Dependence of the shapes of nonzero-field level-crossing signals in rubidium atoms on the laser frequency and power density

Abstract

We studied magneto-optical resonances caused by excited-state level crossings in a nonzero magnetic field. Experimental measurements were performed on the transitions of the D 2 line of rubidium. These measured signals were described by a theoretical model that takes into account all neighboring hyperfine transitions, the mixing of magnetic sublevels in an external magnetic field, the coherence properties of the exciting laser radiation, and the Doppler effect. Good agreement between the experimental measurements and the theoretical model could be achieved over a wide range of laser power densities. We further showed that the contrasts of the level-crossing peaks can be sensitive to changes in the frequency of the exciting laser radiation as small as several tens of megahertz when the hyperfine splitting of the exciting state is larger than the Doppler broadening.

Relaxation mechanisms affecting magneto-optical resonances in an extremely thin cell: Experiment and theory for the cesiumD1line

“…By comparing the results of the theoretical models, one can see that the theoretical curve of the single region model agrees well with experimental measurements for cases were the laser power is low, but starts to deviate significantly in cases where the laser power is higher. This behavior has already been observed experimentally numerous times in ordinary cells ( [13,14,26,28]) where theoretical calculations start to deviate from experimental data at laser powers where absorption at the center of the laser beam has reached saturation. In the case of the ETC even the lowest laser power used is noticeably higher than laser powers used in ordinary cell experiments, but, because of the strong relaxation by collisions with cell walls, noticeable deviations from experimental results start at only very high laser power densities.…”

Coherent and incoherent processes responsible for various characteristics of nonlinear magneto-optical signals in rubidium atoms

“…A full numerical integration over both (Gaussian and Maxwellian) distributions would be too time consuming, while our approach has proven to describe experimental results with high accuracy in previous studies e.g. [18,34].…”

“…Our study focuses on these broader structures, which are interesting in themselves and also for some practical applications at higher magnetic field values, like optical isolators [17]. Using a theoretical model that has been developed over time and mostly was used to describe the narrow magneto-optical resonances but can reproduce the magneto-optical signals with high accuracy over a large range of magnetic field values [18], we investigated the peculiar shape and sign (bright or dark) of these structures, as well as the physical processes that give rise to them.…”

Angular momentum alignment-to-orientation conversion in the ground state of Rb atoms at room temperature

“…The full Hamiltonian can be written as Ĥ = Ĥ0 + ĤB + V , where Ĥ0 is unperturbed system Hamiltonian, ĤB describes the interaction with the external magnetic field, and V = − d • E(t) is the operator which describes atom -laser field interaction in the electric dipole approximation. The operator includes electric field of excitation light E(t) and an electric dipole operator d. The general OBEs (1) can be transformed into explicit rate equations for the Zeeman coherences within the ground (ρ gigj ) and excited (ρ eiej ) states by applying the rotating-wave approximation, averaging over and decorrelating from the stochastic phases of laser radiation, and adiabatically eliminating the optical coherences [27][28][29][30]:…”