Fast Fabrication of a Ag Nanostructure Substrate Using the Femtosecond Laser for Broad-Band and Tunable Plasmonic Enhancement

Using a femtosecond laser, we have transformed the laser-direct-writing technique into a highly efficient method that can process AgO_x thin films into Ag nanostructures at a fast scanning rate of 2000 μm²/min. The processed AgO_x thin films exhibit broad-band enhancement of optical absorption and effectively function as active SERS substrates. Probing of the plasmonic hotspots with dyed polymer beads indicates that these hotspots are uniformly distributed over the treated area.