Observing the optical frequency comb in the blue fluorescence of rubidium vapor
Filipe A Lira, Marco Polo Moreno de Souza, S. S. Vianna
Abstract We report on the direct observation of the frequency comb printed in the blue fluorescence excitation spectrum of rubidium vapor induced by the combined action of an ultrashort pulse train and a cw diode laser. Each laser drives one step of the 5S—5P—5D two-photon transition in a copropagating configuration and the excitation spectrum is obtained while the cw-laser frequency is scanned over the rubidium D 2 lines. Measurements of the fluorescence as a function of the diode intensity and atomic density allow us to investigate how the effect of power broadening and absorption of the diode laser blur the excitation process. The experimental results and the printing process of the comb on the Doppler profile are described well by numerical integration of the Bloch equations for a cascade three-level system.
Journal of Physics B Atomic Molecular and Optical Physics•Oct 23, 2015•1 citation