A Fully-Integrated Diamond Nitrogen-Vacancy Magnetometer with Nanotesla Sensitivity

Ensemble diamond nitrogen-vacancy (DNV) centers have emerged as a promising platform for precise earth-field vector magnetic sensing, particularly in applications that require high mobility. Nevertheless, integrating all control utilities into a compact form has proven challenging, thus far limiting the sensitivity of mobile DNV magnetometers to the $\mu T$-level. This study introduces a fully integrated DNV magnetometer that encompasses all the essential components typically found in traditional platforms, while maintaining compact dimensions of approximately $\Phi$ 13 cm $\times$ 26 cm. In contrast to previous efforts, these challenges are successfully addressed by integrating a high-power laser, a lock-in amplifier, and a digitally-modulated microwave source. These home-made components show comparable performance with commercial devices under the circumstance, resulting in an optimal sensitivity approaching 2.14 nT ($\sqrt{Hz}$)⁻¹. The limitations in this system as well as possible future improvements are discussed. This work paves the way for the use of DNV magnetometry in cost-effective, mobile unmanned aerial vehicles, facilitating a wide range of practical applications.