All-Optical Broadband Atomic Magnetometer Utilizing Raman-Driven Spin Noise Spectroscopy

We report the development and performance of an atomic magnetometer (AM) utilizing the Raman-driven spin noise spectroscopy (RDSNS) technique, which measures the intrinsic spin fluctuations of an atomic medium subjected to a coherent two-photon optical drive. The RDSNS signal is noninvasively detected using a far-off resonant weak probe light utilizing a polarimetric detection scheme. This overcomes the limitations of the small dynamic range and low bandwidth of traditional optically pumped magnetometers (OPMs) or AMs operating in the spin exchange relaxation-free (SERF) regime. We experimentally demonstrate, using both paraffin-coated and buffer-gas-filled vapor cell containing neutral rubidium atoms, that the dynamic range of such magnetometers can reach beyond 150 G while maintaining a dc magnetometer resolution of around 30 pT and a magnetic noise sensitivity of around $30~\text {pT}/\sqrt {\text {Hz}}$ at a bandwidth of 100 Hz and a magnetic field of about 0.6 mT. Being an all-optical setup, this instrument is largely immune to interference with stray radio frequency fields and has the potential to be miniaturized and field deployable. One of the practical applications would be to measure variations in geomagnetic fields precisely without having to shield the magnetometer.