Plasmonic laser nanoablation of solid material
Eversole, Daniel Steven
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We experimentally demonstrate the fabrication of nanostructures ablated on silicon (100) and borosilicate glass substrates by the plasmonic scattering of 780 nm, 220 fs laser pulses in the near-field of gold nanospheres. We take advantage of the enhanced plasmonic scattering of ultrashort laser light in the particle near-field to ablate welldefined nanocraters. Gold nanospheres are deposited onto each substrate surface and irradiated with a single laser pulse. We studied the effect of laser polarization on the morphology of ablated nanostructures and estimated the minimum fluence for plasmonic nanoablation necessary for single particles and particle aggregates. Generated nanocrater morphologies show a direct imprint of the particle dipolar scattering region, as predicted in our theoretical calculations. The largest near-field enhancements for single particle ablation were found when the incident radiation was directed at a 45° angle into the substrate surface. Additionally, larger enhancements were measured for particle aggregates than single particles. The measured near-field enhancement values agree well with the maximum field enhancements obtained in our calculations. The agreement between theory and measurements supports that the nanocraters are indeed formed by the enhanced plasmonic scattering in the near-field of the nanoparticles.