Coupling of single NV Center to adiabatically tapered optical single   mode fiber
  We demonstrated a simple and reliable technique of coupling diamond nanocrystal containing NV center to tapered optical fiber. We carefully studied fluorescence of the fiber itself and were able to suppress it to the level lower than single photon emission from the NV center. Single photon statistics was demonstrated at the fiber end as well as up to 3 times improvement in collection efficiency with respect to our confocal microscope 
Vadim V. Vorobyov, Vladimir V. Soshenko, Stepan V. Bolshedvorskii,   Javid Javadzade, Nikolay Lebedev, Andrey N. Smolyaninov...
quant-ph cond-mat.mes-hall physics.optics