Increasing the photon collection rate from a single NV center with a   silver mirror
  In the pursuit of realizing quantum optical networks, a large variety of different approaches have been studied to achieve a single photon source on-demand. The common goal for these approaches is to harvest all the emission from a quantum emitter into a single spatial optical mode while maintaining a high signal-to-noise ratio. In this work, we use a single nitrogen vacancy center in diamond as a quantum emitter operating at ambient conditions and we demonstrate an increased photon count rate up to a factor of 1.76 by placing a silver mirror fabricated on the end facet of an optical fiber near the emitter. 
Niels M{\o}ller Israelsen, Shailesh Kumar, Mahmoud Tawfieq, Jonas   Schou Neergaard-Nielsen, Alexander Huck, Ulrik Lund Andersen
quant-ph physics.optics