A cavity optomechanical magnetometer is demonstrated where the magnetic field induced expansion of a magnetostrictive material is transduced onto the physical structure of a highly compliant optical microresonator. The resulting motion is read out optically with ultra-high sensitivity. Detecting the magnetostrictive deformation of Terfenol-D with a toroidal whispering gallery mode (TWGM) resonator a peak sensitivity of 400 nT/Hz^.5 was achieved with theoretical modelling predicting that sensitivities of up to 500 fT/Hz^.5 may be possible. This chip-based magnetometer combines high-sensitivity and large dynamic range with small size and room temperature operation.
@article{arxiv.1110.2271,
title = {Cavity Optomechanical Magnetometer},
author = {S. Forstner and S. Prams and J. Knittel and E. D. van Ooijen and J. D. Swaim and G. I. Harris and A. Szorkovszky and W. P. Bowen and H. Rubinsztein-Dunlop},
journal= {arXiv preprint arXiv:1110.2271},
year = {2015}
}