A low-power, high-sensitivity micromachined optical magnetometer

We demonstrate an optical magnetometer based on a microfabricated Rb-87 vapor cell in a micromachined silicon sensor head. The alkali atom density in the vapor cell is increased by heating the cell with light brought to the sensor through an optical fiber, and absorbed by colored filters attached to the cell windows. A second fiber-optically coupled beam optically pumps and interrogates the atoms. The magnetometer operates on 140mW of heating power and achieves a sensitivity below 20 fT/root Hz throughout most of the frequency band from 15 Hz to 100Hz. Such a sensor can measure magnetic fields from the human heart and brain. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770361]