Polarization spectroscopy of the 5S1/2–5D5/2 two-photon transition in rubidium

We describe a one-color, two-photon polarization spectroscopy experiment on the 5S1/2–5D5/2 transition in rubidium, suitable for implementation in an advanced undergraduate instructional laboratory. The proposed laboratory module synergistically combines polarization spectroscopy with established fluorescence detection at a wavelength different from the excitation wavelength. The curriculum provided in this paper allows students to compare experimental results with predicted theoretical lineshapes and to study the intensity dependence of the two-photon transition. The module also provides a springboard that enables instructors to expand the curriculum to incorporate additional measurements and theoretical analyses. These activities include collecting spectra on additional transitions, measuring the temperature dependence of the spectral amplitudes, or using the dispersive polarization spectra to frequency stabilize a laser without modulation.