Full hyperfine frequency modulation in the implementation of coherent population trapping atomic clocks

Abstract

We compared full band modulation (FBM), in which the laser is modulated at the full ground-state hyperfine splitting frequency, and half band modulation (HBM) (widely used in research) in the implementation of coherent population trapping (CPT) atomic clock. Using FBM we can adjust the intensity ratio of the two laser fields to increase the CPT signal contrast as well as reduce the line width. Theoretical and experimental results also indicate that the use of FBM can significantly reduce light shift. Therefore, we can easily improve the stability of CPT clocks by replacing HBM with FBM.