Elliptical polarization of near-resonant linearly polarized probe light in optically pumped alkali metal vapor

Abstract

Optically pumped alkali metal atoms currently provide a sensitive solution for magnetic microscopic measurements. As the most practicable plan, Faraday rotation of linearly polarized light is extensively used in spin polarization measurements of alkali metal atoms. In some cases, near-resonant Faraday rotation is applied to improve the sensitivity. However, the near-resonant linearly polarized probe light is elliptically polarized after passing through optically pumped alkali metal vapor. The ellipticity of transmitted near-resonant probe light is numerically calculated and experimentally measured. In addition, we also analyze the negative impact of elliptical polarization on Faraday rotation measurements. From our theoretical estimate and experimental results, the elliptical polarization forms an inevitable error in spin polarization measurements.

Response optimization of a three-axis sensitive SERF magnetometer for closed-loop operation

“…[8] The detection of the magnitude of the spin polarization projection makes it possible for the SERF AM to be sensitive to the vector fields. However, in most configurations, no matter whether the traditional orthogonal pump-probe configuration, [9][10][11] parallel pump-probe configuration, [12,13] or single beam configuration is adopted, [14,15] the SERF AM just acts as a single-axis sensor. For some applications, however, trixial magnetic vectors are also important such as geophysics and MEG.…”

A dual-axis, high-sensitivity atomic magnetometer

“…[9,[13][14][15] The SERF AMs, whose sensitivities have reached sub-fT/Hz 1/2 and established the new sensitivity record for AMs in the low-frequency range, [11] commonly acted as a singleaxis sensor by using the traditional orthogonal pump-probe configuration, [15][16][17] z-field modulation mode, [18] single el-liptically polarized-beam design [19] or parallel (two-color) pump-probe scheme. [9,20] In most of the cases, single-axis AMs are just oriented along a certain direction to detect the projected components of the fields. However, multi-axis AM will provide a favorable experimental condition for the vector measurements, and thus improve the signal quality and reduce the orientation difficulty of the sensor head.…”