Optimization of Magnetic Properties Measured by Diamond NV-Centered Magnetometer

The NV center (nitrogen-vacancy center, NV) of the diamond can be used to realize the magnetic measurement function by microwave frequency sweep modulation and demodulation at room temperature, with high magnetic field sensitivity. In order to solve the problems of long test time and the low sampling rate of single microwave sweep frequency modulation and demodulation system, a double microwave modulation and demodulation NV magnetic measurement system is designed based on a diamond NV center. The sampling rate of the system is increased to 10kHz, and the measurement uncertainty of 1.76 ×10–<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> is realized at this sampling rate. By optimizing the slope and noise, the sensitivity of magnetic measurement is improved: the slope of the ODMR spectral line is increased from 3.455 V / GHz to 8.43 V/GHz after mixing by the microwave mixing modulation method. The system noise is reduced from 1.87 uV/Hz<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup>to 219.26 nV/Hz<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup>by using the differential optical path, and the magnetic field measurement sensitivity of 0.929 nT/Hz<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup>is realized.