Cavity Optomechanical Magnetometer
  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. 
S. Forstner, S. Prams, J. Knittel, E. D. van Ooijen, J. D. Swaim, G.   I. Harris, A. Szorkovszky, W. P. Bowen, and H. Rubins...
physics.optics