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Nonlinear Faraday rotation with counter-propagating light beams was investigated in a rubidium vapor cell. Observations across all hyperfine and crossover resonances of the D-2 line of Rb-87 atoms were made. Additionally, rotation spectra as a function of pump and probe intensity, pump polarization and external magnetic field strength were studied. The investigations were performed in a regime where the pump beam power was sufficiently low relative to the probe power to avoid polarization rotation due to pump-induced anisotropy. Our results are analyzed in the context of Bennett structures and coherent optical processes. (c) 2007 Elsevier B.V. All rights reserved.

We report experiments demonstrating the effects of optical pumping, coherent population trapping and light polarisation on electromagnetically induced transparency in simple Λ-type configurations of rubidium 87 where the relevant coherences are within the three Zeeman substates of the F=1 component of the 5S1/2 ground level. Inversionless gain is also demonstrated. The sample is cooled to below 1 mK in a magneto-optic trap operating without repumping light to give a working population of F=1 ground state atoms. The experimental results are compared with master equation computations of a closed seven-substate-model representing the ground level (F=1) and the excited levels F′=0 and F′=1.

We have observed electromagnetically induced transparency (EIT) in laser-cooled rubidium in a magneto-optical trap (MOT). Λ-type configurations of hyperfine levels of the D2 line were studied, as well as a system utilising degenerate Zeeman sublevels of the ground state. V-type signals were also seen. The perturbing effects of the MOT were found to be small and the results agree well with standard EIT theory for homogeneously-broadened samples.

The collisional relaxation of photon echoes generated on the 6S built1 2 - 7P built3 2 (455 nm) transition in caesium has been observed and measured as a function of perturber pressure. Values for the collision cross-sections have been obtained using helium, neon, argon and krypton as perturbers. There is good agreement between these results and those obtained from high resolution measurements of pressure-broadened line profiles. The echoes were observed using the polarization rotation technique and all the measurements were made at perturber pressures below 0.5 torr.

In a recent paper Mandel and Wolf use a two-parameter susceptibility function to derive an expression for the spectral density of the induced polarisation in a linear fluctuating medium. Their treatment is restricted to time-stationary fields and media. This paper presents (i) a generalisation of their treatment to include the case of locally stationary fields which is of interest in the study of resonance fluorescence spectroscopy; (ii) a demonstration of the way in which the spectral density of the fluctuations and the atomic spectral response function are combined in the two-parameter description of the susceptibility of an atomic vapour.

We report tri-level echo measurements of collision cross-sections and broadening constants for the electric-dipole-forbidden fine-structure transition in caesium (7p 1 2 - 7P 3 2 ) perturbed by low pressures (