Transient dynamics of nonlinear magneto-optical rotation in the presence of a transverse magnetic field

Nonlinear magneto-optical rotation is studied under nonequilibrium conditions. The polarization rotation of linearly polarized light, traversing a room-temperature rubidium vapor, is observed versus the time-dependent (swept) longitudinal magnetic field in the presence of static transverse magnetic fields. Presence of the transverse fields modifies the character of the observed signals. In particular, for the weaker fields, the longitudinal-field sweep leads to a two-frequency oscillation of the polarization rotation while crossing zero. Unlike the steady state, this was observed independent of the transverse-field direction. For the stronger transverse fields, the oscillations deteriorate eventually reaching a situation when a nonoscillating dynamic signal, with a distinct minimum close to the zero longitudinal field, is observed. The presented experimental results are supported with theoretical analysis based on the density-matrix formalism. The analysis confirms all the features of experimental results while providing an intuitive explanation of the observed behavior based on angular-momentum probability surfaces used for density-matrix visualization