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Journal of the Optical Society of America B

Rubidium chip-scale atomic clock with improved long-term stability through light intensity optimization and compensation for laser frequency detuning

Yaolin Zhang, Wanpeng Yang, Shuangyou Zhang, Jianye Zhao

Published Jul 22, 2016• 46 citations

Abstract

We demonstrate the implementation of a Rb87 chip-scale atomic clock (CSAC) that has improved long-term stability. A simple method of reducing the frequency drift in the CSAC is proposed. As well as the well-known effect of light intensity on the clock frequency, our analysis shows that the frequency drift that is due to laser frequency detuning (LFD) variation originates from asymmetry in the coherent laser fields, and thus, we propose to actively compensate the clock frequency by using variations in the light intensity and LFD. We performed experiments to obtain precise clock frequency sensitivities to the light intensity and LFD, and the frequency drift was reduced from 7.1×10−11/day to 6.9×10−13/day with the frequency compensation method. Additionally, the CSAC with an optimized configuration of light intensity and microwave power showed evident long-term frequency stability improvement, from 8.9×10−11 to 8.7×10−12 at 105 s. Therefore, our method is useful in reducing the frequency drift of CSACs and could be potentially used in applications that require moderate long-term stability of sub-1×10−11.

DOI: 10.1364/josab.33.001756

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Rb vapor cell with differential detection. Elliptically polarized light is used to interact with alkali atoms to generate coherent population trapping (CPT) resonance, and the CPT signal is obtained by detecting the Faraday rotation effect with differential detection technology. To move closer to an actual chip-scale atomic clock (CSAC), we reduce the volume of the experimental apparatus and use a divergent laser beam to interact with the atoms. We obtain the short-term frequency stability of the CSAC based on the differential detection scheme and compare it with that of a conventional CSAC. The results show that the frequency stability is more than two times better than that of current commercial CSAC devices with the same power consumption and volume.