Negative Charge Enhancement of Near-surface Nitrogen Vacancy Centers by Multicolor Excitation

In recent years, there has been increasing interest in understanding the dynamics of nitrogen vacancy (NV) centers under IR excitation, which has a significant impact on the NV centers emission and charge state. Many models have been suggested to explain parts of the experimental results, however a full mechanism describing all the experimental results is yet to be known. In this work we suggest a generalized model for NV center spin and charge state dynamics under green and IR excitation. Using a rate equation approach, we show that this model is consistent with the new and previous experimental works, thus suggesting a complete understanding of the behavior of NV centers under IR excitation, which in turn may be utilized in various NV-based experiments, such as spin readout enhancement and charge control.