Narrow-band single photon emission at room temperature based on a single   Nitrogen-vacancy center coupled to an all-fiber-cavity
  We report the realization of a device based on a single Nitrogen-vacancy (NV) center in diamond coupled to a fiber-cavity for use as single photon source (SPS). The device consists of two concave mirrors each directly fabricated on the facets of two optical fibers and a preselected nanodiamond containing a single NV center deposited onto one of these mirrors. Both, cavity in- and output are directly fiber-coupled and the emission wavelength is easily tunable by variation of the separation of the two mirrors with a piezo-electric crystal. By coupling to the cavity we achieve an increase of the spectral photon rate density by two orders of magnitude compared to free-space emission of the NV center. With this work we establish a simple all-fiber based SPS with promising prospects for the integration into photonic quantum networks. 
Roland Albrecht, Alexander Bommer, Christoph Pauly, Frank M\"ucklich,   Andreas W. Schell, Philip Engel, Tim Schr\"oder, Oli...
physics.optics quant-ph