Modeling fluorescence of single nitrogen–vacancy defect centers in diamond

Abstract

Based on new spectroscopic information retrieved by experiments on individual Nitrogen–Vacancy (NV) defect centers in diamond, we introduced the five-level photophysical model of the center and demonstrate its applicability to describe consistently different experiments on single NV centers. The model takes into account the triplet–triplet character of the optical transition 3A– 3E (637 nm) of the center and the presence of a metastable singlet state 1A. Supposing optical excitation rates B T from spin substates T=X,Y,Z of the ground 3A state as well as the fluorescence emission rates A T to these substates to be different ( B Z/ B X≈11, B X= B Y while A Z/ A X≈18, A X= A Y), we were able to fit consistently the experimental data obtained for green-laser-excited single NV centers at room-temperature: (i) lineshapes of fluorescence-detected magnetic resonance at 2.88 GHz in the ground 3A state and their changes due to the strains in the diamond crystal, (ii) fluorescence saturation and (iii) photon antibunching/bunching in the fluorescence light emitted by a single NV center.