Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Microsystems & Nanoengineering

Suppressing laser-power noise with a multifunctional liquid crystal polarization grating in miniaturized optically pumped magnetometers

Zhibo Cui, Xu Xiao, Zinan Wei, Zhimou Fu, Kun Huang, Liangsong Pei, Xiangyang Zhou, Zhen Chai, Dongbi Bai

Published May 6, 2026• 0 citations
Publisher

Abstract

Optically pumped magnetometers (OPMs) enable high-resolution biomagnetic imaging, yet conventional single-beam designs are constrained by bulky, alignment-intensive polarization optics and susceptibility to laser-power noise. Here, we propose and demonstrate a compact, noise-suppressed OPM that uses a single planar liquid-crystal polarization grating (LCPG) functioning simultaneously as a high-efficiency polarization converter and a beam splitter. At the component level, the LCPG replaces multiple bulk elements, converts 795 nm light with 95% first-order diffraction efficiency and an ellipticity of ~44.6°, and exhibits robust performance against variations in incident-light polarization direction, ambient temperature, and angle of incidence. At the sensor level, a power-differential configuration effectively suppresses noise originating from pump-power fluctuations. We fabricated a probe with a total volume of 4 cm 3 and benchmarked it against a conventional OPM: the LCPG-enabled differential mode achieves a sensitivity of 8.6 fT/Hz 1/2 , representing an ~28% improvement over the conventional configuration. Importantly, the approach is compatible with mature, high-throughput, and cost-effective liquid-crystal manufacturing. These results demonstrate a scalable design strategy for OPMs that unites component-level efficiency, robustness, and cost-effectiveness with sensor-level compactness and noise suppression, paving the way for next-generation chip-scale quantum sensors.

DOI
10.1038/s41378-026-01297-y

Related papers

High‐Efficiency Liquid‐Crystal Polarization Metalens for Chip‐Scale Atomic Magnetometers

Zhibo Cui, Jianyu Pan, Xinyu Tao +8 more

ABSTRACT Atomic magnetometers (AMs) are among the most sensitive magnetic field sensors, with uses in magnetic anomaly detection, geosciences, and fundamental physics research. Despite notable progress, developing highly integrated, miniaturized components with high resolution, sensitivity, and efficiency for chip‐scale AMs remains a significant challenge. Here, we present a novel integrated polarization detection scheme based on a bifocal liquid‐crystal polarization metalens (LCPM) for chip‐scale AMs. By leveraging geometric phase and holographic synthesis principles, the LCPM efficiently separates and focuses left‐ and right‐handed circularly polarized light at the rubidium D1 transition wavelength (795 nm), achieving a high focusing efficiency of up to 80% and extinction ratios of 104 and 134 for the two channels. We demonstrate a prototype AM operating in the spin‐exchange relaxation‐free regime, achieving a high magnetic‐field sensitivity of 17 fT/Hz 1/2 and a dynamic range of ±4.8 nT. The proposed LCPM‐based scheme reduces the optical‐path volume by 94% compared to traditional polarization detection systems. Importantly, our method is compatible with large‐scale, cost‐effective production through established liquid‐crystal manufacturing lines, paving the way for high‐throughput fabrication of chip‐scale AMs. This innovation enables compact, affordable polarization detection with enhanced sensitivity of atomic sensors, opening new opportunities for high‐resolution biomagnetic imaging and quantum precision measurements.

Laser & Photonics Review•Dec 23, 2025•3 citations

Ultra‐compact and high‐precision differential detection method based on liquid crystal polarization grating for miniature atomic magnetometer

Zhibo Cui, Yuhao Wang, Ying Liu +5 more

Abstract Atomic magnetometers (AMs) that use alkali vapors, such as rubidium, are among the most sensitive sensors for magnetic field measurement. They commonly use polarization differential detection to mitigate common‐mode noise. Nevertheless, traditional differential detection optics, including polarization beam splitters (PBS) and half‐wave plates, are typically bulky and large, which restricts further reductions in sensor dimensions. In this study, a combination of liquid crystal polarization grating (LCPG) and liquid crystal quarter‐wave plate is used for differential detection in AMs, with magnetic field strength determined by measuring the intensity of two diffracted beams from the LCPG. The experimental findings indicate that the fabricated LCPG exhibits a circularly polarized extinction ratio of 3,656 and achieves an average diffraction efficiency of 99 %. In addition, the differential detection method based on LCPG can achieve an angular resolution of 1.48 × 10 −7 rad. Subsequently, the method is employed in an AM to achieve an average magnetic sensitivity of 13.8 fT/Hz 1/2 . Compared to the PBS‐based differential detection method, this method enhances the magnetometer response coefficient by 13 % and achieves co‐side distribution of the two diffracted beams, thereby avoiding the need for additional vertical optical paths. The effective thickness of the detection optics is reduced to the micrometer scale, allowing for future integration as thin films onto microfabricated vapor cells. This study offers a practical solution for miniaturized AMs with exceptionally high sensitivity.

Nanophotonics•Oct 3, 2024•11 citations

A Compact Single-Beam Optically Pumped Magnetometer Based on Absorption Detection

Jia-You Liou, Yi‐Hsuan Chen, Hsiang-An Chuang +5 more

We demonstrate a compact single-beam optically pumped magnetometer (OPM) employing a pure 87Rb microfabricated vapor cell with 500 Torr buffer gas. The residual magnetic field is actively minimized to below 400 pT through a combination of mu-metal magnetic shielding and internal compensation coils. We systematically characterize the OPM response as a function of laser detuning and optical intensity, and derive the magnetic-field sensitivity from the signal slope and noise amplitude spectral density. A best sensitivity of 11 fT/Hz^1/2 is achieved near the resonance transition at an optimal optical intensity, using a small cell volume of only 0.027 cm^3. Furthermore, a miniaturized OPM prototype was developed using a folded flexible printed circuit board (FPCB) to integrate the vapor cell, a compact heater, and magnetic-field coils into a cubic sensing head. Two coil configurations patterned directly on the FPCB were investigated. Under optimized operating conditions, the OPM prototype achieved a sensitivity of 66 fT/Hz^1/2. These results demonstrate that high-buffer-pressure single-beam OPMs can achieve excellent sensitivity, establishing a pathway toward compact and scalable arrays.

arXiv:2610.32795•Oct 23, 2026•0 citations

A modular optically pumped magnetometer system

Thomas Coussens, Aikaterini Gialopsou, C. Abel +9 more

Abstract To address the demands in healthcare and industrial settings for spatially resolved magnetic imaging, we present a modular optically pumped magnetometer (OPM) system comprising a multi-sensor array of highly sensitive quantum magnetometers. This system is designed and built to facilitate fast prototyping and testing of new measurement schemes by enabling quick reconfiguration of the self-contained laser and sensor modules as well as allowing for the construction of various array layouts with a shared light source. The modularity of this system facilitates the development of methods for managing high-density arrays for magnetic imaging. The magnetometer sensitivity and bandwidth are first characterised in both individual channel and differential gradiometer configurations before testing in a real-world magnetoencephalography environment by measuring alpha rhythms from the brain of a human participant. We demonstrate the OPM system in a first-order axial gradiometer configuration with a magnetic field gradient sensitivity of 10 fT / cm / Hz at a baseline of 4.5 cm. Single-channel operation achieved a sensitivity of 65 fT / Hz . Bandwidths exceeding 200 Hz were achieved for two independent modules. The system’s increased temporal resolution allows for the measurement of spinal cord signals, which we demonstrate by using phantom signal trials and comparing with an existing commercial sensor.

arXiv:2106.05877•Quantum Science and Technology•May 21, 2024•11 citations

Space-Variant Polarization Distribution Mitigates AC-Stark Shifts in a SERF Atomic Magnetometer

Zihua Liang, Tengyue Long, Lu Liu +5 more

Emerging biomagnetic imaging requires compact optical pumping magnetometer (OPM) arrays that enable high spatial resolution with remarkable sensitivity. In such devices, atomic pumping fundamentally depends on conventional optical systems, yet realizing diverse pumping modalities persists as a critical challenge─particularly in integrated applications. In this study, a space-variant polarization distribution (SPD) pumping source is achieved and integrated with an atomic magnetometer for the first time. Our method enables modification of optical polarization within a 3 × 3 × 3 mm 3 87 Rb micro-vapor cell to spatially separate the atomic pumping and detection regions, resulting in a 56% mean (75% maximum) reduction in the AC Stark effect compared with the conventional scheme. Experiment results demonstrate a 20.1 fT/Hz 1/2 sensitivity and a 52 Hz bandwidth with a dynamic response range of ±3 nT, which is comparable to the state-of-the-art chip-scale OPMs. By leveraging the SPD pumping method, various atomic devices with a diffusion-pumping scheme are able to achieve chip integration, which further paves the way for the development of high-spatial-resolution biomagnetism imaging and portable atomic sensing applications.

ACS Photonics•Apr 8, 2025•7 citations

Meta-Polarizer-Lens Based Integrated Optical Probing Scheme for Atomic Magnetometer

Longkun Yu, Jinsheng Hu, Nan Li +3 more

Optically pumped magnetometers (OPMs) have undergone rapid development in recent years. The optical probing system, which plays a crucial role in interrogating quantum state of atoms under external perturbations, is an essential component in OPMs. However, conventional optical probing schemes rely on bulky optical components and tedious adjustment procedures, which hinder their applications in portable or compact scenarios. In this study, a method has been proposed in order to overcome these limitations by a metasurface, which is based on localized - interference effects. With the metasurface, we can simultaneously convert any incident polarized light into linearly polarized light and manipulate its wavefront. It achieves a maximum transmission efficiency of 91.7 % and a focusing efficiency of 91.3 %. Since the fabrication process of our metasurface is compatible with current complementary-metal-oxide-semiconductor (CMOS) fabrication technology, it can be integrated with a vapor cell, which is the core sensing element for many advanced atomic devices. Our study proposes an optical probing scheme suitable for chip-scale OPMs, and laying the foundation for the mass production of other chip-scale atomic devices.

IEEE Optoelectronics Global Conference (OGC)•Sep 9, 2025•0 citations
Optically pumped magnetometers (OPMs) enable high-resolution biomagnetic imaging, yet conventional single-beam designs are constrained by bulky, alignment-intensive polarization optics and susceptibility to laser-power noise. Here, we propose and demonstrate a compact, noise-suppressed OPM that uses a single planar liquid-crystal polarization grating (LCPG) functioning simultaneously as a high-efficiency polarization converter and a beam splitter. At the component level, the LCPG replaces multiple bulk elements, converts 795 nm light with 95% first-order diffraction efficiency and an ellipticity of ~44.6°, and exhibits robust performance against variations in incident-light polarization direction, ambient temperature, and angle of incidence. At the sensor level, a power-differential configuration effectively suppresses noise originating from pump-power fluctuations. We fabricated a probe with a total volume of 4 cm 3 and benchmarked it against a conventional OPM: the LCPG-enabled differential mode achieves a sensitivity of 8.6 fT/Hz 1/2 , representing an ~28% improvement over the conventional configuration. Importantly, the approach is compatible with mature, high-throughput, and cost-effective liquid-crystal manufacturing. These results demonstrate a scalable design strategy for OPMs that unites component-level efficiency, robustness, and cost-effectiveness with sensor-level compactness and noise suppression, paving the way for next-generation chip-scale quantum sensors.
ABSTRACT Atomic magnetometers (AMs) are among the most sensitive magnetic field sensors, with uses in magnetic anomaly detection, geosciences, and fundamental physics research. Despite notable progress, developing highly integrated, miniaturized components with high resolution, sensitivity, and efficiency for chip‐scale AMs remains a significant challenge. Here, we present a novel integrated polarization detection scheme based on a bifocal liquid‐crystal polarization metalens (LCPM) for chip‐scale AMs. By leveraging geometric phase and holographic synthesis principles, the LCPM efficiently separates and focuses left‐ and right‐handed circularly polarized light at the rubidium D1 transition wavelength (795 nm), achieving a high focusing efficiency of up to 80% and extinction ratios of 104 and 134 for the two channels. We demonstrate a prototype AM operating in the spin‐exchange relaxation‐free regime, achieving a high magnetic‐field sensitivity of 17 fT/Hz 1/2 and a dynamic range of ±4.8 nT. The proposed LCPM‐based scheme reduces the optical‐path volume by 94% compared to traditional polarization detection systems. Importantly, our method is compatible with large‐scale, cost‐effective production through established liquid‐crystal manufacturing lines, paving the way for high‐throughput fabrication of chip‐scale AMs. This innovation enables compact, affordable polarization detection with enhanced sensitivity of atomic sensors, opening new opportunities for high‐resolution biomagnetic imaging and quantum precision measurements.
Abstract Atomic magnetometers (AMs) that use alkali vapors, such as rubidium, are among the most sensitive sensors for magnetic field measurement. They commonly use polarization differential detection to mitigate common‐mode noise. Nevertheless, traditional differential detection optics, including polarization beam splitters (PBS) and half‐wave plates, are typically bulky and large, which restricts further reductions in sensor dimensions. In this study, a combination of liquid crystal polarization grating (LCPG) and liquid crystal quarter‐wave plate is used for differential detection in AMs, with magnetic field strength determined by measuring the intensity of two diffracted beams from the LCPG. The experimental findings indicate that the fabricated LCPG exhibits a circularly polarized extinction ratio of 3,656 and achieves an average diffraction efficiency of 99 %. In addition, the differential detection method based on LCPG can achieve an angular resolution of 1.48 × 10 −7 rad. Subsequently, the method is employed in an AM to achieve an average magnetic sensitivity of 13.8 fT/Hz 1/2 . Compared to the PBS‐based differential detection method, this method enhances the magnetometer response coefficient by 13 % and achieves co‐side distribution of the two diffracted beams, thereby avoiding the need for additional vertical optical paths. The effective thickness of the detection optics is reduced to the micrometer scale, allowing for future integration as thin films onto microfabricated vapor cells. This study offers a practical solution for miniaturized AMs with exceptionally high sensitivity.
We demonstrate a compact single-beam optically pumped magnetometer (OPM) employing a pure 87Rb microfabricated vapor cell with 500 Torr buffer gas. The residual magnetic field is actively minimized to below 400 pT through a combination of mu-metal magnetic shielding and internal compensation coils. We systematically characterize the OPM response as a function of laser detuning and optical intensity, and derive the magnetic-field sensitivity from the signal slope and noise amplitude spectral density. A best sensitivity of 11 fT/Hz^1/2 is achieved near the resonance transition at an optimal optical intensity, using a small cell volume of only 0.027 cm^3. Furthermore, a miniaturized OPM prototype was developed using a folded flexible printed circuit board (FPCB) to integrate the vapor cell, a compact heater, and magnetic-field coils into a cubic sensing head. Two coil configurations patterned directly on the FPCB were investigated. Under optimized operating conditions, the OPM prototype achieved a sensitivity of 66 fT/Hz^1/2. These results demonstrate that high-buffer-pressure single-beam OPMs can achieve excellent sensitivity, establishing a pathway toward compact and scalable arrays.
Abstract To address the demands in healthcare and industrial settings for spatially resolved magnetic imaging, we present a modular optically pumped magnetometer (OPM) system comprising a multi-sensor array of highly sensitive quantum magnetometers. This system is designed and built to facilitate fast prototyping and testing of new measurement schemes by enabling quick reconfiguration of the self-contained laser and sensor modules as well as allowing for the construction of various array layouts with a shared light source. The modularity of this system facilitates the development of methods for managing high-density arrays for magnetic imaging. The magnetometer sensitivity and bandwidth are first characterised in both individual channel and differential gradiometer configurations before testing in a real-world magnetoencephalography environment by measuring alpha rhythms from the brain of a human participant. We demonstrate the OPM system in a first-order axial gradiometer configuration with a magnetic field gradient sensitivity of 10 fT / cm / Hz at a baseline of 4.5 cm. Single-channel operation achieved a sensitivity of 65 fT / Hz . Bandwidths exceeding 200 Hz were achieved for two independent modules. The system’s increased temporal resolution allows for the measurement of spinal cord signals, which we demonstrate by using phantom signal trials and comparing with an existing commercial sensor.
Emerging biomagnetic imaging requires compact optical pumping magnetometer (OPM) arrays that enable high spatial resolution with remarkable sensitivity. In such devices, atomic pumping fundamentally depends on conventional optical systems, yet realizing diverse pumping modalities persists as a critical challenge─particularly in integrated applications. In this study, a space-variant polarization distribution (SPD) pumping source is achieved and integrated with an atomic magnetometer for the first time. Our method enables modification of optical polarization within a 3 × 3 × 3 mm 3 87 Rb micro-vapor cell to spatially separate the atomic pumping and detection regions, resulting in a 56% mean (75% maximum) reduction in the AC Stark effect compared with the conventional scheme. Experiment results demonstrate a 20.1 fT/Hz 1/2 sensitivity and a 52 Hz bandwidth with a dynamic response range of ±3 nT, which is comparable to the state-of-the-art chip-scale OPMs. By leveraging the SPD pumping method, various atomic devices with a diffusion-pumping scheme are able to achieve chip integration, which further paves the way for the development of high-spatial-resolution biomagnetism imaging and portable atomic sensing applications.
Optically pumped magnetometers (OPMs) have undergone rapid development in recent years. The optical probing system, which plays a crucial role in interrogating quantum state of atoms under external perturbations, is an essential component in OPMs. However, conventional optical probing schemes rely on bulky optical components and tedious adjustment procedures, which hinder their applications in portable or compact scenarios. In this study, a method has been proposed in order to overcome these limitations by a metasurface, which is based on localized - interference effects. With the metasurface, we can simultaneously convert any incident polarized light into linearly polarized light and manipulate its wavefront. It achieves a maximum transmission efficiency of 91.7 % and a focusing efficiency of 91.3 %. Since the fabrication process of our metasurface is compatible with current complementary-metal-oxide-semiconductor (CMOS) fabrication technology, it can be integrated with a vapor cell, which is the core sensing element for many advanced atomic devices. Our study proposes an optical probing scheme suitable for chip-scale OPMs, and laying the foundation for the mass production of other chip-scale atomic devices.