Saturable scattering and its application to superresolution microscopy

Recently, several superresolution methods have been demonstrated to revolutionize the way we access the nano-world. However, these techniques are based on switching or saturation of fluorescence, and consequently are limited by switching reversibility and photobleaching. Here we show first superresolution far-field imaging based on scattering, which is a universal phenomenon without bleaching. Our principal finding is that scattering from plasmonics particles is saturable. By extracting the saturated part, sub-80-nm resolution is achieved. This work not only expands the horizon of superresolution imaging from fluorescence to scattering, but also points out the possibility of resolution enhancement for all imaging modalities that utilize plasmon properties.