High-sensitivity and wide-bandwidth fiber-coupled diamond magnetometer with surface coating

Mapping magnetic fields from different materials and structures can provide a powerful means for broad applications of activity probe and feature analysis. Here, we present a high-sensitivity and wide-bandwidth fiber-based quantum magnetometer at the scale of a few hundred micrometers. We propose a fiber-coupled diamond magnetometer. Tracking a pulsed optically detected magnetic resonance spectrum allows a magnetic field sensitivity of 103 pT / Hz and a bandwidth of 2.6 kHz. Additionally, with an approach of coating the diamond surface with silver reflective film, both the fluorescence collection and excitation efficiency are significantly enhanced, and the sensitivity and bandwidth are expected to be further improved to 50 pT / Hz and 4.1 kHz, respectively. Finally, this fiber-based quantum magnetometer is applied as a probe to successfully map the magnetic field induced by the current-carrying copper-wire mesh. Such a stable and compact magnetometer can provide a powerful tool in many areas of physical, chemical, and biological researches.