Integrated fiberized diamond magnetometer with high sensitivity and dynamic range by magnetic flux concentrators

Magnetometers based on nitrogen-vacancy (NV) centers in diamonds have been widely studied. With the use of purified diamond and magnetic flux concentrators (MFCs), the sensitivity of magnetic field measurement has been improved to the subpico-tesla level. However, diamond magnetometers face the challenge of achieving high sensing performance after integration. Here, we demonstrate an integrated fiber-coupled diamond magnetometer based on an MFC with both high sensitivity and a wide dynamic range. We sandwiched a nitrogen-doped diamond film of [111] crystal orientation between the two MFCs. With the polarization direction of the pump laser perpendicular to the NV center axis, the signal-to-noise ratio and its linearity with the magnetic field are enhanced. We demonstrate a sensitivity of 50 pT/√Hz@0.01 Hz and 390(172) fT/√Hz@ > 3 Hz while with a detection range of about 4 times the Earth’s magnetic field. This work demonstrates the feasibility of portable, highly sensitive diamond magnetometers that maintain a large dynamic range in various natural environments. Diamond magnetometers leveraging nitrogen-vacancy centers offer precise magnetic field measurements but struggle with integration and miniaturization. Here, the authors present an integrated fiber-coupled diamond magnetometer using magnetic flux concentrators, achieving 50 pT/√Hz sensitivity and a wide dynamic range, paving the way for portable, high-performance sensing in diverse environments.