A hand-held magnetometer based on an ensemble of nitrogen-vacancy centers in diamond

The development of practical applications of the magnetometer based on ensemble of nitrogen-vacancy centers has been impeded by the large size of the system. In this paper, we present an integrated and miniaturized magnetic field sensor with a volume of approximately 10 cm(3). Compared to the previous design, with the fluorescence waveguide excitation and collection structure, both the optical excitation system and collection system are integrated into a compact device by combining the optical fiber, so that it can be a handheld sensing head. We demonstrated experimentally that this sensor head enables the optically detected magnetic resonance measurements with or without the external magnetic field. Subsequently, we verified that the magnetic-field sensitivity is approximately 67 nT root Hz(-1) , and projected the photon shot noise limited sensitivity to be 2.04 nT root Hz(-1). This novel system has considerable performance regarding previous designs while greatly reducing dimensions.