All-Optical Modulation of NV Centers in Nanodiamonds for Contrast-Enhanced Imaging

With its unique quantum features at room temperature, NV center has been recognized as a promising candidate for many applications in diverse fields. For instance, contrast-enhanced imaging has been achieved based on spin-dependent fluorescence of NV center, which is modulated by applied microwave fields or magnetic fields. Nevertheless, another intrinsic feature of NV center (i.e., polarization-selective excitation) seems to be underestimated in actual applications. For example, contrast-enhanced imaging also can be achieved based on this property. Here, we propose the linear polarization modulation (LPM) method to achieve contrast-enhanced imaging in model systems and living cells. Particularly, we would like to emphasize two advantages of LPM method: 1) high contrast, and 2) wide accessibility. Specifically, the observed contrast for a single NV center is approximately 10-90%, while that for ensemble NV centers is on the order of 20-60%. One should notice that our all-optical method is well fitted with a standard fluorescence microscope with slight modification, being easy for implementation. Therefore, this study paves the way for wider accessibility of NV centers in actual imaging applications.