Flat-response spin-exchange relaxation free atomic magnetometer under negative feedback

• DOI: 10.1364/oe.22.019887
• Publication Date: 2014-08-11T19:39:38Z
• Authors: Hyun Joon Lee; Jeong Hyun Shim; Han Seb Moon; Kiwoong Kim
• Keywords: 0103 physical sciences; 01 natural sciences

We demonstrate that the use of negative feedback extends the detection bandwidth of an atomic magnetometer in a spin-exchange relaxation free (SERF) regime. A flat-frequency response from zero to 190 Hz was achieved, which is nearly a three-fold enhancement while maintaining sensitivity, 3 fT/Hz1/2 at 100 Hz. With the extension of the bandwidth, the linear correlation between measured signals and a magne-tocardiographic field synthesized for comparison was increased from 0.21 to 0.74. This result supports the feasibility of measuring weak biomagnetic signals containing multiple frequency components using a SERF atomic magnetometer under negative feedback.