Ultrabright Room-Temperature Emission from Single Plasmon-Enhanced Nitrogen-Vacancy Centers in Diamond

We report unprecedentedly bright fluorescence from single nitrogen-vacancy centers in nanodiamonds. The intensity enhancement is achieved by placing nanodiamonds in gaps between a metal film and randomly dispersed metal nanoparticles. The shortening of fluorescence lifetime below 1 ns combined with an efficient outcoupling of plasmons into the far-field lead to a detected fluorescence intensity in the range of 107 counts per second (cps). The photostability of nitrogen-vacancy centers allows reaching the saturation regime and estimating the total brightness enhancement resulting from the use of plasmonic nanostructures.