Lin || lin coherent population trapping and its application for vapor-cell-atomic-clocks

The authors presented investigations on the application of CPT effect as alternative to the traditional optical microwave double resonance in small atomic clocks. An important factor which may limit the performances of CPT-based atomic clocks is the reduced signal contrast as compared to optical pumping. To overcome this limit, several excitation schemes have been proposed in the last years. Particularly, a significant enhancement of the CPT contrast can be obtained when co-propagating laser waves with parallel linear polarization (lin | | lin CPT) are resonant with the excited state F_e=l of alkali atoms.