Comparison of field shifts in an atomic clock based on the effect of coherent population trapping in 87Rb atoms under modulation of laser pump current at frequencies of 3.4 and 6.8 GHz

Experimental parameters of the resonance of coherent population trapping (CTP) on D1 line in ⁸⁷Rb and light shifts are compared under modulation of the laser pump current at frequencies of 3.4 and 6.8 GHz. Reproducibility of the parameters of a laser with a vertical cavity needed for long-term stability of an atomic clock is considered. The instabilities of atomic CPT-clock obtained for 1 s are 1.2 × 10^–11 and 3 × 10^–12 for frequencies of 3.4 GHz and 6.8 GHz, respectively.