High-sensitivity operation of a single-beam atomic magnetometer for three-axis magnetic field measurement

Abstract

We demonstrate a single-beam atomic magnetometer (AM) capable of measuring a three-axis magnetic field with high-sensitivity, achieved by applying a small DC offset field and a high frequency modulation field. To satisfy the miniaturization demand of AMs, an elliptically polarized light detuned by 50 GHz from the resonance transition center is employed. The circularly polarized component is used to polarize the alkali-metal atoms, while the linearly polarized light is used to detect the dynamics of the polarized spin under a magnetic field. Based on theoretical analysis, parameters that significantly affect the performance are optimized, and a sensitivity of 20 fT/Hz1/2 in x-axis, 25 fT/Hz1/2 in y-axis, 30 fT/Hz1/2 in z-axis is achieved with a miniature 4 × 4 × 4 mm 87Rb vapor cell. Moreover, we also verify that the operation principle of AMs can be used to null background magnetic fields in-situ with isotropic compensation resolution of 6.7 pT, which provides an effectively precise method for zeroing ambient magnetic field. The high-sensitivity operating of an elliptically-polarized-laser-based magnetometer provides prospective futures for constructing a compact, low-cost AM, which is particularly applicable for non-invasive bio-magnetic imaging such as array-based magnetoencephalography (MEG) and magnetocardiography (MCG).

Integrated Polarization-Splitting Grating Coupler for Chip-Scale Atomic Magnetometer

“…A single elliptically polarized beam that is nearly resonant with transition center (detuned by 50 GHz from 87 Rb D1 line) was employed. The circularly polarized component was utilized to achieve optical pumping, while the linearly polarized component was utilized to realize optical rotation detection [ 48 ]. The procedure of magnetic field measurement can be briefly summarized as follows: firstly, the circularly polarized component of incident light polarizes Rb by optical pumping, which can substantially increase the optical rotation angle [ 67 ].…”

“…In order to illustrate application of designed polarization-splitting grating coupler, in this paper, SERF AM ( 87 Rb, modulated field) with a single elliptically polarized beam nearly resonant with D1 transition of 87 Rb is represented in an instance [ 47 , 48 ]; in practice, this device is capable of being utilized in a variety of AMs. The mechanism of magnetic field sensing is based on magnetically induced circular birefringence in atomic medium [ 51 ].…”

“…The pump and probe beams cross at a small angle at the vapor cell to allow for independent spatial detection of the probe beam only [ 45 , 46 ]. Moreover, it is particularly fascinating for miniaturization of AMs by means of single elliptically polarized beam; the circularly polarized component is utilized to polarize the alkali-metal atoms, while the linearly polarized light is utilized to detect optical rotation angle due to magnetic field [ 47 , 48 ]. The atomic magnetometer (AM) operates with net spin polarization of alkali atoms through optical pumping.…”

Level-crossing resonances on open atomic transitions in a buffered Cs vapor cell: Linewidth narrowing, high contrast and applications to atomic magnetometry

“…To achieve a 7 fT/ √ Hz sensitivity, the SERF regime was engaged. This method has further been devel-oped to perform vector measurements under a near zerofield conditions [38]. A polarization modulation Bell-Bloom-like scheme was studied in [39].…”

VCSEL frequency stabilization for optically pumped magnetometers

“…Benefiting from micro-electromechanical-system (MEMS) technology [2][3][4] , miniaturized OPMs have been applied to magnetocardiography (MCG) and magnetoencephalography (MEG) [5][6][7] . Vertical-cavity surface-emitting lasers (VCSELs) are widely acknowledged as having a small volume and low power consumption, which makes them perfect candidates for built-in laser sources of miniaturized OPMs [8] . The successful application of VCSELs in atomic gyroscopes and atomic clocks further proves their feasibility and dominance [9][10][11][12] .…”