Dual-interrogation method for suppressing light shift in Rb 778 nm two-photon transition optical frequency standard

In this study, a dual-interrogation (DI) method was used to suppress the light shift in the Rb 778 nm 5S →5D two-photon transition optical frequency standard (2hν-OFS). The approach used an auxiliary system to calibrate the light shift of the primary system in real time to mitigate the absolute light shift and suppress the sensitivity of the system to the light power. Results show that after using the DI method, the absolute light shift and light-power sensitivity of the system were reduced by a factor of 10. The proposed method will improve the accuracy of the Rb 778 nm 2hν-OFS and increase the mid- and long-term stability. The method can also be applied to other vapor-cell atomic frequency standards that experience light shifts.