Laser light used to polarize and interrogate NV -centers can also induce charge switching between NV -and its neutral form NV 0 . Photoconversion depends on the presence of nitrogen defects and surface acceptor states, and thus both NV -→ NV 0 and NV 0 → NV -photoconversion routes have been observed in different diamond samples. Recently, we have shown that increasing laser power can substantially increase the availability of shallow NV -produced by nitrogen implantation in ultrapure CVD diamond . However, it is unclear whether a similar strategy may be advantageous in NDs.