Direct frequency-comb spectroscopy is used to probe the absolute frequencies of $6S_{ 1/2}$-$8S_{ 1/2}$ two-photon transitions of atomic cesium in hot vapor environment. By utilizing the coherent control method of temporally splitting the laser spectrum above and below the two-photon resonance frequency, Doppler-free absorption is built in two spatially distinct locations and imaged for high-precision spectroscopy. Theoretical analysis finds that these transition lines are measured with uncertainty below $5\times10^{ -10}$, mainly contributed from laser-induced AC Stark shift.
Categories: physics.atom-ph