Different sensitivities of two optical magnetometers realized in the same experimental arrangement

Abstract

In this article, operation of optical magnetometers detecting static (DC) and oscillating (AC) magnetic fields is studied and comparison of the devices is performed. To facilitate the comparison, the analysis is carried out in the same experimental setup, exploiting nonlinear magneto-optical rotation. In such a system, a control over static-field magnitude or oscillating-field frequency provides detection of strength of the DC or AC fields. Polarization rotation is investigated for various light intensities and AC-field amplitudes, which allows to determine optimum sensitivity to both fields. With the results, we demonstrate that under optimal conditions the AC magnetometer is about ten times more sensitive than its DC counterpart, which originates from different response of the atoms to the fields. Bandwidth of the magnetometers is also analyzed, revealing its different dependence on the light power. Particularly, we demonstrate that bandwidth of the AC magnetometer can be significantly increased without strong deterioration of the magnetometer sensitivity. This behavior, combined with the ability to tune the resonance frequency of the AC magnetometer, provide means for ultra-sensitive measurements of the AC field in a broad but spectrally-limited range, where detrimental role of static-field instability is significantly reduced.

Modulation induced splitting of the magnetic resonance

“…The ubiquitous magnetic field carries vital information on the associated physical processes and thus, its measurement is an important part of the contemporary science [1][2][3][4][5]. Apart from fundamental interest, the prospect of highly sensitive magnetometers in a variety of applications has led to exceptional growth in the associated research area [6][7][8].…”

Ultrasensitive Magnetic Field Sensors for Biomedical Applications

“…Novel advances in the fields of microfabrication and optical interrogation have led to significant progress in optically pumped atomic magnetometers [121][122][123][124]. The operating mechanisms of such sensors are (i) coherent population trapping [125], (ii) non-linear magneto-optical rotation [126], and (iii) spin-exchange relaxation-free [34] regimes. Magnetometers based on (i) and (ii) can reach detection limits of 0.1-1 pT/√Hz [127,128] without requiring magnetic shielding while magnetic sensors based on (iii) provide a detection level of the order of 10 fT/√Hz, but in most cases, they need to be placed in a magnetically shielded room [129][130][131].…”

Design of a multi-laser module for optical pumping in compact atomic gyroscopes

“…15 For atomic magnetometers or atomic clocks, only the alkali metal atoms need to be polarized, thus few hundreds of µW pump power is usually enough. [20][21][22] However, when there are noble gas atoms which require to be hyper-polarized, many research indicated that 1 mW pump power is generally not sufficient. [23][24][25][26] This causes great challenges to the development of compact atomic gyroscopes.…”