Journal article · Preprint article
Optimised frequency modulation for continuous-wave optical magnetic resonance sensing using nitrogen-vacancy ensembles
Magnetometers based on ensembles of nitrogen-vacancy centres are a promising platform for continuously sensing static and low-frequency magnetic fields. Their combination with phase-sensitive (lock-in) detection creates a highly versatile sensor with a sensitivity that is proportional to the derivative of the optical magnetic resonance lock-in spectrum, which is in turn dependant on the lock-in modulation parameters.
Here we study the dependence of the lock-in spectral slope on the modulation of the spin-driving microwave field. Given the presence of the intrinsic nitrogen hyperfine spin transitions, we experimentally show that when the ratio between the hyperfine linewidth and their separation is ≥ 1=4, square-wave based frequency modulation generates the steepest slope at modulation depths exceeding the separation of the hyperfine lines, compared to sine-wave based modulation.
We formulate a model for calculating lock-in spectra which shows excellent agreement with our experiments, and which shows that an optimum slope is achieved when the linewidth/separation ratio is ≥ 1=4 and the modulation depth is less then the resonance linewidth, irrespective of the modulation function used.
Language: | English |
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Year: | 2017 |
Pages: | 14809-14821 |
ISSN: | 10944087 |
Types: | Journal article and Preprint article |
DOI: | 10.1364/OE.25.014809 |
ORCIDs: | Ahmadi, Sepehr , Wojciechowski, Adam , Huck, Alexander and Andersen, Ulrik Lund |