The two-photon transitions in thermal gas of ⁸⁷Rb are obtained using an Er: fiber laser frequency comb.

The signal-to-noise of the transition spectrum is improved by equally dividing the laser powers.

The polarization dependence of two photon transition based on optical frequency comb has been studied in theory and experiments.

The two photon transition can be enhanced or degrade by an appropriate choice of polarization.

The study offers a useful technique in the fields of precision spectroscopy.