Invited Article: Saturation scattering competition for non fluorescence single wavelength super resolution imaging

Stimulated emission depletion nanoscopy and its derivatives based on saturation induced competition effects have become an indispensable tool for studying cellular events and their dynamics in living conditions. The successful implementation of these techniques heavily relies on the competition between excitation induced spontaneous emission and stimulated emission from fluorescent dyes. The use of two laser beams at different wavelengths perplexes the optical system and the high intensity saturation beam inevitably introduces detrimental photobleaching effects. Harnessing the emerging saturation scattering of plasmonic nanoparticles, here, we demonstrate a novel fluorescence-free single-wavelength super-resolution imaging technique using gold nanoparticles. A lateral resolution of 101.2 nm (<λ/5) is achieved through introducing saturation scattering competition (SSC) of 60 nm gold nanospheres between dual beams at the same wavelength. In addition, the SSC drastically reduces the saturation intensity by three orders of magnitude than the conventional stimulated emission depletion process at comparable resolutions. As a proof of concept, we realized robust single-wavelength super-resolved imaging in dMG-63 cells with a simplified system. The current technique provides a new modality of biosample-friendly technology for optical super-resolution imaging.