond laser printing to create plasmonic morphologies on the top Ag layer allows the significant modulation of the surface reflectivity, resulting in plasmonic structural colors. In addition, we compared the transient reflectance (TR) results of the plasmonic structures before and after the fs laser printing, which shows the ultrafast dynamic transition from a delocalized FP cavity mode to a localized surface plasmon resonance (LSPR). Our research reveals the physical mechanism of the fs laser printing from the perspective of ultrafast non‐equilibrium dynamics, providing both theoretical and experimental foundations for achieving high‐throughput, nanometer‐precision plasmonic colors.