Study of the photon echo by polarization beat spectroscopy

Photon echo in polarization beat spectroscopy was studied for a V-type three-level system. When the pump beams have broadband linewidth, one-photon four wave mixing is related to the three-pulse stimulated photon echo with relative time delay τ>0. The result coincides with the case when the beams have narrow linewidth, τ<0. This technique can achieve Doppler-free precision in the measurement of the energy level splitting between two excited states.