Nonlinear laser spectroscopy and magneto-optics

Abstract

An experiment on nonlinear laser spectroscopy and magneto-optics at the Advanced Undergraduate Laboratory at Berkeley is described. The experiment consists of three parts. In the first part, students learn to operate a diode laser system and characterize its performance using a Fabry–Perot spectrum analyzer. In the second part, Doppler-broadened laser-induced fluorescence and Doppler-free saturated absorption spectra of the rubidium ${\mathrm{D}}_{\mathrm{2}}$ line (780 nm) are recorded and analyzed. Finally, in the third part of the experiment, which we describe in greater detail, the near-resonant magneto-optical rotation is investigated. Nonlinear light-atom interaction leads to spectacular manifestations of the resonant Faraday effect—polarization plane rotation in a magnetic field applied along the direction of light propagation radically different from the linear case. In particular, narrow (∼30 Hz) effective line widths are observed in this experiment corresponding to a rotation enhancement by some seven orders of magnitude compared to the linear Faraday rotation.