SELECTION-RULES AND LINE STRENGTHS OF ZEEMAN-SPLIT DARK RESONANCES

In a weak magnetic field coherent dark resonances in cesium vapor are split into up to 15 resolved components, depending on field direction and laser polarizations. We find that the selection rules are differen t for vapor cells with and without buffer gas due to a change in multi polarity of the two-photon coupling. At low laser intensities or suffi ciently high buffer-gas pressure optical pumping between different dar k resonances can be neglected so that a simple model allows one to cal culate the relative line strengths, giving complete agreement with the experimental spectra.