All Optical Scalar Atomic Magnetometer Capable of Vector Measurement

Vector field measurement is demonstrated with an all-optical scalar atomic magnetometer using intrinsic parameters related to its scalar operation. The Bell-Bloom type atomic magnetometer measures the Larmor precession of cesium atoms through on-resonant absorption of a probe beam. While the AC component of the probe signal is used for the field magnitude measurement, the probe DC signal contains information about the polar angle, defined as the angle between the magnetic field and the probe beam. Additional polar angle information is obtained from the light-shift-induced magnetic field caused by the frequency modulation of the probe beam. With a measurement time of 100 ms, better than 0.02° sensitivity has been achieved using a commercial miniaturized sensor at the optimal sensor orientation. The angle measurement accuracy is checked against an optical encoder over the entire polar angle range of 0°–180°. Better than 1° error is recorded over most set polar angles. Azimuthal angle measurement is also exhibited with two orthogonally oriented sensors.Vector field measurement is demonstrated with an all-optical scalar atomic magnetometer using intrinsic parameters related to its scalar operation. The Bell-Bloom type atomic magnetometer measures the Larmor precession of cesium atoms through on-resonant absorption of a probe beam. While the AC component of the probe signal is used for the field magnitude measurement, the probe DC signal contains information about the polar angle, defined as the angle between the magnetic field and the probe beam. Additional polar angle information is obtained from the light-shift-induced magnetic field caused by the frequency modulation of the probe beam. With a measurement time of 100 ms, better than 0.02° sensitivity has been achieved using a commercial miniaturized sensor at the optimal sensor orientation. The angle measurement accuracy is checked against an optical encoder over the entire polar angle range of 0°–180°. Better than 1° error is recorded over most set polar angles. Azimuthal angle measurement is also exhibited with two orthogonally oriented sensors.

arXiv:2011.08943Journal of Applied PhysicsJan 28, 202117 citations

Herriott-cavity-assisted all-optical atomic vector magnetometer

B. Cai, Chongyan Hao, Zheru Qiu +3 more

We report an all-optical atomic vector magnetometer using dual Bell-Bloom optical pumping beams in a Rb vapor cell. This vector magnetometer consists of two orthogonal optical pumping beams, with amplitude modulations at $^{85}\mathrm{Rb}$ and $^{87}\mathrm{Rb}$ Larmor frequencies, respectively. We simultaneously detect atomic signals excited by these two pumping beams using a single probe beam in the third direction, and extract the field orientation information using the phase delays between the modulated atomic signals and the driving beams. By adding a Herriott cavity inside the vapor cell, we improve the magnetometer sensitivity. We study the performance of this vector magnetometer in a magnetic field ranging from 100 mG to 500 mG, and demonstrate a field angle sensitivity better than 10 $\ensuremath{\mu}\mathrm{rad}/{\mathrm{Hz}}^{1/2}$ above 10 Hz.We report an all-optical atomic vector magnetometer using dual Bell-Bloom optical pumping beams in a Rb vapor cell. This vector magnetometer consists of two orthogonal optical pumping beams, with amplitude modulations at $^{85}\mathrm{Rb}$ and $^{87}\mathrm{Rb}$ Larmor frequencies, respectively. We simultaneously detect atomic signals excited by these two pumping beams using a single probe beam in the third direction, and extract the field orientation information using the phase delays between the modulated atomic signals and the driving beams. By adding a Herriott cavity inside the vapor cell, we improve the magnetometer sensitivity. We study the performance of this vector magnetometer in a magnetic field ranging from 100 mG to 500 mG, and demonstrate a field angle sensitivity better than 10 $\ensuremath{\mu}\mathrm{rad}/{\mathrm{Hz}}^{1/2}$ above 10 Hz.

arXiv:2005.11196Physical Review AMay 28, 202036 citations

All-Optical Vector Atomic Magnetometer

Brian Patton, E. Zhivun, D. C. Hovde +1 more

We demonstrate an all-optical magnetometer capable of measuring the magnitude and direction of a magnetic field using nonlinear magneto-optical rotation in cesium vapor. Vector capability is added by effective modulation of the field along orthogonal axes and subsequent demodulation of the magnetic-resonance frequency. This modulation is provided by the ac Stark shift induced by circularly polarized laser beams. The sensor exhibits a demonstrated rms noise floor of $\ensuremath{\sim}65\text{ }\text{ }\mathrm{fT}/\sqrt{\mathrm{Hz}}$ in measurement of the field magnitude and $0.5\text{ }\text{ }\mathrm{mrad}/\sqrt{\mathrm{Hz}}$ in the field direction; elimination of technical noise would improve these sensitivities to $12\text{ }\text{ }\mathrm{fT}/\sqrt{\mathrm{Hz}}$ and $10\text{ }\text{ }\ensuremath{\mu}\mathrm{rad}/\sqrt{\mathrm{Hz}}$, respectively. Applications for this all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron.We demonstrate an all-optical magnetometer capable of measuring the magnitude and direction of a magnetic field using nonlinear magneto-optical rotation in cesium vapor. Vector capability is added by effective modulation of the field along orthogonal axes and subsequent demodulation of the magnetic-resonance frequency. This modulation is provided by the ac Stark shift induced by circularly polarized laser beams. The sensor exhibits a demonstrated rms noise floor of $\ensuremath{\sim}65\text{ }\text{ }\mathrm{fT}/\sqrt{\mathrm{Hz}}$ in measurement of the field magnitude and $0.5\text{ }\text{ }\mathrm{mrad}/\sqrt{\mathrm{Hz}}$ in the field direction; elimination of technical noise would improve these sensitivities to $12\text{ }\text{ }\mathrm{fT}/\sqrt{\mathrm{Hz}}$ and $10\text{ }\text{ }\ensuremath{\mu}\mathrm{rad}/\sqrt{\mathrm{Hz}}$, respectively. Applications for this all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron.

arXiv:1403.7545Physical Review LettersJul 1, 2014186 citations

Pulsed operation of a miniature scalar optically pumped magnetometer

Vladislav P. Gerginov, Sean Krzyzewski, Svenja A. Knappe

A scalar magnetic field sensor based on a millimeter-size Rb87 vapor cell is described. The magnetometer uses nearly copropagating pump and probe laser beams, amplitude modulation of the pump beam, and detection through monitoring the polarization rotation of the detuned probe beam. The circularly polarized pump laser resonantly drives a spin precession in the alkali atoms at the Larmor frequency. A modulation signal on the probe laser polarization is detected with a lock-in amplifier. Since the Larmor precession is driven all-optically, potential cross talk between sensors is minimized. And since the pump light is turned off during most of the precession cycle, large offsets of the resonance, typically present in a single-beam Bell–Bloom scheme, are avoided. At the same time, relatively high sensitivities can be reached even in millimeter-size vapor cells: The magnetometer achieves a sensitivity of 1 pT/Hz1/2 in a sensitive volume of 16 mm3, limited by environmental noise. When a gradiometer configuration is used to cancel the environmental noise, the magnetometer sensitivity reaches 300 fT/Hz1/2. We systematically study the dependence of the magnetometer performance on the optical duty cycles of the pump light and find that better performance is achieved with shorter duty cycles, with the highest values measured at 1.25% duty cycle.A scalar magnetic field sensor based on a millimeter-size Rb87 vapor cell is described. The magnetometer uses nearly copropagating pump and probe laser beams, amplitude modulation of the pump beam, and detection through monitoring the polarization rotation of the detuned probe beam. The circularly polarized pump laser resonantly drives a spin precession in the alkali atoms at the Larmor frequency. A modulation signal on the probe laser polarization is detected with a lock-in amplifier. Since the Larmor precession is driven all-optically, potential cross talk between sensors is minimized. And since the pump light is turned off during most of the precession cycle, large offsets of the resonance, typically present in a single-beam Bell–Bloom scheme, are avoided. At the same time, relatively high sensitivities can be reached even in millimeter-size vapor cells: The magnetometer achieves a sensitivity of 1 pT/Hz1/2 in a sensitive volume of 16 mm3, limited by environmental noise. When a gradiometer configuration is used to cancel the environmental noise, the magnetometer sensitivity reaches 300 fT/Hz1/2. We systematically study the dependence of the magnetometer performance on the optical duty cycles of the pump light and find that better performance is achieved with shorter duty cycles, with the highest values measured at 1.25% duty cycle.

Journal of the Optical Society of America BJun 15, 201757 citations

All-Optical Vector Cesium Magnetometer

Weimin Sun, Qiang Huang, Zongjun Huang +2 more

Based on power modulation of a pump laser and precessional projection detection, we present an all-optical vector magnetometer of cesium, which has a demonstrated magnitude sensitivity of 80 fT/Hz 1/2 and an orientation sensitivity of 0.1°/Hz 1/2 . In the device, four main factors are measured experimentally, which are the Larmor precession frequency of a polarized magnetic moment that depends on the modulus of the measured magnetic field only, two phase shifts and amplitude ratio of the precession projection in the two probe directions relative to the magnetic field orientation. This kind of magnetometer with high sensitivity in the range of the spatial angle is suitable for solving the inverse problem and geomagnetic navigation.Based on power modulation of a pump laser and precessional projection detection, we present an all-optical vector magnetometer of cesium, which has a demonstrated magnitude sensitivity of 80 fT/Hz 1/2 and an orientation sensitivity of 0.1°/Hz 1/2 . In the device, four main factors are measured experimentally, which are the Larmor precession frequency of a polarized magnetic moment that depends on the modulus of the measured magnetic field only, two phase shifts and amplitude ratio of the precession projection in the two probe directions relative to the magnetic field orientation. This kind of magnetometer with high sensitivity in the range of the spatial angle is suitable for solving the inverse problem and geomagnetic navigation.

Chinese Physics LettersMay 1, 201712 citations

All-optical vector atomic magnetometer

E. Zhivun, Brian Patton, Chris Hovde +1 more

We demonstrate an all-optical magnetometer capable of measuring the magnitude and direction of a magnetic field using nonlinear magneto-optical rotation in a cesium vapor. Vector capability is added by effective modulation of the field along orthogonal axes and subsequent demodulation of the magnetic-resonance frequency. This modulation is provided by the AC Stark shift induced by circularly polarized laser beams. The sensor exhibits a demonstrated rms noise floor of 50 fT/ √ Hz in measurement of the field magnitude and 0.5 mrad/ √ Hz in the field direction; elimination of technical noise would improve these sensitivities to 12 fT/ √ Hz and 5 μrad/ √ Hz, respectively. Applications for a precise all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron.We demonstrate an all-optical magnetometer capable of measuring the magnitude and direction of a magnetic field using nonlinear magneto-optical rotation in a cesium vapor. Vector capability is added by effective modulation of the field along orthogonal axes and subsequent demodulation of the magnetic-resonance frequency. This modulation is provided by the AC Stark shift induced by circularly polarized laser beams. The sensor exhibits a demonstrated rms noise floor of 50 fT/ √ Hz in measurement of the field magnitude and 0.5 mrad/ √ Hz in the field direction; elimination of technical noise would improve these sensitivities to 12 fT/ √ Hz and 5 μrad/ √ Hz, respectively. Applications for a precise all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron.

Bulletin of the American Physical SocietyJun 5, 201421 citations

^{85}\mathrm{Rb}

and

^{87}\mathrm{Rb}

Larmor frequencies, respectively. We simultaneously detect atomic signals excited by these two pumping beams using a single probe beam in the third direction, and extract the field orientation information using the phase delays between the modulated atomic signals and the driving beams. By adding a Herriott cavity inside the vapor cell, we improve the magnetometer sensitivity. We study the performance of this vector magnetometer in a magnetic field ranging from 100 mG to 500 mG, and demonstrate a field angle sensitivity better than 10 $\ensuremath{\mu}\mathrm{rad}/{\mathrm{Hz}}^{1/2}$ above 10 Hz.

0.5\text{ }\text{ }\mathrm{mrad}/\sqrt{\mathrm{Hz}}

in the field direction; elimination of technical noise would improve these sensitivities to

12\text{ }\text{ }\mathrm{fT}/\sqrt{\mathrm{Hz}}

and $10\text{ }\text{ }\ensuremath{\mu}\mathrm{rad}/\sqrt{\mathrm{Hz}}$, respectively. Applications for this all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron.