Abstract: The （Coherent Population Trapping）CPT atomic clock is a compact atomic frequency standard based on the principle of coherent population trapping, which does not require a microwave resonant cavity, which is beneficial for reducing the volume and power consumption of physical systems. In order to explore polarization pumping methods suitable for micro CPT atomic clocks, three pumping methods were selected, including single circularly polarized light, parallel linearly polarized light, and elliptical polarized light, under the limitations of physical system volume, power consumption, and complexity. Based on the 6mm × 6mm × 6mm micro ⁸⁷Rb cell, desktop systems were constructed to measure the linewidth and SNR of CPT resonance signals using three methods. The results show that micro CPT atomic clocks are more suitable for using elliptically polarized light method.

Key words: Atomic clock, Coherent Population Trapping(CPT), Optical pumping, Differential detection