Selective excitation of a single rare-earth ion in an optical fiber

A fiber-coupled single-photon source is an essential component for the implementation of optical quantum communication technologies. Using the rare-earth ion doped in an optical fiber as an emitter is a significant method to construct such a photon source at room temperature, as well as achieving high coupling and channeling efficiency. In this study, we experimentally demonstrated the generation of single photons at room temperature by selectively exciting a sole rare-earth ion isolated within a tapered silica fiber. The key advantages of our method are the ability to manipulate a purely single ion and the efficient collection of photons from the guided mode of the fiber, owing to the single ion's emission of photons directly within the fiber. These features make our system a promising building block for realizing all-fiber-integrated optical quantum networks. We have also measured the optical lifetime of a single neodymium ion in the tapered fiber, and the result supports that the single-photon correlation time is practically determined by the absorption time of the ion.