  Two-photon resonance transition technology has been proven to have a wide
range of applications,it's limited by the available wavelength of commercial
lasers.The application of optical comb technology with direct two-photon
transition (DTPT) will not be restricted by cw lasers.This article will further
theoretically analyze the dynamics effects of the DTPT process driven by
optical frequency combs. In a three-level atomic system, the population of
particles and the amount of momentum transfer on atoms are increased compared
to that of the DTPT-free process. The 17% of population increasement in 6-level
system of cesium atoms has verified that DTPT process has a robust enhancement
on the effect of momentum transfer. It can be used to excite the DTPTs of
rubidium and cesium simultaneously with the same mode-locked laser. And this
technology has potential applications in cooling different atoms to obtain
polar cold molecules, as well as high-precision spectroscopy measurement.
