An NV Magnetometer With High Fluorescence Excitation and Collection Efficiency Using Silicon-Based MEMS Process

The fabrication of nitrogen-vacancy (NV) center magnetometers utilizing micro-electro-mechanical systems (MEMSs) has gained popularity due to the low cost, good consistency, and easy of system integration. This article presents the fabrication of an NV magnetometer using MEMS process, which integrates a silicon-based resonator for microwave transmission, a diamond waveguide for fluorescence emission, and a silicon-based reflector for fluorescence collection. The magnetometer operates on the principle of continuous-wave optically detected magnetic resonance (CW-ODMR) for magnetic field detection. The inhomogeneity of the silicon-based resonator in the $1.9\times 1.9$ mm area of hole is 7.7%. The combined effect of the silicon-based reflector and diamond waveguide achieves a 2.82-fold enhancement in fluorescence collection efficiency. The silicon-silicon interface between the resonator and reflector components is fabricated via thermal compression bonding to form a groove for subsequent diamond waveguide integration. The processed components are placed within a ceramic tube shell and subsequently encapsulated in glass. The integrated magnetometer, with dimensions of $14\times 14\times 12$ mm, achieves a sensitivity of 901.96 pT/Hz ${}^{1/2}$ within the 1–55 Hz, a photon shot noise limited sensitivity of 121 pT/Hz ${}^{1/2}$ , and a magnetic field detection range of $\pm 168.2~\mu $ T.