Simultaneous Observation of Nonlinear Magneto-Optical Rotation in the Temporal and Spectral Domains with an Electro-Optic Frequency Comb

We simultaneously observe the Larmor precession of rubidium atoms in both the temporal and spectral domains using an electro-optically generated frequency comb. Rubidium vapor is optically pumped on the F = 2 -> F' = 1 hyperfine transition of the Rb-87 D-1 manifold, while its response is observed with a frequency comb that spans 8 GHz of the spectrum with a temporal resolution of 9.78 mu s. The frequency comb modes experience optical rotation by interacting with the F = 2 -> F' = 1, 2 transitions. The spectral and temporal resolution of the comb allows us to observe that there are two separate channels for polarized atoms to appear in the probe beam: one pathway where atoms travel directly from the pump to the probe region, and a secondary pathway that involves interaction of the polarized atoms with the cell walls. The unique features of the comb allow a direct estimate of the relative density of polarized atoms in the vapor cell, as well as a measurement of the quality of the antirelaxation coating on the cell walls. We show that rotation measurements with the comb approach the limits set by photon shot noise.