New method of wavelength stabilisation in CPT atomic clocks

We propose a novel way of radiation wavelength stabilisation in atomic clocks based on coherent population trapping (CPT). It uses quadrature-phase component of the CPT signal within the CPT resonance feedback loop and automatic wavelength locking of radiation from a VCSEL to the atomic absorption line. We demonstrate advantages and limitations of the new method applied to vapour cells with buffer gas or anti-relaxation coating. Also provided are measurements of short- and long-term stability of a CPT-based atomic clock using the proposed method with various optical cells. Discussed are the prospects of this method in chip-scale atomic clocks.

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