Atomic coherence effects on optically pumped cesium atoms in static magnetic field

The population difference between ground states F = 4 and F = 3 is calculated for Cs atoms pumped on the D2 line by a resonant laser beam. The pumping efficiency for Cs atoms in a static magnetic field on two hyperfine transitions (6S1/2F = 4 → 6P3/2F′ = 3 and F′ = 4) is calculated for various pump laser intensities. The population difference as a function of the static magnetic field exhibits a dip centered at the zero magnetic field, which corresponds well with the Zeeman coherence between sublevels of the F = 4 state. The full-width at half-maximum (FWHM) of the dip as a function of the pump laser intensity shows abnormal power broadening behavior that differs for different hyperfine transitions. We present experimental results that agree with the theoretical calculations.