We present the transformation in the Hanle configuration of the transmission that results from coherent population trapping (CPT) into the level-crossing absorption (LCA) that results from the single-photon optical pumping in the
87Rb D1 line of a Rb vapor cell with a Ne buffer gas when the polarization of the laser field is changed from linear to circular. The LCA spectrum, with a narrow spectral width of
2.4 mG (
1.7 kHz), was observed in the ${F}_{g}\ensuremath{\rightarrow}{F}_{e}\ensuremath{\leqslant}{F}_{g}$ transition with the circularly polarized laser. This may be because the LCA is both related to the transverse magnetic field and the atom-laser interaction time resulting from diffusive atomic motion in the cell with the buffer gas. The CPT and LCA spectra were calculated numerically using the full density matrix equations for the relevant magnetic sublevels of the hyperfine levels, considering the residual magnetic fields perpendicular to laser propagation and the collision effects resulting from the buffer gas. There was good qualitative agreement between theoretical and experimental results.
Level-crossing (LC) resonances in a buffer-gas-filled cesium vapor cell are studied under counterpropagating pump and probe light waves with opposite circular polarizations. The waves excite the D
1-line ground-state level
Fg=4, while a transverse magnetic field (
Bx⊥k) is scanned around zero to observe the resonance of electromagnetically induced absorption (EIA). It is shown that adding the pump light wave significantly improves the properties of the resonances in comparison with the commonly used scheme with a single light wave. As far as a small vapor cell ($\approx\,
0.1cm^3
)atrelativelylowtemperature(\approx\,
45−60\,^\circ$C) is utilized, the results have good prospects for developing a low-power miniaturized atomic magnetometer.
We examine the level-crossing resonance in a cesium vapor cell filled with a buffer gas under counterpropagating pump and probe light waves with orthogonal linear polarizations. An optical transition F g = 4 → F e = 3 is excited in the D 1 line. Probe-wave transmission is analyzed versus a static magnetic field applied along the wave vectors. This configuration can provide ultrahigh-contrast electromagnetically induced absorption resonances. We report here a new, to the best of our knowledge, magneto-optical effect in the resonance shift caused by a transverse magnetic field and discuss how it can be applied in vector magnetometry.