  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.
