High-quality grating-coupled surface plasmon resonances in silver and gold bumps arrays fabricated in thin metallic films using the third harmonic of femtosecond laser

Grating-coupled surface plasmon resonances, generated by periodic metal nanostructure arrays, exhibit strong optical confinement and enhanced field localization. Due to their unique properties, these resonances are interesting in biosensing, nanolasing, surface-enhanced spectroscopy, and nonlinear optics. Here, large-scale bumps arrays fabricated with a wavelength-scale period in silver and gold films by using a direct laser writing technique are presented. These structures exhibit strong plasmonic resonances in Vis and NIR ranges whose quality depends on the coupling conditions and can exceed 100. The highest quality factor of resonances is achieved with p-polarized light. The measured dependence of grating-coupled surface plasmon resonance wavelengths of gold and silver bumps arrays on the incident angle is in good agreement with theoretical considerations. The demonstrated laser-based method shows significant technological progress in the fabrication of gold and silver nanostructures arrays supporting high-quality surface plasmon resonances.