Vector Magnetometry Based on Polarimetric Optically Detected Magnetic Resonance

A robust technique is introduced for vector magnetometry based on polarimetry and optically detected magnetic resonance of ensembles of negatively charged nitrogen-vacancy (NV-) centers in diamond without a magnetic bias field. Ensembles provide a far greater signal-to-noise ratio than single centers, and their creation requires less effort. Previous methods for vector magnetometry using ensembles of NV- centers relied on a calibrated magnetic bias field or on complex detection techniques to distinguish the crystal axes. Instead, this work uses out-of-plane polarized light to selectively excite NV- centers oriented along specific crystal axes. This approach is general for other spin-1 color centers with C3v$C_{3v}$ symmetry, and it is compatible with standard microscopy methods, such as scanning probe, superresolution, confocal, and wide-field imaging.