All-Optical Photoluminescent Signatures of Resonant Interaction between Nitrogen-Vacancies in Diamond

Room-temperature all optical photoluminescence (AO-PL) changes in NV ensembles at low magnetic fields (<2 mT) are correlated with near-degenerate NV spin transitions. These spin transitions with hyperfine interactions included, arise from different NV orientations within the diamond host. . We describe and compare a theoretical model with results from recent experiments. The model provides a microphysical narrative for the experimentally observed AO-PL contrast's dependence on NV concentration and optical excitation intensity. These studies indicate different optimal conditions for low-field AO-PL based NV sensing compared to those of conventional optically detected magnetic resonance (ODMR) techniques.