Toward laser-induced tuning of plasmonic response in high aspect ratio gold nanostructures.

High aspect-ratio gold nanostructures sustain Fabry-Perot-like surface plasmon responses from infrared to visible light energies. We show that some resonances can be tuned by means of laser irradiation, where low energy modes stay unperturbed. After laser irradiation, gold nanowires' tips are transformed into nanoparticles of various sizes joint to gold nanowires, producing high aspect-ratio half-dumbbells and dumbbells structures.