Single-photon emitters based on NIR colour centres in diamond coupled   with solid immersion lenses
  Single-photon sources represent a key enabling technology in quantum optics, and single colour centres in diamond are a promising platform to serve this purpose, due to their high quantum efficiency and photostability at room temperature. The widely studied nitrogen vacancy centres are characterized by several limitations, thus other defects have recently been considered, with a specific focus of centres emitting in the Near Infra-Red. In the present work, we report on the coupling of native near-infrared-emitting centres in high-quality single crystal diamond with Solid Immersion Lens structures fabricated by Focused Ion Beam lithography. The reported improvements in terms of light collection efficiency make the proposed system an ideal platform for the development of single-photon emitters with appealing photophysical and spectral properties. 
D. Gatto Monticone, J. Forneris, M. Levi, A. Battiato, F. Picollo, P.   Olivero, P. Traina, E. Moreva, E. Enrico, G. Brida, ...
cond-mat.mtrl-sci