All-optical method of nanoscale magnetometry for ensembles of nitrogen-vacancy defects in diamond

Abstract

The Nitrogen-Vacancy (NV) defect in diamond has shown considerable promise in the field of small scale magnetometry due to its high localization and retention of favorable optical properties at ambient conditions. Current methods of magnetometry with the NV center achieve high sensitivity to fields aligned with the defect axis; however, with most present methods transverse fields are not directly measurable. The all-optical method of NV magnetometry provides a means to detect transverse fields by monitoring changes in the overall fluorescence profile. In this work the all-optical method is extended to ensembles of non-interacting NV centers. By establishing an external bias field aligned with the (1, 1, 1) axis, the magnitude of an unknown transverse field can be unambiguously identified through the measurement of the signal curvature. The angular orientation can be determined up to a two-fold degeneracy by observing the change in signal curvature produced when the bias field is shifted off-axis. The magnetometry method explored in this thesis thus provides good sensitivity to transverse fields, while reducing to a minimum the experimental apparatus required to operate the magnetometer.