Scattering suppression in plasmonic nanostars using pulsed-beam irradiation for super-resolution optical imaging

In this Letter, we demonstrate the selective excitation and suppression of plasmonic scattering in gold nanostars by using a pulsed laser. We achieve super-resolution optical imaging of gold nanostars with a lateral feature size of 140 nm ( λ /4.5) at an inhibition laser beam power of 0.24 mW. The average power of the inhibition laser beam under a pulsed laser beam is half that of gold nanospheres under a continuous wave laser beam and three orders of magnitude lower than that used in conventional fluorescence-based stimulated emission depletion microscopy. Furthermore, super-resolution optical imaging of gold nanostars inside cells is demonstrated with a lateral feature size of 164 nm at an inhibition laser beam power of 0.3 mW. Using pulsed lasers, the achievement of low-power plasmonic scattering suppression in gold nanostars enables the performance of sub-diffraction observations, which effectively avoids the long-term thermal damage of continuous wave lasers and expands the number of plasmonic nanoprobes for biological super-resolution optical imaging.