In recent years, atomic magnetometers (AMs) have demonstrated sub-femtotesla sensitivities and have emerged as potential replacements for superconducting quantum interference devices (SQUIDs). In an AM, a circularly polarized pump laser aligns the electron spins in a cloud of alkali metal vapor. Changes occur in the optical properties of the vapor when its collective moment interacts with an external magnetic field, resulting in a measurable polarization rotation of a linearly polarized probe beam. We present a unique pump/probe scheme in which a pump beam tuned to the87Rb D1 line (795 nm) and a probe beam tuned to the D2 line (780 nm) share a single optical axis. A dichroic waveplate is used to circularly polarize the pump beam while leaving the probe beam linearly polarized. Based upon this scheme, we have developed a small profile, fiber-coupled AM. By independently optimizing pump/probe power and detuning, we are able to achieve intrinsic single-channel sensitivity of <; 5 fT/√Hz, which is suitable for demanding applications such as magnetoencephalography (MEG). Furthermore, through straightforward adaptations of the current design, it should be possible to create dense, reconfigurable arrays of AMs for whole-head MEG.In recent years, atomic magnetometers (AMs) have demonstrated sub-femtotesla sensitivities and have emerged as potential replacements for superconducting quantum interference devices (SQUIDs). In an AM, a circularly polarized pump laser aligns the electron spins in a cloud of alkali metal vapor. Changes occur in the optical properties of the vapor when its collective moment interacts with an external magnetic field, resulting in a measurable polarization rotation of a linearly polarized probe beam. We present a unique pump/probe scheme in which a pump beam tuned to the87Rb D1 line (795 nm) and a probe beam tuned to the D2 line (780 nm) share a single optical axis. A dichroic waveplate is used to circularly polarize the pump beam while leaving the probe beam linearly polarized. Based upon this scheme, we have developed a small profile, fiber-coupled AM. By independently optimizing pump/probe power and detuning, we are able to achieve intrinsic single-channel sensitivity of <; 5 fT/√Hz, which is suitable for demanding applications such as magnetoencephalography (MEG). Furthermore, through straightforward adaptations of the current design, it should be possible to create dense, reconfigurable arrays of AMs for whole-head MEG.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)Jun 1, 201017 citations

Sensitivity Improvement of Spin-Exchange Relaxation Free Atomic Magnetometers by Hybrid Optical Pumping of Potassium and Rubidium

Yosuke Ito, Hiroyuki Ohnishi, Keigo Kamada +1 more

An optically pumped atomic magnetometer using a hybrid cell of potassium and rubidium atoms was demonstrated to yield high sensitivity to magnetic fields. We operated the magnetometer with the four possible combinations of optically pumped and optically probed atoms and found that the combination of optically pumped potassium and optically probed rubidium showed the highest sensitivity among the four combinations because the rubidium atoms were denser than those of potassium. Furthermore, we investigated the dependence of the sensitivity on the power densities of the pump and probe beams and the wavelength of the probe beam. The magnetometer using the hybrid cell required higher pump-beam power and had narrower magnetic linewidth than those of the single alkali-metal cell. However, the magnetic linewidth was larger than the theoretical value, ignoring the spin relaxation caused by the spin-exchange collisions. By adjusting the laser conditions, the highest sensitivity approached 30 fTrms/Hz1/2.An optically pumped atomic magnetometer using a hybrid cell of potassium and rubidium atoms was demonstrated to yield high sensitivity to magnetic fields. We operated the magnetometer with the four possible combinations of optically pumped and optically probed atoms and found that the combination of optically pumped potassium and optically probed rubidium showed the highest sensitivity among the four combinations because the rubidium atoms were denser than those of potassium. Furthermore, we investigated the dependence of the sensitivity on the power densities of the pump and probe beams and the wavelength of the probe beam. The magnetometer using the hybrid cell required higher pump-beam power and had narrower magnetic linewidth than those of the single alkali-metal cell. However, the magnetic linewidth was larger than the theoretical value, ignoring the spin relaxation caused by the spin-exchange collisions. By adjusting the laser conditions, the highest sensitivity approached 30 fTrms/Hz1/2.

IEEE Transactions on MagneticsOct 1, 201153 citations

Progress in high sensitive atomic magnetometers

Guobin Liu, Xian-Ping Sun, 顾思洪 +2 more

WuliJan 1, 20121 citation

A laser pump-re-pump atomic magnetometer

杨爱林, 杨国卿, 蔡勋明 +2 more

中国物理B：英文版Jan 1, 20130 citations

Robust, High-speed, All-Optical Atomic Magnetometer

Higbie, J M, Corsini, E, Budker, D

A self-oscillating magnetometer based on the nonlinear magneto-optical rotation effect with separate modulated pump and unmodulated probe beams is demonstrated. This device possesses a bandwidth exceeding $1\\khz$ . Pump and probe are delivered by optical fiber, facilitating miniaturization and modularization. The magnetometer has been operated both with vertical-cavity surface-emitting lasers (VCSELs), which are well suited to portable applications, and with conventional edge-emitting diode lasers. A sensitivity of around $3 {\\rm nG}$ is achieved for a measurement time of $1\\s$ .A self-oscillating magnetometer based on the nonlinear magneto-optical rotation effect with separate modulated pump and unmodulated probe beams is demonstrated. This device possesses a bandwidth exceeding $1\\khz$. Pump and probe are delivered by optical fiber, facilitating miniaturization and modularization. The magnetometer has been operated both with vertical-cavity surface-emitting lasers (VCSELs), which are well suited to portable applications, and with conventional edge-emitting diode lasers. A sensitivity of around $3 {\\rm nG}$ is achieved for a measurement time of $1\\s$.

Sep 6, 200634 citations

1\\khz

. Pump and probe are delivered by optical fiber, facilitating miniaturization and modularization. The magnetometer has been operated both with vertical-cavity surface-emitting lasers (VCSELs), which are well suited to portable applications, and with conventional edge-emitting diode lasers. A sensitivity of around

3 {\\rm nG}

is achieved for a measurement time of

1\\s