Optical-power-dependent splitting of magnetic resonance in nitrogen-vacancy centers in diamond

TL;DR

This study reveals that the magnetic resonance splitting in NV centers decreases exponentially with optical power, saturating at a certain point, which impacts the accuracy of magnetic field measurements.

Contribution

It uncovers the optical power dependence of ODMR splitting in NV centers and proposes an intrinsic property related to non-axisymmetry deformation affecting measurement accuracy.

Findings

Splitting width decays exponentially with optical power

Decay saturation point is sample-independent

Less deformed diamonds yield more accurate measurements

Abstract

Nitrogen-vacancy (NV) centers in diamonds are a powerful tool for accurate magnetic field measurements. The key is precisely estimating the field-dependent splitting width of the optically detected magnetic resonance (ODMR) spectra of the NV centers. In this study, we investigate the optical power dependence of the ODMR spectra using NV ensemble in nanodiamonds (NDs) and a single-crystal bulk diamond. We find that the splitting width exponentially decays and is saturated as the optical power increases. Comparison between NDs and a bulk sample shows that while the decay amplitude is sample-dependent, the optical power at which the decay saturates is almost sample-independent. We propose that this unexpected phenomenon is an intrinsic property of the NV center due to non-axisymmetry deformation or impurities. Our finding indicates that diamonds with less deformation are advantageous for accurate magnetic field measurements.