Ultra-low field magnetic field sensors are essential for many applications including geology, mineral exploration, archaeology and medicine [1]. However, such magnetometers typically either require cryogenic systems to operate, or suffer poor dynamic range, limiting their ability to operate in ambient conditions. Here, we introduce the concept of a cavity optomechanical magnetometry[2], and demonstrate microscale room temperature magnetometry operating in the picoTelsa sensitivity range (see Fig. 1a). The peak sensitivity of 200 pT Hz−1/2 exceeds all previous microscale room temperature magnetometers. Furthermore, we demonstrate that an inherent paramagnetic nonlinearity allows mix-up of low frequency to the RF frequency band, enabling magnetic field sensing in the Hz-kHz frequency window crucial for applications such as medical imaging, geosurvey, and magnetic anomaly detection (see Fig. 1b). This presents an enabling step towards real applications of cavity optomechanical magnetometers in high-performance microscale magnetometry.

© 2013 Optical Society of America

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