This paper reports a novel Mzatomic magnetometer based on a low-cost 3D MEMS glass alkali vapor cell with vertical sidewalls for optical pumping/probing transmission. By designing vertical side walls, the 3D MEMS vapor cell provides high-quality centimeter-level optical paths for atom-photon interactions. The wafer-level high-quality multiple optical paths are also acquired for flexible Mzatomic magnetometer designs. Experiments show that the sensitivity of the proposed Mz magnetometer is 3.7 pT/Hz1/2at 1 Hz under 14000 nT.
This paper reports a novel Mzatomic magnetometer based on a low-cost 3D MEMS glass alkali vapor cell with vertical sidewalls for optical pumping/probing transmission. By designing vertical side walls, the 3D MEMS vapor cell provides high-quality centimeter-level optical paths for atom-photon interactions. The wafer-level high-quality multiple optical paths are also acquired for flexible Mzatomic magnetometer designs. Experiments show that the sensitivity of the proposed Mz magnetometer is 3.7 pT/Hz1/2at 1 Hz under 14000 nT.
This paper reports, for the first time, a systematic optimization of beam characteristics for quantum magnetometers utilizing 3D MEMS rubidium vapor cells. A novel single-beam quantum magnetometer is designed where the beam characteristics can be modified and characterized in situ. The optimized beam diameter exhibits more homogeneous spatial distribution, resulting in an increase of up to 327.3% for the polarization lifetime of the atomic ensemble within 3D MEMS vapor cells. In addition, the optimized beam diameter effectively increases the number of atoms interacting with photons, leading to an improvement of 962.5% in the response slope of the quantum magnetometer. The experimental results provide valuable insights and practical guidelines for the design of high-performance single-beam quantum magnetometers based on 3D MEMS alkali vapor cells.
In this letter, we present a novel microfabricated shaped rubidium vapor cell with 3 cm optical path length for miniaturized atomic magnetometers. The novel shaped rubidium vapor cells are manufactured by a wafer-level fabrication process, and the process consists of the following three steps sequentially: first, wet etching to form oblong shallow cavity arrays; second, anodic bonding, glass reflowing, and wet etching to obtain a glass wafer with shaped structures; third, anodic bonding and chemical reaction to obtain the wafer-level shaped rubidium vapor cells. A miniaturized atomic magnetometer using the novel shaped rubidium vapor cell is characterized in the geomagnetic environment. The performance of the novel shaped rubidium vapor cell is compared with the traditional microfabricated rubidium vapor cell of a “glass–silicon–glass” sandwich structure. Results show that the measured geomagnetic field is 47.85 μT. It is demonstrated that the dispersive signal's slope of the novel shaped rubidium vapor cell is 15 times larger than that of the traditional one. Results also indicate that the miniaturized atomic magnetometer working in the geomagnetic environment has a magnetic noise spectral density of 3.5 pT/Hz1/2from 1 to 2 Hz.
Currently, medical magnetic localization necessitates complex and costly gradient coil systems, primarily due to the limited sensitivity of the magnetic sensors in use. This article presents a highly sensitive, compact multipoint quantum magnetometer (CMQM) characterized by a straightforward design and low cost. The core of the sensor is a MEMS 3D Rubidium (Rb) atomic cell with an optical path of 3.0 cm, which is manufactured through a mold foaming process. The size of the compact sensor head is less than 11.5 cm3. The CMQM obtains magnetic field magnitude at six points by measuring Larmor frequency of rubidium atoms within corresponding positions. A uniform magnetic field coils is calibrated with the CMQM within a ferromagnetic shield. The vector synthesis method is used to enhance the accuracy by reducing interference from remanent magnetic field. The deviation between the measured magnetic field and those predicted using closed cylinder approximation (CCA) is less than 1.1%. The magnetic noise density at different points varies between 2.289 pT/Hz1/2and 6.015 pT/Hz1/2. The effective magnetic resolution of the CMQM is ~0.65 nT. Theoretical spatial resolution of the CMQM can reach to$17.5~\mu $m with a simple circular coil. [2024-0230]
With the continuous improvement of weak magnetic detection technology, there has been a growing trend towards more compact and integrated magnetometer. The SERF magnetometer and the Mz magnetometer have many common features in operation. Therefore, we design a new kind of miniaturized atomic sensors to integrate the SERF magnetometer and the Mz magnetometer based on micro-fabricated alkali vapor cell. The sensor structure consists of alkali vapor cell, three-axis magnetic field coils, heating module and optical module. This small size sensor has the potential to achieve a portable multi-function device.
The designs of microfabricated alkali vapor cells play an important role when the atomic magnetometers are developing toward on-chip integration. This paper presents microfabricated spherical alkali vapor cells with improved sensitivity for chip-scale atomic magnetometers. A microfabricated spherical rubidium vapor cell and a traditional microfabricated planar rubidium vapor cell are designed for comparison, which are of the same volume and interconnected by a microchannel to acquire equal inner buffer gas pressure. In chip-scale spin-exchange relaxation-free (SERF) atomic magnetometers, the rubidium polarization lifetimes of three pairs of spherical and planar vapor cells at different buffer gas pressures of 0.35, 0.73, and 2.00 amg are measured, respectively. The sensitivity of SERF atomic magnetometers using the vapor cells at a 0.35-amg buffer gas pressure is also measured. The results show that the transverse polarization lifetime of the spherical vapor cell is 2.46, 1.44, and 1.05 times that of the planar one at 0.35-, 0.73-, and 2.00-amg buffer gas pressures, respectively. Combining the improved polarization lifetime and increased optical path length, chip-scale SERF atomic magnetometer using the microspherical vapor cell has the sensitivity of 60 fT/Hz1/2from 5 to 15 Hz, while that based on the planar one is demonstrated with the sensitivity of 400 fT/Hz1/2from 5 to 15 Hz.
Abstract Microfabricated alkali vapor cells enable the miniaturization of atomic sensors, but require collective wafer-level integration of complex features. In many applications-including magnetometers, gyroscopes, magneto-optical traps, and fluorescence imaging-multiple optical accesses are needed to enhance performance. Yet, achieving this without compromising manufacturability remains challenging. In this work, we present a wafer-level fabrication approach that enables three orthogonal optical pathways in microfabricated alkali vapor cells, using fully scalable and collective processes. Our method relies on the thermal reflow of glass preforms, shaped by laser-assisted etching (LAE) and bonded between silicon frames. The relatively low surface roughness produced by LAE allows for effective reflow, which further smooths the surfaces without significantly compromising the optical planarity of the windows. This process results in multi-axis vapor cells featuring embedded, optics-grade lateral windows. We evaluate the device performance through both single-beam and dual-beam atomic magnetometry measurements. Magnetic sensitivities better than 200 fT Hz − 1 are demonstrated along each of the three orthogonal axes, confirming the potential of the approach for tri-axis magnetic field sensing at sub-picotesla resolution. This fabrication strategy opens new perspectives for versatile, high-performance atomic sensors, fully compatible with wafer-level integration and mass production.