The resonant magneto-optic spectra of the Rb D2 transition in the Voigt configuration was measured by using a tunable, narrow-band, single-mode GaAlAs diode laser. The elliptically polarized laser beam with a small ellipticity Δα was incident upon Rb vapor in a transverse magnetic field of 0.75 T. The polarization change caused by magnetically induced optical anisotropy was analyzed with a birefringent prism placed behind the sample with a small offset angle Δθ from the perfectly crossed direction. The Voigt-effect signal had a Zeeman splitting of 50 GHz. The spectral intensity distribution of the signal, determined by the interference between the hyperfine components of 85Rb and 87Rb, was dependent on Δα, Δθ, and the number density of atoms. The theoretical prediction1 for the Voigt-effect line profiles for various Δα and Δθ agreed with the experimental result. The minimum detectable density of Rb atoms was limited by statistical fluctuations of photon counts.
Nonlinear magneto-optical resonances on the hyperfine transitions belonging to the
D2 line of rubidium were changed from bright to dark resonances by changing the laser power density of the single exciting laser field or by changing the vapor temperature in the cell. In one set of experiments atoms were excited by linearly polarized light from an extended cavity diode laser with polarization vector perpendicular to the light's propagation direction and magnetic field, and laser-induced fluorescence was observed along the direction of the magnetic field, which was scanned. A low-contrast bright resonance was observed at low laser power densities when the laser was tuned to the ${F}_{g}=2\ensuremath{\rightarrow}{F}_{e}=3$ transition of
87Rb and near to the ${F}_{g}=3\ensuremath{\rightarrow}{F}_{e}=4$ transition of
85Rb. The bright resonance became dark as the laser power density was increased above 0.6 mW/cm
2 or 0.8 mW/cm
2, respectively. When the ${F}_{g}=2\ensuremath{\rightarrow}{F}_{e}=3$ transition of
87Rb was excited with circularly polarized light in a second set of experiments, a bright resonance was observed, which became dark when the temperature was increased to around 50${}^{\phantom{\rule{0.16em}{0ex}}\ensuremath{\circ}}$C. The experimental observations at room temperature could be reproduced with good agreement by calculations based on a theoretical model, although the theoretical model was not able to describe measurements at elevated temperatures, where reabsorption was thought to play a decisive role. The model was derived from the optical Bloch equations and included all nearby hyperfine components, averaging over the Doppler profile, mixing of magnetic sublevels in the external magnetic field, and a treatment of the coherence properties of the exciting radiation field.
Various efforts have been made to determine the polarization state of evanescent waves in different structures. The present study shows the reliability of magneto-optical spectroscopy of D1 and D2 lines of rubidium metal and polarization-dependent transitions to investigate and trace the changes in the polarization state of evanescent fields during total internal reflection over different angles. For this purpose, we design and fabricate atomic- evanescent Rb vapor cells and examine the effect of polarization changes of evanescent waves, depending on the propagation direction of evanescent waves in anisotropic rubidium vapor media under 88 mT external magnetic field by different configurations theoretically and experimentally. The results confirm the dependency of allowed [Formula: see text] transitions on the magneto optical configuration as a tool to determine changes in the polarization of evanescent waves in more complicated wave states in anisotropic media.
A general equation is constructed for the magneto-optical spectra of the forward-scattered light observed through an analyzer when an absorption cell in a homogeneous magnetic field is illuminated by a linearly polarized laser beam at an arbitrary angle to the field direction. The Faraday effect and the Voigt effect are deduced as special solutions of this general equation. For the case of Voigt geometry, \ensuremath{\pi}-polarized light whose plane of polarization is parallel to the applied magnetic field gives a simple absorption profile. \ensuremath{\sigma}-polarized light oscillating perpendicularly to the static magnetic field contains an interference term between right and left circularly polarized light as well as absorption terms. For these eigenwaves (\ensuremath{\pi},\ensuremath{\sigma}) for the Voigt effect, the spectral shapes are independent of the angle of the analyzer, only their intensity is modified by the angle. For the general case, experimental results for cesium vapor and theoretical spectra show good agreement.
We have studied experimentally and theoretically Hanle EIA on the closed Fg = 3 goes to Fe = 4 D2 transition of 85Rb. Atoms were excited by the laser light with different polarization, from linear to circular. Results of the theoretical calculations of the laser transmission, based on optical Bloch equations for density matrix elements for the same atomic system, show important effects of magnetic field transverse to the laser light. We were not able to control transverse magnetic field in the experiment but the theoretical results are still applicable to our experimental data due the presence of laboratory stray magnetic field in the vicinity of the Rb cell, occurring because of imperfect magnetic shielding.
Large Faraday rotations can be generated by circular birefringence of atomic samples in an axial magnetic field in the vicinity of atomic resonance lines. More generally, magneto-optical effects in atomic samples include circular dichroism in addition to birefringence, resulting in a modification of the ellipticity as well as the polarization alignment. Usually such effects are investigated for homogeneous linear polarizations, but the mechanisms apply also to polarization structures such as vector vortices. We investigate the effect of optical activity of a rubidium vapor in the hyperfine Paschen–Back regime along the D2 line, for the example of azimuthally polarized input light. We show that for low atomic densities, circular birefringence dominates over dichroism, and azimuthal polarization is rotated toward radial polarization. The rotation angle increases with increasing optical densities. At high vapor temperatures, dichroism becomes more and more relevant, leading to intricate variations of both alignment and ellipticity. Our results shine new light on the interplay between different magneto-optic effects at strong magnetic fields. Their highly sensitive response to detuning may find applications in spectroscopy and quantum sensing.