Two-photon luminescence and stimulated emission depletion with gold nanorods by a single wavelength

Abstract

Single-wavelength two photon STED technique simplifies common STED setup, and decreases the cost of the system. However, this technique limits the fluorescent dye to a few kinds. Because the dye should be excited and depleted by the same single wavelength laser. And the gold nanorods can be excited by near-infrared pulsed laser and produces two photon luminescence, which is brighter than general two-photon autofluorescence by three orders. We found that the gold nanorods can also be depleted by near-infrared pulsed laser. We studied the stimulated emission depletion of gold nanorods with a single wavelength laser in the near infrared. Two photon luminescence was excited with a femtosecond pulse, then depleted by stimulated emission with a stretched pulse. The depletion efficiency with different wavelength was measured to pick out the optimal wavelength. We showed that this method can be applied to super-resolved STED microscopy, which combines the high brightness of the nanorods and the simplicity of the single-wavelength STED system.